633
A third assessment of global
marine fisheries discards
ISSN 2070-7010
FAO
FISHERIES AND
AQUACULTURE
TECHNICAL
PAPER
Cover photograph: © Petri Suuronen
A third assessment of global
marine fisheries discards
FAO
FISHERIES AND
AQUACULTURE
TECHNICAL
PAPER
633
by
Maria Amparo Pérez Roda
FAO Consultant
Rome, Italy
Eric Gilman
FAO Consultant
Honolulu, USA
Tim Huntington
FAO Consultant
Lymington, United Kingdom
Steven J. Kennelly
FAO Consultant
Cronulla, Australia
Petri Suuronen
Head of Research Program
Natural Resources Institute Finland (Luke)
Helsinki, Finland
Milani Chaloupka
Ecological Modelling Services Pty Ltd and
Marine Spatial Ecology Lab, School of Biological Sciences, University of Queensland
St Lucia, Australia
and
Paul A. H. Medley
Independent Fisheries Scientist
York, United Kingdom
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, 2019
Required citation
Pérez Roda, M.A. (ed.), Gilman, E., Huntington, T., Kennelly, S.J., Suuronen, P., Chaloupka, M. and Medley, P.
2019. A third assessment of global marine fisheries discards. FAO Fisheries and Aquaculture Technical Paper
No. 633. Rome, FAO. 78 pp.
Licence: CC BY-NC-SA 3.0 IGO.
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iii
Preparation of this document
This Technical Paper, a third assessment of global marine fisheries discards, was
prepared by Fishing Operations and Technology Branch, Fisheries and Aquaculture
Policy and Resources Division, FAO Fisheries and Aquaculture Department. It is
a part of the regular programme activities and contributes to the fulfilment of the
Department’s mandate by collecting, analyzing and disseminating information on the
sector, in particular on global bycatch and discards, and different types of fishinginduced mortality from marine capture fisheries.
Sections of this document have been compiled by FAO staff and selected invited
experts as indicated by the authorship. Petri Suuronen (former FAO Fishery Industry
Officer, currently Head of research program at Natural Resources Institute Finland)
was responsible for the general coordination while Amparo Pérez for technical editing
of this document with the valuable assistance from Prof Pingguo He.
iv
Abstract
This third update of FAO’s global discard estimate adopted the ‘fishery-by-fishery’
approach employed in the second discards assessment published in 2005. The update
included publicly available discard data in the last 20 years to establish a baseline of
a time series of global marine fisheries discards. This is essential for monitoring the
status and trends of discard management, which is the first step of the ecosystem
approach to fisheries management cycle. In addition, the study developed a new
fisheries data table incorporating landings data from the FAO Global Capture
Production dataset (FishStat J) from 2010 to 2014, which allocated the landings to
over 2 000 fisheries worldwide.
The current study estimated that the annual discards from global marine capture
fisheries between 2010 and 2014 was 9.1 million tonnes (95% CI: 6.7 – 16.1 million
tonnes). About 46 percent (4.2 million tonnes) of total annual discards were from
bottom trawls that included otter trawls, shrimp trawls, pair bottom trawls, twin
otter trawls and beam trawls.
The study included a synthesis of estimates of bycatch and discards of
endangered, threatened and protected (ETP) species. Substantial advances have been
made in quantifying fisheries interactions with such species so as to make informed
decisions on their protection. However, many challenges remain, especially for
small-scale fisheries. The development of standardized data collection techniques,
risk-based sampling and sharing of data across agencies and regions will help to
identify management priorities and allow implementation and enforcement of
mitigation measures.
A review of previous research showed that discard practices were often related
to a wide range of factors, so it is difficult to assess the effectiveness of fishery
management actions on the amount and practice of discards. Many regulations are
inconsistently enforced, and their implementation is often less strict than intended.
Piecemeal approaches in many bycatch and discards management measures can
result in unintended cross-taxa conflicts, where regulations designed to reduce
bycatch and/or discards of one species or species group may increase bycatch and/
or discards of another. Examination of approaches to accounting for and mitigating
against pre-catch, post-capture and ghost fishing mortalities demonstrates that
an understanding of the relative importance of factors affecting indirect fishing
mortality is necessary for estimating total fishing-induced mortality and for
designing and implementing mitigation measures.
v
Contents
Preparation of this document
Abstract
Acknowledgements
Abbreviations and acronyms
Executive summary
Background
iii
iv
viii
ix
xi
xiv
PART I – ESTIMATE OF GLOBAL MARINE FISHERIES DISCARDS
1
1. Introduction
1
1.1. Scope, definitions and terminology
2. Methods
1
3
2.1. Development of a fisheries-based discard dataset
3
2.2. Analytical methods for the processing of the
discard dataset
7
2.2.1. Estimate gear-specific mean discard rates
7
2.2.2. Dataset processing
7
2.3. Assumptions and issues related to the method
3. Results
8
10
3.1. Global discards
10
3.2. Discards by gear type
10
3.3. Discards by ocean region
10
3.4. Discards by target species
10
4. Discussion
4.1. Global quantity of discards
16
16
4.1.1. Estimates by gear type
16
4.1.2. Discards by fishing area
17
4.2. Strengths and limits of the current study
19
4.3. Other issues
21
4.4. Future global discard assessments – lessons learned
22
4.5. Conclusions
24
PART II – RELATED ISSUES
42
5. Bycatch and discards of endangered, threatened and
protected species
25
5.1. Estimates of ETP species bycatch
25
5.2. Mitigation of ETP bycatch mortality
27
5.3. Conclusions
27
vi
6. Measures to manage bycatch and reduce discards
28
6.1. Spatial and temporal measures (area and time restrictions)
28
6.2. Bycatch quotas (and limits)
28
6.3. Effort regulation
29
6.4. No-discard regimes (discard bans or landing obligations)
29
6.5. Selective fishing
31
6.6. Conclusions
32
7. Mortality due to pre-catch, discards and ghost fishing
33
7.1. Pre-catch mortality
33
7.2. Discard mortality
34
7.3. Ghost fishing mortality
35
7.4. Other components of indirect mortality
35
7.5. Conclusions
36
PART III - CONCLUSIONS
37
8. General Conclusions
37
ANNEXES
39
A. Method
39
A.1– The estimate of average global quantity of discard
39
A.2– Codes used in the data tables and dataset:
(gear, area and target)
40
B. Results
41
C. Progress on compliance with the Code of Conduct for
Responsible Fisheries regarding bycatch and discards
44
D. DiscardLess and other efforts in European Union to
mitigate discards
47
REFERENCES
49
vii
Tables
Table 1
Table 2
Table B.1
Table B.2
Table B.3
Data tables (Excel spreadsheets) defined for
estimating discards
Estimated discard level (t) and discard rates
(t discards / t catch) by target species
Posterior mean discard rates, 95% credible intervals
and sample sizes, metric tonnes of discards per metric
tonnes of total catch, for 25 gear categories
Estimates of mean discards levels (t) and 95% credible
intervals by gear type
Discard levels (t) and rates (t discards / t catch) by
FAO Major Fishing Area
6
15
41
42
43
Figures
Figure 1
Nine-step process to develop a fisheries-based discard
dataset
Mean discard rates and 95% credible intervals for
25 gear types
Mean discard levels (thousand tonnes) and 95%
confidence intervals by gear type
Global fisheries discard levels by region
Distribution of global fisheries discard rates (top) and
total discards (bottom) by FAO Major Fishing Area
Figure 2
Figure 3
Figure 4
Figure 5
Annexes
Figure C.1
Percentage of responses from Member countries to
questions of the section on “management of bycatch
and discards”
Percentage of responses from Member countries to
questions of the section on “Most effective measures
taken by Government to promote the improved use of
bycatch in fish processing”
Percentage of responses from Member countries to
questions of the section on “Summary information
relating to the status of national IPOA-Sharks
implementation”
Percentage of responses from Member countries to
questions of the section on “IPOA Seabirds: Mitigation
measures applied to longline fisheries”
Figure C.2
Figure C.3
Figure C.4
4
11
12
13
14
45
45
46
46
Boxes
Box 1
Box 2
Slipping of fish from a purse seine
The Landing Obligation in European Union fisheries
18
30
viii
Acknowledgements
In addition to the authors listed, this report could not have been completed without
assistances of many colleagues who made valuable contributions to collection and
analysis of data and preparation of the document. In particular, thanks are given
to the members of the data collection group: Dr Mike Bergh and Kobus Leach
of OLSPS, Fiona Nimmo and Rod Cappell of Poseidon, Lee Benaka of NOAA,
Suzuette Soomai, Olaya Mahtate and Pablo Obregon. A large number of fisheries
management authorities and regional fisheries management organizations provided
data and information and are also gratefully acknowledged. While names of those who
actually provided data and information from these institutions are not listed here, their
contribution is fully acknowledged. Furthermore, Dr Charles A. Gray of WildFish
Research helped in the preparation of Chapter 5 - Bycatch and discards of endangered,
threatened and protected species. Prof Steve Cadrin of University of Massachusetts
Dartmouth and Dr Mark Dickey-Collas of ICES provided valuable scientific reviews.
Prof Pingguo He of University of Massachusetts Dartmouth provided final revisions
and edits of the entire document.
ix
Abbreviations and acronyms
AIDCP
ALDFG
APFIC
BRD
CCAMLR
CECAF
CFP
CI
CNMI
CO
COFI
CSV
DCF
DID
DTU
EEZ
EI
EM
ETP
EU
FAO
FFA
FID
FishStat
FRDC
GE
HDI
ICES
ID
IPOA
ISSCAAP
ITQ
IUCN
IUU
LED
LFD
LME
LO
MA
MCRS
MSC
N
NA
NGO
Agreement on the International Dolphin Conservation Program
abandoned, lost or otherwise discarded fishing gear
Asia-Pacific Fishery Commission
bycatch reduction device
Commission for the Conservation of Antarctic Marine Living
Resources
Committee for the Eastern Central Atlantic Fisheries
Common Fisheries Policy (EU)
confidence interval
Commonwealth of the Northern Mariana Islands
country-based estimates
Committee on Fisheries (FAO)
comma-separated value
Data Collection Framework (EU)
discard rate identifier (DiscardRates data table)
Technical University of Denmark
Exclusive Economic Zone
empirical estimates
electronic monitoring
endangered, threatened, protected
European Union
Food and Agriculture Organization of the United Nations
Pacific Islands Forum Fisheries Agency
fishery identifier (FisheryTable data table)
FAO Fisheries and Aquaculture Statistics
Australian Fisheries and Development Corporation
global gear-specific estimates
highest posterior density interval
International Council for the Exploration of the Sea
identifier
International Plan of Action
International Standard Statistical Classification of Aquatic Animals
and Plants
individual transferable quota
International Union for Conservation of Nature
illegal, unreported, unregulated
light-emitting diode
length frequency distributions
Large Marine Ecosystem
Landing Obligation
management authority
Minimum Conservation Reference Size
Marine Stewardship Council
number of records
not applicable
non-governmental organization
x
NOAA
NPOA
OECD
RFMO
SA
SAR
SAUP
SDG
SPC
TAC
UN
USA
VBA
WGMIXFISH
National Oceanic and Atmospheric Administration
National Plan of Action
Organization for Economic Cooperation and Development
regional fisheries management organization
scientific authority
South Asia, excluding India
Sea Around Us Project
Sustainable Development Goal
The Pacific Community
total allowable catch
United Nations
United States of America
visual basic for applications
ICES Working Group on Mixed Fisheries Advice
xi
Executive summary
Bycatch and discards threat sustainable fisheries by inflicting unnecessary mortalities.
Sound management of bycatch and reduction of discards in capture fisheries will lead
to healthy ecosystems and sustainable fisheries, contributing to long-term global food
security, and alleviation of poverty, especially for coastal communities and Small Island
Developing States which heavily depend on fish as food, fisheries as the main source of
employment, and fishing as a way of life. Accurate and timely assessment of bycatch
and discards provide necessary data for making sound management decisions and
effective mitigation measures
This report includes three parts. Part I is an estimate of annual discards for the
period 2010-2014 by marine commercial fisheries. Part II includes an evaluation and
discussion of bycatch and discards of endangered, threatened and protected species,
providing an updated overview of this specific dimension of the bycatch and discard
issue. Part II also includes a review of current measures for managing bycatch and
reduction of discards, as well as a discussion of other sources of fishing mortality,
such as pre-catch loss, discard mortality and ghost fishing mortality. Part III is the
conclusion of the whole report.
PART I – METHODOLOGY FOR ESTIMATING GLOBAL MARINE FISHERIES
DISCARDS
The estimate of global discards used a similar approach to that of Kelleher (2005) in
the second FAO global discard estimate, which was based on the assumption that the
amount or rate of discards was a function of a particular fishery. A fishery is defined as
a country fleet fishing in a defined area, using the same gear type and targeting the same
species group. However, the method has been greatly refined to make it more robust
and replicable by integrated data set development and transparent data analysis. The
method to calculate global discards included three types of estimates that were applied
in the following order:
i. Country-based estimates: country-level discard rates from the literature
were applied to all fisheries of countries which either had a discard ban or
which were believed to have extremely low discard rates.
ii. Empirical estimates: Where available, fishery-specific discard rates were
applied to their respective fisheries. Such data was compiled from scientific
publications, national or regional fisheries reports, grey literature, and
correspondences with fisheries experts.
iii. Global gear-specific estimates: Global gear-specific mean discard rates and
margin of error were estimated for 25 gear categories and applied to fisheries
with no country-based or empirical discard rate estimates. Global gearspecific discard rates were estimated based on the empirical estimates from
method ii.
The scope of the current assessment is similar to the 2005 study which included
commercial marine and estuarine fisheries only. This assessment did not analyse
which species were discarded; however, it is understood that species composition is an
important issue that should be covered in future assessments. Knowing which species
have been discarded and why they are discarded is critical for improved food security,
better stock assessments, and sound fishery management.
xii
THE ESTIMATES OF FISHERIES DISCARDS
The magnitude of annual discards in global marine capture fisheries was estimated
to be 9.1 million tonnes (95% CI: 6.7 – 16.1 million), which represent 10.8%
(10.1% –11.5%) of the annual average catch of 2010-2014. These estimates were based
on a sample size of 1 854 fishery records (75.5 million tonnes of landings).
The gear type which contributed the most to annual levels of discards was bottom
trawl with 4.2 million tonnes. Bottom trawl included otter trawls, shrimp trawls, pair
bottom trawls, twin otter trawls and beam trawls.
From a regional perspective, the northwest Pacific (FAO Fishing Area 61) and
northeast Atlantic (FAO Area 27) accounted for a combined 39% (3.6 million tonnes)
of discards. Although the northwestern Pacific Ocean (FAO Area 61) had the highest
discards, contributing more than 22% of global discards, it had the fifth lowest mean
discard rate. The southwest Atlantic (FAO Area 41) had the highest mean discard rate,
but it only contributed 7% of the total annual global discards.
Fisheries targeting tunas and other pelagic species had the lowest discard rates,
while fisheries targeting crustaceans had the highest discard rates. Fisheries targeting
demersal fishes produced the highest volumes of discards and fisheries targeting
molluscs (excluding cephalopods) produced the lowest volumes.
PART II – BYCATCH AND DISCARD OF ENDANGERED, THREATENED AND
PROTECTED SPECIES
A review of available data on estimating and mitigating fisheries interactions with
endangered, threatened and protected (ETP) species in marine commercial and artisanal
fisheries was provided. This review includes annual estimates of 1 million seabirds, 8.5
million turtles, 225 000 sea snakes, 650 000 marine mammals and 10 million sharks for
a total of at least around 20 million individuals. Estimates of global discards are highly
uncertain due to: (i) the occurrences of ETP species are often rare and controversial,
and are frequently not recorded or reported; (ii) different protections are afforded
to different ETP species in different countries and fisheries and; (iii) discarding
practices vary greatly across spatio-temporal scales and according to individual fishing
conditions and procedures, which affect discards mortalities.
Several recent initiatives provided information on such interactions, as well as the
development of novel fishing methods and practices that may reduce ETP mortality.
Reducing ETP interactions in many small-scale artisanal fisheries in developing
countries remains a challenge. This will require comprehensive engagement of all
stakeholders in order to facilitate regional and global scale bycatch assessments and
mitigation initiatives.
MANAGING BYCATCH TO REDUCE DISCARDS
There are various types of measures to manage bycatch and to reduce discards,
including modifications to fishing gear or fishing practice, spatial and temporal gear
restrictions, bycatch quota, effort restriction, and discard ban (landing obligation). In
addition, discards can be reduced through improved fleet communication, awarenessraising, training, better utilization, and economic incentives.
The range of policy options to reduce discards is determined both by the biological
characteristics of the fishery and the socio-economic environment. Best practices in
bycatch reduction are illustrated by a number of countries in the Organization for
Economic Cooperation and Development (OECD), while many countries especially
in Asia provide valuable experiences in utilization of bycatch. Increased bycatch
utilization is now widespread in Asia, Africa and America leading to reduced discards.
xiii
PRE-CATCH, DISCARDS AND GHOST FISHING MORTALITIES
The International Guidelines on Bycatch Management and Reduction of Discards
(FAO 2011) included recommendations for member States to identify, quantify and
reduce impacts of mortality from pre-catch losses and ghost fishing and to maximize
discards survival. All these components of mortality share the characteristic of being
largely undetectable in the course of fishing operations. The relative proportions of
these components vary by fishing gear and method, by fishery, and spatially, temporally
and by vessel within a fishery.
Methods to avoid, minimize and offset pre-catch fishing mortality are similar to
those for mitigating capture and discard mortality. These include modifications to
the gear, for example, by using circle instead of J-shaped hooks in pelagic longlines to
reduce the injury to organisms escaped or discarded. While, methods to reduce ghost
fishing mortality can be preventative such as gear marking to identify the owner and
discourage abandonment and discarding of gear, remedial such as using less durable
and biodegradable gear, or mitigative such as removal and recovery of derelict gear.
PART III – CONCLUSION
This report contains two new outcomes on bycatch and discards in global marine
capture fisheries: (i) an annual discard quantity of around 9.1 million t, or 10.1% of
annual catches, and (ii) an annual estimate of fisheries interactions with at least 20
million individuals of endangered, threatened and/or protected species.
It is difficult to quantify the progress made in reducing discards but this report
indicates that in the last 10 years there has been a greater scrutiny of such issues via the
public reporting of discards.
Regarding fisheries interactions with endangered, threatened and/or protected
species (ETP), there is a lack of solid data for many fisheries and for many parts of the
world. Therefore, more effort is needed to better quantify fisheries interactions with
such species, and to implement measures to reduce interactions and mortality in the
future.
This report also summarized other related issues concerning bycatch and discarding,
including (i) current measures to manage bycatch and discards and (ii) challenges
associated with estimating cryptic sources of fishing mortality such as pre-catch,
discards and ghost fishing mortality.
xiv
Background
FAO is required to report periodically to the United Nations General Assembly on
progress with regard to UN resolutions on fisheries. A number of these resolutions
refer to monitoring bycatch and discards, including various provisions in international
fisheries instruments calling for assessment of bycatch hand discards and their impact
on the sustainable use of living marine resources.
In 1994, FAO published the first estimate of global discards in marine fisheries
(Alverson et al., 1994) which indicated that 27 million tonnes, or approximately 27%
of global fishery catch, was discarded annually. This initial estimate was considered to
be a major achievement, providing an order of magnitude estimate of global discards
and illustrating the difficulty in their estimation, as indicated by the wide range of the
estimate (17.9-39.5 million tonnes). The 1994 assessment also brought the attention to
fishing industries and managers on the magnitude of the issue and therefore may have
helped to reduce discards over the ensuing two decades.
However, in 1996, an FAO Technical Consultation on Reduction of wastage in
fisheries (FAO, 1997a) identified a number of issues with the methods used in the
Alverson et al. (1994) assessment, which were considered to have possibly contributed
to an overestimate of global discards. In response to these concerns, a revised estimate
of 20 million tonnes of global discards was presented in the FAO State of World
Fisheries and Aquaculture 1996 report (FAO, 1997b), which was based on revised
estimates for selected FAO statistical areas that were examined in the 1996 Technical
Consultation (FAO, 1997a).
A decade later, in 2005, FAO provided an update of the estimate of global discards
from marine fisheries (Kelleher 2005) at 8%. Based on this rate, annual average discards
were estimated to be 7.3 million tonnes between 1992 and 2001- substantially less than
that given in the 1994 and 1997 reports.
The methodological approach used in the 2005 study differed substantially from
that used in the 1994 assessment. The 1994 report was based on discard/catch ratios
according to targeted species, or species groups. These ratios were applied to FAO’s
FishStat nominal catch statistics for the 1988-1990 period to derive the global estimate.
In contrast, the 2005 study used a fishery-based approach by compiling an inventory of
the world’s fisheries, their respective catches and used any available discard studies to
estimate rates. As discard rates were not available for all fisheries, the ratio of discards
to catch was assumed for those fisheries based on information from similar fisheries or
based on expert opinion. The quantity of discards for each fishery was then calculated
by raising (extrapolating) discard rates by the total recorded landings for the fishery, as
extracted from national fisheries statistics and other sources. The 2005 report suggested
a substantial reduction in discards compared to the 1994 estimate. The major reasons
for such reduction were believed due to a reduction in unwanted bycatch through the
use of bycatch reduction technologies and increased utilization of previously-assumed
discarded organisms.
A number of policy issues were discussed in the 2005 report. These include
a ‘no discards’ approach to fisheries management; the need for balance between
bycatch reduction and bycatch utilization initiatives; and concerns arising from
incidental catches of marine mammals, seabirds and reptiles. The study advocated the
development of more robust methods for estimating discards, allowances for discards
in fishery management plans, development of bycatch management plans and the
promotion of best practices for bycatch reduction and mitigation of incidental catches.
xv
In this context, FAO developed the International Guidelines on Bycatch Management
and Reduction of Discards (FAO, 2011) that were endorsed during the twenty-ninth
session of FAO’s Committee on Fisheries (COFI) in 2011.
At the Thirtieth Session of COFI in 2012, the Committee recommended continued
attention to bycatch and discards to ensure that they were addressed comprehensively
in conservation and management assessments, within an ecosystem approach. It
was considered important to have timely information on how world fisheries are
performing in reducing discards and seafood wastage, in the context of how countries
are contributing to enhancing the world’s food security.
In 2014, FAO considered it timely and prudent to conduct another update on this
vital fisheries and food security issue. The first step in the development of this updated
assessment of global discards was an Expert Workshop (Casablanca, Morocco, 26-28
May 2015) to develop the scope, timeline, methodology and deliverables for such an
update. It was noted that, compared to the situation in 1994 and 2005, the monitoring
and reporting of bycatches and discards in fisheries has improved throughout the
world, including more observer programs and initiatives such as electronic monitoring,
electronic logbooks and smartphone reporting. However, a detailed analysis of the
species composition of discarded catch is only possible in relatively few fisheries.
Therefore, it was decided that the species composition of discards would not be
included in the scope of the new assessment.
There has been significant difficulty in reaching an agreement on a globally-accepted,
standard definition of the term “bycatch”, which may, depending on the jurisdiction,
include: general discards, retained, released or discarded endangered, threatened or
protected (ETP) species, sold “by-product” species, juveniles, trash fish, pre-catch
losses, slipped fish, mortalities due to ghost fishing, discarded fish heads, frames and
offal, and even broader ecosystem and habitat impacts of fishing (FAO, unpublished).
Notwithstanding this variety of definitions, the most commonly used definitions tend
to settle on “bycatch” being the unintended, non-targeted organisms caught while
fishing for particular species (or sizes of species). This bycatch is then most commonly
divided into those non-target organisms that are kept and eaten/sold (“landed bycatch”
or “by-product”) and “discards” which are those animals thrown back (alive or dead)
into the sea (and can also include “slipped releases”). It is this latter subset of bycatch
(discards) which is the usual focus of studies that seek to report on bycatch, including
two previous global reports on bycatch by FAO, because it is this subset that results
in wastage of resources, impact on ETP species, and threats biodiversity, all of which
have caused significant attention and controversy.
This new global assessment on discards is intended to provide a comprehensive update
of Kelleher’s (2005) estimates using a similar approach (i.e. a fishery-based approach
using discard ratios by fishery and/or fishing method). The current study compiled
available discard rates from the last 20 years as well as a list of the world fisheries which
includes 2,089 fishery records covering 99% of global landings. These data have been
placed online to establish a baseline time series of global marine fisheries discards which
will be used to monitor the status and trends of discard management into the future (this
is step 1 of the Ecosystem Approach to Fisheries management cycle).
In addition to estimating discards in the world’s fisheries, it was also the purpose
of this study to provide an update on three other major issues concerning discards: (i)
estimates of fishing interactions with ETP species, (ii) measures to manage bycatch and
reduce discards, and (iii) current knowledge on mortality due to pre-catch, discards
and ghost fishing losses.
This report is an output of an ongoing FAO initiative that focuses on the magnitude
of discards, trends in discarding, practices associated with discards, and measure to
reduce discards. However, readers should be aware that all assessments of discards are
just estimates with simple assumptions to explain a highly complex subject.
xvi
Ultimately, FAO’s work on bycatch and discard management issues contribute
towards Sustainable Development Goal (SDG) 14 - conserve and sustainably use the
oceans, in particular SDG 14.2 – to sustainably manage and protect marine and coastal
ecosystems, avoiding significant adverse impacts, and SDG 14.4 – to end destructive
fishing practices, restoring fish stocks in the shortest time possible.
1
PART I – ESTIMATE OF GLOBAL
MARINE FISHERIES DISCARDS
1. Introduction
This third update of FAO’s global discard estimates took the ‘fishery-by-fishery’
approach adopted by Kelleher (2005) in the second update and improved it by crossmatching with FAO’s FishStat J landing dataset (FAO, 2016). FishStat J is software
for fishery statistical time series with access to a variety of fishery statistical datasets
(http://www.fao.org/fishery/statistics/software/fishstatj/en). FishStat J landings data
from 2010 to 2014 were allocated to over 2 000 fisheries worldwide. Data on discarding
rates from over 530 fisheries were then applied to 1 854 the fisheries in this dataset to
calculate global discarding rates.
There are many advantages to this new FishStat J-based approach. The most
important one is that it is easily replicable. The fishery data table can be refined and
then updated against the latest FishStat J landings data, and the discard rates data table
can be updated with new information as it is generated. Secondly, the data are highly
transparent. As both tables are open source, it is encouraged that they are further
developed and refined.
It is also notable that the fishery data table, whose fields include landings attributed
to flag state, FAO area and Large Marine Ecosystem (LME), gear type, water depth
and target species, is the first of its kind and is of significant potential use to fisheries
scientists and managers in its own right.
1.1.
SCOPE, DEFINITIONS AND TERMINOLOGY
The scope of the assessment was as follows:
• Discards from marine and estuarine fisheries only. This includes coastal lagoons
that have a predominately marine ichthyofauna but excluded freshwater fisheries.
• Commercial fisheries only. It excludes recreational and subsistence fishing.
• The time reference period was from 2010 to 2014.
As with the 2005 assessment, the definition of discards used in this study is adapted
from FAO Fisheries Report No. 547 (FAO, 1997b).
Discards, or discarded catch is that portion of the total organic material
of animal origin in the catch, which is thrown away, or dumped at sea for
whatever reason. It does not include plant materials and post-harvest waste
such as offal. The discards may be dead, or alive.
Therefore, for this global discard estimation, discards exclude:
• Post-harvest offal.
• Fish deliberately slipped from nets for commercial or safety reasons. This source
of mortality is considered in other sections of this report.
• Carcasses of sharks or other animals where some body parts have been removed
and retained (e.g. fins). Some aspects of this component of discards are considered
in Section 5 of this report.
• Certain other living (corals, sponges, seaweeds / sea grasses and other sessile
organisms), and non-living elements (sand, rocks, dead coral, marine litter, etc.).
Definitions of other key terms that are used in this assessment include:
• Bycatch: the catch of organisms that are not targeted. This includes organisms
that are outside legal-size limits, over-quotas, threatened, endangered and
A third assessment of global marine fisheries discards
2
•
•
•
•
•
•
•
•
•
•
•
•
•
protected species, and discarded for whatever other reasons, as well as nontargeted organisms that are retained and then sold or consumed.
Bycatch reduction device (BRD): devices inserted in fishing gear to reduce
unwanted bycatch. The most common BRDs are in shrimp trawls, close to
the codend, to encourage live escape of unwanted species, sizes, or threatened,
endangered and protected species.
Catch:
Ŋ (verb) Any activity that results in capturing and bringing any fish, alive
or dead, on board a vessel.
Ŋ (noun) The biomass of marine resources that are landed on a vessel,
discarded, consumed on board or used as bait.
Commercial fisheries: fishing activities that are conducted for revenue through
the sale of retained catch.
Country (flag): the State under the responsibility of which a boat is legally
registered.
Discard levels/quantity/volume: the biomass of discards from a particular
fishery over a defined period of time e.g. metric tonnes (hereafter, t) per year.
For most discards, this is usually expressed as weight, but for ETP species, this is
usually expressed as number of individuals.
Discard rate: the proportion of the total catch that is discarded, expressed either
as proportion (0-1) or as a percentage (0-100%). The formula to calculate discard
rate is as follows:
Discard Rate = Discards / (Landings + Discards)
Fishery: A grouping of fishing effort, combined according to a fishing area or
zone, a fishing gear, and one or more target species. Fishery is used as the principal
unit of account for discard rates and fishery data tables.
Gear (fishing gear): a tool used to catch fish, such as hook and line, trawl, gillnet,
trap, spear, etc.
Landed catch: the retained catch that is landed for use ashore.
Management authority: the organization which makes decisions on how the
fishery is regulated, and is also usually responsible for all ancillary services, such as
statistics gathering, assessment, consultation with fishers and other stakeholders,
resource allocation and determining the conditions of access to the fishery.
Non-target species: species for which the gear and fishing effort is not specifically
intended to catch, although they may have immediate commercial value and be a
desirable component of the catch, but in many cases, they are discarded.
Scientific authority: the organization tasked with identifying research and
monitoring needs for the management of a fishery and leading its implementation
and delivery.
Target species: those species that are primarily sought in a particular fishery
and are the subject of directed fishing effort in a fishery. Target species may also
be discarded due to landing size limits, over-quota, low quality as a result of
depredation, scavenging or spoilage, or safety issues.
Part I – Estimate of global marine fisheries discards
3
2. Methods
2.1
DEVELOPMENT OF A FISHERIES-BASED DISCARD DATASET
The development of a fisheries-based discard dataset that can be updated as new
FishStat J landings data becomes available and that is based on robust discard rates
for a variety of different fisheries, requires allocation of the FishStat J landings data to
specific fisheries. This allows the inference of actual catch and discarding volumes. In
order to achieve this, a nine-step process (Figure 1) was developed.
This process was initially done (Steps 1-5) in Microsoft Excel. Various methods,
such as Visual Basic for Applications (VBA) routines, use of drop-down lists and
various cross-checking tools, were used to ensure analytical rigor and assisted in quality
control. To validate the data, estimate discard rates, and allow easy reproduction of
the method for review and updating, an R “markdown” (http://www.fao.org/fishery/
static/TP633/script.Rmd) file was produced with full code and explanation (Steps 6-9).
The code would read data tables and produce a single joined table-output containing
landing and discard estimates.
1. Downloading FishStatJ landings: Global fish landings data were obtained from
FishStat J (version 3.01.0), using (i) the FAO Global Fishery and Aquaculture dataset
v2016.1.2 and the FAO Regional capture fisheries dataset v2016.1.0 (the latter for
CECAF and SE Atlantic only). Annual species-specific landings volumes by country
and FAO fishery area for the period 2010 – 2014 (n=14 563) were downloaded and
compiled in Excel (see FishStat data table).
2. Fishery Table (no landings allocated): A data table was developed on a country-bycountry basis, identifying the main fisheries (n=2,089) being prosecuted by each flag
state in its own exclusive economic zone (EEZ), in the high seas and in others’ EEZs.
This included the following data fields (bold fields were mandatory):
• Country
• Fishery name / description (e.g.
Southern Adriatic trammel fishery)
• FAO area
• Ocean
• Large Marine Ecosystem (LME)
• Target species group(s)
• Gear code
• Reference / data origin
• Managing authority (e.g. regional
fishery management organization,
RFMO)
• Scientific authority
• Water depth
• Location (e.g. Estuarine, inshore,
offshore)
• Vessel length
• Selectivity
• BRD used (yes / no)
• BRD type
4
FIGURE 1
Nine-step process to develop a fisheries-based discard dataset. In parenthesis are the names of the data tables (light blue boxes) and the dataset (dark blue box)
A third assessment of global marine fisheries discards
Part I – Estimate of global marine fisheries discards
5
The original basis for this data table were the fisheries compiled by Kelleher in his
2005 assessment. This was updated by a number of regional teams, using available
literature, national and RFMO fisheries statistics or personal communication with the
flag state authorities involved. Common descriptors were used where appropriate (e.g.
gear codes, etc.) to avoid duplication and enforce standardization of common data
groups. A description of the codes used in the data tables and dataset is in Annex A.2.
At this stage no landings data were assigned to each fishery record.
3. Species volume allocation: A tool was developed in VBA to allocate species-specific
landings by flag state from the FishStat J landings data table to the individual fisheries
record in the Fishery table. This was done by a number of regional specialists using
a variety of sources such national fisheries statistics and databases (where available),
published information on individual fisheries types, Marine Stewardship Council
(MSC) public certification reports (which usually have detailed information at a
fisheries level), etc.
4. Fishery Table (with landings allocated): Following the species allocation in Step 3
above, a revised Fishery Table from Step 2 was produced. As before, these fisheries are
defined by their location, target species and gear type but now include the volumes of
each species by flag state for each fishery.
5. Discard rates table: a new data table was compiled with records of discard rates from
around the world. This included the following data fields (bold fields were mandatory):
•
•
•
•
•
Gear type and code
FAO area
Flag state
Discard rate and range
Data origin (expert opinion/port
records/logbook/observer/survey
(research))
• Robustness (low/medium/high)
• Reference
• Fishery name / description (e.g.
Southern Adriatic trammel fishery)
• Large Marine Ecosystem (LME)
• Water depth
• Period when discard rate was
recorded
• Target species group(s)
• Vessel length
• Management type (input controls/
output controls/market controls/
bycatch management)
These records were primarily sourced from official observed discard data as published
by fisheries management administrations (MAs) and their scientific authorities (SAs). In
addition, other peer reviewed estimates were used. Where this was not possible, other
sources of information, e.g., industry estimates or non-governmental organization
(NGO) observations were used. A total of 530 records were included. The majority
were for bottom (including shrimp) trawls, with the rest mainly from purse seines, boat
seines (mainly Danish seine) and pelagic longlines. All these gear type records made up
the 60% of total discard rate records. Discard rates from 71 flag states were compiled,
with USA, Australia and EU countries providing the majority of data (57% of total
discard rate records).
6. Country-specific discard rates table: Assumed (and low) discard rates were applied
to domestic (locally-based) fisheries of certain countries which either have a discard
ban (Norway and Iceland) or which were believed to have extremely high bycatch
utilization rates (Bangladesh, Cambodia, China, India, Indonesia, the Democratic
People’s Republic of Korea, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand, and
A third assessment of global marine fisheries discards
6
Viet Nam). This additional country-specific data table fed into the final fisheries-based
discard dataset in Step 9.
7. DiscardLink data table: this links the Fishery Table records with the relevant
Discard Rates records where such a link was identified. The data table contained
several attributes of both Discard Rates and Fishery Table data tables to assist matching
as these were not explicitly matched on data entry. However, the fields of interest were
just the discard rate ID (DID) and the fishery ID (FID) as these would provide the link
between the two data tables.
8. Global discard rate estimation: discard rates were assumed for a large number of
fisheries for which no discard rates were observed or estimated. In these cases, global
gear-specific discard rates were estimated using the method described in Subsection 2.3.1.
9. Fisheries-based discard dataset: the final product derived from Steps 6, 7 and 8
included estimated discard rates. To check the data, estimate discard rates, and allow
easy reproduction of the method for review and updating, a RStudio “markdown” file
(script.Rmd) was produced with full code and explanation. The code would read the
data files, produce summary statistics to check the data consistency and outputs a single
joined table containing fishery-by-fishery landings and discard estimates (http://www.
fao.org/fishery/static/TP633/landdisc.csv). The system was designed so that any data
correction or updates can be incorporated by running two routines, the VBA routine
for producing the CSV files from each data table, and the “DiscardCalculations.Rmd”
in RStudio. In all, seven data tables were created to produce the discard estimates (see
Table 1).
TABLE 1
Data tables (Excel spreadsheets) defined for estimating discards
Spreadsheet
Description
FishStat
Landings data taken from the FAO FishStat J datasets. No changes were
made to these records, which consisted of the raw landings data by species
category as reported by each country.
FisheryTable
All fishing fleets operating under the flag of each country that landed the
fish quantities defined in FishStat.
FishStatLink
It links each FishStat record to the relevant Fishery Table records, with a
percentage allocation. It consists of three fields: the FishStat and Fishery
Table IDs and an integer percentage (1-100).
DiscardRates
It includes all discard rate estimates collected from publicly available
sources (national observer programs, scientific journals, grey literature,
etc.).
DiscardLink
It links the Fishery Table records with the relevant Discard Rates records
where such a link has been identified. The table contained several
attributes of both Discard Rate and Fishery tables to help with matching as
these were not explicitly matched on data entry. However the only fields
of interest were the discard rate ID (DID) and the fishery ID (FID) as these
provide the link.
GearSpecificDiscard
Estimated global discard rates by gear type (see Section 2.3.1 for details on
how they were estimated).
CountrySpecificDR
Country-specific discard rates for countries with discard bans or where
almost all catches were believed to have been utilised, resulting few
discards.
Part I – Estimate of global marine fisheries discards
2.2
ANALYTICAL METHODS FOR THE PROCESSING OF THE DISCARD
DATASET
2.2.1 Estimate Gear-Specific Mean Discard Rates
Using the empirical discard rates records gathered (see Discard Rates table), posteriori
mean discard rates and 95% credible intervals were estimated for 25 gear types (see
Table B.1 in annex B) from gear-specific zero-inflated beta regression models (Ferrari
and Cribari-Neto, 2004; Grun et al., 2012; Liu and Eugenio, 2018) fitted within a
Bayesian inferential framework (as employed by Gilman et al., 2018).
2.2.2 Dataset Processing
The LandDisc file contains pooled data from the FishStat and Fishery Table data tables.
Methods of estimating discard rates
One of three methods for estimating discard rates was employed for each fishery:
i. Country-based estimates (CO): Discard rates from the literature (see
CountrySpecificDR data table) were applied to all fisheries of countries
which either had a discard ban (Norway and Iceland) or which were
believed to have extremely low discard rates: Bangladesh, Cambodia, China,
India, Indonesia, the Korean Democratic People’s Republic, Malaysia,
Myanmar, Philippines, Sri Lanka, Thailand, and Viet Nam. This method has
been applied to more than 45% of global landings.
ii. Empirical estimates (EI): Fishery-specific discard rates obtained from
observed discard rates, with records entered in the Discard Rate data table,
were applied to their respective fisheries in the Fishery Table. If more than
1 observed discard rate estimates were available for a fishery, the average
of the observed rates was used, recognizing that calculating a mean of rates
may result in highly uncertain results. This method has been applied to less
than 20% of global landings.
iii. Global gear-specific estimates (GE): Global gear-specific discard rates were
estimated using the method described in Section 2.2.1 above. This method
has been applied to less than 35% of global landings.
For individual gear type and ocean region estimates, the 95% confidence interval
was constructed assuming a uniform prior distribution and that the original estimate
was derived from a binomial likelihood with an effective sample size of 100. In some
cases, the maximum likelihood estimate (e.g. 0 discard rate) falls outside this range,
so the median Bayes estimate was also calculated. For the gear-based estimates, the
95% confidence interval from the model was used. To indicate relative precision, the
estimate’s standard error was calculated from the confidence interval range scaled to
the equivalent standard error for the normal distribution.
Dataset processing steps
i. Removed records from LandDisc.csv file with Fishery ID = “0” and “NA”
for ocean region, target species and fishing gear fields. These were entries
in FishStat which had not been allocated to a “fishery”. Many landed catch
records with ID=0 likely belonged to gear types with relatively small discard
rates, e.g., spearfishing, hand collection, coastal gillnet, handline, and troll.
But there are some obvious exceptions, e.g., thresher shark spp., albacore,
and swordfish reported by American Samoa, Guam, Commonwealth of the
Northern Mariana Islands (CNMI), which were classified as mesopelagics and
assigned fishery ID=0, should have been allocated to pelagic longline fisheries.
ii. Confirmed that the field “Gear” contained one of the 26 categories that
were previously identified.
7
8
A third assessment of global marine fisheries discards
iii. Confirmed that the field “Target” contained one of the 7 codes that were
agreed.
iv. Confirmed that the field “Ocean” contained one of the 16 categories.
However, for Ocean=AO, Antarctic / Southern Ocean fisheries, some of the
records might not be Antarctic fisheries, e.g., the Korea distant water pelagic
longline and trawl fisheries.
v. Eliminated records with a gear type of “MIS” for which neither an empirical
discard rate (EI) was estimated nor a country-based discard rate (CO) have
been applied. Some fisheries (those that have been eliminated in this step),
were tagged with miscellaneous (MIS) gear type because the gear type used
was unknown or not included in the other 25 gear-type categories. As a
consequence, these “fisheries” were removed from the assessment, as they
did not meet the definition of a fishery, i.e. a fleet using a defined gear type,
targeting the same species group in a specific area. The final number of
fisheries included in the global estimate at this step was 1 854.
vi. Calculate 95% CI discard levels as follows:
(i). Sort the LandDisc processed file by DRsource.
(ii). Use the CO high and low 95% CI rates for DRsource=CO. Same for
DRsource=GE and DRsource=IE.
(iii). Calculate: low discard level = low CI discard rate x landed t/ (1-low rate).
Same for high discard level.
vii. Calculate 95% CI catch levels in the LandDisc processed file: lowest catch
level = Disc Lo and Landings, and highest catch levels = Disc Hi + Landings.
viii. Use pivot tables to sum 95% low and high discard and catch levels for each
unique FisheryId record.
Results tables and figures
Results (Section 3.1) reports discard levels and rates employing different methods for
estimates. The global discard rate was estimated using the two input values (discard
level, catch level) and rescaling by 10 000 because they are such large numbers, and
sampling the rate from a binomial data likelihood coupled with a Bayes-Laplace beta
prior (Gelman et al., 1997; Tuyl et al., 2008).
The summed discard levels were then calculated using the delta method (Jackson,
2011; Oehlert, 1992).
The discard rates by FAO Area and target species categories were estimated using
summed discard levels and summed catch levels using a binomial (x=discard, n=catch)
in a Bayesian framework to produce expected and 95% highest posterior density
intervals (HDIs).
2.3
ASSUMPTIONS AND ISSUES RELATED TO THE METHOD
Discard rates were assumed for some fisheries, based on rates that were available for
similar fishery types (i.e. similar target species, gear types and area). The advantage
of this approach is that the results can be fine-tuned over time as fisheries allocations
and the discard rate data tables are refined. However, it is fully accepted that this first
attempt will have methodological and data allocation weaknesses that will need to be
addressed in future runs.
The key assumptions and issues were:
• A linear relationship between landings and discards within fisheries was assumed,
which is a common practice for the extrapolation of sample discard rates to total
discards.
• The identification of key fisheries at a national level was based on a combination
of national and regional fisheries statistics and sector reviews. In many countries,
the structure of key commercial fisheries e.g. gear and vessel types, target species,
Part I – Estimate of global marine fisheries discards
location, etc. (see Step 2 in Figure 1) are well known, but not in others. For
example, many of the distant water activities of some flag states are not well
characterized. Characterizing multi-gear inshore fisheries that are common in
many parts of the world was also difficult. In countries where the knowledge of
specific fisheries was low, we assumed a fisheries structure based upon similar
countries in the same region, the composition of landed species, and discussions
with national fisheries authorities where possible. See Annex A.1 for further
information on countries which are not included in the assessment.
• The allocation of species to these fisheries from the national FishStat J landings
data table (see Steps 3-4 in Figure 1) is also vulnerable to error. Although many
countries provided fish landing statistics for key commercial fleets, many did not.
In such cases, the regional teams used fisher’s knowledge, MSC and other thirdparty certification reports, and other published sources to make the allocation
decision. Where there were no published data, assumptions were made on the
susceptibility of certain species to specific gear types in inshore and offshore
fisheries. These cases appeared in the Fishery Table data table as “Expert Opinion”
records (field “RefNotes”).
The Discard Rates data table compiled records from a wide range of published
scientific and industry studies. Many of these estimates were from robust analyses
based on large sample sizes, often as part of long-term discard monitoring, especially
in Europe and the North America. However, many other areas lacked a robust discard
monitoring scheme (e.g., SE Asia and sub-Saharan Africa). Although some gear types
had been the focus of discard monitoring (e.g., mobile bottom gears), there was
relatively little information on widely used gears such as purse seines and ring nets,
specific types of bottom trawls (other than otter trawls) and pelagic gillnets.
We attempted to estimate relative quality of the discard estimates by labelling each
as being high, medium or low robustness based on their source, sample sizes, level of
peer review, etc. Approximately 55% of the discard data records were ranked as highly
robust, 24% medium, and 20% low.
9
A third assessment of global marine fisheries discards
10
3. Results
3.1
GLOBAL DISCARDS
The estimate of annual discards in global marine capture fisheries for 2010-2014
was around 9.1 million t (95% credible interval: 6.7 – 16.1), not accounting for the
unknown discards from some countries and fisheries that account for approximately
6.5% of global landings (see Annex A.1). The global discard rate (t of discards / t of
total catch) was 0.108 (95% highest posterior density interval or HDI: 0.101 – 0.115).
These estimates were based on a sample size of 1 854 fishery records, with an estimated
total annual catch of 84.6 million t (95% CI: 82.2 – 91.6) and annual landed (retained)
catch of 75.5 million t.
3.2
DISCARDS BY GEAR TYPE
Discard rates vary widely among gear types (Figures 2, 3 and Tables B1 and B2 in
Annex B). About 45.5 percent (4.2 million t) of total annual discards were from bottom
trawls that included otter trawls, shrimp trawls, pair bottom trawls, twin otter trawls
and beam trawls. The average discard rate (t of discards*100 / t of total catch) of
bottom trawls was 21.8%. Boat seines only accounted for 0.48 million t of discards,
but it had a high average discard rate of 23.5%. Dredges made up 2% of total discards
(0.2 million t) with an average discard rate of 13.6%.
Gillnet fisheries produced 0.80 million t of discards with an average discard rate of
about 10.1%. The main part of gillnet discards came from bottom gillnets. Longline
fisheries accounted for 0.36 million t of discards with an average discard rate of 12.3%.
Likewise, bottom longlines produced the most discards from all longline fisheries.
Relatively high discard volumes were associated with purse seines (1.02 million t)
and midwater trawls (0.9 million t). Discard rates in these fisheries, and in particular in
purse seines, were however relatively low (3.9%). The high overall quantity of discard
was a result of large catch volumes of pelagic species in purse seines.
3.3
DISCARDS BY OCEAN REGION
Discard levels and discard rates varied by geographic region (i.e., FAO Major Fishing
Area; Figure 4, 5 and Table B3 in Annex B). The northwest Pacific (Area 61) and
northeast Atlantic (Area 27) together accounted for 39% (3.57 million t) of the
estimated global discards. Some regions with relatively high discard rates had relatively
low discard levels, and vice versa. For instance, the southwest Atlantic (Area 41) had
the highest mean discard rate. This region, however, only contributed less than 7.5% of
the total annual global discards. While the northwest Pacific Ocean (Area 61) had the
greatest amount of discards, contributing 22% of the total annual global discards, but
it had the fifth lowest mean discard rate.
3.4
DISCARDS BY TARGET SPECIES
Discards and discard rates varied by target species of fisheries that they pursued
(Table 2). Fisheries targeting tunas and other pelagic species had the lowest discard
rates, while fisheries targeting crustaceans had the highest discard rates. Fisheries
targeting demersal fish had the highest discard levels, while fisheries targeting molluscs
(excluding cephalopods) had the lowest discards levels.
Part I – Estimate of global marine fisheries discards
11
FIGURE 2
Mean discard rates and 95% credible intervals for 25 gear types, estimated from gear-specific
zero-inflated beta regression models fitted within a Bayesian inferential framework. Discard rates are
expressed in tonnes of discards per tonnes of total catch. The solid dots represent mean discard rates
for different gear types, and their sizes are proportional to their sample sizes
12
A third assessment of global marine fisheries discards
FIGURE 3
Mean discard levels (thousand tonnes) and 95% confidence intervals by gear type.
The solid dots represent mean discard levels for different gear types, and their sizes
are proportional to their sample sizes
Part I – Estimate of global marine fisheries discards
13
FIGURE 4
Global fisheries discard levels by region. The solid dots represent mean discard levels for different
regions, and their sizes are proportional to their sample sizes
A third assessment of global marine fisheries discards
14
FIGURE 5
Distribution of global fisheries discard rates (top) and total discards (bottom) by FAO Major Fishing
Area. Discard rates are metric tonnes of discards per metric tonnes of catch. Discards are metric
kilotonnes (kt)
A
FAO Major Fishing Areas
50°N
discard
rate
latitude
0.25
0.20
0°
0.15
0.10
0.05
50°S
120°W
60°W
0°
60°E
120°E
longitude
B
FAO Major Fishing Areas
50°N
discard
(metric kt)
latitude
2000
1500
0°
1000
500
0
50°S
120°W
60°W
0°
longitude
60°E
120°E
Part I – Estimate of global marine fisheries discards
15
TABLE 2
Estimated discard level (t) and discard rates (t discards / t catch) by target species.
CI=confidence interval, HDI=highest posterior density interval
Target species
category
Discard Level (t)
Mean
Discard Rate (t discards / t catch)
Lower
95% CI
Upper 95%
CI
Expected
Lower
95% HDI
Upper
95% HDI
N
molluscs
except
cephalopods
207 196
179 228
235 163
0.132
0.118
0.144
57
tunas
485 652
391 020
580 284
0.054
0.044
0.062
429
497 205
275 508
718 903
0.156
0.092
0.176
58
mixed*
cephalopods
1 258 684
1 159 450
1 357 918
0.098
0.093
0.103
149
crustaceans
1 411 578
1 339 332
1 483 825
0.324
0.325
0.314
229
pelagic fishes
2 205 060
1 996 577
2 413 543
0.062
0.057
0.065
418
demersal
fishes
3 074 432
2 291 129
3 857 735
0.167
0.131
0.180
514
* Mixed category includes pelagic and demersal organisms
A third assessment of global marine fisheries discards
16
4. Discussion
4.1
GLOBAL QUANTITY OF DISCARDS
An overall discard rate of 10.8% and an annual average discard quantity of 9.1 million
t for marine capture commercial fisheries during the period of 2010-2014 are the key
overarching results of this third decadal report on global fisheries discards. The annual
quantity of discard is about the same as the recent estimate of global discards derived
by Zeller et al. (2018) using data from the Sea Around Us Project (SAUP). The latter
analysis suggests that annual global discards peaked at around 18.8 million t in 1989 and
gradually declined to less than 10 million t by 2014. The Zeller et al. (2018) assessment
relied on a wide variety of data and information sources, and unlike this study, tried to
account for unreported landings.
Comparison of our latest estimate with the previous estimates by FAO in 1994
and 2005 suggest that significant changes have occurred in global discards during the
last twenty years, from Alverson et al. (1994) initial estimate of 27 million t, down to
Kelleher’s (2005) estimate of 7.3 million t, to the slightly elevated estimate of 9.1 million
t by this study. The dramatic decline in the estimates from the 1990s may be explained
by significant differences in the methods used to derive estimates, improvements in
the data availability and a host of gear-specific differences in assumptions made among
the studies which will be discussed in detail below. In addition, during the past few
decades, we have also seen the implementation of more selective fishing gears in many
fisheries throughout the world and great expansions in the utilization of catches that
were previously discarded, which may also have contributed to the declines in discards.
4.1.1 Estimates by gear type
The estimate of global discards from bottom trawls (4.2 million t, which made up
45.5% of the estimated total annual discards), which includes otter trawls, shrimp
trawls, pair bottom trawls, twin otter trawls, and beam trawls, was consistent with
that of the SAUP global catch reconstruction database (Zeller et al., 2016) for the same
period (41.9%).
Gillnet fisheries contributed 0.8 million t to global discards with an average discard
rate of about 10.1%. The main part of gillnet discards came from bottom gillnets.
Bottom set gillnets are widely used throughout the world, and improved materials and
operational techniques have allowed the expansion of their use on rougher grounds and
in deeper waters, resulting in the capture of a wider range of non-target species which
are often discarded (Suuronen et al., 2012).
Boat seines, primarily Danish seines, had high discard rate (Figure 2). Although the
gear is lighter in construction and the area swept is much smaller than bottom trawls,
bottom seines have many common features with bottom trawls (Suuronen et al., 2012).
Bycatch of undersized individuals of target species and non-target species can be high,
leading to relatively high discard rates (Walsh and Winger, 2011).
Longline fisheries produced 3.8% (0.4 million t) of the global discards. Pelagic
longline fisheries had an average discard rate of 6.7% and global annual discards of
less than 0.1 million t. These estimates were similar to those of Gilman et al., (2017)
who reported an annual discards of 0.1 million t. However, Kelleher (2005) had much
higher estimates for this gear, a 28.5% discard rate and 0.5 million t of global discards
for pelagic longline fisheries. These high estimates came mostly by applying a discard
rate of 40% for distant-water longline fisheries, and 15% for smaller, locally-based
longline fisheries that lacked available estimates of discard rates. Kelleher (2005) also
used advices from regional experts in deriving these estimates, including the discarded
catch that had been damaged via depredation by sharks and whales. Such catch might
have not been usually recorded as discards (Kieran Kelleher, personal communication,
Part I – Estimate of global marine fisheries discards
1 Oct. 2016). Discards of damaged catch is currently recorded as discards by some
longline observer programs (e.g., SPC and FFA, 2014). Furthermore, unlike the
present study, Kelleher’s discard estimates included shark carcass after finning which
he reported to be 0.2 million t.
In the current assessment, relatively high discard levels were associated with purse
seining (1.0 million t) and midwater trawling (0.9 million t). However, discard rates in
these fisheries, in particular in purse seining (discard rate 3.9%), are often relatively
low. On the one hand, the high overall quantity of discard is largely a result of
large catch volumes in pelagic fisheries. On the other hand, current discard rate data
suggest that there are some pelagic fisheries where discard rates are high, for example
the herring purse seine fishery in Sea of Okhotsk (discard rate 26.5%, see Discard
Rates data table). Similarly, the SAUP estimate of discards in midwater trawling (ca
1.0 million t) is similar to our estimate. This observation is inconsistent with that
of Kelleher (2005) who noted that midwater trawl and purse seine fishing for small
pelagic fish generated little discards. Kelleher (2005) estimated the global discards in
midwater trawling as 0.15 million t, 0.75 million t lower than the current estimate. This
considerable difference might have been caused, in part, by some pelagic fisheries (e.g.
midwater trawl fisheries in Celtic-Biscay shelf grounds) with relatively high discard
rates included in the current estimates.
In many purse seine fisheries it is a common practice to release the catch when the
size or species composition of catch is not desirable, or when the crew safety is under
threat. The practice of releasing unwanted catches from purse seines while the catch is
still in the water is known as “slipping” (Box 1). Slipped catches have not been included
in the current study, and there is little data available on quantities of such “discards”
in the global scale. Nonetheless, it is known that quantities slipped can be high and
the mortality of fish that are slipped from a purse seine may be variable depending on
factors such as crowding density and exposure time (Tenningen et al., 2012, Marçalo
et al., 2018).
4.1.2 Discards by fishing area
From a regional perspective, we observed the lowest discard levels in southern regions
such as Antarctic and southwest Pacific. These results are consistent with previous
studies (Kelleher, 2005). In the Antarctic region, the Commission for the Conservation
of Antarctic Marine Living Resources (CCAMLR) has been implementing Conservation
Measures dealing with discards and collecting data on this practice for more than ten
years. However, inconsistencies between the different terms used in Conservation
Measures makes it impossible to derive an appropriate quantification of discards
(Marschoff & Serra, 2017). In southwest Pacific, New Zealand, the major fishing nation
of the region, has a policy of a discard ban associated with an individual transferable
quota (ITQ) system since 1986 (Borges et al., 2016).
In terms of discard rates, the lowest are in southeast Pacific, eastern Indian, and
western central Pacific Ocean. These results are also consistent with Kelleher (2005). In
the southeast Pacific purse seine fishery targeting small pelagic fish (mainly Engraulis
ringens and Sardinops sagax) discard rates appear to be very low (Torrejón-Magallanes
et al., 2016) or even negligible in the case of Chile (Vega Muñoz et al., 2016). Chilean
Fisheries Law introduced a general discard ban in 2001, which was amended in 2012
to allow for some exemptions (Borges et al., 2016). Such exemptions are subject to the
implementation and development of monitoring programs and mitigation plans. In
this study, discard data from Chilean purse seine, bottom trawl and shrimp trawl fleets
were obtained from an observer program and logbooks. Unfortunately, robustness
of such data is low due to the low coverage of the observer program (1.8%) and low
availability of logbook data (23.8%) in 2016, and consequently discard estimates are
not conclusive.
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A third assessment of global marine fisheries discards
BOX 1
Slipping of fish from a purse seine
In purse seine fisheries it is a common practice to deliberately release fish from the
net over the float line of the purse seine after it has been partially hauled or “dried-up”
towards the end of a fishing operation while the catch is still in water. The release is
generally known as “slipping”. Slipping is done when the size or species composition of
fish is found not desirable, or the amount of the catch in the net is excessive. Release may
also be a response to regulatory restrictions or market demands. Usually, only a part of the
catch is slipped, but in some cases, the entire catch is slipped. There is little data available
on the quantities of catches that are slipped in the global scale, but it can be substantial.
Whilst slipped fish is not usually considered as discards because the fish had not yet been
brought on to the deck, it can lead to mortality in the released fish if the slipping is not
done properly. Mortality of slipped fish of small pelagic species such as sardines, herring
and mackerel may result in unacceptably high rates of unaccounted collateral fishing
mortality (Huse and Vold, 2010; Tenningen et al., 2012; Marçalo et al., 2018). The mortality
of slipped fish is directly related to the conditions and interactions that occur within the
net, with higher mortality in conditions of higher crowding densities and longer holding
time before slipping, both of which can cause hypoxia and scale loss. These operational
stressors are elevated at later stages of the operation. Therefore, slipping at earlier stages of
operation, when fish are less crowded, would likely lead to lower mortality. However, it is
a challenge to fishers to accurately characterize the fish in the net in terms of species and
sizes for which the decision on slipping is often based. New methods and technologies to
address this challenge are being developed so that operational improvements can be made
to significantly reduce stress and mortality in released fish (Breen et al., 2012).
In contrast, in eastern Indian and western central Pacific oceans, there are no
discard bans nor observer programs that record discard data. In the countries of these
areas almost all catch is utilized. Even when the catch has a low commercial value by
virtue of their low quality, small size or low consumer preference, it is either used for
human consumption (often processed or preserved) or as feed for livestock animal or
aquaculture species, either directly, or in the form of fish meal or fish oil. “Trash fish”
is a term often used to describe mixed, unsorted and unidentified assemblages of small
fish that are caught in fisheries (APFIC, 2005), in particular in Southeast Asia, but
also in other tropical regions. These fish were often discarded decades ago but have
gradually grown in importance as a landed bycatch.
The highest discard levels during 2010-2014 occurred, as reported by Zeller et al.
(2018), in the northwest Pacific and the northeast Atlantic, which together account for
39% of the total discards. However, in the northwest Pacific the discard rate appears
to be relatively low (9.12%) due to low to negligible discard rates of Chinese fisheries
(Kelleher, 2005) which make up 62% of total catch in that region. In contrast, discard
rates are relatively high in the northeast Atlantic as 33% of the total catch come from
bottom trawl fisheries, which have the highest discard rates among all gear types.
4.2
STRENGTHS AND LIMITS OF THE CURRENT STUDY
Several factors have contributed to a more comprehensive assessment of fisheries
discards in the current study than in the previous two FAO reports on discards. In
many countries, the capacity for monitoring and reporting in fisheries has improved
during the last 10-15 years. More programs and methods are in place throughout
the world to monitor and report catches and discards, including (i) dockside and at
Part I – Estimate of global marine fisheries discards
sea observer programs, (ii) electronic monitoring (including onboard video camera
monitoring schemes) and electronic logbooks, (iii) smartphone reporting, (iv) fisheries
surveys, and (v) fisher interviews and collaborative sampling schemes (Gilman et al.,
2012; Mangi et al., 2015). Many countries have developed sophisticated systems for
collecting such data that were not available a decade ago. As a result, there are more
bycatch and discard data available during the period covered by this study than those
covered by Alverson et al., (1994) and Kelleher (2005).
The most reliable and accurate means to collect data on bycatch and discards is
through onboard observer programs, including conventional human observers and
electronic monitoring (EM) systems. Bycatch and discards data collected and reported
by independent onboard human observers and EM systems contain more accurate and
detailed information than those reported in logbooks by fishers. Fishers may lack time
and training to record data according to prescribed data collection methods and may
have an economic or regulatory disincentive to accurately record data, e.g., to avoid
catch or size limits (Brown, 2001; FAO, 2003; Walsh et al., 2002, 2005; Gilman et al.,
2018). Observer programs have become a mainstream source of fisheries information
for the collection of data on bycatch and discards and other information (e.g. Gilman
et al. 2012). In fact, more than 78% of the discard rate records in this study have come
from observer programs (see Discard Rates data table). However, onboard observer
programs are expensive, leading to low coverage rates, and consequently less certainty
in estimates. Low-cost complementary methods such as the Length Frequency
Distributions (LFD) method to explore commercial landings may complement and
extend information from observer trips for those fisheries where main driving factors
of discarding are known (Depestele et al., 2011). Recent developments in the use of
EM systems can augment coverage by human onboard observers. Studies comparing
the precision and accuracy of data collected by EM and onboard observers found
that EM data had relatively high precision than those collected by onboard observers.
However, EM systems are in need of improvement in some areas, such as detection of
some discarded species (Gilman et al., 2018).
Research vessels are increasingly used to quantify bycatch and discards but it relies
on whether these vessels are able to mimic conventional commercial fishing operations.
A considerable part of the data in the current assessment has been based on fisheries
survey data (see the Discard Rates data table).
Post-trip interviews of captains and crews are also used to collect data on bycatch
and discards. However, as mentioned above, discarding is a bad practice (in some cases
illegal) and fishermen could tend to underestimate the amount or volume of discarded
organisms or they may simply lack training to record data according to prescribed data
collection methods. As a consequence, the data collected on discards are considered to
be less reliable than other methods. The advantage is that such techniques can be quite
inexpensive.
The new fisheries-based discard dataset developed in this study can be easily
updated and modified. The Fishery Table can be refined and then updated against the
latest FishStat J landings data, and the Discard Rates data table can be updated with
new information as is becomes available. The data protocol used is highly transparent,
with all data tables being open source, and further development and refinement is
encouraged. The Fishery Table is the first of its kind and may be of significant value for
a variety of uses by fisheries scientists and managers. The results obtained in this study
can be fine-tuned over time as fisheries allocations and discard rates are added to the
data tables. Notwithstanding these advantages, this first attempt at using this dataset to
estimate discards has methodological and data allocation weaknesses that will need to
be addressed in future applications (see Subsection Next steps for more details).
Although more and better data on discards are available now, many shortcomings
and challenges encountered by Kelleher (2005) are still relevant in the current study (see
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Specific challenges in the current assessment Subsection for more details). Furthermore,
bycatch and discards have never been assessed in many fisheries, particularly in many
small-scale fisheries (e.g. Zimmerhackel et al., 2015). Significant efforts were made in
this study to obtain data from as many countries, regions and agencies as possible.
Where data had been traditionally difficult to obtain, regional experts were contacted
to provide their estimates (regarding both fisheries landings allocations and discard
rates). Nonetheless, many data gaps remained with a number of countries not included
in the current assessment (see Annex A.1).
As a global study, it was not possible to evaluate all factors affecting discards.
We focused primarily on differences between gear types, but we may have lost
some resolution regarding discards in different areas and by different target species.
Nonetheless, the lack of focus on target species may have been compensated by the fact
that the gear type often infers a specific target species. For other fisheries, some of our
lower resolution gear-categories with a small sample of observed discard rate records
may not have provided accurate estimates of discard rates. For example, we included
a single gear category of handline, which includes fisheries targeting both demersal
and pelagic species. The discard rate estimate for this gear type was based on only two
records, one from a demersal handline fishery and the other from a fishery with a mix
of demersal and pelagic target species. The extremely small sample size of records used
to estimate the discard rate for handline has resulted low certainty in the discard level
and rate estimates for this gear type.
We did not address the issue of species and size composition of discards in this
study. These are important issues for food security and stock assessments, but it
was not possible to include this information in this study, although there was an
extensive literature regarding species and size composition of discards in various
fisheries and regions.
Specific challenges in the current assessment
The current assessment was based on several assumptions which are sources of
uncertainty but had not been completely reflected in the estimates of precision. For
example, a linear relationship between discards and total landings was assumed although
this may not be realistic for some species, e.g. in a particular fishery the discard rate for
a non-commercial species can be 100% and then landings would be 0 (all individuals
are discarded). The total quantity of discards was derived by extrapolating the discard
rates from limited studies to the total catch of these fisheries. No estimation at a
fisheries level was made for domestic fisheries in specific countries where there is few
or no data on discards. Instead, in such countries the same discard rate (country-level
discard rate) was applied to all domestic fisheries. These countries either have had a
discard ban policy (e.g. Norway and Iceland) or were believed to have extremely low
discard rates because (almost) all landed catch is used either for human consumption,
and/or aquaculture and livestock feeds, including Bangladesh, Cambodia, China,
Democratic People’s Republic of Korea, India, Indonesia, Malaysia, Myanmar,
Philippines, Sri Lanka, Thailand and Viet Nam. However, it should be noted that
in the case of East and Southeast Asian countries, no empirical discard data exists
and assumptions used in other studies were also used in the present study (see
CountrySpecificDR data table). In the case of Norway and Iceland, their countrylevel discard rates are based on a few discard data on commercial species reported to
the European Commission (Data Collection Framework programme). Together, all
these countries produced more than 45% of annual landings included in this study
(see Subsection Methods of estimating discard rates). Therefore, when interpreting the
results of this study, due consideration should be given to the fact that the uncertainty
generated by this group of countries might not be well captured.
Part I – Estimate of global marine fisheries discards
FishStat landings records seldom exactly match with national statistics, which made
it difficult on allocation of landings to specific fisheries. As a consequence, almost all
countries have a fishery named “other fisheries in X area” which include either the
multi-gear inshore fisheries that are common in many parts of the world and/or species
that are recorded in FishStat but not in national statistics. Another similar issue is the
category “Marine fishes nei” in the FishStat data table. This category includes marine
fish “not elsewhere included” (nei), which are fish that have not been identified by
species or family, including hundreds of fish species and 10.84 million t of landings in
total (14.35% of total landings included in this assessment).
National fisheries statistics are not always readily available by fleet, gear or by
fishery. In these cases, we have assumed that certain fisheries exist, based on similar
countries elsewhere in the region, the composition of landed species where possible, or
discussions with national fisheries authorities. The source of data for these fisheries is
flagged as Expert Opinion in the Fishery Table (see RefNotes field).
The structures of some key commercial fisheries (in terms of gear and vessel types,
target species, and location) are not well known. For example, many of the distant
water activities of some flag states are not well characterized. In such cases, we based
our assumptions on similar fisheries in countries elsewhere in the region. Furthermore,
some fishing countries, which only contribute 0.13% (772 117 t) of the total landings
worldwide, were not included in the assessment, because no information was found
about the characteristics of the commercial fisheries in these countries.
The Discard Rate data table was compiled with records from a wide range of
published scientific and industry studies. Many of these analyses were based on large
sample sizes, often as a part of long-term discard monitoring, especially in Europe and
North America. However, many other areas lacked robust discard monitoring, e.g.
North and Southeast Asia, sub-Saharan Africa. In terms of types of fishery, the focus
of discard monitoring are bottom trawls and boat seines (mainly Danish seines). In fact,
mobile bottom gears are the best represented within our discard records. By contrast,
trolling, handlines, pole-lines and in general artisanal gears (e.g. beach seines) are the
least represented.
4.3
OTHER ISSUES
Economic and social impacts of discards
Discarding, from a societal perspective, can have economic impacts (Pascoe, 1997)
which can be classified into four categories (FAO, unpublished): (i) discarding of
juvenile and adult target species with an associated impact on future stock growth,
resulting in forgone income; (ii) discarding juvenile bycatch species can reduce target
species catch and revenue in other fisheries; (iii) costs associated with discarding of
non-commercial species (time spent removing the individuals from the fishing gear
or sorting on deck); and (iv) cost associated with measuring/estimating the levels of
discards (observer programs are known to be costly).
However, discarding is also an economically rational decision by fishers to maximize
benefits. The benefits of discarding to individual fishers can be considered in terms of:
(i) the increased value of the commercial catch (quality, size, species mix) as a result of
discarding unwanted catch; (ii) reduced costs of handling and storing non-commercial
catch and onshore disposal; and (iii) avoiding sanctions if vessels are catching illegal fish
(and are not able to sell it undetected on black market).
Management regimes (such as quota, size and sex restrictions, and effort controls)
can incentivize discarding (see Section 3 of Pascoe 1997 for more details). However,
independent of management systems, discarding is influenced by specific characteristics
of fishery and status of stocks being harvested. Moreover, social spheres (fishing
community and market) have been identified as factors influencing discarding and
selective fishing behaviors (Eliasen et al., 2014). Therefore, solving the discard problem
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A third assessment of global marine fisheries discards
requires a suite of measures tailored to a fishery, taking into account all factors that
incentivize or discourage discard behavior as well as interactions between different
fisheries in terms of target species and species caught (both target and bycatch species).
In all cases, achieving a common perception on the problem of discarding among fishers,
fishery managers and other relevant stakeholders is essential to foster cooperation and
trust to reduce discards (Eliasen et al., 2014; Johnsen and Eliasen, 2011).
4.4
FUTURE GLOBAL DISCARD ASSESSMENTS – LESSONS LEARNED
Reliable information on fisheries bycatch and discards is an important step towards
more effective management and improved utilization of fisheries resources. Failure to
effectively manage bycatch and reduce discards jeopardizes long-term sustainability
of fisheries, threatens biodiversity and impact on food security, thus affecting the
livelihoods of those dependent on fisheries resources. It is thus important to monitor
the performance of fishing sector in reducing discards and seafood wastes over time.
Accurate information on discards is also critical for improving quality and reliability of
stock assessments. The lack of reliable data on the level of discards in fisheries represents
a significant uncertainty in the assessment of total fishing mortality, thereby decreasing
the quality of scientific advice. However, assessment of fisheries discards is a daunting
task because discards have not been properly estimated for many fisheries. Although
there have been increases in the number and diversity of observer programs, logbook
programs and EM systems, there are still many fisheries, regions and fishing methods for
which no such data exist. Therefore, our estimates incorporate many assumptions and
extrapolations as we assign estimates from other fisheries to fisheries with few or no data,
and as we aggregate data across regions, fisheries and fishing methods.
New solutions for improved data acquisition and processing are an increasingly
important global topic, especially in Europe with the new reform of the European
Union Common Fisheries Policy which established a discard ban (or Landing
Obligation). New approaches are being developed by the scientific community and
the fishing sector in order to get better data on catch quantities and composition, for
example, optical technologies used for the identification and quantification of the catch
on board (iObserver system). This information has been used to develop better models
that more reliably predict discards hot-spot areas (Vilela and Bellido, 2015; Pennino
et al., 2017), which can be used by the fishing sector to avoid high levels of discards.
Considering public ownership of natural resources in the sea, the general public in
any society are the key fisheries stakeholders. Therefore, governments are responsible
for undertaking all appropriate activities, including discard monitoring, for the
management of these public resources. In recent years, the importance of bycatch
and discards monitoring has also been recognized in many formal international
agreements, guidelines and policies, such as FAO’s International Guidelines on
Bycatch Management and the Reduction of Discards (FAO, 2011). Finally, it is widely
recognized that all key stakeholders, in particular the fishing sector, should participate
in the process of the management of fisheries bycatch and discards. The status of
the global implementation of the relevant paragraphs of the Code of Conduct for
Responsible Fisheries (FAO, 1995) is a useful index of this progress (see Annex C).
The discard assessment described in this report can be improved in many ways.
Reporting on fisheries landings by species and by gear types would be the first step. In
order to do so, enhanced national buy-ins and engagement would be needed. The scope
could further be extended by adding or completing the data fields regarding the state of
the fishery, value, total ‘wastage’, discard composition and food security dimensions.
Moreover, best practices in protocols for inclusion of discards in stock assessments,
pathways for discard reduction or elimination, and elements of environmental
accounting are some areas for consideration and development.
Part I – Estimate of global marine fisheries discards
It is important to have a clear goal for future assessments. The ultimate goals should
be informing fishery management and policy initiatives (e.g., the reduction of wastage
in capture fisheries) and reporting to the public owners of these resources. A direct
engagement with Regional Fisheries Management Organizations (RFMOs) and UN
member states is fundamental to generate discard estimates. Furthermore, engagement
with Regional Fisheries Bodies (RFBs) to capture small country and developing
country information is important, and if necessary, regional experts should be engaged
to work closely with these countries.
Next steps
An important objective of this update of global discards estimates was to develop an
open and repeatable methodology linking FAO’s FishStat J landings data with discard
records. This has largely been achieved, but it is also recognized that considerable
work is needed to update and refine various datasets and their linkages.
In particular, two tables need further development:
1. Fishery table: this table allocates species data from FishStat J with
individual, gear-related fisheries conducted by each flag state. This list of
fisheries is well defined in countries where fishing fleet métiers are well
documented, and catches are reported against these. However, this is not the
case for many other countries, so further work needs to be done to better
identify specific fisheries and their characteristics (e.g. gear type, location,
water depth, vessels sizes, selectivity, etc.)
2. Discard rates table: this second table was compiled with records of discard
rates from around the world. It was the result of an extensive literature
review but needs further attention to ensure it contains all recent discard
rate records and is updated as new data become available. For instance, on
the latter it would be useful if there were an easy way to import new data
from the European Union’s Data Collection Framework (DCF) when it is
released, as well as other data sources such as Marine Stewardship Council
reports which contain these types of data.
A second area for development is the joining between the various data tables. This
was found to be more complicated than first thought, especially when joining the
Fishery Table with the Discard Rates table. Information on discard rates was often
insufficient to identify which fishery observations were taken and it was not always
clear to which species the discard rates might apply. A more rigorous evaluation of
fishing operations might yield better discard rate estimates so that they may be used to
infer discard rates in other similar fisheries using a model-based approach.
The third area for development is to further refine the fisheries-specific nature of
discarding. For instance, whilst some fisheries may generate large volumes of fish
not desirable for human consumption (e.g. some bottom tropical shrimp fisheries),
the natural assumption, which is also often supported by official observer trip
reports, is that they are discarded. However, in reality it is often retained and sold in
the fish reduction market, thus discarding levels would be overestimated. Another
scenario is that fisheries which have discard ban policy instated may have a number
of derogations, or indeed unreported discarding, which may mean that discard levels
are underestimated. The challenge for further development of this approach will be
capturing these particular anomalies.
4.5
CONCLUSIONS
The current study established a method for assessing discards at the global level by
creating a fishery-by-fishery dataset of landings and discards (landdisc.csv file). The
estimate can be checked and updated through changes to individual records in the data
tables which are the source from which the dataset is built. The majority of the Fishery
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A third assessment of global marine fisheries discards
Table and Discard Rates data tables contain fields with standardized codes. Thus, the
dataset can be easily updated as new discard and/or fishery data become available.
The estimate of annual discards in global marine capture fisheries for 2010-2014 was
around 9.1 million t (95% CI: 6.7 – 16.1), with a wide range of discard rates among
fisheries, regions and gear types. Fisheries using bottom towed gears – trawls and boat
seines - accounted for almost 51% of the estimated global discards. Hence, it is well
justified that the focus in bycatch management and discard reduction is still focused on
mobile bottom fishing gears.
The assessment still excludes a number of fisheries, and no allowances were made
for illegal, unreported and unregulated (IUU) catch, recreational catch or freshwater
fisheries. Small-scale fisheries from many countries were poorly represented in the
data. The assessment was built on the FAO landings data table (FishStat J) which is not
totally coherent with other landing databases (national or regional databases) in terms
of species composition and area allocation.
Unfortunately, no coherent time series of discard rates at the global level can be
constructed on the basis of the series of FAO assessments. Therefore it is not possible
to estimate temporal trends in discard levels. However, it is worth noting that new
countries and regions start including in their legislation the words “bycatch” and
“discards” as a sign of an emerging political will to mitigate the wasteful practice of
discarding. Some examples are the European Union (reform of the Common Fisheries
Policy of 2013), Chile (Borges et al. 2016) and Australia. Moreover, efforts are being
made by RFMOs and RFBs in addressing bycatch and discard issues, but generally
they only include commercial species (FAO, 2015).
The range of policy options to reduce discards is determined both by the biological
characteristics of the fishery and its social and economic environment. Best practice in
discard reduction is illustrated by a number of countries in the Organization for Economic
Cooperation and Development (OECD), while many other countries, especially in Asia,
provide valuable experiences in the utilization of bycatch. Increased bycatch utilization
is now widespread in Asia, Africa and America leading to reduced discards (e.g. FungeSmith et al., 2005; Hutchinson et al, 2007; Lobo et al., 2010; Bage, 2013).
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PART II - RELATED ISSUES
5. Bycatch and discards of
endangered, threatened and
protected species
This chapter provides a global synthesis of the available data concerning one of the
most controversial components of bycatch associated with the capture and discarding
of endangered, threatened and protected (ETP) species in commercial and artisanal
marine capture fisheries. The chapter contains information in a report commissioned
by FAO for this project, which has recently been published in peer-reviewed journal
Reviews in Fisheries Biology and Fisheries (Gray and Kennelly, 2018). That review
examined the available data for key taxa in this category of bycatch (seabirds, turtles,
sea snakes, marine mammals, sharks, rays and teleosts) and provided a preliminary
estimate of discards in a global scale.
ETP species are generally defined by national legislations and international
agreements and assessments (e.g. the IUCN Red List, the MSC fishery standard, etc.).
The previous FAO report on global discards (Kelleher, 2005) contained a section
“Incidental catch and discards of charismatic and endangered species” (Section 4.2.3),
which briefly described the discarding of ETP and charismatic species. However, that
report did not provide an estimate of discards of ETP species.
5.1
ESTIMATES OF ETP SPECIES BYCATCH
Assessing the impact of fishing on ETP species poses several problems. In particular, there
is a lack of data because: (i) the species involved are almost always in low abundances so
their interactions with fishing gears are often sporadic; and (ii) fisheries interactions with
ETP species are usually viewed negatively and therefore are often not reported by fishers.
This means that the main source of reliable data on the discarding of ETP species comes
from observer programs using human observers and/or more recently EM system. When
Kelleher (2005) prepared his report, the number and extent of observer programs was
far less than the time frame covered by this report. There have been substantial advances
in identifying, quantifying and ameliorating incidental catches and discarding of ETP
species in marine fisheries throughout the world in the past 10-15 years. This, for the
first time, allowed FAO to make global estimates (albeit imprecise) of the bycatch and
discarding of ETP species in the world marine capture fisheries.
It was estimated that one million seabirds, 8.5 million sea turtles, 225 000 sea
snakes, 650 000 marine mammals and 10 million sharks, amounting to a total of
around 20 million individuals, were captured and discarded annually in global fisheries
(Gray and Kennelly, 2018). However, the study highlighted gaps and constraints in
datasets (across taxa, fisheries and regions) to produce such estimates with certainty
and precision. The inherently rare nature of ETP interactions with fisheries usually
preclude the conventional estimation of variances around extrapolated estimates.
The above estimates of the bycatch of ETP species are skewed to particular fisheries
and regions, with the most notable gap being small-scale (multi-method) coastal and
artisanal fisheries – both in developed and developing countries. Small-scale fisheries
could collectively have very large quantities of bycatch of ETP species, which might
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even exceed larger scale fisheries (Lewison et al., 2014; Pott and Wiedenfeld, 2017;
Temple et al., 2018). The major concern is that it is not only logistically difficult to
obtain reliable and robust estimates of bycatch, but it is also challenging to develop and
implement measures to reduce bycatch in these fisheries.
Much of the available data on ETP bycatch (particularly for marine megafauna) has
come from observer programs in high-value large industrial fleets (mostly longline and
trawl gear) that fish in the high seas. Whilst bycatch data from such direct observations
are most reliable, many observer-based programs have relatively small (< 10%)
coverage and restricted spatial and temporal resolutions that compromise the utility of
the data (for more discussion, see Babcock et al., 2003). Different levels of protection
are also afforded to different ETP species across countries and fisheries, complicating
the need and objectives of region-wide conservation efforts.
It is logistically difficult and expensive, and in most cases not viable, to implement
widespread observer surveys across all fisheries, particularly in the small-scale, multimethod artisanal fisheries in developing countries to quantify ETP species bycatch.
Consequently, alternative data collection methodologies are used, including self-reported
(e.g. logbook) data, and fisher and community-based surveys that rely on recall and
trust. Although such methodologies can provide valuable information, there is often a
reluctance by fishing industries and communities to report ETP species interactions (and
especially mortalities) in logbooks and other self-reporting schemes because of perceived
negative connotations and other socio-economic reasons. Validation and auditing systems
are therefore required to meet data quality standards (Kraan et al., 2013). It is noteworthy
that electronic monitoring using cameras can be quite useful in collecting bycatch data on
ETP species in such cases, especially megafauna species which can easily be identified by
video cameras. There is an urgent need to develop novel methods to quantify and report
ETP interactions in small-scale fisheries, which may include educational outreach and
collaboration with local communities.
Despite these data uncertainties, over the past decade there have been substantial
advances in the estimate of bycatch and associated mortality of ETP species (as well
as ameliorating these interactions) in marine fisheries (e.g. Anderson et al., 2011;
Lewison et al., 2014). But such advances have been far from uniform among groups
of organisms, fisheries and regions. For example, assessments of bycatch of sharks and
rays are still hampered by broad-scale species identification and amalgamation issues,
as well as basic non-reporting across fisheries and regions, despite worldwide concerns
of their overexploitation (Oliver et al., 2015).
Large knowledge gaps remain concerning fishery interactions with ETP species
throughout the world. Importantly, prioritizing the quantification and amelioration
of ETP bycatch both within and across fisheries also requires concomitant
assessments of discard mortality. In addition, sublethal effects on the fitness (in
terms of growth and reproductive success) of discarded individuals also requires
consideration (Wilson et al., 2014).
Part II – Related issues
5.2
MITIGATION OF ETP BYCATCH MORTALITY
The development and implementation of various bycatch mitigation measures have
reduced fishing-induced mortalities for certain ETP species in several fisheries. Although
further developments and refinements are required, the lack of implementation and
enforcement of existing best-practice mitigation techniques in many fisheries has
compromised reduction of mortality of ETP species (Gilman et al., 2008; Boyd, 2014).
A significant challenge to mortality reduction will be the uptake of existing and new
measures in many small-scale artisanal fisheries in developing countries. It is important
to note that when gear modifications are not viable or practicable, small changes in
fishing behavior and handling practice can have a positive impact on the survival of
discarded or released ETP species, notably sea turtles. Nevertheless, before we have
improved management policies and greater adoption of available mitigation measures
across all fisheries globally, bycatch remains a significant threat to many ETP species.
5.3
CONCLUSIONS
Improvements in future reporting of fishery interactions with ETP species will require
the implementation of internationally-agreed standardized data collection, analysis
and report criteria, with a particular focus on regions and fisheries that currently lack
any such reporting (i.e. the world’s many small-scale fisheries). Greater precision in
estimates of bycatch and associated mortality will require greater observer coverage
in spatial and temporal scales, augmented with novel analytical and modelling
techniques. Costs and benefits need to be weighed when determining optimal levels of
coverage across different types of fisheries. Risk-based analyses should be used to help
identify priority areas and appropriate types of data collection, particularly for datapoor fisheries. Whilst not addressed here, given the scale and importance of marine
recreational fisheries worldwide and their possible interactions with ETP species, ETP
bycatch and mortality in recreational fisheries should also be included in such data
collection regimes.
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6. Measures to manage bycatch
and reduce discards
There are various types of measures to manage bycatch and to reduce discards, including
modifications to fishing gear or fishing practices, spatial and temporal measures (time
and area restrictions), bycatch limits, effort restrictions and discard bans (landing
obligations). In addition, discards can be reduced through fleet communication,
awareness raising, training, and economic incentives. Many of these measures are aimed
at protecting juveniles and reducing discards of unwanted or prohibited species, but
they also often have other management objectives (Kelleher, 2005; Suuronen and Sardà,
2007; FAO, 2011).
6.1
SPATIAL AND TEMPORAL MEASURES (AREA AND TIME RESTRICTIONS)
Spatial management measures are widely used to manage bycatch and reduce discards
(Dunn et al., 2011; Little et al., 2015). These measures are usually established for
multiple purposes, for instance, to protect juveniles, spawning and foraging grounds,
migratory pathways, and areas of special biological interest. Spatial measures include
the creation of areas reserved for traditional fishing activities and areas where certain
gears are prohibited (e.g. no-trawl areas). Protected areas can be useful in ensuring that,
for example, portions of the spawning stock are protected.
Spatial measures are likely to be of particular use in regions and fisheries where
more sophisticated measures are not feasible, such as in multispecies fisheries in
tropical areas. With the increased use of vessel monitoring systems on smaller vessels,
such spatial measures are gradually less expensive to implement over large archipelagic
sea areas than, say, output-based measures. However, when impacts of establishing
closed areas are not assessed both before and during their implementation, it may
unintentionally increase discarding and cause other unexpected effects because of the
reallocation of fishing areas (e.g. Pastoors et al., 2000; Suuronen et al., 2010).
Real-time dynamic area closure schemes have emerged across Europe and North
America to protect juvenile fish and reduce discards (Little et al., 2015). Areas to be
closed are often related to distribution of juveniles, with information from real-time
monitoring on fishing activities. High catch of unwanted fish can trigger an area closure.
Real-time fleet communication can be an efficient tool to enable vessels to avoid fishing
grounds with high bycatch (Little et al., 2015; Gilman et al., 2006a). In Australia, this
type of dynamic spatial management is successfully used to avoid Bluefin tuna bycatch
and concomitant discards (Hobday et al., 2010). Real-time closures have the advantage
of responding to current conditions on the fishing grounds. They provide benefit to
fishers to develop, use and share information and technology to avoid undesired catch.
The disadvantage may be the high costs of administering such regimes.
Temporal measures such as seasonal closures are commonly used to reduce
mortality and discards of juveniles. For instance, a fishery may be open only when
the majority of fish in the area have reached a certain size. Time restrictions are often
applied in varying levels of detail, and seldom achieve full protection. For example,
often a particular season of the year is banned for a particular type of fishing.
6.2
BYCATCH QUOTAS (AND LIMITS)
Bycatch quotas are implemented in many fisheries, especially in the United States and
New Zealand. Because exceeding bycatch quota would trigger an early closure of the
Part II – Related issues
fishery, which would have serious economic consequences for fishers, they would more
likely to adapt or change their fishing gear and/or fishing strategy to reduce bycatch
(e.g. Holland, 2007). Fishers in general are concerned that bycatch quotas result in
loss in fishing opportunity and profit from their fishing. Furthermore, feasibility
and cost of establishing an observer program capable of providing the required level
of coverage to accurately estimate catch composition is a major concern in bycatch
quota management. Combining bycatch quotas with other measures, such as bycatch
avoidance through fleet communication, may help better achieve bycatch objectives
than a single management tool (O’Keefe et al., 2014).
6.3
EFFORT REGULATION
Overfishing contributes to discarding through declining average sizes of fish captured
which make the catch less marketable and hence more likely to be discarded (Cook,
2003). Alverson et al. (1994) noted that no other actions would likely contribute more
to reduction of bycatch and discards than the reduction of fishing effort, especially if
fisheries resources are overexploited. Reduction of fishing effort for instance through
a fleet capacity reduction or days-at-sea program, if properly applied, can make a
significant impact on discard quantities.
6.4
NO-DISCARD REGIMES (DISCARD BANS OR LANDING OBLIGATIONS)
Several countries pursue a no-discard (discard ban) policy and prohibit discards at sea.
The ultimate goal is to reduce or eliminate catch of unwanted fish through incentives
that promote selective fishing. No-discard legislation is often enforced only partially
in recognition of the unpredictable nature of fishing operations and various concerns
of the fishing industry. Some allowance is made to ensure that fisheries remain
economically viable with such a measure. A ban may stimulate opposition from the
fishing sector as has taken place in many regions in Europe as the EU started enforcing
its landing obligation measures (e.g. Damalas, 2015; Sarda et al., 2005 and Box 2).
Discard bans require broad industry support, flexibility in output controls, incentives,
and extensive surveillance and enforcement (Hall et al., 2000; Poos et al., 2010; Batsleer
et al., 2013; Guillen et al., 2018).
Guillen et al. (2018) noted that banning discards will inevitably induce diverse
short- and long-term ecological, economic and social impacts, which may determine
whether the objectives of the ban will be achieved. Thus, to ensure compliance but also
to mitigate fishers’ costs to meet the obligation, it is essential to further involve fishers
in the design of tailored and flexible policies at a métier level (Deporte et al., 2012).
On a positive note, as a consequence of the new EU Common Fisheries Policy
(CFP), a significant joint effort is being made in Europe by governments, the scientific
community, and the fishing industry to mitigate discarding practices by following an
Ecosystem Approach to Fisheries Management (see Annex D for more details).
Developing a financially viable mechanism for the disposal of landings of
unwanted catch may also be a challenge in many fisheries. Nonetheless, promoting
the development of new products from unwanted bycatch, and innovative trade and
marketing channels are required, but can be especially challenging in fisheries that land
their catch in remote locations with small human population sizes (e.g. for non-tuna
catch of some tuna purse seine fisheries; Lewis, 2016).
There are also measures banning the retention of some ETP species, encouraging
their non-capture. These measures may lead to fishing practices with enhanced
selectivity.
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BOX 2
The Landing Obligation in European Union fisheries
In the early 2000s, discarding in European Union (EU) fisheries received significant
attention and substantial political focus. Consequently, a ban on discarding (the landing
obligation) in EU fisheries was introduced as a core element of the Common Fisheries
Policy (CFP) reform in 2013. The landing obligation (LO), as defined in the basic
regulation of the CFP, required gradual phasing-in of the obligation to land all catches
across areas, fisheries and species (Article 15 of REGULATION (EU) No 1380/2013).
Under the landing obligation, which contains numerous exemptions, all catches must
be kept on board, landed, and deducted from established quotas. The LO applies only
to species or stock with established total allowable catch (TAC) and species covered
by minimum landing size regulations, the latter has since referred to as Minimum
Conservation Reference Size (MCRS). All fish that are below MCRS size must be landed
and deducted from the quota, but they cannot be sold for human consumption. This
is intended to discourage fishermen to catch small fish that cannot be sold. Overall,
introducing the LO has represented a fundamental shift in the management of EU
fisheries, switching from the regulation of landing to catch.
The reform aims at gradually eliminating the practice of discarding. It also aims to
provide more accurate data on catch by changing from a system that records the landed
fraction to the entire catch. The implementation of the landing obligation has taken place
gradually from 2015 and will continue through 2019 to cover all commercial fisheries in
European waters and European vessels fishing in high seas.
Exemptions to the landing obligation were established in order to lessen economic
impact to fishers and create a gradual transition to the new system. These exempt catches
must be documented in the logbook, but are not deducted from the quota. Species
Exemption means that species where discard survival is shown to be “high” may be
exempt from the LO based on scientific evidence. Differing, and contentious opinions
exist on the definition of this “high” survival. The exemptions also include a concept of
Minimum Allowable Discards. A small percentage (de Minimis) of continued discarding
is permitted annually. This is defined as a percentage of total annual catches subject to
the landing obligation and is based on two conditions: (i) improvements in selectivity
are difficult to achieve and (ii) handling and sorting present disproportionally high costs.
Defining the volume of these discarded fish is ambiguous. Other key issues include quota
flexibility (inter-annual vs. established) and species with minimum allowable discards.
Overall, the volume and justification for a minimum allowed discard system presents
significant challenges.
There are indications that “choke species” issues in mixed species fisheries managed
by single species TACs may present a strong driver to continue underreporting unwanted
catches of such species. Additionally, documentation of unwanted catches is difficult to
quantify in practice (e.g. slipped catches from purse seine). Overall, the adoption of the
landing obligation presents a fundamental shift in the management of European Union
fisheries. Numerous issues in the execution of the LO system must be continually
re-evaluated in order to ensure continued success and health of EU fisheries under the
new system.
6.5
SELECTIVE FISHING
Promoting more selective fishing is often the principal approach to reduce discards,
which has worked in many fisheries (e.g. Kennelly and Broadhurst, 2002; Hall and
Mainprize, 2005; Enever et al., 2009).
Part II – Related issues
Changes in fishing gear design and operation have long been employed by fishers to
achieve desired selective properties of fishing gear toward preferred catch compositions,
often to minimize the capture of certain age groups or unwanted species (Lokkeborg
and Bjordal, 1992; Kennelly and Broadhurst, 2002; Valdemarsen and Suuronen,
2003; Broadhurst et al., 2007; Graham et al., 2007; Madhu, 2018). Gear modifications
include, for example, changes in the size and shape of mesh and hook, longlines
leader material, escape panels in traps, acoustic alarms, biodegradable panels, square
mesh panels, underwater lights, sorting grids, and other bycatch reduction devices
(BRDs). Depending on the type of problem, solutions may also involve adjustments to
operational procedures and rigging of the gear.
Typically, active gears such as trawls and boat seines are less selective compare
to passive gears (e.g. Broadhurst et al., 2007). As in almost all fishing gear types,
the selectivity of trawl gears includes species selectivity and size selectivity. In size
selectivity research, the starting point for modifications has often been the trawl
codend, since this is where most size selection occurs (e.g. Wileman et al., 1996).
Selection in conventional diamond-mesh codends is highly variable and influenced by
numerous factors including size of mesh, as discussed above, but also hanging ratio,
twine thickness, diameter of codend, towing speed, towing depth, gear hauling practice
and weight of the catch (Lowry and Robertson, 1996; Broadhurst and Kennelly, 1996;
Dahm et al., 2002). The shape of mesh (e.g., square mesh) and knot orientation (e.g.,
T-90 mesh) of the codend also have great impacts on selectivity (He, 2007; Wienbeck
et al., 2011).
Developing species selective designs for trawls is particularly difficult when the
species to be separated are of the same size. To be effective, the selectivity system
has to utilize potential behavioral differences of these species (e.g. He, 2010). More
recently, innovative gear modifications that attempt to separate unwanted fish species
before they enter into trawls have been tested. Melli et al. (2018) demonstrated that
a simple counter-herding rope system (FLEXSELECT) installed in the front of the
trawl mouth significantly reduced finfish bycatch in crustacean trawls, but the rate
of reduction varied considerably among species and sizes of bycatch fish species.
Furthermore, studies that use LED lights in the headline or fishing line of a trawl have
shown promising results in reducing bycatch (Hannah et al. 2015).
In some cases, a shift away from demersal trawl toward more selective gear may
be the best option. Broadhurst et al. (2007) illustrated the potential of trap to harvest
penaeid shrimp, which may be considerably more selective than towed gears. Use
of alternative methods to capture fish may provide a completely different selectivity
pattern and in some cases could profitably substitute the problematic gear (Suuronen
et al., 2012). The switch to an alternative gear may also take place through regulations
that make the use of certain gear types illegal, like a trawl ban in Indonesia (Endryono,
2017), and the high seas driftnet ban enforced globally.
A necessary condition for any successful new regulation is the industry support.
The successful use of gear-related technical measures to reduce bycatch and discards
appears to depend largely on acceptance by industry (e.g. Suuronen and Sardà, 2007).
Effective management should create incentives for fishers to change their behavior, so
that in the long run the entire industry can benefit economically from the use of fishing
methods that reduce bycatch. This emphasizes the need for a close partnership with
industry in the introduction of more selective gears in a gradual and adaptive manner.
To ensure industry acceptance and adoption of modified designs, the implementation
process has to address the fact that the fishing sector has a limited capacity to accept
loss of catch of target species. The issue frequently becomes on what is the acceptable
loss of the targeted catch in order to improve selectivity and reduce bycatch (Kennelly,
2007). The loss of targeted catch could be offset via some compensatory increases in
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the value of catch or other measures such as additional days at sea or quota allocated
(Broadhurst et al., 2007; Suuronen and Sardà, 2007).
6.6
CONCLUSIONS
A wide range of measures to manage bycatch and reduce discards is presented.
However, such measures have to be employed as a package, often in conjunction with
other management measures in order to achieve desired goals.
Because discard practices are resulted from a wide range of factors and conditions,
the piecemeal approach used in many bycatch management measures can result in
unintended cross-taxa conflicts (Gilman et al., 2018). Hence, fisheries managers may
face a dilemma where regulations designed to reduce bycatch and discards of one
species, or species group, may increase bycatch or discards of another. It is therefore
essential, first, to have a good understanding of both environmental and socio-economic
dynamics of the fishery or fisheries concerned by the discard problem. Second, the
implication of relevant stakeholders should be identified in the decision-making
process in order to create a common vision to ensure acceptance and adoption of the
management measure. Finally, data collection of both fishery dependent (including
socio-economic data) and independent data has to be consistent with management
objectives in order to measure the effectiveness of the management plan and revise or
modify where needed.
Part II – Related issues
7. Mortality due to pre-catch,
discards and ghost fishing
Gear-related measures to reduce discards are considered important tools for conservation
on the assumption that fish escaping from a fishing gear or released following capture
survive and are subsequently recruited to the exploited population. But escapees may
not always survive (Main and Sangster, 1990; Suuronen, 2005; Broadhurst et al., 2006;
Gilman et al., 2013). In general, a fish has better chances to survive when it is released
or escaped from a fishing gear at early stages of capture and at the fishing depth than
those escaped during hauling or those released or discarded from the vessel deck after
capture (He, 2015). For many species and fishing gears, there are currently no reliable
estimates of escapee survival and failing to quantify the biological impact of this
mortality can result in biased evaluations on the benefit of bycatch reduction devices
and designs.
The main sources of such mortality include pre-catch losses and discards mortality.
However, losses may also occur from ghost fishing mortality and other combined
effects of interacting sources of stress and injury from fishing operations (Chopin and
Arimoto, 1995; Gilman et al., 2013). All these components of mortality have one thing
in common: they are generally not easily quantifiable during fishing operations, but
instead must be estimated through elaborative research. The relative proportions of
these components vary by fishing gear, method, fishery and vessel, as well as spatially
and temporally (Gilman et al., 2007, 2013).
7.1
PRE-CATCH MORTALITY
Pre-catch losses occur when organisms are caught, or collide with the vessel or gear,
and die but are not brought on board when the gear is retrieved (Chopin and Arimoto,
1995; Broadhurst et al., 2006; Gilman et al., 2013). For example, fish may die and fall
from the gear before retrieval, or crew may intentionally release a portion of or the
entire catch prior to landing on board, often referred to as ‘slipped’ catch (Box 1). Precatch losses may also occur when organisms are excluded or escape from the gear but
die later.
Most experiments that have examined pre-catch losses have focused on mortality
of fish escaping from trawl codends, and documented, in general, relatively high precatch survival rates for those finfish species investigated (Broadhurst et al., 2006).
However, survival is highly species- and size-dependent (Soldal et al., 1993; Misund
and Beltestad, 2000; Ingolfsson et al., 2007). Demersal species generally have a higher
likelihood of survival compared to small pelagic species that are sensitive to process of
capture by and escape from a trawl (Suuronen et al., 1996a; 1996b).
Fish size is an important factor affecting pre-catch mortality in some gear types, with
smaller size classes in general having higher vulnerability (Breen et al., 2007; Tenningen
et al., 2012). There can also be great variations in pre-catch mortality by season, time of
day, gear soak time, haul duration, and gear design, including the location and design
of BRDs in trawl nets (Breen et al., 2007; Suuronen and Erickson, 2010).
Stresses and injuries that contribute to the probability of pre-catch mortality happen
during the process of interacting with the gear. Stresses include enduring swimming
that may lead to exhaustion and suffocating due to a lack of oxygen when density of
fish is high in the catch. Injuries are resulted from crushing and wounding when in
contact with the trawl netting, colliding with other organisms, scale loss when escaping
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through a mesh or a BRD (Davis, 2002; Broadhurst et al., 2006). High catch densities
amplify the effects of these stressors. Other stressors are related to environmental
factors that the organism encounters after escape from the gear, such as water
temperature, light conditions, currents, water pressure and sea state.
Fish may also escape from a gear near the surface while the gear is being hauled on
board (e.g. Madsen et al., 2008) and little is known about the mortality of these fish.
Preliminary experiments, however, has showed that a much smaller proportion of
haddock escaping at the surface survived compared to those escaping at fishing depth
(Breen et al., 2007). The higher mortality rate of surface escapees was most likely due
to barotrauma, aerial predation and higher or lower water temperatures.
Methods to avoid, minimize and offset pre-catch fishing mortality are similar to
those for mitigating capture and discard fishing mortality. For example, the use of
small gillnet mesh sizes to reduce catches of sea turtles, marine mammals, large species
of seabirds and other large organisms (Price and Van Salisbury, 2007; Murray, 2009)
will likely reduce pre-catch mortality of these larger organisms. However, some
methods that reduce catch may have unintended consequences of increasing pre-catch
mortality. For example, using monofilament leaders instead of wire leaders can reduce
shark bycatch in pelagic tuna longlines, but it might increase shark pre-catch mortality
because these sharks swim away with a hook in their mouth (Ward et al., 2008; Gilman
et al., 2016b). Some methods that reduce discards such as using circle hooks instead of
J-hooks, may reduce pre-catch mortality due to less injury to escaped organisms (e.g.,
Gilman and Huang, 2017).
7.2
DISCARD MORTALITY
Discard mortality occurs when fish die after they are brought on board and
subsequently discarded; it may be alive when they are discarded but stressed and
injury they suffered during capture, handling and discarding process may cause them
to die later. Some species, such as flatfishes, crustaceans, and elasmobranchs, are more
“hardy” and may survive better (Hill and Wassenberg, 1990; Van Beek et al., 1990). For
example, 90% of blue sharks released alive from pelagic longline vessels were believed
to have survived the capture and release process (Moyes et al., 2006; Campana et al.,
2009; Musyl et al., 2011).
Studies on the survival of finfish discarded from trawler decks have generally
documented high discard mortality rates, although types and severity of injuries which
generally impact mortality are highly specific to the fishing gear used, operational
modes, environmental conditions, species and size, and handling and release practices
(Broadhurst et al., 2006; Parker et al., 2006; Benoît et al., 2010). Discard mortality
may occur due to fatal wounds or increased probability of fatal diseases resulting
from injuries incurred during interactions with the gear (Swimmer et al., 2006; Snoddy
and Southwood Williard, 2010; Gilman, 2011). In many multi-species bottom trawl
fisheries discard mortality may represent a large source of uncertainty for estimates of
total fishing mortality (Suuronen, 2005).
Lower discard mortality probability is often associated with shorter air exposure time
and lower air temperature (above freezing) on deck (Broadhurst et al., 2006; Suuronen
and Erickson, 2010). Impacts of air temperature on fish deck may be compounded by
direct sunlight and many other stressors. Extreme thermoclines with high surface water
temperature may adversely affect survival of discarded fish (Erickson et al., 1997). Soak
time in passive gears or tow duration in active gears, fishing depth, catch amount and
composition in towed nets, and the temperature of sea water are other factors that may
significantly affect discard mortality (Gilman et al., 2012, 2013).
The size and species of pelagic sharks has been observed to have a significant effect
on the probability of discard mortality (Diaz and Serafy, 2005; Hight et al., 2007;
Mandelman et al., 2008). Smaller fish are generally weaker and more sensitive to
Part II – Related issues
capture and handling stress (Broadhurst et al., 2006). Fish species with gas bladders
and other organs that enable positive buoyancy are vulnerable to barotrauma, and
as a result, are more likely to suffer internal injuries compared to species lacking gas
bladders. They are less capable of returning to the depth after release, and more likely
predated by pelagic and aerial predators (Davis, 2002; Benoît et al., 2013).
Differences in discard mortality between and within taxonomic groups are also
related to fragility and other physical characteristics of the animal. For instance,
invertebrates with protective shells or exoskeletons are less likely fatally damaged
from gear contact and handling than animal without such protection (e.g. Hill and
Wassenberg, 1990; Lancaster and Frid, 2002; Bremec et al., 2015). Likewise, leatherback
sea turtles (Dermochelys coriacea) may be more delicate and experience higher risk of
injury from fishery interactions than hard-shelled turtles (Ryder et al., 2006). Other
reasons for differential probabilities of cryptic mortality between species and between
taxonomic groupings include differences in their propensity for scale loss and skin
damage, and differences in sensitivity to changes in temperature, both in the water
during haul back and air temperature on deck (Davis and Olla, 2001, 2002; Suuronen
and Erickson, 2010).
7.3
GHOST FISHING MORTALITY
Ghost fishing occurs when lost, abandoned or otherwise discarded fishing gear
(ALDFG) continues to catch and kill organisms (Fowler, 1987; Matsuoka et al., 2005;
Macfadyen et al., 2009). Various factors affect the ability, efficiency and duration of
ALDFG to ghost fish. Organisms caught in derelict nets, traps and other gear types can
attract scavengers, which subsequently are caught, causing long-term ghost fishing due
to this self-baiting mechanism (Kaiser et al., 1996; Matsuoka et al., 2005).
Methods to reduce ghost fishing mortality include preventative approaches that
reduce gear loss and abandonment such as gear marking (He and Suuronen, 2018).
Properly marked gear can help identify the owner, which may create a disincentive for
intentional abandonment or discarding of gear, increase visibility of passive gear, which
could reduce gear conflicts and damage by passing vessels to reduce accidental gear
loss (Huntington, 2017 a & b). Remedial methods to mitigate ghost fishing include,
for example, programs to detect and remove ALDFG and the use of less durable
and biodegradable gear to reduce their ghost fishing duration (Gilman et al., 2016a).
The newly-adopted FAO Voluntary Guidelines on the Marking of Fishing Gear will
greatly contribute to the prevention of ALDFG and reduction of its harmful impact
on marine environment, ghost fishing and entanglements of ETP species (FAO, 2018).
7.4
OTHER COMPONENTS OF INDIRECT MORTALITY
Collateral sources of fishing mortality are those that are indirectly caused by various
ecological effects of fishing (ICES, 2005). Examples in this category are diverse,
complex and difficult to quantify, in part, because there is great uncertainty in inferring
main factors that cause mortalities (Jones, 1992; Gilman et al., 2013). For example,
animals escaped from fishing gear or discarded from vessels are often displaced from
suitable habitat for shelter and may experience predation near the sea surface and in
the water column, increasing the risk of predation as they sink or swim back to their
preferred habitat (Broadhurst et al., 2006).
Injuries and stress sustained by organisms interacting with fishing operations can
be caused by many factors, where cumulative and interacting effects of these factors,
both individually and repeated sub-lethal interactions, result in mortality (Davis, 2002).
For example, Caddy and Seijo (2011) estimated that high proportions of juveniles may
be subject to mortality from repeated interactions when trawling occurs in nursery
areas. Jorgensen et al. (2005) and Ingolfsson et al. (2007), however, did not observe
any marked additional mortality in Atlantic cod as a result of repeated escape from
35
36
A third assessment of global marine fisheries discards
trawls. It is worth noting, however, that the latter is a species that has proven to have a
relatively low probability of escapee mortality (Breen et al., 2007).
Cumulative and interacting effects of multiple factors that an organism encounters
during the capture process may result in higher mortality than the sum of mortality
resulting from individual factors (Gilman et al., 2013). For example, while moderate
damage to finfish skin alone is unlikely to induce mortality, when combined with
exhaustive swimming in a trawl, plus extreme temperature changes, this may cause fish
to die, for instance, through metabolic acidosis or osmoregulatory failure.
7.5
CONCLUSIONS
The International Guidelines on Bycatch Management and Reduction of Discards
(FAO, 2011) included recommendations for member States to identify, quantify
and reduce impacts of mortality from pre-catch losses and ghost fishing and to
maximize discard survival. A good understanding of factors causing such indirect
fishing mortality is necessary to estimate levels and rates of removals, and to devise
measure for mitigation. As a result of the complexity that causes such removals during
various aspects of fishing operations, few studies have estimated such fishing-related
mortality accounting for the full suite of ways an organism can interact with the gear
and stresses and injuries caused by fishing operations (Suuronen, 2005; Broadhurst
et al. 2006). This creates uncertainty in estimates of the probability of mortality. This is
especially relevant to collateral, cumulative and interactive sources of mortalities, due
to indirect and relatively highly complex nexus between stressors and removals for
these components.
There remains limited understanding of collateral mortality rates or broader
community-level changes caused by fishing. For example, there is limited knowledge
of the relative importance of collateral removal resulting from artificial drifting floating
objects, including FADs and masses of derelict gear and other marine debris, or from
enduring or permanent shifts in benthic community structure and functions resulting
from direct physical contact with fishing gear and discards (Hall et al., 2000; Kaiser
et al., 2006; Dagorn et al., 2010; FAO, 2010).
For some gear types and species groups, significant progresses have been made
to identify best handling and release practices to maximize probability of survival
of discarded animals. For example, best practices handling and release methods for
seabirds and sea turtles captured in longline fisheries, and to release dolphins from
purse seines, have been developed (Hall, 1996; AIDCP, 2009; FAO, 2010). Certain
factors that significantly affect finfish discard mortality can be controlled, such as
controlling crowding and aerating the net prior to landing, minimizing the time
exposed to air, avoiding adverse environmental conditions on deck (e.g. high air
temperatures), reducing the risk of barotrauma, employing best practices to remove
tackle prior to release, and reducing stress and injury from the release process
(Davis, 2002; Broadhurst et al., 2006).
37
PART III – CONCLUSIONS
8. General Conclusions
This report is the third decadal report concerning a major part of fisheries resources
–unwanted and discarded fish, and endangered, threatened and/or protected species.
The report contains two major new outcomes concerning marine fisheries: (i) an
annual discard quantity of around 9.1 million t, and (ii) at least 20 million individuals
of endangered, threatened and/or protected species interacted with capture fisheries
annually.
The first outcome indicate that world fisheries are still discarding some organisms,
despite of a general improvement in fisheries management, the implementation of
bycatch reduction devices in many problematic fisheries and greater utilization of the
fish. While there is still long way to go to achieve optimum selectivity and utilization,
it is encouraging that new countries and regions (including RFMOs and RFBs) start
including in their legislation the words “bycatch” and “discards” as a sign of an
emerging political will to mitigate the wasteful practice of discarding.
It is difficult to quantify the progress in reducing discards but this report indicates
that in the last 10 years there is a greater scrutiny of such issues via the public reporting
of discards. This may include country-specific reports such as the USA’s National
Bycatch Reports, reporting and minimizing discards required by third-party certifying
entities such as the Marine Stewardship Council, and the consequential increase in the
number and scale of onboard observer and electronic monitoring programs.
Regarding fisheries interactions with endangered, threatened and/or protected
species (ETP), it was estimated that twenty million individuals interacted with fishing
operations worldwide, some of which lead to mortality of the animals. While overall
impact is difficult to assess for all species, for some species that are in very low
population levels, mortality associated with fishing is a major concern. However, such
an estimate was noted in this report to be very tenuous due to the lack of solid data
for many fisheries and for many parts of the world. Therefore, more effort is needed
to better quantify fisheries interactions with such species, and to implement measures
to reduce such interaction, especially those leading to mortality, with a collaborative
approach that involves all relevant stakeholders.
This report also summarized the status of other issues concerning bycatch and
discarding, including (i) measures to manage bycatch and to reduce discards and
(ii) challenges associated with estimating cryptic sources of fishing mortality such as
pre-catch, discard and ghost fishing mortality.
39
Annexes
A. Method
A.1– THE ESTIMATE OF AVERAGE GLOBAL QUANTITY OF DISCARD HAS EXCLUDED:
FAO areas
Countries1
Taxa
Fisheries2
Europe - Inland waters
American Samoa
Algae
MIS gear type
Africa - Inland waters
Bermuda
Aquatic plants
under the gear
America, North - Inland waters
Bonaire/S.Eustatius/Saba
Rhodophyceae
type estimate GE
America, South - Inland waters
Bosnia and Herzegovina
Gracilaria spp
Asia - Inland waters
British Indian Ocean Ter
Porphyra spp
Oceania - Inland waters
China, Hong Kong SAR
Gelidium spp
China, Macao SAR
Phaeophyceae
French Southern Terr
Macrocystis spp
Greenland
Lessonia spp
Guam
Chlorophyceae
Iraq
Ulva spp
Mayotte
Invertebrates (except sea urchins)
Netherlands Antilles
Ascidiacea
Niue
Asteroidea
Northern Mariana Is.
Echinodermata
Palau
Polychaeta
Réunion
Gorgoniidae
Saint Barthélemy
Actiniaria
Saint Helena
Scleractinia
Saint-Martin
Antipatharia
Sint Maarten
Rhopilema spp
St. Pierre and Miquelon
Cnidaria
Sudan (former)
Spongiidae
United Arab Emirates
Spongilla spp
Wallis and Futuna Is.
Reptiles
Zanzibar
Amphibian
Marine
mammals
Freshwater fish
1
2
The total sum of landings from these countries is 772 117 tonnes.
The total sum of landings from these fisheries is 4 460 179 tonnes. See Subsection 2.2.2 in Methods.
A third assessment of global marine fisheries discards
40
A.2– CODES USED IN THE DATA TABLES AND DATASET: (GEAR, AREA AND TARGET)
Gear code
Gear name
FAO Area Code
Ocean code
Area name
DRB
Boat dredges
Area 21
nwA
northwest Atlantic
FPO
Pots
Area 27
neA
northeast Atlantic
FSN
Stow nets
Area 31
wcA
western central Atlantic
FWR
Barriers, fences, traps, etc.
Area 34
ecA
eastern central Atlantic
GNB
Gillnet, bottom
Area 37
mbs
Mediterranean and Black sea
GNP
Gillnet, pelagic
Area 41
swA
southwest Atlantic
GNS
Gillnet Surface & Bottom
Area 47
seA
southeast Atlantic
GTR
Trammel nets
Area 51
wIO
western Indian ocean
HL_
Handlines
Area 57
eIO
eastern Indian ocean
LL_
Longlines, Surface & Bottom
Area 61
nwP
northwest Pacific
LLB
Longlines, bottom
Area 67
neP
northeast Pacific
LLP
Longlines, pelagic
Area 71
wcP
western central Pacific
LNB
Boat-operated lift nets
Area 77
ecP
eastern central Pacific
LTL
Trolling lines
Area 81
swP
southwest Pacific
MIS
Miscellaneous/not known
Area 87
seP
southeast Pacific
OTB
Otter trawls, bottom
Area 48
AO
Antarctic ocean
OTM
Otter trawls, midwater
Area 58
AO
Antarctic ocean
OTS
Shrimp trawl
Area 88
AO
Antarctic ocean
OTT
Otter twin trawls
PL_
Pole-and-line
PS_
Purse seine
PTB
Pair trawls, bottom
PTM
Pair trawls, midwater
SB_
Beach seines
SV_
Boat seines
TBB
Beam trawls
Target Species Group
Definition
demersal fish
all demersal fish including reef associated fish and the majority of coastal fish
pelagic fish
all pelagic fish but tunas, bonitos and billfish
tuna
tunas, bonitos and billfish (ISSCAAP group 35)
crustaceans
all crustaceans (ISSCAAP groups from 41 to 47)
cephalopods
all cephalopods (ISSCAAP group 54)
molluscs (excluding cephalopods)
all molluscs (excluding cephalopods) (ISSCAAP groups 51, 52, 53, 55 and 56)
mixed
can include a mix of 2 (or more) different categories
Annexes
41
B. Results
Supplementary tables
TABLE B.1.
Posterior mean discard rates, 95% credible intervals and sample sizes (N, number of compiled
discard rate records per gear type3), for 25 gear categories
Discard Rate
3
Gear Category
Gear
Code
Barrier, fence, trap, etc.
FWR
0.039
0.002
0.568
2
Purse seine
PS
0.047
0.039
0.056
60
Longline, pelagic
LLP
0.074
0.058
0.094
42
Pole-and-line
PL
0.094
0.064
0.144
5
Handline
HL
0.095
0.019
0.442
2
Lift net, boat-operated
LNB
0.100
0.012
0.619
1
Gillnet, pelagic (driftnet)
GNP
0.117
0.074
0.190
13
Otter trawl, midwater
OTM
0.121
0.082
0.182
26
Longline, bottom and pelagic
LL_
0.134
0.110
0.164
66
Boat dredge
DRB
0.138
0.110
0.173
15
Seine, beach
SB
0.148
0.057
0.344
6
Pots
FPO
0.166
0.121
0.222
30
Stow net
FSN
0.172
0.080
0.361
2
Gillnet, surface and bottom
GNS
0.174
0.088
0.329
4
Trammel net
GTR
0.182
0.132
0.251
21
Trawl, pair, midwater
PTM
0.192
0.033
0.735
1
Trolling lines
LTL
0.199
0.068
0.498
5
Longline, bottom
LLB
0.239
0.180
0.311
24
Gillnet, bottom
GNB
0.261
0.198
0.338
28
Otter trawl, bottom
OTB
0.309
0.275
0.346
118
Trawl, otter twin
OTT
0.435
0.285
0.600
9
Trawl, beam
TBB
0.457
0.377
0.538
22
Trawl, pair, bottom
PTB
0.482
0.141
0.878
1
Seine, boat
SV
0.506
0.358
0.657
9
Trawl, shrimp
OTS
0.549
0.500
0.596
68
See Discard Rate table.
Mean
Lower
95% CI
Upper
95% CI
N
A third assessment of global marine fisheries discards
42
TABLE B.2.
Estimates of mean discards levels (t) and 95% credible intervals by gear type.
N=number of fishery records4
Annual discard level (t)
4
Gear type
Gear
Code
Lower
95% CI
Stow net
FSN
149
0
308
2
Longline, bottom and pelagic
LL_
6 530
5 312
7 747
6
Trammel net
GTR
10 565
9 052
12 077
30
Mean
Upper
95% CI
N
Barrier, fence, trap, etc.
FWR
13 393
0
50 218
22
Lift net, boat-operated
LNB
27 836
8 470
47 202
8
Pole-and-line
PL_
33 487
30 052
36 923
44
Trolling lines
LTL
39 872
0
87 853
36
Seine, beach
SB_
40 754
21 592
59 917
27
Trawl, pair, midwater
PTM
58 791
0
188 622
14
Longline, pelagic
LLP
97 761
93 264
102 257
233
Gillnet, surface and bottom
GNS
100 152
83 307
116 997
28
Pots
FPO
177 720
169 280
186 161
141
Boat dredge
DRB
198 365
170 441
226 289
38
Trawl, pair, bottom
PTB
225 981
0
900 841
11
Longline, bottom
LLB
252 082
227 015
277 149
111
Trawl, otter twin
OTT
291 505
200 827
382 184
11
Gillnet, pelagic
GNP
299 451
278 840
320 062
132
Handline
HL_
323 116
90 692
555 539
124
Gillnet, bottom
GNB
393 499
369 233
417 764
78
Trawl, beam
TBB
423 905
356 222
491 588
16
Seine, boat
SV_
478 112
398 800
557 423
50
Miscellaneous
MIS
526 292
485 699
566 885
61
shrimp trawl
OTS
836 397
787 175
885 619
90
Otter trawl, midwater
OTM
881 240
770 777
991 703
102
Purse seine
PS_
1 019 002
916 306
1 121 699
203
Otter trawl, bottom
OTB
2 383 849
1 994 561
2 773 138
236
See Fishery Table.
Annexes
43
TABLE B.3
Discard levels (t) and rates (t discards / t catch) by FAO Major Fishing Area. CI=confidence interval,
HDI=highest posterior density interval, N=number of fishery records
Annual discard level (t)
FAO Area
Region name
48, 58,
88
Antarctic
Mean
18 773
Lower
95% CI
15 630
Discard rate
Upper
95% CI
21 916
Expected
Lower
95%
HDI
Upper
95%
HDI
0.075
0.064
0.085
N
37
81
Southwest Pacific
58 584
50 178
66 991
0.095
0.083
0.104
28
47
Southeast Atlantic
201 160
176 514
225 805
0.131
0.119
0.137
56
37
Mediterranean and
Black sea
239 824
206 801
272 848
0.184
0.165
0.191
176
77
East central Pacific
298 277
245 501
351 052
0.170
0.146
0.183
69
31
Western central
Atlantic
332 832
299 633
366 031
0.228
0.214
0.229
225
57
Eastern Indian
340 800
318 144
363 457
0.045
0.042
0.047
81
67
Northeast Pacific
341 336
259 005
423 667
0.123
0.096
0.140
34
87
Southeast Pacific
366 877
159 725
574 029
0.041
0.018
0.060
62
21
Northwest Atlantic
424 333
385 473
463 193
0.205
0.194
0.211
87
41
Southwest Atlantic
683 798
585 248
782 347
0.291
0.267
0.284
78
71
Western central
Pacific
706 291
692 202
720 379
0.055
0.054
0.056
131
51
Western Indian
743 352
679 670
807 034
0.150
0.143
0.150
210
34
East central Atlantic
811 547
736 021
887 073
0.181
0.175
0.178
245
27
Northeast Atlantic
1 551 318
757 833
2 344 803
0.162
0.086
0.184
271
61
Northwest Pacific
2 020 705
1 864 773
2 176 636
0.091
0.086
0.095
64
44
A third assessment of global marine fisheries discards
C. Progress on compliance
with the Code of Conduct for
Responsible Fisheries regarding
bycatch and discards
Article 4 of the Code of Conduct for Responsible Fisheries (hereafter, the Code)
states, inter alia, that FAO will report regularly to the Committee on Fisheries (COFI)
concerning the implementation of the Code, including issues related to bycatch and
discards (FAO, 1995). Progress reports are produced based on the responses from
Members, RFBs and NGOs to a web-based version of the questionnaire on the
implementation of the Code (add citation for the website). This web-based reporting
system has resulted in the possibility of analysing important information on the
activities and applications of the Code at the various levels, hence making the key
findings of the progress report more valuable. The following summary of the analyses
on the implementation of the Code is focused on sections of FAO’s web-based
reporting system related to bycatch and discards for years 2011, 2013 and 2015.
There has been an increase in the number of responses per year in all sections of the
questionnaire. These responses reflect that, on the one hand, an increased number of
countries are monitoring bycatch and discards and implementing measures to minimize
them, including protection of juveniles and ghost fishing prevention (Figure C.1). On
the other hand, countries reporting that bycatch problems do exist in their fisheries
has slightly decreased in 2013 and 2015 compared to 2011 (Figure C.2). Among those
countries which were implementing measures to promote the improved use of bycatch
in fish processing, awareness raising and training/dialogue with processors together
with the implementation of a mandatory landing of bycatch in given fisheries appeared
to be the most effective measures (Figure C.2).
Regarding the status of IPOA-Sharks implementation, an increasing number of
countries were conducting assessments from 2011 to 2015 to determine whether
a NPOA-Shark is needed (Figure C.3). At least 80% of respondents that haven’t
conducted the assessment were willing to do so. More than 70% of those which
concluded that an NPOA-Shark was needed already had one in place and the rest were
willing to develop it.
In relation to the status of national IPOA-Seabirds implementation, respondents
in 2011 where longline, trawl and/or gillnet fisheries occurs in their national waters,
conducted more assessments to determine the necessity of implementing a NPOASeabirds than those that responded in 2013 and 2015. In turn, there was a decline on
assessments which concluded that an NPOA-seabirds was necessary respectively from
2011 to 2015. More than 60% of those which concluded that an NPOA-Seabirds was
necessary already had one in place and 100% of the rest were willing to develop one
only in 2011 and 2013.
Annexes
45
FIGURE C.1
% of respondents
Percentage of responses from Member countries to questions of the section on “management of
bycatch and discards” for 2011 (blue), 2013 (red) and 2015 (green). Numbers in parentheses represent
total numbers of responses to each question per year. Responses come from Member countries from
the following regions: Africa, Asia, Europe, Latin America and Caribbean, Near East, Northern America
and southwest Pacific. *Number of positive responses only
100
90
80
70
60
50
40
30
20
10
0
Formally
Bycatch and
Countries where
bycatches and monitor bycatch discards are
found to be
discards occur in and discards
unsustainable*
major fisheries
Global (45) and averages 2011
Management
measures to
minimize
bycatch and
discards are in
place*
Global (78) and averages 2013
Protection of
juveniles*
Ghost fishing*
Global (92) and averages 2015
FIGURE C.2
% of respondents
Percentage of responses from Member countries to questions of the section on “Most effective
measures taken by Government to promote the improved use of bycatch in fish processing” for 2011
(blue), 2013 (red) and 2015 (green). Numbers in brackets represent total numbers of responses to each
question per year. Responses come from Member countries from the following regions: Africa, Asia,
Europe, Latin America and Caribbean, Near East, Northern America and southwest Pacific
100
90
80
70
60
50
40
30
20
10
0
Countries
reporting that
bycatch
problems do
exist in their
fisheries
No measure
taken
Global (44) and averages 2011
Awareness
raising and
training/
dialogue with
processors
Mandatory
Improvement of
Fostering
landing of
handling
adoption of new
bycatch in given infrastructures
processing
fisheries
and conservation
techniques and
facilities
technology
Global (81) and averages 2013
Global (91) and averages 2015
A third assessment of global marine fisheries discards
46
FIGURE C.3
Percentage of responses from Member countries to questions of the section on “Summary information
relating to the status of national IPOA-Sharks implementation” for 2011 (blue), 2013 (red) and 2015
(green). Numbers in brackets represent total numbers of responses to each question per year. Responses
come from Member countries from the following regions: Africa, Asia, Europe, Latin America and
Caribbean, Near East, Northern America and southwest Pacific. * only refer to the group of countries that
have conducted an assessment; ** only refer to the group of countries which have not yet conducted an
assessment; *** only refer to the group of countries that concluded that a plan was needed
100
90
% of respondents
80
70
60
50
40
30
20
10
0
Countries where
sharks are caught
(target or
bycatch)
Assessment
conducted
Global (44) and averages 2011
Intention to
Assessment not NPOA-sharks is
Assessment
in place ***
develop an
concluded that an conducted but
NPOA-sharks***
NPOA-sharks is planning to **
needed *
Global (78) and averages 2013
Global (90) and averages 2014
FIGURE C.4
Percentage of responses from Member countries to questions of the section on “IPOA Seabirds:
Mitigation measures applied to longline fisheries” for 2011 (blue), 2013 (red) and 2015 (green).
Numbers in brackets represent total numbers of responses to each question per year. Responses come
from Member countries from the following regions: Africa, Asia, Europe, Latin America and Caribbean,
Near East, Northern America and southwest Pacific. * only refer to the group of countries that have
conducted an assessment; ** only refer to the group of countries that has not yet conducted an
assessment; *** only refer to the group of countries that concluded that a plan was needed
100
90
% of respondents
80
70
60
50
40
30
20
10
0
Countries where
longline, trawl
and/or gillnet
fishing occurred in
waters under their
jurisdiction
Assessment
conducted
Total (42) and averages 2011
Assessment
concluded that an
NPOA-seabirds is
needed *
Assessment not
conducted, but
planning to**
Total (77) and averages 2013
NPOA-seabirds is
Intention to
in place***
develop an NPOAseabirds***
Total (89) and averages 2015
Annexes
D. DiscardLess and other efforts
in European Union to mitigate
discards
The landing obligation in the new EU Common Fisheries Policy (CFP) aims for a
gradual elimination of discards of commercially exploited stocks on a case-by-case
basis (Regulation (EU) No 1380/2013 of the European parliament and of the council
of 11 December 2013 on the Common Fisheries Policy).
As a consequence of the reform of the CFP, governments, scientific institutions,
fishing industry, fishermen and other stakeholders in the European Union have worked
together to find technologically feasible, environmentally sustainable and economically
viable solutions for realization of the landing obligation. Large EU-wide projects such
I-Seas (I-Seas project, n.d.), Minouw (Minouw, n.d.) and DiscardLess (DiscardLess,
n.d.), funded by the EU (EU, n.d.), address this issue in a comprehensive manner.
Each project has its own unique characteristics defined by their main focus, yet they
share many common features such as: (i) avoid unwanted catches, or where this cannot
be reasonably or practically achieved, to utilize them productively and sustainably;
(ii) involve multi-stakeholder engagement in the design and implementation of actions;
(iii) demonstrate the environmental and socio-economic impacts/benefits that the
implementation of proposed innovative solutions and the new management model
may have to the fishing sector; (iv) increasing awareness of the problem of unwanted
catches and the solutions that are available; and (v) disseminate knowledge through
open-access publications and scientific papers.
The objective of the DiscardLess project was to develop practical, achievable,
acceptable and cost-effective Discard Mitigation Strategies to either avoid or utilise
unwanted catch, in order to reduce discards while maintaining viable fisheries.
DiscardLess were to integrate knowledge, tools and technologies at local, national,
EU and international levels to provide and promote solutions needed to implement
such strategies throughout the seafood supply chain. Further, the project were also to
assess the effects of discard reduction policies on the ecosystem, economic and social
sustainability, and provide feedback for improved fisheries management. DiscardLess
results are thus essential in the achievement of policy goals of reducing waste and
increasing the net economic value of fisheries for society.
The good intentions of reducing discards in EU fisheries must be followed by effective
implementation using the right methods and processes on a fishery specific basis. In the
2015 North Sea demersal fishery alone, the introduction of a landing obligation without
changes in behaviour of the fishery or marketing of currently discarded catches, would
result in forgone landings worth 300 million euros (about 47% of total landed value), as
the fishery being halted when the first TAC was exhausted (ICES, WGMIXFISH 2014
report). However, on longer time scales, landing discards has the potential to increase the
return for the fishery while promoting human health.
DiscardLess addresses both the short-term challenges and the potential benefits
to allow the practical implementation of the landing obligation while making it
understandable and legitimate across the whole supply chain, from stakeholders to
consumers. To specifically address these challenges, DiscardLess are working in close
cooperation with stakeholders and policy makers to:
47
A third assessment of global marine fisheries discards
48
•
•
•
•
Assess the impact of discards on the ecosystem, economy and society
Investigate the drivers of discarding, and identify how those can be abated
Develop user-based innovative tools and strategies to avoid unwanted catches
Develop innovative methods and new value chains to handle and use unavoidable
unwanted catches
• Enhance controllability of and compliance with the landing obligation policy
via the development of operational and cost-effective tools for traceability and
monitoring
• Formulate policy guidelines to reduce incentives to discard and promote the
adoption of alternative mitigation strategies, and support other maritime policies
• Integrate the gathered knowledge on discard mitigation strategies and transfer it
widely
The collaborative approach of DiscardLess ensures that the developed tools,
information and strategies will provide relevant, acceptable and cost-effective means
with a wide uptake by the fishing industry which would result in the achievement of the
goals of the landing obligation. The DiscardLess project was to extend for 48 months
(2015-2019). The project has been funded by EU and the partners, and is coordinated
by DTU Aqua (Denmark). The project has 31 partners in 12 countries, including
9 universities, 9 small medium enterprises, 8 research institutes, 3 multinational
companies and 2 organisations.
49
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Bycatch and discards threat sustainable fisheries by inflicting unnecessary mortalities.
Sound management of bycatch and reduction of discards in capture fisheries will lead to
healthy ecosystems and sustainable fisheries, contributing to long-term global food
security, and alleviation of poverty, especially for coastal communities and Small Island
Developing States which heavily depend on fish as food, fisheries as the main source of
employment, and fishing as a way of life. Accurate and timely assessment of bycatch and
discards provide necessary data for making sound management decisions and effective
mitigation measures
This report includes three parts. Part I is an estimate of annual discards for the period
2010-2014 by marine commercial fisheries. Part II includes an evaluation and discussion of
bycatch and discards of endangered, threatened and protected species, providing an
updated overview of this specific dimension of the bycatch and discard issue. Part II also
includes a review of current measures for managing bycatch and reduction of discards, as
well as a discussion of other sources of fishing mortality, such as pre-catch loss, discard
mortality and ghost fishing mortality. Part III is the conclusion of the whole report.
ISBN 978-92-5-131226-1
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