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Variaciones espacio-temporales de la captura por unidad de esfuerzo en la pesquería artesanal costera del pargo rayado Lutjanus synagris, en el Caribe colombiano y su relación con variables ambientales Spatio-temporal variations of the catch per unit effort in the coastal small-scale fishery of s...more
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Artisanal fisheries are essential, but for most the status of the stock supporting the fishing activity remains unknown due to lack of data and difficult access to sampling. For example, the artisanal fishery of sea silverside Odontesthes... more
Artisanal fisheries are essential, but for most the status of the stock supporting the fishing activity remains unknown due to lack of data and difficult access to sampling. For example, the artisanal fishery of sea silverside Odontesthes (Austromenidia) regia, in the Los Lagos administrative region of Chile, requires a data-limited approach to determine its status because the fishery administration has not invested in its monitoring. The approach consisted of estimating the spawning potential ratio (SPR) from length-frequency data collected in 2019 using length-based spawning potential ratio (LBSPR) and biological reference points using the only-catch optimized method (OCOM) to catch data covering from 1960 to 2020. In addition, five age-structured sea silverside populations were simulated considering uncertainty in recruitment and utilizing life-history parameters estimated by FishLife. According to LBSPR, the SPR was 0.58 (95% confidence intervals: 0.5-0.7), suggesting a fully ex...
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The abundance of juvenile fish changes due to endogenous processes, and determining the functional relationships among conspecifics is essential for fisheries’ management. The hake (Merluccius gayi) is an overexploited demersal fish... more
The abundance of juvenile fish changes due to endogenous processes, and determining the functional relationships among conspecifics is essential for fisheries’ management. The hake (Merluccius gayi) is an overexploited demersal fish widely distributed in Chile, from 23°39′ S to 47°00′ S in shallow and deep water over the continental shelf and shelf break. We studied the spatiotemporal distribution of hake juveniles (from ages 0 and 1), emphasizing endogenous relationships among juveniles and adults. The abundance per age data were obtained from bottom trawl cruises carried out in the austral winter between 1997 and 2018. Generalized additive models showed a similar spatiotemporal pattern for ages between 0 and 1, and negative effects of adult hake aged seven and older on the abundance of the young generation. Regarding the changes in juvenile abundance, the residual deviance of selected models explained 75.9% (for the age 0) and 95.3% (for the age 1) of the null deviance, revealing ...
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River runoff to the coastal zone is one of the most important environmental variables that influences the structure and functioning of the neritic trophic web and modulates temporal fluctuations of coastal fishery production in many... more
River runoff to the coastal zone is one of the most important environmental variables that influences the structure and functioning of the neritic trophic web and modulates temporal fluctuations of coastal fishery production in many ecosystems worldwide. The relationship between recruitment of anchovy (Engraulis ringens) and common sardine (Strangomera bentincki) in central-south Chile (34°–40°S) and fluctuations in river runoff was analyzed during the last two decades (1999–2018) using linear and nonlinear regression models. River runoff was also incorporated as a co-variate in Beverton-Holt (BH) stock-recruitment models. Anchovy recruitment was found to be positive and significantly associated with river runoff for all analyzed rivers both for the runoff calculated during its main reproductive period (July–October) and for each single month during this period. This detected nonlinear relationship remained significant when runoff was analyzed for the central macrozone (CMZ) and sou...
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Research Interests: Biology and Trophic Level
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ABSTRACT
The dusky finless skate Gurgesiella furvescens appears sporadically as part of the bycatch in the trawl fishery targeting demersal crustaceans on the continental shelf and upper slope of the north-central area of Chile (26ºS-33ºS).... more
The dusky finless skate Gurgesiella furvescens appears sporadically as part of the bycatch in the trawl fishery targeting demersal crustaceans on the continental shelf and upper slope of the north-central area of Chile (26ºS-33ºS). Demersal crustaceans could be forage for deep-water predators such as G. furvescens, and sizes and shapes of prey eaten could be restricted by mouth size. The diet composition of G. furvescens was determined based on specimens collected from the bycatch of trawls targeting demersal crustaceans in 2013. Stomach contents revealed nylon shrimp Heterocarpus reedi (32.8% by weight), deep-water shrimp Haliporoides diomedeae (7.2% by weight), and indeterminate crustaceans (9.0% by weight). The diet composition was similar between sexes, body length, or depth strata. Prey size was a linear function of Gurgesiella furvescens mouth width, and prey mass positively related with G. furvescens individual mass. Although squat-lobsters Pleuroncodes monodon and Cervimunid...
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The diet of jumbo squid (Dosidicus gigas) off southern-central Chile is described to examine potential biases in the determination of their main prey. Specimens were collected from catches using different fishing gear (jigging, trawl and... more
The diet of jumbo squid (Dosidicus gigas) off southern-central Chile is described to examine potential biases in the determination of their main prey. Specimens were collected from catches using different fishing gear (jigging, trawl and purse-seine), from July 2003 to January 2004, and from December 2005 to October 2006. The stomach contents were analyzed in terms of frequency of occurrence, number, and weight of prey items and the diet composition was analyzed using Detrended Correspon-dence Analysis. In the industrial purse-seine fleet for jack mackerel (Trachurus murphyi), the dominant prey of D. gigas was T. murphyi. In the industrial mid-trawl fishery for Patagonian grenadier (Macruronus magellanicus), the dominant species in the diet of D. gigas was M. magell-anicus. Similarly, Chilean hake (Merluccius gayi) was the main prey in the diet of D. gigas obtained in the industrial trawl fishery for Chilean hake; and, in both artisanal fish-eries (purse-seine for small pelagics and...
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Increasing attention is paid to the interdependence between the ecological and human dimensions to improve the management of natural resources. Understanding how artisanal fishers see and use the common-pool resources in a co-management... more
Increasing attention is paid to the interdependence between the ecological and human dimensions to improve the management of natural resources. Understanding how artisanal fishers see and use the common-pool resources in a co-management system may hold the clue to establishing effective coastal fisheries policies or strengthening existing ones. A more comprehensive planning of the system will also have a bearing on how to reduce conflicts and strengthen social networks. We surveyed artisanal fishers and decision-makers to determine their perceptions about the Management and Exploitation Areas of Benthic Resources (known as MEABR) in Chile’s Biobio region. We performed a field study from November 2018 to August 2019, applying a set of questionnaires to determine the ecological and human attributes that contribute to MEABR outcomes, and then constructed composite scores for those attributes according to a multidimensional scaling technique (“Rapfish”). We find that fishers have differ...
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Abstract The Territorial Use Rights for Fisheries (TURF) system are a kind of marine property where user rights are assiged to collective entities of artisanal fishers’ organizations. But their effectivity continues to be limited, which... more
Abstract The Territorial Use Rights for Fisheries (TURF) system are a kind of marine property where user rights are assiged to collective entities of artisanal fishers’ organizations. But their effectivity continues to be limited, which demands a comprehensive evaluation of their social, economic, and ecological performance. Consequently, the practical integration and application of these aspects continue to be a significant challenge for their management. The “RAPFISH” multidimensional scaling technique was applied to assess the sustainability status of 19 TURFs of the Biobio Region (Chile), using 51 transdisciplinary attributes relating to ecological, economic, social, among other dimensions. The results obtained in the two-dimensional arrangement presented a sustainability gradient, due to the marked variations among the different TURFs, and only four cases had very weak sustainability scores. Broadly speaking, this study determined that the social dimension (score: 61.37%) had a “high” influence on the best performance of the TURF system, while the ecological, ethical, and institutional dimensions were rated from ‘regular’ to ‘bad’. Overall, results indicate an average performance in the “medium” sustainability range (score: 54.68%), and these results generated questions about the TURFs’ viability, mainly in those that have not reached their sustainability objectives. Therefore, more local studies are needed on the social dimension of this system, in order to define the effective participatory tools and social management plans in TURFs, which will contribute to improve their performance.
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Abstract The management of small pelagic fisheries is a complex task due to its large variability of both environmental and biological processes. This high variability can impact the reliability of stock assessment models and fishery... more
Abstract The management of small pelagic fisheries is a complex task due to its large variability of both environmental and biological processes. This high variability can impact the reliability of stock assessment models and fishery management recommendations. When this occurs, management decisions should explore alternative control rules based on empirical abundance indices or pragmatic management procedures. In this paper, we examined the performance of a harvest control rule (HCR) for the Chilean fleet in the shared Chile-Peru anchovy (Engraulis ringens) fishery (16°S–24°S), which is one of the most important stocks in the Humboldt marine ecosystem in the Southeast Pacific. The HCR uses the annual changes in spawning biomass estimated by Daily Egg Production Method (DEPM) surveys in the waters off northern Chile. Analyzes are carried out through operating models simulating population regime shifts under different uncertainty sources. The results show that despite the latent risk of overfishing caused both by recruitment variability and the lack of fisheries management coordination between two jurisdictions, the control of one of the parties' fishing mortality can enable the sustainability of the entire stock, provided the fishing effort of the other jurisdiction be remained at similar levels as in the last decade. The use of an HCR would avoid increases in fishing mortality and would facilitate BMSY-based management goals. This research determined conditions under which the shared Chile-Peru anchovy fishery can be sustainable considering different sources of uncertainty of the biological-fishing system.
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In habitats impacted by bottom trawling that influences the resilience of few and widely distributed abundant species, it is relevant to analyze how populations are structured according to their niche and niche overlap, and hence... more
In habitats impacted by bottom trawling that influences the resilience of few and widely distributed abundant species, it is relevant to analyze how populations are structured according to their niche and niche overlap, and hence contributing to the ecosystem-based management approach. We evaluated and compared the isotopic niche width and determined the isotopic niche overlap for target and bycatch species of crustaceans and demersal fish caught with bottom trawling on the continental shelf and upper slope of the central-southern zone of Chile. Stable isotope analysis relied on carbon and nitrogen isotopes (13 C and 15 N) and Bayesian statistics of niche size and community metrics. Crustaceans and fish species are structured in three clusters according to the stable isotope values and the Chilean hake Merluccius gayi, which was probably clustered isolated due to its pelagic stable isotope values due to diel vertical migrations associated with feeding on euphausiids in the water column. The first group was constituted by demersal fish, that showed higher δ 15 N (19‰) and narrower δ 13 C (− 16‰). The two other groups constituted a mix of crustaceans and fish, with access to different carbon sources. There were degrees of specialization for most species within the groups and overlap in the isotopic niche between populations. The benthic and demersal macrofauna species are structured by sharing resources in the habitat, probably on available sources supported by the productive pelagic system.
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Marine biota is redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and... more
Marine biota is redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. We further found that single surveys do not cover the full range of the main commercial demersal fish species and that an average of 18 sur...
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ABSTRACT
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In age-structured fisheries stock assessments, ageing errors within age composition data can lead to biased mortality rate and year-class strength estimates. These errors may be further compounded where fishery-dependent age composition... more
In age-structured fisheries stock assessments, ageing errors within age composition data can lead to biased mortality rate and year-class strength estimates. These errors may be further compounded where fishery-dependent age composition data are influenced by temporal changes in fishery selectivity and selectivity misspecification. In this study, we investigated how ageing error within age composition data interacts with time-varying fishery selectivity and selectivity misspecification to affect estimates derived from a statistical catch-at-age (SCA) model that used fishery-dependent data. We tested three key model parameters: average unfished recruitment (R0), spawning stock depletion (Dfinal), and fishing mortality in the terminal year (Fterminal). The Patagonian toothfish (Dissostichus eleginoides) fishery in southern Chile was used as a case study. Age composition data used to assess this fishery were split into two sets based on scale (1989–2006) and otolith (2007–2012) reading...
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Research Interests: Biology and Trophic Level
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ABSTRACT Literature on the trophic ecology of small pelagic fish (primarly anchovy Engraulis spp. and sardine Sardinops spp. but including the genera Brevoortia, Clupea, Sardina, Sprattus, and Strangomera) and their interactions with... more
ABSTRACT Literature on the trophic ecology of small pelagic fish (primarly anchovy Engraulis spp. and sardine Sardinops spp. but including the genera Brevoortia, Clupea, Sardina, Sprattus, and Strangomera) and their interactions with plankton are reviewed using case studies describing research on some economically and ecologically important small pelagic fish from up-welling and temperate non-upwelling ecosystems. Information from morphological studies of the feeding apparatus, field studies on dietary composition and foraging behaviour, and laboratory studies that have provided data for the parameterization of bio-energetic and other models of these small pelagic fish are presented, where available. Two or more small pelagic fish species are described in each case study, and disparities in trophic dynamics between co-occurring anchovy and sardine are consistently seen, supporting the hypothesis that species alternations between the two species could be trophically mediated. Linkages between climate and fish are described for many of the systems, and possible impacts of climate change on some of the species are described. Introduction Small pelagic fish are, in general, microphagous planktivores, and their high abundance levels in upwelling systems, in particular, was attributed to their ability to feed directly on phytoplankton and hence benefit from a short and efficient food chain (Ryther, 1969; Walsh, 1981). This two-step food chain hypothesis, with small pelagic fish being regarded as essentially phytophagus and feeding on large, chain forming diatoms such as Chaetoceros and Fragilaria (Yoneda and Yoshida, 1955; Bensam, 1964; Loukashkin, 1970; King and Macleod, 1976) was initially well supported (Longhurst, 1971; Durbin, 1979; Walsh, 1981).
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Niklitschek, E. J., Secor, D., Toledo, P., Valenzuela, X., Cubillos, L., and Zuleta, A. 2014. Nursery systems for Patagonian grenadier off Western Patagonia: large inner sea or narrow continental shelf? – ICES Journal of Marine Science,... more
Niklitschek, E. J., Secor, D., Toledo, P., Valenzuela, X., Cubillos, L., and Zuleta, A. 2014. Nursery systems for Patagonian grenadier off Western Patagonia: large inner sea or narrow continental shelf? – ICES Journal of Marine Science, 71: 374–390. Adjacent to Chile's long and narrow continental shelf, the Patagonian Inner Sea (PES) is among the largest and most complex estuarine systems in the world. The PES harbours high concentrations of juveniles and adults of important groundfishes, which spawn within or in near proximity to it. A dominant view is that recruitment primarily originates here rather than in adjacent coastal regions. We used otolith stable isotopes to evaluate the relative contribution of several PES and continental shelf regions to recruitment of Patagonian grenadier, one of the most abundant groundfishes in the area. Seawater chemistry confirmed that δ13C and δ18O differentiated these nursery and feeding regions. Estimated recruitments from PES nurseries to ...
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ABSTRACT In Chile, anchovy (Engraulis ringens) and common sardine (Strangomera bentincki) are two commercially important small pelagic fish. In southern Chile (32–41° S), both species coexist and inhabit the coastal zone. In northern... more
ABSTRACT In Chile, anchovy (Engraulis ringens) and common sardine (Strangomera bentincki) are two commercially important small pelagic fish. In southern Chile (32–41° S), both species coexist and inhabit the coastal zone. In northern Chile (18–25° S), only anchovy is present in the coastal zone. The determine onset, peak, end, and duration of the spawning periods in these small pelagic fish are key factors in population studies and of great interest for fisheries management. The objective of this study is to determine the temporal trends of spawning in these two species. A quantitative method was developed to obtain objective indicators of the spawning periods and the method is a useful tool for comparative studies between populations as well as to study the relationship of spawning periods with other demographic variables affected by fishing or environmental variability. Peak spawning in the three populations was consistent through time but showed changes in the duration of the maximum reproductive period. Anchovy and common sardine of the southern zone show synchrony and a shortening of the duration of spawning periods, probably in response to environmental fluctuations. Anchovy in northern Chile have shown an increase in duration from 1986 that is coincidental with the regime shift reported for the Humboldt Current Ecosystem in the mid-1980s.