Catch-per-unit-effort (CPUE) is often the main piece of information used in fisheries stock asses... more Catch-per-unit-effort (CPUE) is often the main piece of information used in fisheries stock assessment; however, the catch and effort data that are traditionally compiled from commercial logbooks can be incomplete or unreliable due to many reasons. Pacific bluefin tuna (PBF) is a seasonal target species in the Taiwanese longline fishery. Since 2010, detailed catch information for each PBF has been made available through a catch documentation scheme. However, previously, only market landing data with a low coverage of logbooks were available. Therefore, several nontraditional procedures were performed to reconstruct catch and effort data from many alternative data sources not directly obtained from fishers for 2001–2015: (1) Estimating the catch number from the landing weight for 2001–2003, for which the catch number information was incomplete, based on Monte Carlo simulation; (2) deriving fishing days for 2007–2009 from voyage data recorder data, based on a newly developed algorithm; and (3) deriving fishing days for 2001–2006 from vessel trip information , based on linear relationships between fishing and at-sea days. Subsequently, generalized linear mixed models were developed with the delta-lognormal assumption for standardizing the CPUE calculated from the reconstructed data, and three-stage model evaluation was performed using (1) Akaike and Bayesian information criteria to determine the most favorable variable composition of standardization models, (2) overall R 2 via cross-validation to compare fitting performance between area-separated and area-combined stan-dardizations, and (3) system-based testing to explore the consistency of the standardized CPUEs with auxiliary data in the PBF stock assessment model. The last stage of evaluation revealed high consistency among the data, thus demonstrating improvements in data reconstruction for estimating the abundance index, and consequently the stock assessment.
Marine Stewardship Council (MSC) eco-labelling is among the widely known market-based management ... more Marine Stewardship Council (MSC) eco-labelling is among the widely known market-based management approaches that are considered effective in solving the problem of overfishing. The approach has been applied in several marine capture fisheries worldwide; however, it was found not to be fully workable in many fisheries for various reasons. The sergestid shrimp (Sergia lucens) fishery in Tungkang County of Taiwan has been managed well in recent decades through a bottom-up community-based co-management scheme and is probably the best candidate for obtaining the first MSC certification in Taiwan. This study assessed the fishery in relation to the three principles of MSC eco-labelling and investigated responses from experts, managers, industry representatives, and consumers on improving the fishery in order to obtain the MSC certification. The results suggested that three major problems confronted the fishery: (1) the fishery was unlikely to meet the MSC standards unless it could reduce its high bycatch rate; (2) the economic and/or political benefits were not attractive enough to the relevant sectors for them to cover the high costs and responsibility of obtaining and maintaining the MSC certification; and (3) the fishery was reputed to be well managed without any eco-label, suggesting no strong incentive to obtain one from a management perspective. The benefits of MSC eco-labelling could be consolidated, however, and the role of government was crucial in this regard.
The overfishing of large vertebrates and shellfish is the first major disturbance to all the valu... more The overfishing of large vertebrates and shellfish is the first major disturbance to all the valuable coastal ecosystems that have been studied. However, usable logbook data has not been required or of concern in many small-scale fisheries operating in the coastal or offshore regions, rendering impact evaluation and further management difficult. Various studies have taken advantage of vessel monitoring systems (VMSs) that were originally developed for purposes such as surveillance, to derive high-resolution spatiotemporal effort data or further develop logbook-like data. These systems are usually installed on large-scale fishing vessels but seldom on small-scale vessels. Taiwan provides fuel subsidies to fishery operations, evaluated according to active moving hours at sea, as calculated with customized voyage data recorders (VDRs) that have been installed on most small-scale offshore fishing vessels. The device provides temporal position and speed data similar to that of VMSs, not in real time but with cheaper device cost, no data transmission fee and higher resolution at 3-min intervals. This paper takes the offshore trawl fishery of southwestern Taiwan as example to demonstrate that the VDR data used for subsidy evaluation could also be used for high-resolution effort estimation. After briefly documenting the development of Taiwanese trawl fisheries and the application of VDR in Taiwan, the paper proposes a simple five-step procedure for managers to categorize major fishing patterns of fisheries by reviewing the speed and track profiles of vessels on a trip-by-trip basis, and finally to develop speed criteria for defining fishing efforts.
... in the Indian Ocean up to 2002 applying targeting index in the model Hiroaki OKAMOTO 1),Shui-... more ... in the Indian Ocean up to 2002 applying targeting index in the model Hiroaki OKAMOTO 1),Shui-Kai CHANG 2), Yu-Min YEH 2) and Chien-Chung HSU 3) 1) National Research Institute of Far Seas Fisheries, 5 chome 7-1, Shimizu-Orido, Shizuoka-City, 424-8633, Japan ...
White marlin is a bycatch of the Taiwanese longline fishery and its catch constitutes only 1-2% o... more White marlin is a bycatch of the Taiwanese longline fishery and its catch constitutes only 1-2% of the Taiwanese total tuna and tuna-like species catch. As a bycatch species, the data quality for white marlin was not as good as it was for target species. This report preliminarily ...
Abstract Taiwanese distant water longline fishery has operated throughout the WCPO since the 1960... more Abstract Taiwanese distant water longline fishery has operated throughout the WCPO since the 1960s with the following target species: northern albacore in Regions 1 and 2 of the WCPO, bigeye and yellowfin in Regions 3 and 4, and southern albacore in Regions 5 and 6. Among the regions, fishing operations in Region 6 have the most complete time series of data, with more consistent fishing activity and species targeting than indices available from other distant water fishing nations.
Taiwanese longline fishery in the Indian Ocean commenced in mid-1950s and targeted on yellowfin t... more Taiwanese longline fishery in the Indian Ocean commenced in mid-1950s and targeted on yellowfin tuna in the beginning. Following the development of the fishery, two different operation patterns were currently established: The first targets on albacore (ALB) for ...
Jen-Chieh Shiao1,*, Tzen-Fu Yui2, Hans Høie3,4, Ulyssess Ninnemann5, and Shui-Kai Chang6 1Institu... more Jen-Chieh Shiao1,*, Tzen-Fu Yui2, Hans Høie3,4, Ulyssess Ninnemann5, and Shui-Kai Chang6 1Institute of Oceanography, College of Science, National Taiwan University, Taipei 106, Taiwan 2Institute of Earth Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan 3Department ...
Catch-per-unit-effort (CPUE) is often the main piece of information used in fisheries stock asses... more Catch-per-unit-effort (CPUE) is often the main piece of information used in fisheries stock assessment; however, the catch and effort data that are traditionally compiled from commercial logbooks can be incomplete or unreliable due to many reasons. Pacific bluefin tuna (PBF) is a seasonal target species in the Taiwanese longline fishery. Since 2010, detailed catch information for each PBF has been made available through a catch documentation scheme. However, previously, only market landing data with a low coverage of logbooks were available. Therefore, several nontraditional procedures were performed to reconstruct catch and effort data from many alternative data sources not directly obtained from fishers for 2001–2015: (1) Estimating the catch number from the landing weight for 2001–2003, for which the catch number information was incomplete, based on Monte Carlo simulation; (2) deriving fishing days for 2007–2009 from voyage data recorder data, based on a newly developed algorithm; and (3) deriving fishing days for 2001–2006 from vessel trip information , based on linear relationships between fishing and at-sea days. Subsequently, generalized linear mixed models were developed with the delta-lognormal assumption for standardizing the CPUE calculated from the reconstructed data, and three-stage model evaluation was performed using (1) Akaike and Bayesian information criteria to determine the most favorable variable composition of standardization models, (2) overall R 2 via cross-validation to compare fitting performance between area-separated and area-combined stan-dardizations, and (3) system-based testing to explore the consistency of the standardized CPUEs with auxiliary data in the PBF stock assessment model. The last stage of evaluation revealed high consistency among the data, thus demonstrating improvements in data reconstruction for estimating the abundance index, and consequently the stock assessment.
Marine Stewardship Council (MSC) eco-labelling is among the widely known market-based management ... more Marine Stewardship Council (MSC) eco-labelling is among the widely known market-based management approaches that are considered effective in solving the problem of overfishing. The approach has been applied in several marine capture fisheries worldwide; however, it was found not to be fully workable in many fisheries for various reasons. The sergestid shrimp (Sergia lucens) fishery in Tungkang County of Taiwan has been managed well in recent decades through a bottom-up community-based co-management scheme and is probably the best candidate for obtaining the first MSC certification in Taiwan. This study assessed the fishery in relation to the three principles of MSC eco-labelling and investigated responses from experts, managers, industry representatives, and consumers on improving the fishery in order to obtain the MSC certification. The results suggested that three major problems confronted the fishery: (1) the fishery was unlikely to meet the MSC standards unless it could reduce its high bycatch rate; (2) the economic and/or political benefits were not attractive enough to the relevant sectors for them to cover the high costs and responsibility of obtaining and maintaining the MSC certification; and (3) the fishery was reputed to be well managed without any eco-label, suggesting no strong incentive to obtain one from a management perspective. The benefits of MSC eco-labelling could be consolidated, however, and the role of government was crucial in this regard.
The overfishing of large vertebrates and shellfish is the first major disturbance to all the valu... more The overfishing of large vertebrates and shellfish is the first major disturbance to all the valuable coastal ecosystems that have been studied. However, usable logbook data has not been required or of concern in many small-scale fisheries operating in the coastal or offshore regions, rendering impact evaluation and further management difficult. Various studies have taken advantage of vessel monitoring systems (VMSs) that were originally developed for purposes such as surveillance, to derive high-resolution spatiotemporal effort data or further develop logbook-like data. These systems are usually installed on large-scale fishing vessels but seldom on small-scale vessels. Taiwan provides fuel subsidies to fishery operations, evaluated according to active moving hours at sea, as calculated with customized voyage data recorders (VDRs) that have been installed on most small-scale offshore fishing vessels. The device provides temporal position and speed data similar to that of VMSs, not in real time but with cheaper device cost, no data transmission fee and higher resolution at 3-min intervals. This paper takes the offshore trawl fishery of southwestern Taiwan as example to demonstrate that the VDR data used for subsidy evaluation could also be used for high-resolution effort estimation. After briefly documenting the development of Taiwanese trawl fisheries and the application of VDR in Taiwan, the paper proposes a simple five-step procedure for managers to categorize major fishing patterns of fisheries by reviewing the speed and track profiles of vessels on a trip-by-trip basis, and finally to develop speed criteria for defining fishing efforts.
... in the Indian Ocean up to 2002 applying targeting index in the model Hiroaki OKAMOTO 1),Shui-... more ... in the Indian Ocean up to 2002 applying targeting index in the model Hiroaki OKAMOTO 1),Shui-Kai CHANG 2), Yu-Min YEH 2) and Chien-Chung HSU 3) 1) National Research Institute of Far Seas Fisheries, 5 chome 7-1, Shimizu-Orido, Shizuoka-City, 424-8633, Japan ...
White marlin is a bycatch of the Taiwanese longline fishery and its catch constitutes only 1-2% o... more White marlin is a bycatch of the Taiwanese longline fishery and its catch constitutes only 1-2% of the Taiwanese total tuna and tuna-like species catch. As a bycatch species, the data quality for white marlin was not as good as it was for target species. This report preliminarily ...
Abstract Taiwanese distant water longline fishery has operated throughout the WCPO since the 1960... more Abstract Taiwanese distant water longline fishery has operated throughout the WCPO since the 1960s with the following target species: northern albacore in Regions 1 and 2 of the WCPO, bigeye and yellowfin in Regions 3 and 4, and southern albacore in Regions 5 and 6. Among the regions, fishing operations in Region 6 have the most complete time series of data, with more consistent fishing activity and species targeting than indices available from other distant water fishing nations.
Taiwanese longline fishery in the Indian Ocean commenced in mid-1950s and targeted on yellowfin t... more Taiwanese longline fishery in the Indian Ocean commenced in mid-1950s and targeted on yellowfin tuna in the beginning. Following the development of the fishery, two different operation patterns were currently established: The first targets on albacore (ALB) for ...
Jen-Chieh Shiao1,*, Tzen-Fu Yui2, Hans Høie3,4, Ulyssess Ninnemann5, and Shui-Kai Chang6 1Institu... more Jen-Chieh Shiao1,*, Tzen-Fu Yui2, Hans Høie3,4, Ulyssess Ninnemann5, and Shui-Kai Chang6 1Institute of Oceanography, College of Science, National Taiwan University, Taipei 106, Taiwan 2Institute of Earth Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan 3Department ...
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