Kuwait's shrimp fishery presents typical tropical shrimp fishery characteristics with highly variable recruitment, fast growth and strong seasonal patterns. Both the General Production Model and Age-structured Mod...Kuwait's shrimp fishery presents typical tropical shrimp fishery characteristics with highly variable recruitment, fast growth and strong seasonal patterns. Both the General Production Model and Age-structured Model were chosen to assess the stock status of the Kuwait's shrimp fishery. The estimated Maximum Sustainable Yield(MSY) was 2 518 metric ton(t) with a corresponding fishing eff orts( f MSY) 7 265 standard boat-days from the General Production Model. Similar results from the Age-structured Model were 1 936 t and 6 449 boat-days respectively. Comparing these results with the average annual shrimp landings(1 772 t) and average fishing eff ort(9 710 boat-days) in the past 10 years, we concluded that the fishery was overfished. Model simulations to show the changes of recruitment, biomass and possible catch under different fishing eff ort scenarios indicated possible stock collapse if the fishing eff ort continually increase. But both shrimp recruitment and biomass will increase if the current fishing eff ort is reduced. Model simulations also showed a possible increase of MSY by delaying the opening or by closing the season earlier. Based on these results, recommendations to improve the management of Kuwait's shrimp fishery are presented.展开更多
The eastern fall cohort of the neon flying squid, Ommastrephes bartramii, has been commercially exploited by the Chinese squid jigging fleet in the central North Pacific Ocean since the late 1990s. To understand and i...The eastern fall cohort of the neon flying squid, Ommastrephes bartramii, has been commercially exploited by the Chinese squid jigging fleet in the central North Pacific Ocean since the late 1990s. To understand and identify their optimal habitat, we have developed a habitat suitability index （HSI） model using two potential important environmental variables -- sea surface temperature （SST） and sea surface height anomaly （SSHA） -- and fishery data from the main fishing ground （165°-180°E） during June and July of 1999-2003. A geometric mean model （GMM）, minimum model （MM） and arithmetic weighted model （AWM） with different weights were compared and the best HSI model was selected using Akaike＇s information criterion （AIC）. The performance of the developed HSI model was evaluated using fishery data for 2004. This study suggests that the highest catch per unit effort （CPUE） and fishing effort are closely related to SST and SSHA. The best SST- and SSHA-based suitability index （SI） regression models were SISST-based = 0.7SIeffort-SST ＋ 0.3 SICPUE-SST, and SISSHA-based =0.5Sleffort-SSHA ＋ 0.5SICPUE-SSHA, respectively, showing that fishing effort is more important than CPUE in the estimation of SI. The best HSI model was the AWM, defined as HSI=0.3SISSHA-based＋ 0.7SISSHA-based, indicating that SSHA is more important than SST in estimating the HSI of squid. In 2004, monthly HSI values greater than 0.6 coincided with the distribution of productive fishing ground and high CPUE in June and July, suggesting that the models perform well. The proposed model provides an important tool in our efforts to develop forecasting capacity of squid spatial dynamics.展开更多
Fishing activities result in a depletion of fish resources and an increase in bycatch probability of non-target species,which are thought to be the cause of the recent demographic change experienced by coastal cetacea...Fishing activities result in a depletion of fish resources and an increase in bycatch probability of non-target species,which are thought to be the cause of the recent demographic change experienced by coastal cetaceans in waters off Guangdong province,China.However,fishing intensity and its spatiotemporal pattern remain poorly examined in this region.Here,random daily tracks from 100 fishing vessels were used to estimate fishing operations in the coastal waters off Guangdong province.The performance of two methods was tested with Automatic Identification System(AIS)data collected in the Pearl River Delta region(PRD).This assessment found that the Density-Based Spatial Clustering of Applications with Noise(DBSCAN)could falsely identify port regions as fishing grounds,while the speed-based method provided a more accurate estimate of fishing grounds with less computational effort.Subsequently,the spatiotemporal pattern of fishing intensity in the coastal waters off the entire Guangdong province was examined with the speed-based method.Our results showed that 87.75%of the coastal fishing activities occurred in waters<40 m in depth.The method detected two spatially heterogeneous fishing grounds extending from the PRD to either the west or east sides of Guangdong province.In the west fishing ground,43.4%of fishing vessels operated in the waters off Yangjiang city;while in the east fishing ground,fishing activities were more evenly distributed.The present study suggests that the AIS is able to provide high-resolution data to monitor the development of fishing activities,which may be useful for informing marine resource management and spatial planning.展开更多
The main objective of this study is to provide,for the first time,fisheries-dependent,spatially explicit information on the activity for the black scabbard fish(Aphanopus carbo)longline fleet operating off the Portugu...The main objective of this study is to provide,for the first time,fisheries-dependent,spatially explicit information on the activity for the black scabbard fish(Aphanopus carbo)longline fleet operating off the Portuguese coast.Fisheries monitoring data were analysed,covering the period 2014–2016,aiming at identifying deep-sea fishing grounds,gaining a better understanding of the fleet spatial dynamics,quantifying fishing effort and providing information on the species distribution and abundance.E-logbooks were used to define general patterns of fishing activity,while the combined analysis of Vessel Monitoring System(VMS)and Automatic Identification System(AIS)data allowed to spatially identify fishing trips and define haul-back trajectories corresponding to fishing events.A total of 19 vessels were found to be involved in this fishery,mainly operating at depths from 1000 to 1500 m,landing the black scabbard fish in two main ports located in the centre and three secondary ports in the northern region.Fishing effort and catch per unit of effort(CPUE)were estimated and mapped for the period in study and the geographic extension of the fishery in the Portuguese continental slope was highlighted.Vessels keep their activity spatially restricted,in a clear strategy to avoid competition;their areas of activity are contiguous and generally related to the closest port.Some recommendations are drawn in support of a continuous monitoring programme for this fishery.展开更多
Small-scale fisheries,particularly those targeting small pelagic fish,are a vital sector in Liberia,providing essential food for the local population and generating income for livelihoods.Sardinella maderensis,predomi...Small-scale fisheries,particularly those targeting small pelagic fish,are a vital sector in Liberia,providing essential food for the local population and generating income for livelihoods.Sardinella maderensis,predominantly caught by motorized canoes using gill nets and seine nets,is the primary species in these fisheries.To establish management target reference points for the S.maderensis fishery,this study applied the Schaefer production model to aggregated and disaggregated catch and effort data collected by Liberia's National Fisheries and Aquaculture Authority(NaFAA)from 2018 to 2022.The findings indicate that,in both the aggregated and disaggregated models,the current(2022)fishing effort exceeds the MEY level,leading to diminishing economic returns and approaching economic overfishing thresholds.The economic reference points,MEY and EMEY,were estimated to be 3%and 19%lower in the aggregated model,and 30%and 44%lower in the disaggregated model,compared to the current(2022)catch and relative fishing effort.This situation arises when the cost of fishing exceeds the price of fish,driven by inefficient and ineffective fishing boats,which leads to high unit costs of effort compared to unit revenue.To fully realize the potential of the S.maderensis fishery,this study recommends a combination of input and output control management strategies,the adoption of more efficient fishing technologies,and the provision of alternative livelihoods for coastal communities.展开更多
基金Supported by the project "A Comprehensive Management Strategy for Long-term Sustainability of Kuwait’s Shrimp Stock",which was jointly supported by Kuwait Foundation for the Advancement of Sciences(KFAS)the Public Authority for Agricultural Affairs and Fisheries Resources of the State of Kuwait(PAAFR)the Kuwait Institute for Scientific Research
文摘Kuwait's shrimp fishery presents typical tropical shrimp fishery characteristics with highly variable recruitment, fast growth and strong seasonal patterns. Both the General Production Model and Age-structured Model were chosen to assess the stock status of the Kuwait's shrimp fishery. The estimated Maximum Sustainable Yield(MSY) was 2 518 metric ton(t) with a corresponding fishing eff orts( f MSY) 7 265 standard boat-days from the General Production Model. Similar results from the Age-structured Model were 1 936 t and 6 449 boat-days respectively. Comparing these results with the average annual shrimp landings(1 772 t) and average fishing eff ort(9 710 boat-days) in the past 10 years, we concluded that the fishery was overfished. Model simulations to show the changes of recruitment, biomass and possible catch under different fishing eff ort scenarios indicated possible stock collapse if the fishing eff ort continually increase. But both shrimp recruitment and biomass will increase if the current fishing eff ort is reduced. Model simulations also showed a possible increase of MSY by delaying the opening or by closing the season earlier. Based on these results, recommendations to improve the management of Kuwait's shrimp fishery are presented.
基金Supported by the PhD Programs Foundation of Ministry of Education of China (No. 20093104110002)the National High Technology Research and Development Program of China (863 Program) (Nos. 2007AA092201, 2007AA092202)+2 种基金the National Natural Science Foundation (No. NSFC40876090)the Shanghai Leading Academic Discipline Project (No. S30702)Y. Chen's involvement in the project was partially supported by the Shanghai Dongfang Scholar Program
文摘The eastern fall cohort of the neon flying squid, Ommastrephes bartramii, has been commercially exploited by the Chinese squid jigging fleet in the central North Pacific Ocean since the late 1990s. To understand and identify their optimal habitat, we have developed a habitat suitability index （HSI） model using two potential important environmental variables -- sea surface temperature （SST） and sea surface height anomaly （SSHA） -- and fishery data from the main fishing ground （165°-180°E） during June and July of 1999-2003. A geometric mean model （GMM）, minimum model （MM） and arithmetic weighted model （AWM） with different weights were compared and the best HSI model was selected using Akaike＇s information criterion （AIC）. The performance of the developed HSI model was evaluated using fishery data for 2004. This study suggests that the highest catch per unit effort （CPUE） and fishing effort are closely related to SST and SSHA. The best SST- and SSHA-based suitability index （SI） regression models were SISST-based = 0.7SIeffort-SST ＋ 0.3 SICPUE-SST, and SISSHA-based =0.5Sleffort-SSHA ＋ 0.5SICPUE-SSHA, respectively, showing that fishing effort is more important than CPUE in the estimation of SI. The best HSI model was the AWM, defined as HSI=0.3SISSHA-based＋ 0.7SISSHA-based, indicating that SSHA is more important than SST in estimating the HSI of squid. In 2004, monthly HSI values greater than 0.6 coincided with the distribution of productive fishing ground and high CPUE in June and July, suggesting that the models perform well. The proposed model provides an important tool in our efforts to develop forecasting capacity of squid spatial dynamics.
基金funded by the Natural Science Foundation of Guangdong province in China[Grant number 2018A030313870]the Ocean Park Conservation Foundation Hong Kong[Grant number MM01.1920],Alashan Society of Entrepreneurs and Ecology(SEE)+1 种基金the Shenzhen Zhilan Foundation[Grant number 2019040231B]the“One Belt One Road”Science and Technology Cooperation Special Program of the International Partnership Program of Chinese Academy of Sciences[Grant number 183446KYSB20200016].
文摘Fishing activities result in a depletion of fish resources and an increase in bycatch probability of non-target species,which are thought to be the cause of the recent demographic change experienced by coastal cetaceans in waters off Guangdong province,China.However,fishing intensity and its spatiotemporal pattern remain poorly examined in this region.Here,random daily tracks from 100 fishing vessels were used to estimate fishing operations in the coastal waters off Guangdong province.The performance of two methods was tested with Automatic Identification System(AIS)data collected in the Pearl River Delta region(PRD).This assessment found that the Density-Based Spatial Clustering of Applications with Noise(DBSCAN)could falsely identify port regions as fishing grounds,while the speed-based method provided a more accurate estimate of fishing grounds with less computational effort.Subsequently,the spatiotemporal pattern of fishing intensity in the coastal waters off the entire Guangdong province was examined with the speed-based method.Our results showed that 87.75%of the coastal fishing activities occurred in waters<40 m in depth.The method detected two spatially heterogeneous fishing grounds extending from the PRD to either the west or east sides of Guangdong province.In the west fishing ground,43.4%of fishing vessels operated in the waters off Yangjiang city;while in the east fishing ground,fishing activities were more evenly distributed.The present study suggests that the AIS is able to provide high-resolution data to monitor the development of fishing activities,which may be useful for informing marine resource management and spatial planning.
文摘The main objective of this study is to provide,for the first time,fisheries-dependent,spatially explicit information on the activity for the black scabbard fish(Aphanopus carbo)longline fleet operating off the Portuguese coast.Fisheries monitoring data were analysed,covering the period 2014–2016,aiming at identifying deep-sea fishing grounds,gaining a better understanding of the fleet spatial dynamics,quantifying fishing effort and providing information on the species distribution and abundance.E-logbooks were used to define general patterns of fishing activity,while the combined analysis of Vessel Monitoring System(VMS)and Automatic Identification System(AIS)data allowed to spatially identify fishing trips and define haul-back trajectories corresponding to fishing events.A total of 19 vessels were found to be involved in this fishery,mainly operating at depths from 1000 to 1500 m,landing the black scabbard fish in two main ports located in the centre and three secondary ports in the northern region.Fishing effort and catch per unit of effort(CPUE)were estimated and mapped for the period in study and the geographic extension of the fishery in the Portuguese continental slope was highlighted.Vessels keep their activity spatially restricted,in a clear strategy to avoid competition;their areas of activity are contiguous and generally related to the closest port.Some recommendations are drawn in support of a continuous monitoring programme for this fishery.
文摘Small-scale fisheries,particularly those targeting small pelagic fish,are a vital sector in Liberia,providing essential food for the local population and generating income for livelihoods.Sardinella maderensis,predominantly caught by motorized canoes using gill nets and seine nets,is the primary species in these fisheries.To establish management target reference points for the S.maderensis fishery,this study applied the Schaefer production model to aggregated and disaggregated catch and effort data collected by Liberia's National Fisheries and Aquaculture Authority(NaFAA)from 2018 to 2022.The findings indicate that,in both the aggregated and disaggregated models,the current(2022)fishing effort exceeds the MEY level,leading to diminishing economic returns and approaching economic overfishing thresholds.The economic reference points,MEY and EMEY,were estimated to be 3%and 19%lower in the aggregated model,and 30%and 44%lower in the disaggregated model,compared to the current(2022)catch and relative fishing effort.This situation arises when the cost of fishing exceeds the price of fish,driven by inefficient and ineffective fishing boats,which leads to high unit costs of effort compared to unit revenue.To fully realize the potential of the S.maderensis fishery,this study recommends a combination of input and output control management strategies,the adoption of more efficient fishing technologies,and the provision of alternative livelihoods for coastal communities.
