Understanding the catch composition of multispecies fisheries is fundamental to effective spatial fishery management.In the Equatorial Western and Central Pacific Ocean(EWCPO),the main catches of the tuna purse-seine ...Understanding the catch composition of multispecies fisheries is fundamental to effective spatial fishery management.In the Equatorial Western and Central Pacific Ocean(EWCPO),the main catches of the tuna purse-seine fishery include skipjack tuna(Katsuwonus pelamis),yellowfin tuna(Thunnus albacares),and bigeye tuna(Thunnus obesus).Studying the spatiotemporal distribution of the catch composition in the context of climate change contributes to the sustainable development of this fishery.Our study analyzed purse seine fishery data and environmental data from 1997 to 2019,using a random forest model to explore the changing mechanisms of catch composition under different El Niño-Southern Oscillation(ENSO)episodes with catch mean trophic level(CMTL)as the response variable.Emerging hot spot analysis was used to identify significant spatiotemporal hot(cold)spot areas.The results revealed two hot spot areas,namely the western hotspot area(WHA)and the eastern hotspot area(EHA),and two cold spot areas,namely the northern cold spot area(NCA)and the southern cold spot area(SCA).EHA spans the entire central Pacific east of 170°E among different ENSO episodes,expanding and contracting in tandem with the 28℃isotherm.WHA is mainly influenced by surface organic matter and the Western Boundary Currents and remains among different ENSO episodes.NCA is formed by the westerly anomalies and positive wind stress curl anomalies and exists only under La Niña episodes.SCA persists within the unproductive South Equatorial Current(SEC)and remains stable among different ENSO episodes.Our study contributes to revealing the spatiotemporal dynamics in tuna catch composition and their relationships with environmental factors and interspecies competition,providing valuable insights for ecosystem-based dynamic fishery management.展开更多
Catch,bycatch and discard information is important for the assessment and management of fisheries.Using Chinese pelagic tuna longline observer data from 2010 to 2018,we studied the catch composition in the Chinese pel...Catch,bycatch and discard information is important for the assessment and management of fisheries.Using Chinese pelagic tuna longline observer data from 2010 to 2018,we studied the catch composition in the Chinese pelagic tuna longline fisheries in Atlantic targeting bigeye tuna(Thunnus obesus)and bluefin tuna(Thunnus thynnus),and analyzed the survival status and discard rates of common bycatch species.A total of 55 species,including tunas,billfishes,sharks,sea turtles,cetaceans,seabirds,and other pelagic species,were observed.The results indicated that the catch composition of the Chinese pelagic tuna longline fishery targeting bigeye tuna was significantly different from that targeting bluefin tuna.The annual discard rates of common species decreased over this period.Discard rate by length and discard mortality for common species were varied among species.This is the first study to estimate catch,bycatch,and discard using Chinese pelagic tuna longline observer data in the Atlantic Ocean,which is important for the management of Chinese tuna longline fisheries in Atlantic Ocean.展开更多
基金The National Key Research and Development Program of China under contract No.2023YFD2401303.
文摘Understanding the catch composition of multispecies fisheries is fundamental to effective spatial fishery management.In the Equatorial Western and Central Pacific Ocean(EWCPO),the main catches of the tuna purse-seine fishery include skipjack tuna(Katsuwonus pelamis),yellowfin tuna(Thunnus albacares),and bigeye tuna(Thunnus obesus).Studying the spatiotemporal distribution of the catch composition in the context of climate change contributes to the sustainable development of this fishery.Our study analyzed purse seine fishery data and environmental data from 1997 to 2019,using a random forest model to explore the changing mechanisms of catch composition under different El Niño-Southern Oscillation(ENSO)episodes with catch mean trophic level(CMTL)as the response variable.Emerging hot spot analysis was used to identify significant spatiotemporal hot(cold)spot areas.The results revealed two hot spot areas,namely the western hotspot area(WHA)and the eastern hotspot area(EHA),and two cold spot areas,namely the northern cold spot area(NCA)and the southern cold spot area(SCA).EHA spans the entire central Pacific east of 170°E among different ENSO episodes,expanding and contracting in tandem with the 28℃isotherm.WHA is mainly influenced by surface organic matter and the Western Boundary Currents and remains among different ENSO episodes.NCA is formed by the westerly anomalies and positive wind stress curl anomalies and exists only under La Niña episodes.SCA persists within the unproductive South Equatorial Current(SEC)and remains stable among different ENSO episodes.Our study contributes to revealing the spatiotemporal dynamics in tuna catch composition and their relationships with environmental factors and interspecies competition,providing valuable insights for ecosystem-based dynamic fishery management.
文摘Catch,bycatch and discard information is important for the assessment and management of fisheries.Using Chinese pelagic tuna longline observer data from 2010 to 2018,we studied the catch composition in the Chinese pelagic tuna longline fisheries in Atlantic targeting bigeye tuna(Thunnus obesus)and bluefin tuna(Thunnus thynnus),and analyzed the survival status and discard rates of common bycatch species.A total of 55 species,including tunas,billfishes,sharks,sea turtles,cetaceans,seabirds,and other pelagic species,were observed.The results indicated that the catch composition of the Chinese pelagic tuna longline fishery targeting bigeye tuna was significantly different from that targeting bluefin tuna.The annual discard rates of common species decreased over this period.Discard rate by length and discard mortality for common species were varied among species.This is the first study to estimate catch,bycatch,and discard using Chinese pelagic tuna longline observer data in the Atlantic Ocean,which is important for the management of Chinese tuna longline fisheries in Atlantic Ocean.
