| The Western and Central Pacific tuna purse seine fishery is an important component of China's deep sea fisheries and an important part of China's strategy to develop ocean powers.The tuna purse seine in mainland China began in 2001.So far,there are 32 large-scale tuna-pelagic purse seiners,of which 30 are in the Central and Western Pacific region.In recent years,the challenges faced by the tuna purse seine fishery have continued:policy factors such as the increase in the cost of fishing in the Western anf Central Pacific island countries have been increasing year by year,and catches have been subject to changes in environmental factors that have led to instability in production.Therefore,accurately grasping changes in fishing conditions during the fishing season can effectively improve the comprehensive benefits of the seine fishery.This article is based on the fishing logsheet data of the Shanghai Kaichuang Deep Sea Fisheries Co.Ltd from January 1,2008 to August 31,2017,combined with Sea Surface Temperature?SST?.,Sea Surface Chlorophyll-a?Chl-a?,and Oceanic Nino Index?ONI?data on the temporal and spatial distribution of tuna purse seine fisheries in the Western and Central Pacific Ocean and their relationship with environmental factors Relationships do research.The main conclusions are as follows:?1?Based on the factors of yield data and marine survey data,the generalized additive model?GAM?and generalized linear model?GLM?were used to analyze the correlation test of each factor to CPUE.The results showed that the cumulative interpretation rate of the optimal model for the FAD group carp CPUE was 12.7%,of which latitude contributed the most?8.1%?.According to the Akaike Information Criterion?AIC?,the optimal model is identified as:Ln(CPUEi,j,k,l+1)=s?yeari?+s?latj?+s?SST?+s?Chl-a?+s?monthl,lonj?+s?yeari,lonk?.The cumulative interpretation rate of CPUE of free-floating water carp was 13.7%,of which sea surface temperature contributed the most?6.6%?.According to AIC confirm the optimal model is:Ln?CPUEi,j,k,l+1?=s?yeari?+s?latj?+s?SST?+s?Chl-a?+s?monthl,lonj?+s?yeari,lonk?.The cumulative interpretation rate of the CPUE of the yellowfin tuna by the optimal model was 14.6%,of which the contribution rate of the year was the largest?7.5%?,and the expression was:Ln?CPUEi,j,k,l+1?=s?yeari?+s?latj?+s?SST?+s?Chl-a?+s?monthl,lonj?+s?yeari,lonk??2?From the perspective of yield,the latitudes are mainly distributed in the south latitude,and the fishery center of longitude 2008-2013 is concentrated in the western waters of 165°E.In the year of 2014-2017,the fishery center has a high latitude and longitude is distributed east of 165°E.In 2015,the longitude of fishing is east of175°E.The main focus of the production of yellow fin tuna is that the focus of fisheries for free-floating fish schools in 2008-2011 was concentrated in the western waters of 162°E,and the latitudes of fishery centers in 2009-2010 were all in the waters south of 2°S;in 2012-2017,the fishery centers were all Distributed between0.5°N-1°S and 165°E-175°E,of which the fishing center latitude was around2.5°S in 2012;the focus of the FAD group 2008-2013 was on the south latitude and west of 165°E.In the sea areas,the latitudes of the fishing grounds in 2008 and2010-2011 were all in the south of the 1.5°S sea area.In 2014-2017,the fishery centers were all distributed between 0.5°N-1°S and 165°E-175°E.?3?The temporal and spatial distribution of yields and catch per Unit Effort?CPUE?of main fishing species?Skipjack tuna and Yellowfin tuna?found that annual average and average monthly CPUE and average yields of skipjack tuna and yellow fin were significant.Sexual difference?P<0.05?.The highest year of yellow fin CPUE in the fish aggregating device?FAD?group appeared in 2008,which was 10.63t/d?F=38.392?;the highest month appeared in November,CPUE8.82t/net?F=12.128?.For longitude,the CPUE of 140°E-160°E is the highest,which is 7-8t/net?F=21.45?.For latitude,the highest CPUE is between 0°S-5°S,which is 6.34t/net?F?.=9.75).The highest year of the yellow fin CPUE in the free-floating group appeared in 2008,which was20.50t/d?F=8.579?;the highest month appeared in August-November,CPUE was15-20t/net?F=2.710?;for longitude,the CPUE of 140°E—180°E is the highest,which is 25.56t/net?F=18.52?.For latitude,the highest CPUE is between 0°S—5°S,which is 16.53tnet?F=9.14?.The highest year of FAD group CPUE appeared in 2016,which was 42.28t/d?F=7.282?;the month mainly appeared in January-June,CPUE35-40t/net?F=3.25?;for longitude,the CPUE of 160°W-170is the highest,which is 46.65t/net?F=21.45?.For latitude,the highest is between 0°S and 5°S,which is 34.86t/net?F=9.75?.The free-floating group CPUE has the highest year in2016,which is 20.08t/d?F=11.233?;the month appears in November,CPUE is about30t/net?F=3.25?;for longitude,160°W-170°W The highest CPUE was 46.65t/net?F=21.45?;for latitude,the highest was between 0°S and 5°S,which was 34.86t/net?F=4.203?. |
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