| Based on the data of sea surface temperature(SST)Sea surface height(SSH)and sea surface salinity(SSS)and upper depth of the thermocline(UDT)obtained from satellite remote sensing,using the variance analysis,the least significant difference method(LSD)and geographic information software Arc GIS analysis of temporal and spatial distribution of albacore fishery in Fiji exclusive economic zone of South Pacific,analysis of fishing and flood and the relationship between fishing grounds and marine environmental factors.At the same time,the maximum entropy model was used to research the distribution of albacore high-yielding fishery areas in Fiji ’s exclusive economic zone and the effect of marine environmental factors on the catch per unit effort(CPUE)of albacore.Research indicates:1)In the time series on the South Pacific Fiji exclusive economic zone albacore CPUE changes in the situation,three years CPUE sorted according to the high and low rankings in 2014,2015 and 2013.The third quarter of South Pacific Fiji exclusive economic zone albacore fishery is the highest quarter of the CPUE of the year,followed by the fourth quarter,the second quarter and the first quarter,respectively,on the seasonal scale,the difference between the CPUE of the season is also significant.2)In the spatial sequence of the South Pacific Fiji exclusive economic zone albacore CPUE changes in the analysis of the longitude,the overall distribution of fishing grounds between 173°-180°E,something span is not large.In the second quarter,the central fishery began to change eastward,and the center fishery was distributed at 175°-178°E.In the second quarter,the center fishery was distributed in the first quarter,and the center fishery was distributed between 174°-177°E.The third quarter,the central fishery began to change westward,the center fishery distributed between 174°-177°E;the fourth quarter,the central fishery continued to change westward,the center fishery distributed between 173°-176°E.In terms of latitude,the fishing grounds are generally distributed between 10°-28°S,northsouth span is larger(Figure 2).With the 16°-19°S as the middle area of the fishery,the distribution of the center fishery showed a tendency to separate from both sides and then to the middle.In the first quarter,the center fishery was distributed between 16°-19°S;in the second quarter,the center fishery began to disperse on both sides,with a high fishing effort in the north and south,respectively between 13°-16°S and 19°-22°S In the third quarter,there was a high fishing effort in the north and south,respectively,between 13°-16°S and 19°-25°S.In the fourth quarter,the distribution of the center fishery began to move closer to the 16°-19°S,Distributed between 16°-22°S.3)In the year of the flood season,the number of occurrences occurred in 2013 was the lowest,and the number of occurrences in 2015 was the highest because the longest time of the flood season.But on the whole,the CPUE is less than 2014..4)To study the relationship between the CPUE and the SST of albacore in the Fiji exclusive economic zone of the South Pacific,higher fishing effort are distributed in the SST is more than 28°C in the region In the first quarter,and the SST of the fishery was higher and the fishery fishing effort was distributed in the SST area of 28°C or more,of which 29-30 ° C Accounting for 73.3% of all fishing efforts;CPUE at 29-30° C when the highest,5.69 kg / hook,CPUE with the increase in SST has a downward trend.In the second quarter,the SST of the fishery was reduced and the fishing effort was distributed in the SST area of 23-30°C.The distribution of the fishing effort was relatively dispersed and the distribution trend was basically distributed.The CPUE was the highest at 27-28° C,Hook,the same,CPUE with the increase in SST has increased the trend.In the third quarter,the SST of the fishery continued to decrease,and the fishing effort was distributed in the SST area of 19.8-29°C.The distribution of fishing effort was more dispersed,but there was a share of 22-23% fishing effort in the low temperature area Small peak,accounting for 35.29% of all fishing effort;CPUE at 26-27°C when the highest,4.02 kg / hook,higher or lower than the scope of the SST CPUE has a downward trend.In the fourth quarter,the SST of the fishery began to rise and the fishing effort was distributed in the SST area of 23°C.The distribution of fishing effort began to concentrate,with the highest fishing effort of 25-27°C,which accounted for the total amount of fishing effort 63.4%;CPUE is the highest at 27-28 oC,6.25 kg / hook,the same,higher than or below the scope of the SST CPUE has a downward trend.In general,the SST of the fishery showed a tendency to rise first and then descend with the seasons,and the area at 27-28° C in the fishery could produce highyielding CPUE.5)To study the relationship between the perimeter of the albacore CPUE and sea surface salinity in the Fiji exclusive economic zone of the South Pacific Ocean,the first quarter;the SSS of the fishery is between 33.93 and 35.2 ‰,and the fishing force is concentrated in the salinity of 34.4-35% of the sea area;the second quarter,the fishery SSS increased,SSS range of 34.91-35.35 ‰ between the fishing ground fishing effort concentrated in the salinity of 34.6-35.2 ‰ of the sea;the third quarter,the fishing ground SSS The SSS of the fishery began to fall in the fourth quarter,ranging from 34.27 to 35.5 ‰,and the fishing effort was concentrated in the waters with salinity of 34.8-35 ‰.The range of SSS in fishery is increasing first and then decreasing,and the trend of change of CPUE varies with SSS in different quarters,but in general,the suitable SSS of fishery is between 34.2 and 35 ‰.6)To study the relationship between the length of the long-finned tuna CPUE and the upper thermocline in the Fiji exclusive economic zone of the Fiji,and concluded that the depth of the upper layer of the fishery was 21.3-44.5m in the first quarter,-30 m when the highest,CPUE also 20-30 m when the highest;the second quarter,the fishery thermocline deepened,UTD between 32.5-71.2m,which fishing fishery effort in the 60-70 m when the highest,but the CPUE or In the shallow thermocline region the highest,the highest CPUE occurred at UTD of 30-40cm;in the third quarter,the thermocline of the fishery continued to deepen,UTD between 37.7-83.2m,where the fishing fishery effort in 60-80 m,the highest in the second quarter,the highest CPUE at UTD 40-50m;in the fourth quarter,the thermocline of the fishery began to become shallow,the UTD of the fishing grounds was between 23.8-46.2m,Effort in the highest 30-40 m,CPUE UTD 30-40 m when the highest.In general,the thermocline of the fishery becomes lighter as the seasons change,but for the CPUE of the fishery,it is advantageous for the formation of the high value CPUE in the shallow thermocline.7)The GAM model shows that,in addition to SSH,other environmental factors have a significant impact on the CPUE.When the temperature is below 25°C,the CPUE tends to decrease slowly with the increase of SST.After 25°C,the CPUE increases slightly with the increase of SST.After the temperature exceeds 28°C,the CPUE starts with the increase of SST Rapid decline;CPUE with the SSS changes with two peaks,34.2-34.4 ‰ and 35.2-35.5 ‰;for UDT,20-30 m with its value increases and then decline,then the trend is flat,after its CPUE The impact of a significant decline.8)The results of the maximum entropy model show that the change of the potential distribution area of the long-finned tuna in Fiji’s exclusive economic zone is basically consistent with the change of the actual operating position.The distribution of the long-fin tuna on the 2013-2014 is mainly distributed in the Fiji exclusive economy The southern part of the area is slightly offset from the south in August.The albacore is mainly distributed in the northern part of Fiji’s exclusive economic zone.The Jackknife test shows that SST is the primary environmental factor affecting the distribution of albacore in Fiji’s exclusive economic zone,and 26-28°C can be used as an indicator for high-yielding fishing areas. |
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