热带中西太平洋黄鳍金枪鱼栖息水层空间分析

为了解热带中西太平洋黄鳍金枪鱼(Thunnus albacares)延绳钓适宜水层的空间分布,分析黄鳍金枪鱼垂直空间分布对渔获率的影响,采用Argo浮标剖面温度数据挖掘热带中西太平洋17℃和距海洋表层水温8 ℃(△8℃)的月平均等温线场,网格化计算17、△8℃等温线深度值和下界深度差,量化黄鳍金枪鱼游动水层,并结合中西...

Spatial Analysis of Suitable Habitat for Yellowfin Tuna in the Tropical Central and Western Pacific Ocean

In order to investigate the distribution of the yellowfin tuna （Thunnusalbacares） fishing grounds in the tropical Central and Western Pacific Ocean， the isothermal distribution of subsurface temperatures in the yellowfin tuna fishing grounds was evaluated. The depths of 17 and 8 ℃ isotherm from the sea surface temperature （SST） （Δ8 ℃） were plotted on spatial overlay maps using data collected on a monthly basis from Argo buoys and monthly CPUE data （catch per unit effort） from Thunnusalbacares long-lines supplied by the Western and Central Pacific Fisheries Commission （WCPFC）. In addition， the differences in depth between the 17 /Δ8 ℃ isolines and the lower boundary of the thermocline were computed to determine the relationship between Thunnusalbacares vertical distribution and thermocline depth. The overlay maps suggested that the distribution of Δ8 ℃ isothermal depth showed obviously seasonal variation， roughly in the zonal striped distribution on the annual mode. The spatial distribution of the Δ8 ℃ isothermal depth was deep in winter and shallow in summer. The catches per unite of effort （CPUE） were highest in areas where the 17 ℃ isothermal depth ranged from 180 to 279 m with the average depth 228 m. If the depth of 17 ℃ isothermal was greater than 300 m or shallower than 150 m， the CPUE tended to be lower. Similarly， the highest CPUEs were observed in areas where the Δ8 ℃ isothermal depth ranged from 120 to 239 m with the average depth 186 m. The horizontal distribution of high hook rates was concentrated in the area between 5°S and 10°N. The vertical distribution of Thunnusalbacares in the Central and Western Pacific Ocean was affected by the 17 and Δ8 ℃ isothermal depth， and the foraging depth of Thunnusalbacares was affected by the low boundary temperature and depth of the thermocline. At last the optimum ranges of subsurface factors were computed by the frequency analysis and the empirical cumulative distribution function. The optimum ranges for 17 and Δ8 ℃ isothermal depths were 160～300 m and 160～240 m， respectively. The optimum ranges of depth difference were 0～70 m for 17 ℃ isothermal depths and 30～109 m for Δ8 ℃ isothermal depths. The results were confirmed by using the Kolmogorov-Smirnov test. The distribution interval and vertical depth range for the central fishing ground of Thunnusalbacares were documented， and the results provided a reference for improving the efficiency of long-line fleet and resource management.