南极磷虾中层拖网捕捞参数对CPUE变动的影响

根据中国在南极海洋生物资源养护委员会(CCAMLR)48.1亚区和48.2亚区内2010—2014年南极磷虾拖网渔船的捕捞数据,采用广义可加模型(generalized additive model, GAM)分析各拖网捕捞参数(因子)对南极磷虾汛期单位捕捞努力量渔获量(catch per unit effort, CPUE )的影响。结果表明:2010—2014年我国南极磷虾作业渔场主要位于南极半岛等岛屿的周边海域,CPUE 值月变化明显,2—5月为捕捞高峰期。 CPUE 最高值为2014年,最低值为2012年,年平均CPUE呈略上升趋势。从月变化来看,除6月外,标准化 CPUE 均大于名义 CPUE;且最大值出现在4月或5月,最小值均出现在10月。GAM分析表明各捕捞参数对 CPUE 的影响由大到小依次为:拖网速度、网口高度、网口水平扩张、拖曳水深、曳纲长度;各因子的偏差解释率分别为22.8%、14.5%、12.7%、6.0%、1.6%,所有因子对 CPUE 的总体偏差解释率为57.6%。研究认为,我国南极磷虾捕捞作业中最适拖网速度范围2.6~3.1 kn;最适网口高度范围22~30 m;最适网口水平扩张范围20~25 m;最适曳纲长度范围100~200 m;最适拖曳水深范围0~40 m。

Effects of fishing coefficients of mid-water trawler on CPUE in Chinese Antarctic krill fishery

According to the Antarctic krill trawlers’ fishing data of China in 48.1, 48.2 subregions in Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) from 2010 to 2014, this study analyzed the effect on variations of catch per unit effort ( CPUE ) for fishing parameters of controllable trawl in Antarctic krill fishery from China. The results showed that the Antarctic krill fishery was mainly distributed in the surrounding waters of the Antarctic Peninsula and its adjacent water areas. The monthly CPUE showed obviously seasonal changes, while the period from February to May was the peak fishing period of krill stocks in 48.1, 48.2 subregions. In 2010-2014, the nominal CPUE and standardized CPUE had similar variation characteristics. The highest CPUE value appeared in 2014 and the lowest in 2012. From April or May, the CPUE was the highest, while the lowest was in October. The significance order from the highest to the lowest of the effects for all fishing parameters on CPUE were trawling speed, net mouth height, horizontal expansion of net mouth, trawling depth, length of warp by GAM model. They could explain the deviance of fishing factors by 22.8%, 14.5%, 12.7%, 6.0%, 1.6%, respectively. The accumulation of deviance explained of model to CPUE was 57.6%. Overall, the suitable values of trawling speed in Antarctic krill fishing ranged in 2.6~3.1kn;the suitable values of net mouth height ranged in 22~35m. The suitable values of horizontal expansion of net mouth ranged in 20~25m. The suitable range of length of warp was 100~200m, which of trawling depth was 0~40m. Therefore, we should considere the fishing parameters to the standardization of CPUE used in the resource assessment for Antarctic krill in the future.