再议东黄渤海带鱼种群划分问题

本研究根据中国水产科学研究院东海水产研究所早年收集的1971—1982年带鱼(Trichiurus lepturus)捕捞统计资料,从地理隔离、数量动态方面分析我国近海带鱼种群的划分问题。研究结果表明,东黄渤海带鱼存在两个种群,即黄渤海种群和东海种群。通过带鱼鱼群移动影像发现,黄渤海带鱼和东海带鱼在江苏北部近海(34?00?N,121?00?E)附近发生了混栖,这一海域的带鱼产量仅占当月总产量的1.16%;两种群带鱼在外海越冬场也发生混栖,这一海域带鱼产量仅占当月总产量的5.51%。本研究认为,之所以分为黄渤海带鱼和东海两个种群,主要证据有6个:其一,可能发生混栖海域带鱼群体的数量很少,均仅占当月带鱼产量的极少数;其二,在混栖海域,不同带鱼鱼群并未发生群体间个体完全混合,在产卵洄游过程中,各自群体将仍旧依照各自洄游路线回到越冬场,因而在产卵场发生遗传杂交的可能性很少;其三,带鱼在越冬场的混合不属于产卵场杂交,因此,不同种群带鱼因为产卵和杂交发生种群遗传性状融合的可能性较少;其四,黄渤海带鱼和东海带鱼有着各自不同的数量变化规律,两者近年来产量差距悬殊,黄渤海种群带鱼资源在衰退的同时,没有得到东海带鱼群体的补充;其五,除了在江苏北部近海和外海发生群体混栖,黄渤海带鱼和东海带鱼各自的分布空间完全隔离;其六,这两个不同带鱼种群在洄游中存在不同的水团背景。结合以往带鱼种群体征差异分析的结果,可以认为,黄渤海带鱼和东海带鱼分属不同的带鱼种群。在东黄渤海,带鱼整体上可以划分为黄渤海带鱼种群和东海带鱼种群。

A new discussion on division of the Trichiurus lepturus populations in the East China Sea, Yellow Sea, and Bohai Sea

In this paper, we discuss the geographical isolation and population dynamics of the largehead hairtail (Trichiurus lepturus) populations in the East China Sea (ECS), Yellow Sea (YS), and Bohai Sea (BS). The results showed that only two largehead hairtail populations exist in the nearshore regions of the ECS, YS, and BS. The largehead hairtail population in the Northern Yellow Sea and Bohai Sea was designated as the Yellow Sea and Bohai Sea population (YSBSP), and the other population in the South Yellow Sea and the East China Sea was designated as the East China Sea population (ECSP). By evaluating moving images of largehead hairtail, we found that the YSBSP rear-ended the population in Jiangsu''s northern nearshore waters at 34°00''N, 121°00''E. However, the largehead hairtail output from the overlapping waters accounted for only 1.16% of the total output. The two populations shared the same overwintering ground, and so these populations were mixed in the offshore waters to the west of Cheju Island. Only 1.16% of the total output was fished during the month in which the two populations mixed. We present six lines of evidence that there are two main populations of largehead hairtail in the studied waters. First, the output of largehead hairtail from the overlap waters is small, accounting for less than 5.51% of the total output in the same month. Second, the two groups do not produce hybrids when in overlapping waters because each group follows its own migratory route back to its wintering grounds. Third, the groups of largehead hairtail only mix in overlapping waters and not in spawning grounds, which is another reason why hybridization between the two populations is unlikely. Fourth, the two populations show different trends in their quantitative dynamics; for example, the outputs differ markedly between the two populations, suggesting that the ECSP did not contribute to the YSBSP in recent years. Fifth, there is significant geographical isolation between YSBSP and ECSP, except those in the overlapping waters. Sixth, the two different populations of largehead hairtail showed different migration patterns. Together, all of these results indicate that largehead hairtail inhabiting the East China Sea, Yellow Sea, and Bohai Sea belong to two different populations:the Yellow Sea and Bohai Sea population, and the East China Sea population.