长江口北支凤鲚深水张网渔获种类组成及其危害性分析

On species composition and damage of deepwater stow-net catches of Coilia mystus in the north branch of the Yangtze Estuary

为评估长江口北支水域凤鲚(Goilia mystus)深水张网捕捞对凤鲚及其它鱼类的危害性,2017年6-9月,在长江口北支水域进行连续8个航次采样,共采集凤鲚样本11 630尾,其它鱼类495 440尾。所获鱼类隶属15科,26种,其中海洋性鱼类15种,河口性鱼类9种,洄游性鱼类2种。渔获物中凤鲚多为洄游至长江口的繁殖亲体,而其它鱼类多处于幼鱼阶段。不同采样时间所获第一优势种不同,其中6月上旬、6月下旬至7月下旬、8月和9月的第一优势种分别为棘头梅童鱼(Collichthys lucidus,91. 44%)、小黄鱼(Larimichthys polyactis,90. 32%)、龙头鱼(Harpadon nehereus,51. 67%)和凤鲚(36. 92%)。研究结果表明,凤鲚深水张网作业不仅对凤鲚繁殖亲体产生重大危害,对其它重要经济鱼类幼体的损害也很严重,尤其对小黄鱼和棘头梅童鱼的幼鱼损害最大。为了更好地保护长江口鱼类的繁殖群体和增加补充资源,建议渔政等管理部门根据不同优势种繁殖群体和幼体在长江口的繁殖和育幼时间及主要分布范围,限制和调控凤鲚深水张网的作业船只数量、作业时段和区域,并严格控制网具规格。

To assess the damage of deepwater stow-net to Coilia mystus and other commercial fishes in the northern branch of the Yangtze Estuary,a total of11630C.mystus and495440other fishes were collected representing26species from15families,including15marine fishes,9estuarine fishes and2migratory fishes,during8consecutive voyages from June to September in2017.Most of the captured C.mystus were breeding parents migrating to the Yangtze Estuary,while most of the other fishes were in the young stage of development.The most dominant species obtained at different periods were different.Among them,the most dominant species in early June,from late June to late July,August and September were Collichthys lucidus with the percentage of number of91.44%,Larimichthys polyactis90.32%,Harpadon nehereus51.67%and C.mystus36.92%,respectively.The results showed that the stretching operation of deepwater stow-net not only caused great harm to the reproduction population of C.mystus,but also seriously damaged the larvae of other important economic fishes,especially the larvae of L.polyactis and C.lucidus.In order to protect the fish recruitment stock and recover fishery resources,it is suggested that the management should be made to limit and control the operational periods and area of deepwater stow-net according to the breeding and rearing time and distribution sites of dominant species in the Yangtze Estuary,and the net size should be strictly controlled.