浙江南部近海食物网特征及其对增殖放流活动的响应

Stock enhancement is one of the most popular management tools in fisheries. Enhancement activities not only increase the biomass and catch of target species but also impact other species even the food webs through complexity trophic interactions. However, most evaluations of enhancement activities are focus on re-catch rate and the recovery of target species, and knowledge of the impact of enhancement activities on food webs and ecosystems are limit. Therefore, this study uses the southern Zhejiang coastal area as an example, to analysis the food web structure and its response mechanisms for stock enhancement. Common enhancement species such as Rhopilema esculenta, Nibea albiflora, and Sparus microcephalus were chosen in this study. By analysis the structure and characters of southern Zhejiang coastal area food web, main predators and prey items of those species will be identified and the impact of enhancement activities on food web will be quantified. Besides, the potential ecosystem impact of different enhancement strategies will be evaluated by ecosystem simulation. This study will help to provide basic information for ecosystem-based fisheries management in southern Zhejiang coastal area, improve our understanding on the response mechanisms of enhancement activities on food webs. The implement of this study will help to improve the evaluation system and management for stock enhancement, and high-quality development for ocean exploitation.

增殖放流是恢复和保护海洋渔业资源的重要手段之一。放流物种通过捕食和被捕食行为，不可避免的会与其它种类产生交互作用，从而对整个海域的食物网结构产生影响。然而长久以来，人们对增殖放流效果的评价多集中在增殖群体的恢复程度以及物种回捕率上，忽视了放流种类对食物网的影响。因此，本项目拟以浙江南部近海为例，选定增殖种类海蜇 Rhopilema esculenta、黄姑鱼Nibea albiflora和黑鲷Sparus macrocephalus，通过分析和比较浙江近海食物网结构及特征，确定增殖种类在该海域的主要捕食者和饵料生物，量化增殖放流对食物网的影响；通过生态系统模拟，评估不同增殖管理策略的潜在生态效应。本项目有助于为浙江南部近海开展生态系统渔业管理提供基础资料，有助于深入了解增殖放流活动对食物网的影响机制，完善我国增殖放流评价体系，有助于科学的管理增殖放流活动，促进海洋开发的高质量发展。

长期以来，增殖种类的回捕率是评估增殖放流效果的主要指标，然而，增殖放流活动带来的生态效应并未得到足够的重视。本项目以浙江南部近海为例，通过综合调查，室内分析，文献搜集等方式，系统分析和梳理了该海域主要生物的摄食习性。根据实验和文献收集的相关生物学和资源量信息，构建了浙江南部近海生态系统模型，评估了该海域生态系统结构状况。以常见增殖种类海蜇Rhopilema esculenta和黑鲷Sparus macrocephalus为例，模拟了浙江南部近海生态系统在不同增殖策略下的响应。研究表明，浙江南部近海龙头鱼Harpadon nehereus、黑姑鱼Argyrosomus nibe、带鱼Trichiurus lepturus等底层高营养级鱼类主要以七星底灯鱼Benthosema pterotum为食，蓝圆鰺Decapterus maruadsi、竹荚鱼Trachurus japonicus等中上层高营养级鱼类则主要以虾类为主要饵料生物。浙江南部近海生态系统能量来源主要为浮游植物，展现出以中上层食物链为主的特征。生态系统系统杂食性指数、Finn’s 循环指数和连接指数等表征生态系统结构稳定性的指标均较低，反映该水域生态系统较为脆弱，抗干扰能力低，同时，生态系统在初级消费者至次级消费者的转换效率过低，为可能的增殖放流种类提供了充裕的生态位空间。增殖放流模拟表明，黑鲷和海蜇的增殖放流活动均对各功能群的生物量产生一定的影响，它们的放流活动均导致了海域内初级生产者生物量的增加。黑鲷的增殖放流会降低浙江南部近海鱼类总生物量，而海蜇的放流则刺激了蟹类生物量的增加，浙江南部近海生态系统中各种类对海蜇和黑鲷增殖放流的响应不容忽视。这些发现表明仅以传统的增殖种类回捕率并不足以反映其实际的贡献及影响，强调了基于生态系统的渔业管理重要性。