中街山列岛海洋保护区曼氏无针乌贼产卵生境选择偏好及其机制研究

Overfishing and pollution had severely depleted fishery resources so that there were almost "no fish" in the East China Sea, and the fishing industry was confronted with the "prisoner's dilemma", especially the loss, degradation and fragmentation of cuttlefish spawning habitat. As for Sepiella maindroni, some effective measures had been implemented for the stock enhancement such as releasing eggs and larvae on traditional spawning grounds. However, it was insufficient to restore S. maindroni resources relying only on government public investments. Therefore, it was of great significance to identify the preferential spawning habitat mechanism of S. maindroni, and to investigate the spontaneous restoration of the natural structures for egg laying. This project was mainly conducted around the Zhongjieshan Islands, and focused on the preferred water depth where Plexaauraa sp. dwelled in. Advanced investigation methods and statistical analytic approaches were used to analyze the collected data. We aimed to reveal the following results: 1) find out the indicative factors and the spawning habitat selection ranges of S. maindroni; 2) build up the habitat suitability model; and 3) discuss on the horizontal distribution rules of habitat suitability index. In addition, we investigated the response characteristics of Plexaauraa sp. according to habitat changes, and analyzed the fact of the loss of natural affiliated stuff on laid eggs, and illustrated the preferential spawning habitat mechanism of S. maindroni. Our findings can provide theoretical bases for conserving the population of S. maindroni and the conservation of spawning habitat diversity, as well as provide scientific bases for the implementation of “The Restoration and Revitalization Plan for Fishery Grounds in Zhejiang Province”.

“东海无鱼”导致捕捞业陷入“囚徒困境”，特别是乌贼产卵生境丧失、退化和破碎化现象严重。目前，在曼氏无针乌贼传统产卵场开展受精卵和幼体增殖放流虽取得了一定的效果，但从长远来看仅仅依靠政府主导的增殖放流投入远不能满足资源恢复的需要。因此，通过研究曼氏无针乌贼产卵生境选择偏好及其机制，进行乌贼天然产卵附着物的自然恢复是产卵场可持续利用的有效途径。本项目以中街山列岛为研究海域，基于目标水层柳珊瑚为本体的靶位调查数据，利用新方法和技术，查明曼氏无针乌贼产卵生境指示因子和生境选择范围，构建曼氏无针乌贼产卵栖息地适宜度模型，探讨栖息地适宜度指数平面分布规律。通过野外和室内条件控制试验，聚焦柳珊瑚对生境因子变化的响应(反馈)特点，解析天然产卵附着物缺失的主因，阐明曼氏无针乌贼产卵生境选择偏好机制。本项目旨在为曼氏无针乌贼种群及产卵场生物多样性保护提供理论基础，为浙江渔场修复振兴计划的实施提供科学依据。

“东海无鱼”导致捕捞业陷入“囚徒困境”，特别是乌贼产卵生境丧失、退化和破碎化现象严重。在天然柳珊瑚资源严重缺失、人工产卵附着物存在不同程度的弊端、实施增殖放流远不能满足资源恢复需要的现状下，着眼点在于开展曼氏无针乌贼产卵生境选择机制的研究。本研究基于柳珊瑚和乌贼卵为本体的靶位调查，得到如下8个重要结论：（ⅰ）查明了曼氏无针乌贼洄游不是南北之间长距离的洄游，而是由深水到浅水，再由浅水到深水局部海区的短距离洄游，其洄游移动受到季风、潮流和温度的影响；（ⅱ）与30多年前比较乌贼产卵亲体大量捕获期平均提前了20天，预测未来曼氏无针乌贼的产卵期可能还会提前，夜光藻可作为乌贼渔发的直观指标；（ⅲ）过高或过低流速对柳珊瑚和乌贼卵均不利，柳珊瑚偏好在持续的0.28m/s中等偏上强度流速和硬底质区生息，乌贼卵偏好在持续的0.21 m/s中等偏下强度流速和泥质砂区内/附近生息；（ⅳ）北面为柳珊瑚的重点优势分布区，西侧和东北侧为乌贼卵重点优势分布区，乌贼卵主要分布区位于乌贼产卵洄游通道上；（ⅴ）经度和底层流速是柳珊瑚和乌贼卵分布的共性因子，柳珊瑚缺失主因是缺乏适宜柳珊瑚生长的底层流速、北面岸线长度和硬底质；（ⅵ）中街山列岛海域广泛分布的3种柳珊瑚为小月柳珊瑚、Guaiagorgia anas和Guaiagorgia sp.，乌贼产卵亲体对多枝柳珊瑚的偏好度高于颜色，柳珊瑚具有顽强的生命力，但是生长缓慢，其资源保护势在必行；（ⅶ）乌贼亲体表现出了集群、异性吸引、求偶、护卫、争斗等系列产卵行为偏好，雌雄个体间集群表现为群居期、求偶期和交配期等3个时期，雄性个体在性别角色中分化突出，表现为个体更大，越容易获得交配权，当产卵亲体出现比例失衡时，数量少的个体容易成为焦点，均表现出对异性的吸引力；（ⅷ）乌贼卵潜在的敌害生物较少，主要来自于孵化后的威胁。本研究的基础研究结论，可为后续开展曼氏无针乌贼种群保护及产卵场生物多样性保护提供理论基础，为浙江渔场修复振兴计划的实施提供科学依据。