Evaluating Impacts of Trophic Interactions on the Effectiveness of Single-Species Fisheries Management Frontiers in Marine Science

Single-species fisheries management (SSFM) is applied to many fisheries ecosystems around the world. The associated ecological impacts are usually not well understood due to the lack of considering trophic interactions among species in the ecosystem. This impedes the implementation of SSFM in an ecosystem context and reduces our ability to understand the possible ecological impacts of fishing activities. This study focuses on two economically important species in the Jiaozhou Bay, China: the short-lived, fast-growing, and relatively abundant Japanese mantis shrimp (Oratosquilla oratoria) and the long-lived, slow-growing, and less abundant Korean rockfish (Sebastes schlegelii). We evaluated how varying trophic interactions influenced O. oratoria and S. schlegelii (i.e., target-species) who were managed under constant fishing pressure. The increase of fishing pressure to other species (i.e., non-target species) was beneficial to O. oratoria and S. schlegelii. O. oratoria was more sensitive to the decrease of fishing pressure to other species. The predation mortality of age-0 O. oratoria increased with the increased fishing pressure to other species. The predation mortality of age-1 O. oratoria and age-0 S. schlegelii had negative relationships with the fishing pressure to other species. Age-1 S. schlegelii seemed not to be sensitive to the changes in trophic interactions. The predation mortality of O. oratoria and S. schlegelii had bigger changes than the starvation mortality after fishing changed. It suggested the prey-predator relationship had a bigger impact than the food competition. The increase of high-trophic-level fish Johnius belangerii fishery positively impacted O. oratoria, but negatively impacted S. schlegelii. S. schlegelii was more sensitive to the changes of the low-trophic-level fish Pholis fangi fishery. Given the complex dynamics of ecosystems, this study highlights the importance of species-specific responses of fishes to shifting trophic interactions in fisheries management.

单物种渔业管理（Single-species fisheries management, SSFM）已在全球众多渔业生态系统中得到应用。但由于未充分考虑生态系统内物种间的营养相互作用，其相关生态效应通常尚未得到清晰阐释。这不仅阻碍了在生态系统框架下推行单物种渔业管理，也削弱了我们认知捕捞活动潜在生态影响的能力。本研究聚焦中国胶州湾两种具有重要经济价值的物种：寿命短促、生长迅速且种群相对繁盛的日本螳螂虾（Oratosquilla oratoria），以及寿命悠长、生长迟缓且种群较为稀少的许氏平鲉（Sebastes schlegelii）。我们评估了动态变化的营养相互作用对恒定捕捞压力下的两类目标物种——日本螳螂虾与许氏平鲉的影响。对非目标物种捕捞压力的提升，对日本螳螂虾和许氏平鲉均具有正向效应。其中日本螳螂虾对非目标物种捕捞压力的下降更为敏感。0龄日本螳螂虾的捕食死亡率随非目标物种捕捞压力的升高而上升；1龄日本螳螂虾与0龄许氏平鲉的捕食死亡率，则与非目标物种的捕捞压力呈负相关关系。1龄许氏平鲉似乎对营养相互作用的变化并不敏感。捕捞压力改变后，日本螳螂虾与许氏平鲉的捕食死亡率波动幅度大于饥饿死亡率，这表明捕食者-猎物关系相较于食物竞争，对种群动态的影响更为显著。高营养层级鱼类皮氏叫姑鱼（Johnius belangerii）捕捞活动的增强，对日本螳螂虾具有正向影响，却对许氏平鲉产生负向作用。而许氏平鲉对低营养层级鱼类方氏锦鳚（Pholis fangi）捕捞活动的变化更为敏感。鉴于生态系统复杂的动态特性，本研究强调了在渔业管理中，鱼类对营养相互作用变化的物种特异性响应的关键意义。