Data_Sheet_1_Evaluating Impacts of Trophic Interactions on the Effectiveness of Single-Species Fisheries Management.docx

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）目前被广泛应用于全球众多渔业生态系统中。由于未考虑生态系统内物种间的营养级相互作用，其相关生态影响通常尚未得到充分认知。这阻碍了SSFM在生态系统框架内的落地实施，同时削弱了我们认知捕捞活动潜在生态影响的能力。本研究以中国胶州湾两种具有重要经济价值的物种为研究对象：寿命短、生长快且种群相对丰富的日本螳螂虾（Oratosquilla oratoria），以及寿命长、生长缓慢且种群相对稀少的许氏平鲉（Sebastes schlegelii）。我们评估了动态变化的营养级相互作用，对处于恒定捕捞压力下的日本螳螂虾（O. oratoria）与许氏平鲉（S. schlegelii，即目标物种）的影响。对其他物种（即非目标物种）施加的捕捞压力提升，对日本螳螂虾与许氏平鲉均产生有利影响。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提升而升高。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级相互作用的变化并不敏感。捕捞压力变化后，日本螳螂虾与许氏平鲉的捕食死亡率的变化幅度，高于其饥饿死亡率的变化幅度。这表明捕食者-猎物关系对种群的影响强于食物竞争。高营养级鱼类白姑鱼（Johnius belangerii）的捕捞压力提升，对日本螳螂虾产生正向影响，但对许氏平鲉产生负向影响。许氏平鲉对低营养级鱼类方氏锦鳚（Pholis fangi）的捕捞压力变化更为敏感。鉴于生态系统动态的复杂性，本研究强调了在渔业管理中，鱼类对营养级相互作用变化的物种特异性响应的重要性。