The Aleutian Islands ecosystem is a highly dynamic marine environment that supports commercially important fish species, such as Atka Mackerel Pleurogrammus monopterygius and Northern Rockfish Sebastes polyspinis, and several large marine mammals, including the Steller sea lion (SSL) Eumetopias jubatus. To protect SSL foraging behavior and prey, trawl exclusion zones (TEZs) were established around SSL rookeries and haulouts across the Aleutian Islands and are closed to bottom trawling. The Atka Mackerel fishery is concentrated at small, local patches (~37.04 km [~20 nautical miles]) across the Aleutian Islands, often near and adjacent to TEZs. Food web models and fishery stock assessments predict sufficient prey for both the fishery and foraging SSLs at the level of large management areas (each area is ~463 km [~250 nautical miles] longitudinally), but little is known about local fish distribution (~37.04 km) in proximity to SSL rookeries and haulouts. We used CPUE to examine the spatial distribution of two SSL prey species (Atka Mackerel and Northern Rockfish) and marine invertebrates (as a proxy for habitat quality) at large (across the Aleutian Islands) and small (~37.04‐km) scales. Although Atka Mackerel abundance estimates were similar across the Aleutian Islands, the density of Atka Mackerel differed. In the eastern Aleutian Islands, where SSL population trends have stabilized, Atka Mackerel aggregations were dense. In contrast, in the far western Aleutian Islands, where SSL populations are still in decline, Atka Mackerel distributions were diffuse and Northern Rockfish exhibited a greater density. Results indicated no significant difference in CPUE between areas open to fishing and closed areas (i.e., TEZs) at all study sites for Atka Mackerel and at all but one study site for Northern Rockfish, whereas invertebrate densities were significantly higher inside of TEZs at all study sites. We discuss how fish distributions across the Aleutian Islands may impact the success and behavior of foraging SSLs.

中文翻译：

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阿留申群岛上与斯特勒海狮Eumetopias jubatus的饮食和丰富度相关的主要猎物物种的较高聚集度

阿留申群岛生态系统是一个高度动态的海洋环境，可为商业上重要的鱼类提供支持，例如Atka Mackerel Pleurogrammus monopterygius和Northern Rockfish Sebastes polyspinis以及几种大型海洋哺乳动物，包括Steller海狮（SSL）Eumetopias jubatus。为了保护SSL的觅食行为和猎物，在阿留申群岛上的SSL游击队和拖网处周围建立了拖网禁区（TEZ），并禁止拖网底拖网。阿特卡鲭鱼渔业集中在整个阿留申群岛上的局部小片地区（〜37.04 km [〜20海里]），通常靠近和邻近经济特区。食物网模型和渔业种群评估预测大型管理区域（每个区域纵向为〜463 km [〜250海里]）上的渔业和觅食SSL都有足够的猎物，但对当地鱼类分布知之甚少（〜 37.04 km）靠近SSL队列和传输。我们使用CPUE在大范围（整个阿留申群岛）和小规模（〜37.04-km）的尺度上研究了两种SSL猎物（Atka Mackerel和Northern Rockfish）和海洋无脊椎动物（代表栖息地质量）的空间分布。尽管阿留申群岛上阿特卡鲭鱼的丰度估计值相似，但阿特卡鲭鱼的密度却有所不同。在SSL人口趋势趋于稳定的阿留申群岛东部，Atka Mackerel聚集密集。相反，在远东的阿留申群岛上，SSL人口仍在下降，阿特卡鲭鱼分布较分散，北部石鱼的密度较高。结果表明，开放捕鱼区和封闭区之间的CPUE没有显着差异（即，在所有研究地点的Atka Mackerel以及除北部岩鱼以外的所有研究地点的TEZ区域，而在所有研究地点的TEZ内部的无脊椎动物密度显着更高。我们讨论了阿留申群岛上的鱼类分布如何影响SSL觅食的成功和行为。