ABSTRACT: Wild fish aggregate at aquaculture net-pens, but the underlying mechanisms are not fully understood. This study examined how salmon farms attract coastal Atlantic cod Gadus morhua from their inshore spawning grounds. Acoustic receivers were deployed at 5 known cod spawning grounds and 6 salmon Salmo salar farms located at varying distances from these grounds in a mid-Norway study site. Cod were caught at each spawning ground annually from 2017-2019, fitted with acoustic transmitters and released (n = 535). A total of 289 tagged cod (54%) were detected at the salmon farms, with more cod detected at farms closest to the focal spawning grounds and at operational farms. The latter result is likely linked to the availability of feeding opportunities at farm locations. Those cod that were detected by the receivers spent less time at farms farther from their release locations. For the farm-associated cod, 70% were detected for <1 wk at the farms. However, 48 cod spent >1 mo close to the farms, with 1 individual staying 720 d underneath the farm. A total of 135 cod visited 2 or more farms, with farms in proximity more connected in terms of inter-farm movement. Some of the cod utilizing these local spawning grounds likely have considerable dietary input from salmon feed.

中文翻译：

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从沿海产卵场到鲑鱼养殖场吸引鳕鱼 Gadus morhua

摘要：野生鱼在水产养殖网中聚集，但其潜在机制尚不完全清楚。这项研究调查了鲑鱼养殖场如何从其近岸产卵场吸引沿海大西洋鳕鱼Gadus morhua 。在 5 个已知的鳕鱼产卵场和 6 个鲑鱼Salmo salar部署了声学接收器在挪威中部的一个研究地点，位于与这些场地不同距离的农场。从 2017 年到 2019 年，每年在每个产卵场捕获鳕鱼，安装声波发射器并释放（n = 535）。在鲑鱼养殖场共检测到 289 条带标签的鳕鱼（54%），在离集中产卵场最近的养殖场和运营养殖场检测到更多的鳕鱼。后一个结果可能与农场地点的喂养机会的可用性有关。接收器检测到的那些鳕鱼在远离其释放地点的农场停留的时间更少。对于与农场相关的鳕鱼，70% 的鳕鱼在农场检测不到 1 周。然而，48 条鳕鱼在养殖场附近停留了 >1 个月，其中 1 条鳕鱼在养殖场下方停留了 720 天。共有 135 条鳕鱼参观了 2 个或更多养殖场，就农场间的流动而言，附近的农场之间的联系更加紧密。利用这些当地产卵场的一些鳕鱼可能从鲑鱼饲料中获得大量膳食输入。