ABSTRACT: Salmon farming in marine net pens is a major activity in many temperate regions. This industry may affect coastal ecosystems in several ways, such as with waste pollution and parasite spillover. Less is known about the extent to which salmon farming disrupts the use of inshore spawning grounds by wild fish, such as the Atlantic cod Gadus morhua. Acoustic telemetry was therefore used to explore cod space use during the spawning season in a coastal region in mid-Norway with multiple salmon farms. Acoustic receivers were placed in clusters at 5 known cod spawning grounds and 6 nearby salmon farms. Data from 481 adult cod caught at the spawning grounds during 2017-2019 and equipped with acoustic telemetry transmitters were analysed. Overall, fewer fish were detected at farms than spawning grounds, even when accounting for distance from release point. Individual cod residency (days detected / duration of spawning period) was generally higher at the spawning grounds close to farms but low at the farms themselves, with little apparent spawning at the farm localities. In contrast, spawning was clearly occurring at the nearby spawning grounds, with cod spending weeks (n = 316) or months (n = 158) there during the spawning period. Males had longer residence times at spawning grounds than females, likely linked to the cod mating system. Overall, we found little support for the assertion that salmon farms disrupt inshore spawning dynamics of cod using nearby spawning grounds presently, either by attracting spawners to farms or causing fish to leave these grounds.

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三文鱼养殖对大西洋鳕鱼时空繁殖动态的影响

摘要：在许多温带地区，海洋网围栏的鲑鱼养殖是一项主要活动。该行业可能会以多种方式影响沿海生态系统，例如废物污染和寄生虫外溢。关于鲑鱼养殖在多大程度上干扰了大西洋鳕鱼Gadus morhua等野生鱼类对近海产卵场的利用，我们知之甚少. 因此，在拥有多个鲑鱼养殖场的挪威中部沿海地区，在产卵季节期间使用声学遥测技术来探索鳕鱼空间的使用情况。声学接收器成组放置在 5 个已知的鳕鱼产卵场和 6 个附近的鲑鱼养殖场。分析了 2017-2019 年期间在产卵场捕获并配备声学遥测发射器的 481 条成年鳕鱼的数据。总体而言，在养殖场检测到的鱼少于产卵场，即使考虑到与释放点的距离也是如此。在靠近养殖场的产卵场，鳕鱼个体（检测到的天数/产卵期持续时间）通常较高，但在养殖场本身较低，养殖场附近几乎没有明显的产卵。相比之下，产卵明显发生在附近的产卵场，鳕鱼在产卵期间在那里度过数周（n = 316）或数月（n = 158）。雄性在产卵场的停留时间比雌性长，这可能与鳕鱼的交配系统有关。总体而言，我们发现几乎没有证据支持鲑鱼养殖场目前使用附近产卵场破坏鳕鱼近海产卵动态，要么通过吸引产卵者到养殖场，要么导致鱼类离开这些产卵场。