Norwegian Veterinary Institute, 1433, Ås, Norway.
Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870, Frederiksberg, Denmark.
Sci Rep. 2021 Jul 19;11(1):14702. doi: 10.1038/s41598-021-93874-6.
In 2019, it was estimated that more than 50 million captive Atlantic salmon in Norway died in the final stage of their production in marine cages. This mortality represents a significant economic loss for producers and a need to improve welfare for farmed salmon. Single adverse events, such as algal blooms or infectious disease outbreaks, can explain mass mortality in salmon cages. However, little is known about the production, health, or environmental factors that contribute to their baseline mortality during the sea phase. Here we conducted a retrospective study including 1627 Atlantic salmon cohorts put to sea in 2014-2019. We found that sea lice treatments were associated with Atlantic salmon mortality. In particular, the trend towards non-medicinal sea lice treatments, including thermal delousing, increases Atlantic salmon mortality in the same month the treatment is applied. There were differences in mortality among production zones. Stocking month and weight were other important factors, with the lowest mortality in smaller salmon stocked in August-October. Sea surface temperature and salinity also influenced Atlantic salmon mortality. Knowledge of what affects baseline mortality in Norwegian aquaculture can be used as part of syndromic surveillance and to inform salmon producers on farming practices that can reduce mortality.
2019 年，据估计，挪威有超过 5000 万尾养殖大西洋鲑在海洋网箱养殖的最后阶段死亡。这种死亡率对生产者来说是一个重大的经济损失，也需要提高养殖鲑鱼的福利。单一的不利事件，如藻类大量繁殖或传染病爆发，可以解释鲑鱼网箱中的大规模死亡。然而，对于导致其在海上阶段基线死亡率的生产、健康或环境因素知之甚少。在这里，我们进行了一项回顾性研究，包括 2014 年至 2019 年期间下海的 1627 个大西洋鲑鱼群体。我们发现，虱子处理与大西洋鲑鱼的死亡率有关。特别是，非药物性虱子处理的趋势，包括热除虱，会增加鲑鱼在处理当月的死亡率。不同的生产区域死亡率存在差异。放养月份和体重也是其他重要因素，8 月至 10 月放养的较小鲑鱼死亡率最低。海表温度和盐度也影响大西洋鲑鱼的死亡率。了解哪些因素会影响挪威水产养殖的基线死亡率，可以作为综合征监测的一部分，并告知鲑鱼养殖者哪些养殖做法可以降低死亡率。
