Abstract The most controversial environmental problems in commercial salmon farming are the negative effects of sea lice (Lepeoptheirus salmonis, Caligus spp.), the genetic introgression of farmed salmon in wild populations, nutrient waste load and the emission of potentially toxic waste to coastal waters. Moving production from sea cages to land-based facilities, offshore farming or marine closed containment systems (CCS) are suggested as possible ways to solve these problems. However, there are few published studies on production capacity and fish welfare in such systems. The main aim of this study was to describe growth rates, mortality rates and mortality causes in the commercial-scale production of Atlantic salmon (Salmo salar) post-smolts in CCS from sea transfer until the size of 1000 g. From October 2014 to May 2017, we recorded growth rates, feed use, mortality and mortality causes during 23 CCS production cycles, including 18 CCS periods with off-season smolt (S0) and 5 CCS periods with one-year smolt (S1). The mean (SD) growth rate, thermal growth coefficient (TGC), for all 23 CCS was 3.03 (0.34), with no difference between cages with S1 (n = 5) and cages with S0 (n = 1 8). Cumulative mortality three months after sea transfer (CM3mo) was 2.6%, while cumulated mortality throughout the total trial period (CMtotal, mean number of days = 159) was 3.6%. Both CM3mo and CMtotal were higher in S1 groups than in S0 groups. Mean (SD) feed conversion ratio in CCS with S0 (n = 18) was 1.11 (0.07). The two main mortality causes were ‘Ulcers and fin rot’ (S1 and S0) and ‘Failed smolt’ (S1), accounting for 36.1% and 19.3% of the total mortality, respectively. Water flow, oxygen saturation and other water quality parameters were within safe limits for fish health and welfare.

中文翻译：

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近距离观察封闭网箱：海洋封闭禁闭系统中大西洋鲑鱼生产过程中的生长和死亡率

摘要 商业鲑鱼养殖中最具争议的环境问题是海虱（Lepeoptheirus salanis, Caligus spp.）的负面影响、养殖鲑鱼在野生种群中的基因渗入、营养废物负荷以及向沿海水域排放潜在有毒废物。建议将生产从海洋网箱转移到陆基设施、近海养殖或海洋封闭式围护系统 (CCS) 作为解决这些问题的可能方法。然而，关于此类系统中生产能力和鱼类福利的已发表研究很少。本研究的主要目的是描述从海上转移到 1000 g 大小的 CCS 中大西洋鲑鱼 (Salmo salar) 后小鲑鱼的商业规模生产的增长率、死亡率和死亡率原因。2014年10月至2017年5月，我们记录了 23 个 CCS 生产周期中的生长率、饲料使用、死亡率和死亡原因，包括 18 个 CCS 淡季（S0）周期和 5 个 CCS 一年（S1）周期。所有 23 个 CCS 的平均 (SD) 生长率、热生长系数 (TGC) 为 3.03 (0.34)，S1 网箱 (n = 5) 和 S0 网箱 (n = 1 8) 之间没有差异。海上转运后三个月的累积死亡率 (CM3mo) 为 2.6%，而整个试验期间的累积死亡率（CMtotal，平均天数 = 159）为 3.6%。S1 组的 CM3mo 和 CMtotal 均高于 S0 组。在 S0 (n = 18) 的 CCS 中，平均 (SD) 进料转化率为 1.11 (0.07)。两个主要的死亡原因是“溃疡和鳍腐烂”（S1 和 S0）和“幼鱼失败”（S1），分别占总死亡率的 36.1% 和 19.3%。水流，