Anadromous Atlantic salmon (Salmo salar) rely on long ocean migrations to build energy stores for maturation and spawning. In seawater, wild Atlantic salmon are threatened by high salmon lice (Lepeophtheirus salmonis) infestation levels resulting from intensive salmonid sea-cage aquaculture. Salmon lice infection can cause a stress response and an osmotic imbalance in the host. The lice infection intensity threshold values for these responses, however, remain to be identified in Atlantic salmon. In order to define this under laboratory conditions, individually tagged F1 wild origin Atlantic post-smolts (40 g) were infected with salmon lice copepodids or left as uninfected controls. Twenty-eight days post infection, infected post-smolts had a mean of 0.38 (range of 0.07–0.9) mobile lice g⁻¹ fish weight. During this period, specific growth rates (SGRs) were lower in infected than control fish (0.4 vs 1.0% day⁻¹). Higher plasma Na⁺, Cl⁻ and osmolality in infected fish also indicate osmoregulatory impairment. SGR correlated negatively with plasma Na⁺, Cl⁻, osmolality and cortisol in the infected, but not in the control group. Infection intensity (lice g⁻¹ fish) correlated positively with mortality rate and plasma Na⁺, Cl⁻, osmolality and cortisol and correlated negatively with SGR and condition factor. Calculated lice intensity threshold values for changes in plasma ions were 0.18 lice g⁻¹ for plasma Cl⁻, and 0.22 lice g⁻¹ for plasma Na⁺. Moribund infected fish occurred at infection intensities above 0.2 lice g⁻¹, and these fish had extreme plasma Cl⁻, Na⁺, osmolality and cortisol levels. There was a positive correlation between plasma cortisol and plasma Na⁺, Cl⁻ and osmolality in infected fish. This study provides vital information that can be used to define thresholds in the monitoring and conservation of wild Atlantic salmon populations affected by aquaculture-driven salmon lice infestations.

中文翻译：

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实验室鲑鱼虱感染对大西洋鲑鱼渗透调节，生长和存活的影响

大西洋淡水鲑鱼（Salmo salar）依靠漫长的海洋迁移来建立能量储存库，以进行成熟和产卵。在海水中，野生大西洋鲑鱼受到鲑鱼虱子（Lepeophtheirus鲑鱼）鲑鱼网箱养殖的密集度。鲑鱼虱子感染可导致宿主压力反应和渗透失衡。然而，这些反应的虱子感染强度阈值仍有待在大西洋鲑鱼中确定。为了在实验室条件下确定这一点，将单独标记的F1野生起源大西洋大后嗅（40 g）感染鲑鱼虱足，或作为未感染的对照。感染后第二十八天，被感染的后鼻鸭平均移动虱子克^-1鱼重为0.38（范围为0.07-0.9）。在此期间，受感染的鱼的特定生长率（SGR）低于对照鱼（0.4 vs 1.0％^-1天）。较高的血浆钠⁺，氯^-受感染鱼的渗透压和渗透压也表明渗透调节受损。SGR与血浆的Na负相关⁺，氯^- ，重量克分子渗透压浓度和皮质醇在感染，而不是对照组中使用。感染强度（虱克^-1鱼）与死亡率和等离子体的Na正相关⁺，氯^{- ，}重量克分子渗透压浓度和皮质醇和与SGR和条件因子负相关。计算虱强度阈值等离子体中的离子的变化分别为0.18虱克^-1用于等离子体氯^- ，和0.22虱克^-1为等离子体的Na ⁺。感染莫里宾德鱼的感染强度超过0.2虱g ^-1，而这些鱼有极端的血浆氯^- ，钠⁺，渗透压和皮质醇水平。有血浆皮质醇和血浆娜之间的正相关性⁺，氯^-在被感染的鱼和渗透压。这项研究提供了重要信息，可用于确定受水产养殖驱动的鲑鱼虱子侵染影响的野生大西洋鲑鱼种群监测和保护的阈值。