The effect of photoperiod manipulation on growth, smoltification and maturation was assessed in Atlantic salmon through an observational study performed in a commercial RAS facility from June (25.0 ± 11.0 g) to October 2018 (151.1 ± 25.5 g). Half of the commercial cohort 721 was raised in continuous light LD24:0 (LL) while the other received a 6‐week LD12:12 winter signal (WS) for smoltification from 12 August to 21 September. Parameters related to growth (body weight, gene expression of pituitary gh1 and gh2, and liver ghr1, igf1 and igfbp1a), smoltification (condition factor, plasma sodium and cortisol, gill NKA activity and nka1a, nka1b and nkcc1a expression) and maturation (GSI and pituitary fshb and lhb expression) were analysed. Afterwards, a multivariate analysis was performed on production data from five commercial cohorts raised in the facility (including 721) to identify variables potentially linked to early maturation in RAS. Results from the observational study indicated weak compensatory growth and slightly better smoltification in WS, although signs of size‐induced smoltification were present in LL. Smoltification indicators were poor in both treatments, suggesting that smolts may not be yet ready for seawater. No maturation was observed in any photoperiod treatment; however, the multivariate assessment suggested that such lack of maturation might be rather linked to the low mean temperature and SGR experienced by our cohort.

中文翻译：

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光周期操作对大西洋鲑鱼生长，糖化和性成熟的影响：以商业RAS为例

通过商业RAS设施从6月（25.0±11.0 g）到2018年10月（151.1±25.5 g）进行的观察研究，评估了大西洋鲑中光周期操作对生长，糖化和成熟的影响。商业队列721的一半在连续光照LD24：0（LL）下饲养，而另一组则在8月12日至9月21日接受了为期6周的LD12：12冬季信号（WS）进行糖化。与生长有关的参数（体重，垂体gh1和gh2以及肝ghr1，igf1和igfbp1a的基因表达），糖化（条件因子，血浆钠和皮质醇，g NKA活性以及nka1a，nka1b和nkcc1a表达）和成熟（GSI和垂体fshb和lhb表达式）进行了分析。之后，对来自该设施中的五个商业队列（包括721个）的生产数据进行了多变量分析，以识别可能与RAS早期成熟有关的变量。观察性研究的结果表明，尽管LL中存在大小诱发的粘液化的迹象，但WS中的代偿性生长较弱，且其粘液化略好。两种处理中的化指标均较差，表明可能尚未准备好入海水。在任何光周期处理中均未观察到成熟；但是，多变量评估表明，这种缺乏成熟的现象可能与我们这个队列所经历的平均温度低和SGR较低有关。