Data from: Predation, metabolic priming and early life-history rearing environment affect the swimming capabilities of growth hormone transgenic rainbow trout

The period of first feeding, when young salmonid fishes emerge from natal stream beds, is one fraught with predation risk. Experiments conducted in semi-natural stream mesocosms have shown that growth hormone transgenic salmonids are at greater risk of predation than their non-transgenic siblings, due partly to the higher metabolic demands associated with transgenesis, which force risky foraging behaviours. This raises questions as to whether there are differences in the swim-performance of transgenic and non-transgenic fishes surviving predation experiments. We tested this hypothesis in wild-origin rainbow trout (Oncorhynchus mykiss) that were reared from first feeding in semi-natural stream mesocosms characterized by complex hydrodynamics, the presence of predators and oligotrophic conditions. Using an open-flume raceway, we swam fish and measured their capacity for burst-swimming against a sustained flow. We found a significant genotype effect on burst-performance, with transgenic fish sustaining performance longer than their wild-type siblings, both in predator and predator-free stream segments. Importantly, this effect occurred before differences in growth were discernable. We also found that mesocosm-reared fish had greater burst-performance than fish reared in the controlled hatchery environment, despite the latter being unexposed to predators and having abundant food. Our results suggest a potential interaction between predation and metabolic priming, which leads to greater burst capacity in transgenic trout.

幼鲑科鱼类从出生地溪流底床孵出后的首次摄食阶段，是充满捕食风险的关键时期。在半自然溪流中宇宙系统（semi-natural stream mesocosms）中开展的实验表明，生长激素转基因（growth hormone transgenic）鲑科鱼类比其非转基因同胞面临更高的捕食风险，部分原因是转基因带来的更高代谢需求，迫使它们采取高风险的觅食行为。这一发现引发了一个疑问：经历捕食实验并存活下来的转基因与非转基因鱼类，其游泳性能是否存在差异？
我们以野生起源的虹鳟（Oncorhynchus mykiss）为实验对象，从首次摄食阶段开始，在具备复杂水动力条件、存在捕食者且为寡营养环境（oligotrophic conditions）的半自然溪流中宇宙系统中饲养。利用开放式水槽跑道（open-flume raceway），我们对鱼类进行游泳测试，并测定它们在持续水流中的冲刺游泳能力。
我们发现基因型对冲刺性能存在显著影响：在有捕食者和无捕食者的溪流区域中，转基因鱼类的冲刺性能维持时长均长于其野生型（wild-type）同胞。值得注意的是，该效应在生长差异可被观测到之前就已显现。
我们还发现，中宇宙系统饲养的鱼类比在可控孵化场环境中饲养的鱼类具有更强的冲刺性能，尽管后者未接触过捕食者且食物充足。本研究结果表明，捕食作用与代谢预激活（metabolic priming）之间存在潜在的相互作用，该相互作用使得转基因虹鳟具备更强的冲刺能力。