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（salmonid）从其出生溪流河床中钻出后的首次摄食阶段，是一个充满捕食风险的时期。在半自然溪流中型实验生态系统（semi-natural stream mesocosms）中开展的实验表明，生长激素转基因（growth hormone transgenic）鲑科鱼类相较于其非转基因同胞，面临更高的捕食风险；这一现象部分源于转基因带来的更高代谢需求，迫使它们采取风险更高的觅食行为。这一现象引发了相关研究疑问：在捕食实验中存活的转基因与非转基因鱼类，其游泳性能（swim-performance）是否存在差异？本研究以野生起源虹鳟（Oncorhynchus mykiss）为实验对象，这类个体从首次摄食阶段起，便在具备复杂流体动力学环境、存在捕食者且为贫营养（oligotrophic）条件的半自然溪流中型实验生态系统中饲养。借助开放式水槽跑道（open-flume raceway），我们让受试鱼类进行游泳运动，并测定了它们在持续水流下的爆发游泳（burst-swimming）能力。结果显示，基因型对爆发游泳性能存在显著影响：在有捕食者与无捕食者的溪流区段中，转基因鱼类的爆发游泳性能维持时长均显著长于其野生型同胞。值得注意的是，该效应在生长差异可被辨识之前就已显现。此外我们还发现，相较于在可控孵化场环境中饲养的鱼类（后者未接触捕食者且食物供给充足），中型实验生态系统饲养的受试个体具备更强的爆发游泳性能。本研究结果表明，捕食压力与代谢启动（metabolic priming）之间可能存在交互作用，该作用使得转基因虹鳟具备更强的爆发游泳能力。