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.

幼鲑科鱼类从出生溪流底床钻出后的初次摄食阶段，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）中开展的实验显示，生长激素转基因鲑科鱼类的捕食风险高于其非转基因同胞个体，部分原因在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。这引发了一个疑问：经历捕食实验后存活的转基因与非转基因鱼类，其游泳性能是否存在差异？我们以野生起源虹鳟（Oncorhynchus mykiss）为实验对象，这些个体自初次摄食阶段起便饲养于兼具复杂水动力环境、存在捕食者且处于贫营养条件的半自然溪流中型实验生态系统中。我们借助开放式水槽式流水槽开展游泳实验，测定了鱼类对抗持续水流的冲刺游泳能力。研究发现，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段中，转基因虹鳟的冲刺性能维持时长均显著长于其野生型同胞个体。值得注意的是，该差异在生长差异可被检测到之前便已出现。我们还发现，相较于在受控孵化场环境中饲养的个体，在中型实验生态系统中饲养的鱼类具备更强的冲刺性能——尽管后者未接触捕食者且食物供应充足。本研究结果表明，捕食压力与代谢启动之间可能存在交互作用，这使得转基因虹鳟具备更强的冲刺能力。