Data from: Growth potential can affect timing of maturity in a long-lived semelparous fish

Many diadromous fishes such as salmon and eels that move between freshwater and the ocean have evolved semelparous reproductive strategies, but both groups display considerable plasticity in characteristics. Factors such as population density and growth, predation risk or reproduction cost have been found to influence timing of maturation. We investigated the relationship between female size at maturity and individual growth trajectories of the long-lived semelparous European eel, Anguilla anguilla. A Bayesian model was applied to 338 individual growth trajectories of maturing migration-stage female silver eels from France, Ireland, the Netherlands, and Hungary. The results clearly showed that when growth rates declined, the onset of maturation was triggered, and the eels left their growth habitats and migrated to the spawning area. Therefore, female eels tended to attain larger body size when the growth conditions were good enough to risk spending extra time in their growth habitats. This flexible maturation strategy is likely related to the ability to utilize diverse habitats with widely ranging growth and survival potentials in the catadromous life-history across its wide species range.

诸多往返于淡水与海洋的洄游鱼类（diadromous fishes），如鲑鱼与鳗鲡，均演化出一次性繁殖（semelparous）的生殖策略，但这两个类群的相关性状均表现出显著的可塑性。研究表明，种群密度、生长状态、捕食风险以及繁殖成本等因素，均可影响个体的成熟时机。本研究以长寿命一次性繁殖（semelparous）的欧洲鳗鲡（Anguilla anguilla）为对象，探讨其成熟雌性个体的体型与个体生长轨迹之间的关联。研究团队采用贝叶斯（Bayesian）模型，对采自法国、爱尔兰、荷兰与匈牙利的338条处于成熟洄游阶段的雌性银鳗的生长轨迹开展分析。结果清晰显示：当生长速率下降时，个体将触发成熟启动过程，离开其生长栖息环境并洄游至产卵场。由此可见，当生长条件足够优越，值得承担额外停留于生长栖息环境的风险时，雌性鳗鲡往往能够获得更大的体型。这种灵活的成熟策略，很可能与其在广布物种范围内的降海洄游（catadromous）生活史中，利用生长与生存潜力差异显著的多样栖息环境的能力密切相关。