Age of fish at maturation depends on the species and environmental factors but, in general, investment in growth is prioritized until the first sexual maturity, after which a considerable and increasing proportion of resources are used for reproduction. The present study summarizes for the first the key elements of the maturation of European smelt (Osmerus eperlanus) young of the year (YoY) in the North-eastern Gulf of Riga (the Baltic Sea). Prior to the changes in climatic conditions and collapse of smelt fishery in the 1990s in the Gulf of Riga, smelt attained sexual maturity at the age of 3–4 years. We found a substantial share (22%) of YoY smelt with maturing gonads after the collapse of the smelt fisheries. Maturing individuals had a significantly higher weight, length and condition factor than immature YOY, indicating the importance of individual growth rates in the maturation process. The proportion of maturing YoY individuals increased with fish size. We discuss the factors behind prioritizing reproduction overgrowth in early life and its implications for the smelt population dynamics.

中文翻译：

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幼龄成熟，欧洲冶炼规模小（Osmerus eperlanus）：人口过度开发或气候变化的结果？

鱼类成熟时的年龄取决于物种和环境因素，但一般来说，在初次性成熟之前，应优先投资于生长，然后再将相当大比例的资源用于繁殖。本研究首先总结了在里加东北海湾（波罗的海）欧洲年度（Osmerus eperlanus）幼年（YoY）成熟的关键要素。在1990年代里加湾气候条件变化和熔炼渔业崩溃之前，熔炼在3-4岁时达到了性成熟。在冶炼渔业崩溃之后，我们发现，性腺成熟时，冶炼产量同比增长了很大一部分（22％）。成熟的个体比未成熟的YOY个体具有明显更高的体重，体长和条件因子，表明个体增长率在成熟过程中的重要性。随着鱼的大小，成年个体的比例增加。我们讨论了优先考虑早期生活中繁殖过度生长的因素及其对冶炼种群动态的影响。