The salmonid lifecycle has been studied for over a 100 years. Our literature search indicated that the Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) are among the most studied of fish species. By reviewing both their anadromous and non-anadromous lifecycles, we show that there is a growing body of evidence of considerable variation in many aspects of their lifecycle. However, variation in migration patterns and life history strategies are still poorly studied and not well understood, such as juvenile autumn migration, repeat spawning, marine migrations, straying and homing. Growing evidence supports a group of downstream autumn migrants in both species, which may represent as much as 25–40% of the spring class. Some males and females mature sexually as parr very early in life. They probably contribute to genetic variation and stability to populations in a changing environment and are likely very common in many rivers, but rarely considered. Information on marine migrations have been restricted by available methods, and particularly for brown trout, this may have resulted in underestimating straying and long-distance migrations. Repeat spawning is another understudied aspect of the salmonid life history but should be viewed as an opportunity to understand ecological and evolutionary dynamics. We conclude that both brown trout and Atlantic salmon appear to have aspects of their lifecycle overlooked, and that the description of their lifecycle should acknowledge the variation we observe in natural systems as well as the flexibility between strategies.

中文翻译：

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Salmo salar 和 Salmo trutta 生命周期中被忽视的方面

鲑鱼的生命周期已经被研究了 100 多年。我们的文献搜索表明，大西洋鲑鱼 (Salmo salar) 和褐鳟鱼 (Salmo trutta) 是研究最多的鱼类。通过审查它们的溯河和非溯河生命周期，我们表明越来越多的证据表明它们生命周期的许多方面都有相当大的变化。然而，迁徙模式和生活史策略的变化仍然很少被研究和理解，例如幼年秋季迁徙、重复产卵、海洋迁徙、流浪和归巢。越来越多的证据支持这两个物种的一组下游秋季迁徙者，它们可能占春季类的 25-40%。一些雄性和雌性在生命的早期就性成熟。它们可能有助于在不断变化的环境中种群的遗传变异和稳定性，并且在许多河流中可能非常普遍，但很少被考虑。有关海洋洄游的信息受到现有方法的限制，特别是对于褐鳟鱼，这可能导致低估了流浪和长距离洄游。重复产卵是鲑鱼生活史的另一个未充分研究的方面，但应被视为了解生态和进化动态的机会。我们得出的结论是，褐鳟鱼和大西洋鲑鱼似乎都忽略了它们生命周期的各个方面，并且对它们的生命周期的描述应该承认我们在自然系统中观察到的变化以及策略之间的灵活性。