For riverine fishes threatened by fragmentation and flow modification, effective management requires an understanding of when and where key life history processes (spawning, recruitment and movement) take place. The structural and chemical properties of otoliths provide a unique means to recount a fish’s life in time and space. We investigated the age structure of the migratory, pelagic-spawning golden perch (Macquaria ambigua) in the Murray River, Australia, and used water and otolith ⁸⁷Sr/⁸⁶Sr ratios to delineate the natal origin and movement of fish from discrete cohorts. Water ⁸⁷Sr/⁸⁶Sr was distinct among the Darling River (a major tributary) and lower and mid-Murray River. Otolith chemistry revealed golden perch collected in the lower Murray River were progeny of spawning in either the Murray or Darling rivers, during years characterised by within-channel rises in flow, or in both rivers in a year of overbank flooding. Movement of juvenile fish from the Darling River substantially influenced population structure in the lower Murray River, whereby post-flood population growth was largely due to the immigration of age-1+ fish. This study demonstrates the potential importance of tributary recruitment sources, dispersal and connectivity on main-stem population dynamics and the utility of otolith chemistry for spatially reconciling population structure and the life histories of freshwater fishes.

对于受到破碎和水流改变威胁的河流鱼类，有效管理需要了解关键生活史过程（产卵、补充和移动）发生的时间和地点。耳石的结构和化学特性提供了一种独特的方法来在时间和空间上叙述鱼的生命。我们调查了澳大利亚墨累河的洄游、远洋产卵金鲈 ( Macquaria ambigua )的年龄结构，并使用水和耳石⁸⁷ Sr/ ⁸⁶ Sr 的比率来描绘来自离散群体的鱼类的出生起源和运动。水⁸⁷ Sr/ ⁸⁶Sr 在达令河（主要支流）和墨累河下游和中游之间是不同的。耳石化学显示，在墨累河下游收集的金鲈是在墨累河或达令河产卵的后代，这些年份的特点是河道内流量增加，或者在河上泛滥的一年中在两条河流中产卵。达令河幼鱼的迁移极大地影响了墨累河下游的种群结构，洪水后种群的增长主要是由于 1 岁以上鱼类的迁入。这项研究证明了支流补充来源、分散和连通性对主干种群动态的潜在重要性，以及耳石化学在空间协调种群结构和淡水鱼类生活史方面的效用。