Reconstructing salmon growth trajectories through biochronologies across a highly variable growthscape

Measuring the growth of migratory fish across habitats is difficult because field observations only provide a snapshot into their life; yet, understanding which habitats provide better growth opportunities is crucial for their conservation. We experimentally enclosed individually tagged juvenile Chinook Salmon (Oncorhynchus tshawytscha) in habitats with known differences in growth potentials to evaluate four different models (Dahl-Lea, Fraser-Lee, Biological Intercept, Modified Fry) used to back-calculated size-at-age from otoliths. We found that otolith-derived fish size reconstructions were most accurate using the Biological Intercept or Modified Fry model, though bias remains for slow growing fish. This tool was then used in a case study to reconstruct the mosaic of inter- and intra-habitat growth opportunities available to fishes, providing a useful framework for assessing and monitoring fish responses to habitat restoration and a changing environment.量化洄游鱼类在不同生境中的生长状况颇具挑战，因野外实地观测仅能捕捉其生命历程的瞬时快照；然而明确哪些生境能提供更优的生长机会，对鱼类的保护工作至关重要。本研究将携带个体标记的奇努克鲑（Oncorhynchus tshawytscha）幼鱼实验性围置于生长潜力存在明确差异的生境中，以评估四种用于从耳石反推年龄对应体长的模型（Dahl-Lea、Fraser-Lee、Biological Intercept、Modified Fry）的性能。研究结果显示，采用Biological Intercept模型或Modified Fry模型时，基于耳石的鱼类体长重建结果准确度最高，不过针对生长缓慢的个体仍存在一定偏差。随后，本研究将该分析工具应用于案例研究，以重建鱼类可利用的生境间与生境内生长机会的镶嵌格局，为评估和监测鱼类对生境修复及环境变化的响应提供了一套实用的分析框架。