Data_Sheet_2_Diversity in Habitat Use by White Sturgeon Revealed Using Fin Ray Geochemistry.PDF

Understanding life-history diversity in a population is imperative to developing effective fisheries management and conservation practices, particularly in degraded environments with high environmental variability. Here, we examined variation in habitat use and migration patterns of White Sturgeon (Acipenser transmontanus), a long-lived migratory fish that is native to the San Francisco Estuary, CA, United States. Annual increment profiles were combined with respective geochemical (87Sr/86Sr) profiles in sturgeon fin rays to reconstruct annual salinity chronologies for 112 individuals from 5 to 30 years old. Results indicated a complex and diverse amphidromous life history across individuals, characterized largely by estuarine residence, a general ontogenetic trend toward higher-salinity brackish habitats, and high variability in habitat use across all age groups. Hierarchical clustering based on fin ray geochemistry during the first 10 years of life, prior to sexual maturation, indicated at least four distinct migratory phenotypes which differed largely in the timing and duration of juvenile to subadult movements between fresh- and brackish-water habitats. This study provides information regarding habitat use and migration in sub-adult fish that was previously lacking. Different migratory phenotypes vary in exposure to stressors across time and space and populations. Understanding White Sturgeon habitat distributions through space and time at different life stages can help identify areas where habitat restoration would be most effective and develop management actions to reduce stressors associated with specific areas where White Sturgeon are present.

解析种群的生活史多样性，对于制定高效的渔业管理与保护策略至关重要，在环境多变的退化生境中这一点尤为关键。本研究以美国加利福尼亚州旧金山河口的本土洄游性长寿鱼类——白鲟（*Acipenser transmontanus*）为研究对象，探究其栖息地利用与洄游模式的变异特征。我们结合白鲟鳍条的年轮序列与对应的地球化学（⁸⁷Sr/⁸⁶Sr）剖面数据，为112尾5至30龄的个体重建了年度盐度时序。研究结果显示，个体间存在复杂多样的双洄游型生活史类型，整体以河口栖息为主要特征，且呈现出随个体发育向高盐度咸淡水生境转移的一般趋势，同时各年龄组的栖息地利用均存在显著变异。基于性成熟前最初10年的鳍条地球化学数据开展的系统聚类分析表明，至少存在4种独特的洄游表型，这些表型的差异主要体现在幼鱼至亚成体在淡水与咸淡水生境间移动的时间与持续时长上。本研究填补了此前关于亚成体鱼类栖息地利用与洄游模式的信息空白。不同洄游表型的个体在时空尺度及种群间所面临的胁迫暴露情况存在差异。明晰白鲟在不同生活史阶段的时空栖息地分布特征，有助于确定栖息地修复的最优区域，并制定针对性管理措施，以减轻白鲟栖息的特定区域所面临的胁迫压力。