Humston R, Doss S S, Wass C, Hollenbeck C, Thorrold S R, Smith S, Bataille C P
Biology Department, Washington and Lee University, 204 West Washington St, Lexington, VA, 24450, U.S.A.
Environmental Studies Program, Washington and Lee University, 204 West Washington St, Lexington, VA, 24450, U.S.A.
J Fish Biol. 2017 Feb;90(2):528-548. doi: 10.1111/jfb.13073. Epub 2016 Sep 12.
Radiogenic strontium isotope ratios ( Sr: Sr) in otoliths were compared with isotope ratios predicted from models and observed in water sampling to reconstruct the movement histories of smallmouth bass Micropterus dolomieu between main-river and adjacent tributary habitats. A mechanistic model incorporating isotope geochemistry, weathering processes and basin accumulation reasonably predicted observed river Sr: Sr across the study area and provided the foundations for experimental design and inferring fish provenance. Exchange between rivers occurred frequently, with nearly half (48%) of the 209 individuals displaying changes in otolith Sr: Sr reflecting movement between isotopically distinct rivers. The majority of between-river movements occurred in the first year and often within the first few months of life. Although more individuals were observed moving from the main river into tributaries, this pattern did not necessarily reflect asymmetry in exchange. Several individuals made multiple movements between rivers over their lifetimes; no patterns were found, however, that suggest seasonal or migratory movement. The main-river sport fishery is strongly supported by recruitment from tributary spawning, as 26% of stock size individuals in the main river were spawned in tributaries. The prevailing pattern of early juvenile dispersal documented in this study has not been observed previously for this species and suggests that the process of establishing seasonal home-range areas occurs up to 2 years earlier than originally hypothesized. Extensive exchange between rivers would have substantial implications for management of M. dolomieu populations in river-tributary networks.
将耳石中的放射性锶同位素比率（Sr: Sr）与模型预测并在水样中观测到的同位素比率进行比较，以重建小口黑鲈（Micropterus dolomieu）在主河道和相邻支流栖息地之间的移动历史。一个结合了同位素地球化学、风化过程和流域积累的机理模型合理地预测了研究区域内观测到的河流Sr: Sr，并为实验设计和推断鱼类来源提供了基础。河流之间的交换频繁发生，在209个个体中，近一半（48%）的耳石Sr: Sr发生了变化，这反映了它们在同位素特征不同的河流之间移动。大多数河流间的移动发生在第一年，且通常在生命的最初几个月内。虽然观察到更多个体从主河道移入支流，但这种模式不一定反映交换的不对称性。一些个体在其一生中在河流之间进行了多次移动；然而，没有发现表明季节性或洄游性移动的模式。主河道的休闲渔业得到了支流产卵补充的有力支持，因为主河道中26%的种群个体是在支流中产卵的。本研究记录的早期幼鱼扩散的普遍模式此前在该物种中未曾观察到，这表明建立季节性活动范围区域的过程比最初假设的提前了2年。河流之间的广泛交换将对河网中小口黑鲈种群的管理产生重大影响。
