McKee Graydon, Hornsby Rachael L, Fischer Friedrich, Dunlop Erin S, Mackereth Robert, Pratt Thomas C, Rennie Michael
Department of Biology, Lakehead University, Thunder Bay, ON, P7B5E1 , Canada.
Upper Great Lakes Management Unit, Ontario Ministry of Natural Resources and Forestry, Thunder Bay, ON, P7E6S7, Canada.
Mov Ecol. 2022 Mar 2;10(1):10. doi: 10.1186/s40462-022-00308-7.
While Pace of Life Syndrome predicts behavioural differences between individuals with differential growth and survival, testing these predictions in nature is challenging due to difficulties with measuring individual behaviour in the field. However, recent advances in acoustic telemetry technology have facilitated measurements of individual behaviour at scales not previously possible in aquatic ecosystems.
Using a Walleye (Sander vitreus) population inhabiting Black Bay, Lake Superior, we examine whether life history characteristics differ between more and less mobile individuals as predicted by Pace of Life Syndrome. We tracked the movement of 192 individuals from 2016 to 2019 using an acoustic telemetry study, relating patterns in annual migratory behaviour to individual growth, and seasonal changes in optimal thermal-optical habitat.
We observed two consistent movement patterns in our study population-migratory individuals left Black Bay during late summer to early fall before returning to the bay, whereas residents remained within the bay year-round. The average maximum length of migrant Walleye was 5.5 cm longer than residents, and the sex ratios of Walleye caught during fall surveys was increasingly female-biased towards the mouth of Black Bay, suggesting that a majority of migrants were females. Further, Walleye occupancy outside of Black Bay was positively associated with increasing thermal-optical habitat.
Walleye in Black Bay appear to conform to Pace of Life Syndrome, with migrant individuals gaining increased fitness through increased maximum size, which, given size-dependent fecundity in this species, likely results in greater reproductive success (via greater egg deposition vs. non-migrants). Further, apparent environmental (thermal) controls on migration suggest that migratory Walleye (more so than residents) may be more sensitive to changing environmental conditions (e.g., warming climate) than residents.
虽然生活节奏综合征预测了生长和生存差异个体之间的行为差异，但由于在野外测量个体行为存在困难，在自然环境中检验这些预测具有挑战性。然而，声学遥测技术的最新进展促进了在水生生态系统中以前无法实现的尺度上对个体行为的测量。
利用苏必利尔湖黑湾的大眼鲈种群，我们检验了生活节奏综合征预测的移动性较强和较弱的个体之间生活史特征是否存在差异。我们在2016年至2019年期间使用声学遥测研究跟踪了192个个体的移动情况，将年度洄游行为模式与个体生长以及最佳热光学栖息地的季节性变化联系起来。
我们在研究种群中观察到两种一致的移动模式——洄游个体在夏末至初秋离开黑湾，然后返回该湾，而定居个体全年都留在湾内。洄游大眼鲈的平均最大长度比定居个体长5.5厘米，秋季调查期间捕获的大眼鲈的性别比例在黑湾河口处越来越偏向雌性，这表明大多数洄游个体是雌性。此外，黑湾外大眼鲈的占有率与热光学栖息地的增加呈正相关。
黑湾的大眼鲈似乎符合生活节奏综合征，洄游个体通过增加最大体型获得了更高的适应性，鉴于该物种的繁殖力依赖于体型，这可能导致更高的繁殖成功率（通过比非洄游个体更多的卵子沉积）。此外，对洄游的明显环境（温度）控制表明，洄游大眼鲈（比定居个体更甚）可能比定居个体对不断变化的环境条件（如气候变暖）更敏感。
