Roberts Brien H, Morrongiello John R, Morgan David L, King Alison J, Saunders Thor M, Banks Sam C, Crook David A
Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia.
Fisheries Research, Department of Industry, Tourism and Trade, Berrimah, Northern Territory, Australia.
J Anim Ecol. 2024 Jan;93(1):83-94. doi: 10.1111/1365-2656.14019. Epub 2023 Nov 20.
Many animals exhibit partial migration, which occurs when populations contain coexisting contingents of migratory and resident individuals. This individual-level variation in migration behaviour may drive differences in growth, age at maturity and survival. Therefore, partial migration is widely considered to play a key role in shaping population demography. Otolith chemistry and microstructural analysis were used to identify the environmental- and individual-specific factors that influence migratory behaviour in the facultatively catadromous barramundi (Lates calcarifer) at two distinct life history stages: firstly, as juveniles migrating upstream into fresh water; and secondly, as adults or sub-adults returning to the estuarine/marine spawning habitat. Monsoonal climate played an important role in determining the migration propensity of juveniles: individuals born in the driest year examined (weak monsoon) were more than twice as likely to undergo migration to freshwater than those born in the wettest (strong monsoon) year. In contrast, the ontogenetic timing of return migrations to the estuary by adults and sub-adults was highly variable and not strongly associated with the environmental parameters examined. We propose that scarce resources within saline natal habitats during lower rainfall years may provide an ecological incentive for juveniles to migrate upstream, whereas more abundant resources in higher rainfall years may promote resident life histories within estuaries. We conclude that inter-annual climatic variation, here evidenced by monsoonal strength, likely plays an important role in driving the persistence of diversified life histories within wild barramundi populations.
许多动物表现出部分洄游现象，即种群中同时存在洄游个体和定居个体。这种洄游行为在个体层面上的差异可能导致生长、成熟年龄和生存方面的差异。因此，部分洄游被广泛认为在塑造种群动态方面起着关键作用。耳石化学和微观结构分析被用于确定在两个不同生活史阶段影响兼性降海洄游的尖吻鲈（Lates calcarifer）洄游行为的环境和个体特异性因素：首先，作为幼鱼向上游洄游进入淡水；其次，作为成鱼或亚成鱼返回河口/海洋产卵栖息地。季风气候在决定幼鱼的洄游倾向方面起着重要作用：在所研究的最干旱年份（弱季风）出生的个体向上游洄游进入淡水的可能性是在最湿润年份（强季风）出生个体的两倍多。相比之下，成鱼和亚成鱼返回河口的洄游个体发育时间高度可变，且与所研究的环境参数没有很强的关联。我们认为，降雨较少年份咸水出生地栖息地内稀缺的资源可能为幼鱼向上游洄游提供了生态诱因，而降雨较多年份更丰富的资源可能促进河口内的定居生活史。我们得出结论，以季风强度为证的年际气候变化可能在推动野生尖吻鲈种群内多样化生活史的持续存在方面发挥重要作用。
