Fowler Ashley M, Smith Shannen M, Booth David J, Stewart John
New South Wales Department of Primary Industries, Sydney Institute of Marine Science, Mosman, NSW 2088, Australia.
Fish Ecology Laboratory, School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia.
Mar Environ Res. 2016 Aug;119:238-44. doi: 10.1016/j.marenvres.2016.06.010. Epub 2016 Jun 16.
Partial migration affects the ecology and evolution of animal populations, and is an important consideration for the management of harvested species, yet the phenomenon is understudied in fish. We provide the first insights into partially diadromous migration of grey mullet (Mugil cephalus) in Australia by examining the otolith chemistry of old individuals (aged 7-10 years) from two regions on the east coast. Strontium and Barium concentrations were measured across the otolith using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and indicated considerable diversity in migratory histories among individuals. Only 15% of individuals made repeated movements from estuaries to the marine environment, consistent with the annual spawning run in the region. The remainder either made irregular movements between salinity environments (70%), or resided in estuaries or fresh water for their entire life following the early juvenile stage (15%). The patterns are consistent with 'skipped spawning' partial migration, where a proportion of the mature population forgoes spawning each year. If confirmed, the behavior may afford the east coast population of M. cephalus some resilience to fishing pressure on the annual spawning run.
部分洄游影响动物种群的生态和进化，是管理被捕捞物种时的一个重要考量因素，然而鱼类中的这一现象尚未得到充分研究。我们通过检测澳大利亚东海岸两个地区7至10岁老龄个体的耳石化学成分，首次深入了解了鲻鱼（ Mugil cephalus）的部分溯河洄游情况。使用激光烧蚀电感耦合等离子体质谱法（LA-ICP-MS）测量了耳石中锶和钡的浓度，结果表明个体之间的洄游历史存在显著差异。只有15%的个体从河口到海洋环境进行了反复移动，这与该地区的年度产卵洄游一致。其余个体要么在盐度环境之间进行不规则移动（70%），要么在幼鱼早期阶段后终生栖息在河口或淡水中（15%）。这些模式与“跳过产卵”的部分洄游一致，即每年有一部分成熟种群放弃产卵。如果得到证实，这种行为可能会使东海岸的鲻鱼种群对年度产卵洄游的捕捞压力具有一定的恢复力。
