Comparative studies on reproductive strategies and stock managements of variable and stable fish populations

南亚热带和北亚北极水域鱼类种群数量波动的纬度差异在3种团头鱼之间、2个亚群之间以及太平洋秋刀鱼3个种群之间存在明显差异；北部水域变化较大，南部水域相对稳定。这种纬度差异是基于太平洋秋刀鱼的一种环境因素。另一方面，在丛枝类物种中，它们在物种和繁殖策略上是不同的。团头鱼的纬度差异被认为是基于遗传和环境因素造成的。鲱鱼从生活在南方水域的团头鱼祖先进化而来，形成了适应亚北极水域多变环境条件的繁殖策略。异位性和不确定生长是适应北方水域多变环境条件的繁殖策略。据了解，这种押注对冲策略通过产卵多年并通过将能量摄入分配给生殖和成熟年龄后的生长来减少招募变异性的大小。然而，在该物种中，招募的变异性很大。如果该物种是半生性的和/或生长决定的，它应该已经灭绝，或者它应该不能扩展到北部水域。招募的可变性，也就是说，在北部水域，招募失败和出现主导年班是不可避免的。北方渔业种群的适应性管理的这些特点需要适应在招募中的较大变异性。每补充一次的产量政策可能是北方可变物种种群管理的一种选择。

Latitudinal difference in population fluctuations in fish stocks in the southern subtropical and northern subarctic waters is distinct among 3 species of clupeid fishes, between 2 subpopulations of chub mackerel Scomber japonicus, and among 3 cohorts of Pacific saury Cololabis saira ; largely variable in the northern waters, relatively stable in the southern counterparts. This latitudinal difference is environmentally based in a species of chub mackerel of Pacific saury. In clupeid species, on the other hand, they are different in species and in reproductive strategies. Latitudinal difference in clupeid fishes are considered to be genetically based as well as environmentally induced. Through the course of evolution from the ancestor of clupeid fishes inhabiting the southern waters, herring have developed reproductive strategy that is adaptive to the variable environmental conditions in the subarctic waters.Iteroparity and indeterminate growth are reproductive strategies that are adaptive to variable environmental conditions in the northern waters. This bet-hedging strategies are understood to reduce the magnitude of recruitment variability by spawning multiple years and by allocating energy intake to reproduction as well as growth after the age-at-maturity. Nevertheless, recruitment variability is large in the species. If the species were semelparous and/or determinate in growth, it should have become extinct or it should not be capable of expanding to the northern waters. Recruitment variability, in other words, recruitment failure and occurrence of dominant year classes are inevitable in the northern waters. Adaptive management of the northern fishery stocks of these characteristics need to be adaptive to large variability in the recruitment. The yield-per-recruitment policy may be a choice for stock management of the variable northern species.