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

南亚热带和北方亚北极水域鱼类种群数量波动的横向差异在3种鲱类、2个鲭鱼亚群和3个秋刀鱼群之间存在明显差异，北方沃茨变化较大，南方水域相对稳定。这种纬度差异是基于太平洋秋刀鱼的一种鲭鱼的环境。在鲱类中，另一方面，它们在物种和繁殖策略上是不同的。鲱科鱼类的横向差异被认为是由遗传和环境引起的。青鱼从生活在南方沃茨的鲱类祖先进化而来，形成了适应亚北极沃茨环境变化的繁殖策略，其中重复生殖和无限生长是适应北方沃茨环境变化的繁殖策略。这种赌注对冲策略被理解为通过产卵多年和分配能量摄入到繁殖以及成熟年龄后的生长来减少招聘变异的幅度。然而，招募变异性是大的物种。如果该物种是单胎和/或有限生长的，它应该已经灭绝，或者它不应该能够扩展到北方沃茨。补充变异，换句话说，补充失败和优势年级的发生在北方沃茨是不可避免的。具有这些特点的北方渔业种群的适应性管理需要适应补充量的大变化。在北方可变种的种群管理中，可以选择一次补充收获量的策略。

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.