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

南亚热带和北亚北极海域鱼类种群数量波动的纬度差异在3种长尾鱼、2个鲐鱼亚群和3个太平洋银鲛群之间存在显著差异；北部海域变化很大，南部海域相对稳定。这种纬度差异是基于一种太平洋刀鱼的鲭鱼的环境。另一方面，在棍棒类物种中，它们在种类和繁殖策略上是不同的。棍棒类鱼类的纬度差异被认为是基于遗传和环境诱导的。鲱鱼从生活在南部水域的羽类鱼类祖先进化而来，形成了适应亚北极水域多变环境条件的繁殖策略。互操作性和不确定性生长是适应北方水域多变环境条件的繁殖策略。这种下注对冲策略被理解为通过多年产卵和通过将能量摄入分配给繁殖和成熟年龄后的生长来减少招募变异性的大小。然而，该物种的招募变异性很大。如果该物种是半胎生和/或生长决定的，它应该已经灭绝，或者它不应该能够扩展到北方水域。在北方水域，招募变异，即招募失败和优势年类的出现是不可避免的。适应性管理的北方渔业种群的这些特点需要适应大变异性的招聘。单倍率政策可作为可变北方品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.