Faculty of Biosciences and Aquaculture, Nord University, NO, 8049, Bodø, Norway.
Faculty of Education and Arts, Nord University, NO, 8049, Bodø, Norway.
Theriogenology. 2019 Jul 15;133:201-209. doi: 10.1016/j.theriogenology.2019.03.034.
Males compete pre- and post-mating to fertilize the maximum number of eggs. In polyandry, sperm competition occurs when sperm from two or more males compete to fertilize eggs from a female. Here we review how sperm competition from hatchery origin fish can cause loss of genetic variability in fish populations kept in captivity and in wild populations. In fish hatchery practices, sperm competition occurs in mass spawners that release gametes in tanks, and in artificial fertilizations when pooled semen is used. In mass spawnings sperm competition is difficult to tease apart from pre-mating competition and other post-mating selective mechanisms, whereas, studies focused on the use of pooled semen in different fish species have shown a clear relationship between sperm motility parameters and precedence in fertilization. In both situations, sperm competition will result in a loss of genetic variability that accumulates over generations, but hatchery protocols can be adjusted to mitigate it. Another source of concern regarding sperm competition for hatchery produced fish is the spatial and temporal overlap in spawning with wild individuals, either via aquaculture escapees or purposeful stocking programs. This may result in sperm competition between hatchery origin and wild males and impact natural populations. Our review suggests that in order to give every adult selected as broodstock an equal opportunity to produce offspring in captivity, mass spawning and the use of pooled semen should be limited.
雄性在交配前和交配后竞争以受精尽可能多的卵子。在多配偶制中，当来自两个或更多雄性的精子竞争受精雌性的卵子时，就会发生精子竞争。在这里，我们回顾了来自养殖场鱼类的精子竞争如何导致圈养鱼类种群和野生鱼类种群遗传变异性的丧失。在鱼类养殖场的实践中，精子竞争发生在大量产卵者在水箱中释放配子的情况下，以及在 pooled semen 被使用的人工受精的情况下。在大量产卵中，精子竞争很难与交配前竞争和其他交配后选择机制区分开来，而在不同鱼类物种中使用 pooled semen 的研究表明，精子运动参数与受精中的优先顺序之间存在明显的关系。在这两种情况下，精子竞争都会导致遗传变异性的丧失，这种丧失会随着世代的积累而积累，但养殖场的方案可以进行调整以减轻这种影响。另一个需要关注的问题是，养殖场生产的鱼类与野生个体在空间和时间上的重叠，无论是通过水产养殖逃逸还是有目的的放流计划，都会导致养殖场和野生雄性之间的精子竞争，并对自然种群产生影响。我们的综述表明，为了让每一条被选为亲鱼的成年鱼都有平等的机会在圈养环境中繁殖后代，应该限制大量产卵和 pooled semen 的使用。
