【摘要】 东海带鱼有春、夏和秋季生殖之别,秋季并出现分群现象。带鱼第一个生殖周期与其出生季节相适应;从第二个生殖周期开始则消失了与出生季节的相应关系。根据种群结构的组成特性以及耳石相对生长的分析,从种群概念上阐明了不同季节出生的带鱼群体的相互关系。论证了春、夏和秋季产卵群体系为同一种群的不同生物学群。文中讨论了种下阶元的不同分化程度和位置:繁殖群(种群)——繁殖下群——生物学群。更多还原

【Abstract】 There have been differences of opinion about whether spring-summer and autumn spawning hairtails in the Bast China Sea are discrete populations. It is desirable to reexamine the biological characteristics of hairtail, in an attempt to answer the question of the interrelation of the groups.All individuals hatched at different seasons of the same year will be sexually mature when they are one full year-old in subsequent year. Maturation is completed in the course of one year. Because of the difference in brood seasons, the upsurge of first spawning in the hairtail is also varied. The gonado somatic index (GSI) was determined for female fish. The spawning upsurge of the early-brood group for 1 year-old occurs in June and July while that of the late-brood group occurs in September. Therefore, the first upsurge of spawning is closly related to the seasons of brood in the hairtail. The spawning upsurge after third year (2 year-olds) in hairtail has nothing to do with seasons of brood. The spawning upsurge of both broods aocurs in May and June. The GSI of the 2 year-old reaches up to 26% and 29% in early -brood and up to 26% and 16% in late-brood. It is shown that the spawners of the different broods of seasons are of the same population unit in which the chances of mating are of random distribution.There were two discrete groups in autumn which exhibited obvious difference in biological conditions. One was predominated by the spawning group in which individuals are mainly descendants of the late-brood of the previous year, and the other, by the recovering spent fish group in which individuals are mainly descendants of the early-brood of the previous year. The average length of 1+ age group spent fish was larger than that of the 1+ age group in spawning run, while the size of the latter group was also larger than that of 1 age group in the spawning run.It has been shown that a large first ring in otolith signifies that the fish is descended from spring spawner and a small ring, from autumn spawner, The spawning activity of the hairtail is continuous, but the recruitment consisted of shoal of different seasonal broods continually one after the other entering the spawning population, so that the first ring gradually becomes small. In body length, there is a steady monthly increase in both broods.In addition, the relationships of otolith weights and lengths to body lengths in both broods were compared, the results are same (P<0.10). It seems warranted to consider that spawners from different broods do have close affinity. They may sepa- rate temporarily into biological groups of different behaviors in certain period of their life. So a population, is often a unit of stock which is relatively stable over successive generations while subpopulations are often lower category than population. A unit of population exists even smaller biological groups, however, they have no clearly distinguishing characters.更多还原