光照周期对曼氏无针乌贼(Sepiella japonica)繁殖、性类固醇激素系统及生长性能的调控作用

EFFECT OF PHOTOPERIOD ON REPRODUCTON, SEX STEROID HORMONE SYSTEM AND GROWTH PERFORMANCE OF CUTTLEFISH SEPIELLA JAPONICA

养殖条件下的性早熟、个体小型化是影响曼氏无针乌贼(Sepiella japonica)的养殖效益的重要因素。为探讨养殖条件下曼氏无针乌贼性早熟的可能因素,本文探讨了3种不同光照周期(23D:1L;12D:12L;1D:23L)对其繁殖性能及个体生长的影响。结果表明:光照周期对曼氏无针乌贼的繁殖性能总体影响不大,除长光照周期(1D:23L)下,睾酮(T)、雌二醇(E2)等激素水平有较显著的降低外(P<0.05),光照对乌贼繁殖时间、性腺重及性腺发育指数等指标均无明显影响。但光照周期对曼氏无针乌贼生长却有明显影响,在胴长、体重、瞬时生长率(IGR)及肥满度等生长指标上均呈现出短光照组>中光照组>长光照的趋势。短光照组雌乌贼在体重、瞬时生长率和肥满度,雄乌贼在胴长等指标上,均显著优于长光照组(P<0.05)。该结果表明光照周期可作为影响曼氏无针乌贼生长性能的重要因素,在今后的养殖条件优化中应加以考虑。

Prematuration and miniaturization in cultured cuttlefish Sepiella japonica have largely affected the farming industries in China. To cope with the problem, we examined the effect of photoperiod on the reproductive and growth performance of S. japonica for the first time. Three photoperiods(23D:1L; 12D:12L; 1D:23L) were set. Results show that photoperiod had generally no obvious effect on the sexual maturation of S. japonica, or on the reproductive performance parameters, such as spawning time, gonad size, and gonad somatic index(GSI) of both sex. However, significant decrease in testis testosterone(T) and ovary estradiol(E2) contents were found in S. japonica in the long light group(23D:1L), and the growth performance was affected significantly by photoperiod. The body length, body weight, instantaneous growth rate(IGR) and relative fatness of both sex in shorter light group(23D:1L) were generally greater than that in medium light group(12D:12L) and even more much greater than that in the long light group(1D:23L). However, significant advantage was only found in body weight, IGR, and relative fatness of female, and body length of male in the short light group(23D:1L) compared to that of the long light group(P<0.05). Therefore, photoperiod affected the growth performance of S. japonica in aquaculture and should be adjusted for optimization.