盐度对棘头梅童鱼胚胎发育和仔鱼存活的影响

观察比较了11个盐度梯度0、5、10、15、20、25、30(自然海水)、35、40、45、50]下,棘头梅童鱼(Collichthys lueidus)胚胎的沉浮情况、孵化时间、孵化率和畸形率,并测定了初孵仔鱼的不投饵存活系数(SAI)。结果表明:(1)棘头梅童鱼胚胎在海水盐度为30及以上时100%漂浮;盐度为25时,95%漂浮,5%悬浮;盐度为20时95%悬浮,5%沉底;盐度为15时95%沉底,5%悬浮;盐度为10及以下时100%沉底。在水温18～20℃的条件下,棘头梅童鱼胚胎在盐度5～40范围内经28～32 h能孵化出仔鱼,盐度对孵化时间影响不显著(P>0.05)。但孵化率和畸形率因盐度不同而有显著差异。综合分析表明棘头梅童鱼胚胎孵化的适宜盐度范围为15～35,孵化最适盐度范围在20～30之间。(2)在可孵出鱼苗盐度范围(5～40)内,棘头梅童鱼仔鱼SAI值为(1.80±0.03)～(11.85±0.02),与卵的孵化率呈正相关关系。仔鱼生存的适宜生长盐度为10～30,最适盐度范围为20～25。

Effects of salinity on embryo development and larval survival of Collichthys lucidus

Sinkage,incubation time,hatching rate and abnormality rate of embryos of Collichthys lueidus were analyzed and survival activity index(SAI) of newly hatched larvae were observed under a gradient of different salinities.11 different levels of salinity were set as follows:0,5,10,15,20,25,30(natural seawater salinity),35,40,45 and 50.The results showed:(1) the embryo floated 100% above salinity 30,and sank 100% below 10;at the salinity of 25,95% floated and 5% suspended;at the salinity of 20,95% suspended and 5% sank;at the salinity of 15,95% sank and 5% suspended.The larvae were hatched after 28-32 h in water temperature 18-20 ℃,and the incubation time was not significantly affected by the salinity(P>0.05).Some larvae were hatched at salinity 5-40,however,the hatching rate and abnormality rate were significantly different with the salinity changes.The results showed that salinities 15-35 were suitable and 20-30 were the best for hatching C.lucidus;(2) the SAI values of C.lucidus larvae at salinities 5-40 were(1.80±0.03)-(11.85±0.02) and showed positive relationship to the hatching rate.The suitable salinity range for larval survival activity was 10-30 and the optimum was 20-25 according to SAI values.