漠斑牙鲆仔鱼、稚鱼和幼鱼对低盐度的耐受力和淡水驯化技术的研究

Tolerance of southern flounder to low salinity with fresh water acclimation

研究了漠斑牙鲆仔鱼、稚鱼和幼鱼对低盐度的耐受力和漠斑牙鲆的淡水驯化技术。初孵仔鱼在盐度为5的水中最多存活5d,5d以后全部死亡。30日龄稚鱼在4h10min淡水组全部死亡,对淡水的耐受力较低,而盐度为5～25的各组72h的存活率都在95.00%以上。90日龄幼鱼经缓慢淡水驯化9d后存活率可达98%以上,对漠斑牙鲆幼鱼进行淡水驯化的最佳年龄为90日龄。淡水驯化影响幼鱼初期的摄食,以后则逐渐趋于正常;急性淡水驯化对幼鱼的伤害比缓慢淡水驯化大;漠斑牙鲆对低盐的耐受力随生长和发育逐渐增加,年龄是影响幼鱼对低盐度耐受力的主要因素。

Southern flounder was a euryhalinous fish which could even survive fresh water. In this experiment, the tolerance of southern flounder larvae and juveniles to brine or fresh water was studied. The initially hatched larvae could live for 5 days at the most at the salinity of 5. The 30 days larvae during metamorphosis all died within 4h 10min after being put directly into fresh water, whereas the survival rates of the larvae at the test groups of salinity 5--25 were all higher than 95 % in 72h. The survival rates of 90 days juveniles undergone slow fresh water acclimation were higher than 98% in 9d, suggesting that 90 days were the optimal age for southern flounder juveniles to be acclimatized in fresh water. Juveniles could be affected in feeding by fresh water acclimation initially, but they would become normal later. Acute fresh water acclimation had more harmful effects on juveniles than slow fresh water acclimation. The toler-ance of southern flounder to fresh water increased with age, so age was the main factor affecting the tolerance of juveniles to low salinity.