温度和盐度对宝石鲈胚胎发育的影响

Effects of temperature and salinity on the embryonic development of jade perch Scortum barcoo

宝石鲈(Scortum barcoo)是原产于澳大利亚的一种杂食性、中型经济淡水鱼类,对饵料要求不高,生长速度较快,肌肉的Omega-3不饱和脂肪酸含量很高,具有较高的食用价值.2001年首次被引进中国,2004年人工繁殖获得成功.为了让人们充分了解该物种的繁殖生物学特性,同时为宝石鲈的开发利用提供基本数据,本研究对宝石鲈的胚胎发育时序及不同水温和盐度对胚胎发育的影响做了较为祥细的观察与研究.采用人工催产、授精获得受精卵,在水温(27.0±0.5)℃孵化,观察胚胎发育情况.成熟卵圆形、透明、漂浮性,卵径0.87～0.92 mm,吸水后卵膜膨胀直径为2.10 mm左右;胚胎明显特征是有一个直径为0.50 mm左右的大油球.出膜仔鱼全长2.00 mm左右,出膜4 d后卵黄完全吸收,并开始摄食,此时仔鱼全长3.5～3.7 mm.胚胎发育的最低和最高临界水温分别是21 ℃和31 ℃,最适水温范围是24～27 ℃,胚胎发育所需时间与水温成负相关关系.胚胎发育的最适盐度范围为0～8,盐度8时,各个发育时期的胚胎和仔鱼的存活率最高,12为临界盐度.因此在生产实践中要掌握好温度和盐度,以获得最佳的种苗生产效果.

In order to investigate the propagation characters of jade perch(Scortum barcoo) and provide basic data for its aquaculture,studies on embryonic development process and the effects of temperature and salinity on embryonic development of jade perch were carried out in this study.The fertilized eggs obtained by induced spawning and artificial insemination were incubated at(27±0.5)℃ and the characters of embryonic development were recorded.The fertilization eggs are transparent and floating.It is round in shape and has a diameter of 0.87-0.92 mm.The diameter of eggs will increase to about 2.10 mm when the eggs absorb water.One main character of jade perch embryo is that there is a big fat ball in its yolk vesicle with diameter of 0.50 mm.The embryo takes 18 h 32 min to hatch to fry and the fry is 2 mm in length and it will be 3.5-3.7 mm when its egg yolk is absorbed completely after four days and it begins to feed at that time.The lowest and highest critical temperatures of embryonic development were 21 ℃ and 31 ℃ respectively and the range of optimal temperature was from 24 ℃ to 27 ℃.The relationship between the time for embryonic development and water temperature was negative.The optimal salinity range of embryonic development was 0-8.In salinity of 8,the survival rate of embryo and larva were the highest in different development stages.The critical salinity of embryonic development was 12.The results suggest that the water temperature and salinity should be controlled well in practice in order to achieve optimal effects in seed production.