真鲷人工繁殖与苗种培育的初步研究

THE PRELIMINARY STUDY OF ARTIFICIAL PROPAGATION AND SEED CULTURE OF RED SEA BREAM, Pagrosomus major(Temminck et Schlegel)

广东遮浪海区真鲷于10月至次年3月繁殖,其盛期为11月中旬至1月中旬。对成熟亲鱼用 LRH—A和 HCG 注射均可达到自然产卵的效果。对仔鱼以轮虫作开口饵料,以后逐步改喂卤虫无节幼体和鱼虾肉浆碎片。其成活率前期高,由仔鱼期向稚鱼期转化后其成活率降低。经205天的培育,真鲷体长平均可达135mm、体重平均可达199g。

The breeding season of red sea bream in the Zhelang sea area of Guangdong is from Oct.to Mar.The flourishing period is from mid-November to mid-January.So long as the maturity of brood fish is qualified,to inject the spwawners with LRH-A of 30-40,μg/kg or HCG of 1000-1500IU/kg(the injecting dose for milter being half of that for the spawner).Whether injecting once or at twice(the interval being 24-48hrs),the resnlt of natural propagation may be gained.When the water temperature is 18.5-19.5℃, the response hour is 18-20hrs. The fertilized eggs float on the water surface.The unfertiilzed eggs sink into the water bottom.When the water temperature is 18-19.5℃,the specific gravity of seawater is 1.023 under fhe nosmal warer quality,the larvae will hatch out in 40-41 hrs.Whether hatching instagnant water or in slightly flowing water,comparatively high hatching rate may be gained.The larva just hatched out is2.3-2.6mm in lenght,It lies on its back or lies on its side on the water snrface.After 2-3 days,the lavae scatter in the water lay- ers and begin to eat the small-sized Brachionus plicatilis,after 25days,when the Iarvae are 7-8ram in Iength,we begin to feed them the non-segmental larvae of Artemia salina After 40 days,when the Iarvae are 12-13ram in length,we begin to feed them the bits of fish meat or shrimp meat.Brachionus plicatilis and Artimia salina are preferable to be soaked for 4-6hrs in unsaturated fatty acid so as to raise the 20:5w3 and 22:6 ω3 of unsatruated fatty acid. the survial rate of thelarvae within 5-10 days may be as high as above 80%.The survival rate of the larvae within 15-20 days begins to drop.After 30-35 days,when they are 8-10mm in length and transf rm fhe larval stage into the young fish stage,be -cause of the forming of camineiteeth,the Iarvae cruelly eat one another,the survival rate drops to around 45-50%. Through 205 days' culture,the average body Iength reaches 135mm,the averagebo- dy weight reaches 100g.After 30 days,the growth rates in the body length and body weight all increase as astraight line relation with the increase of their mothly age.The interrelation between the boby length and body weight is a funetion of powerw=0.0008 67.L^(2.433)orLogw=2.433.LogL-3.062.(w in g,L in mm)