紫红笛鲷繁殖特性及诱导产卵的初步研究

A PRELIMINARY STUDY ON REPRODUCTIVE CHARACTERISTICS AND INDUCED SPAWNING OF MANGROVE RED SNAPPER LUTJANUS ARGENTIMACULATUS

描述紫红笛鲷Lutjanusargentimaculatus繁殖特性及人工诱导产卵的试验结果。紫红笛鲷养殖群体具有不完全的先雄后雌的性转化现象。1、2龄鱼全部为雄鱼,性腺成熟系数(GSI)为2.07%—4.85%;3龄亲鱼80%为雄鱼,20%转化为雌雄同体;4龄亲鱼性别转化基本确定,多数亲鱼为纯粹具有生殖机能的雄鱼,而在雌雄同体的亲鱼性腺中具有明显雌性第一性征的雌鱼仅占30%左右;雌雄同体的亲鱼性腺GSI为4.12%—8.09%,其中的卵巢GSI小于2%,4龄雌鱼怀卵量约70—100万粒;紫红笛鲷卵母细胞属非同步性发育,一个生殖季节能多次产卵。试验结果表明:低剂量的LHRH A2(3μg·kg-1)多次注射能有效地促进性腺发育、逐步成熟,并最终产卵,但对卵径小于300μm的亲鱼卵巢没有明显的诱导效果。在5μgLHRH A2+1000I UHCG·kg-1或5μgLHRH A2+500IUHCG·kg-1两种不同剂量的混合激素作用下,亲鱼的性腺都能迅速发育成熟,并能在小型循环式产卵池中自然产卵和受精。在水温为26.0—29.5℃的产卵池中,激素效应时间为35—43h。LHRH A2和HCG混合激素对卵母细胞直径达到400μm以上的紫红笛鲷亲鱼具有良好的促熟和催产效果,催产率达100%。如何减轻亲鱼之间相互残杀是改善雄鱼生理状况、保证雄鱼质量和提高卵子受精率必需解决的重要问题。

Mangrove red snapper,Lutjanus argentimaculatus,is a highly valued fish cultured in the coastal waters of southern China.The cultured group showed incomplete sex reverse in gonad.Both the oneyearold and the twoyearold fish were all male,with gonadosomatic index (GSI) between 2.07% and 4.85%.Some individuals in the threeyearold group were hermaphrodite.70% of individuals in the fouryearold group were all male,while 30% of individuals were hermaphrodite,with GSI between 4.14% and 8.09%.The fecundity of the fouryearold females changed from 700 000 to 1000 000 eggs.The development of oocytes in ovary is nonsynchronous.This species of fish can spawn many times during a spawning season.The reproductive period is from May to September for the cultured broodstock.The experimental results showed that multiinjections with lowerdose LHRHA2 (3μg ·kg-1BW) could effectively accelerate the development of ovary to mature and spawn eventually,but couldn't obviously improve the development of ovary with oocytes less than 300μm in diameter.The mixed hormone injections (5μg LHRHA2+1000IU HCG·kg-1BW or 5μg LHRHA2+500IU HCG·kg-1BW) were more effective than single hormone injection (LHRHA2).The mature parents induced with mixed hormone could spawn and inseminate eggs spontaneously in the small spawning pool.There were severe mutual assaults among the parents.It is important to ease the carnage among parents for improving physiological situation of parents and fertilization rate of egg cell .