雅鲁藏布江黑斑原鮡繁殖生物学研究

对2004-2006年采集于雅鲁藏布江拉萨河的190尾黑斑原鮡进行了繁殖生物学研究。雄性最小性成熟(精巢Ⅳ期)个体体长141.7mm,体重45.2g,性体指数1.09%,雌性最小性成熟(卵巢Ⅳ期)个体体长146.8mm,体重66.7g性体指数11.52%,相应年龄均为5龄。初次性成熟年龄(L50):♂,170.1mm相应年龄为7龄;♀,150.2mm,相应年龄5龄。通过组织切片法和GSI的周年变化分析,繁殖时间集中在5-6月,每年繁殖一次,繁殖之后的6-8月卵巢从Ⅵ期回复到Ⅲ期,9月卵巢发育到Ⅳ期越冬。卵径频率分布显示,卵巢发育类型为分批同步型,卵巢中至少存在2批卵径,每年成熟一批卵并同时产出,产卵类型为完全同步产卵。卵黏性,成熟卵卵径在2.04-3.37mm之间,平均(2.83±0.16)mm。对19尾产卵前夕(体长为151.0-210.0mm)的标本进行统计,其绝对繁殖力范围在525-2058粒之间,平均为(1244±346)粒,相对繁殖力为(14.7±5.8)粒/g。绝对繁殖力与体长呈直线正相关,表达式为F=13.624L-1187。  

REPRODUCTIVE BIOLOGY OF GLYPTOSTERNON MACULATUM IN YARLUNG TSANGPO RIVER IN TIBET,CHINA

Glyptosternon maculatum is an endemic Tibetan catfish that comprises an important part of local fishery.The present study describes and characterizes the reproductive biology of female and male G.maculatum,based on monthly samples taken off Lhasa River,the largest tributary of Yarlung Tsangpo River,from November 2004 to September 2006.Annual changes in gonadal histology,gonadosomatic index (GSI) and size-frequency distribution of oocyte were studied.The results of gonadal histology analysis showed that the development of gonads could be divided into six stages.The gonad of stage Ⅵ in the spawned female degenerated into stage Ⅲ from June to July,and then gradually developed into stage Ⅳ in August to September,the gonad remained at stage Ⅳduring winter (from October to March of next year),and gonad developed into stage Ⅴ during April and May and spawned in May to June.GSI values for females increased in April,reached to the peak in May,and declined in June,and then increased slowly during June to September.Therefore,G.maculatum have a short spawning season (April to May) in Lhasa River as determined from GSI values and histological assessments.The youngest mature male was age 5 with a standard length (L) of 141.7 mm,and the youngest mature female was age 5 with the L of 146.8 mm.The standard length at which 50% of the individuals attain sexual maturity (L50) was 170.1 mm for males and 150.2 mm for females.The size distribution of oocytes,with at least two groups of ooctes in the ovaries,but this fish spawns only once a year,and all of mature eggs in the ovary will be laid out during spawning.In 19 pre-spawning females (the standard length ranged from 151.0 to 210.0 mm),the absolute fecundity ranged from 525 to 2058 eggs,with a mean value of (1244±346) eggs,and the relative fecundity was (14.7±5.8)eggs/g.A linear relationship existed between absolute fecundity (F) and L: F=13.624L?118.