青海湖裸鲤不同繁殖群体繁殖特性的比较研究

2017年7月~2018年6月,在青海湖的洱海、大湖、黑马河口、泉吉河口、沙柳河口和布哈河口6处采样点,共采集青海湖裸鲤(Gymnocypris przewalskii)繁殖群体样本295尾,对不同繁殖群体的繁殖特性进行比较研究。结果显示,除泉吉河口的性比(♀∶♂)<1(即0.82∶1)外,其余5个繁殖群体雌性个体数量均大于雄性(♀∶♂>1);6个繁殖群体的所有样本中,雌性的生物学最小型大于雄性。其中,雌性群体(布哈河口)的生物学最小型的年龄、全长和体重分别为5龄、157 mm和42.5 g,雄性(沙柳河口)为4龄、124 mm和24.5 g;6个繁殖群体的雌性性成熟系数(GSI)显著高于雄性(P<0.05),沙柳河口雌性GSI(19.67±1.36)%显著高于洱海(10.28±1.36)%和大湖(13.35±1.24)%(P<0.05),而不同繁殖群体雄性GSI间差异不显著(P>0.05);黑马河口平均绝对繁殖力Ft(3338.18±324.25)粒]和相对繁殖力Fr(21.88±2.10)粒/g]分别与沙柳河口的Ft(10699.40±613.91)粒]和Fr(82.68±4.63)粒/g]存在显著差异(P<0.05)。以上研究结果表明,青海湖裸鲤的繁殖特性在不同群体之间已出现分化趋势或已经分化。本研究可为进一步了解青海湖裸鲤的种群结构以及制定合理的渔业资源管理措施提供基础数据,特别是增殖放流策略的优化。

A comparative study of reproductive characteristics among different spawning stocks of naked carp Gymnocypris przewalskii

From July 2017 to June 2018, a total of 295 naked carp Gymnocypris przewalskii, which were used for comparative study of reproductive characteristics, were collected from Erhai, Dahu, and the estuaries of Heima River, Quanji River, Shaliu River, and Buha River in Qinghai Lake. With the exception of the Quanji estuary, spawning stock, sex ratios (female to male, SR) in all locations showed more female than male individuals (i.e., SR>1). The biological minimum size (BMS) of naked carp differed among spawning stocks, and all males reached sexual maturity at a smaller size compared with the females. The smallest BMS of female and male individuals, whose age, total length, and body weight, respectively was 5 y, 157 mm, and 42.5 g, and 4 y, 124 mm, and 24.5 g, was found in the Buha and Shaliu estuary stocks. The gonadosomatic index (GSI) of female naked carp was significantly higher than that of the males for each spawning stock (P<0.05). The GSI of Shaliu estuary female fish (19.67±1.36)% was significantly higher than that of Erhai (10.28±1.36)% and Dahu (13.35±1.24)% fish (P<0.05). However, the GSI of male fish did not differ significantly among the six stocks (P>0.05). Mean total fecundity (Ft) and relative fecundity (Fr) varied from (3338.18±324.25) eggs/female and (21.88±2.10) eggs/g Wb (from Heima estuary) to (10699.40±613.91) eggs/female and (82.68±4.63) eggs/g Wb (from Shaliu estuary), and significant differences were observed in both Ft and Fr between these two stocks (P<0.05). According to these results, the reproductive characteristics of naked carp in Qinghai Lake show a differentiation trend, with differentiation among different spawning populations already visible. The present study can provide potential data for a more accurate fish stocking and fisheries management plan, including stock optimization, enhancement, and release schedules, for naked carp.