千岛湖黄尾密鲴产卵场及繁殖生态条件

Investigation on Ecological Conditions of Spawning Ground and Breeding Habit of Xenocypris da(?)idi Bleeker in Thousand—isles Lake

黄尾密鲴(Xenocypris davidi Bleeker)在千岛湖(新安江水库)中自然形成了一个优势种群,1984年渔获量曾达到410吨,颇具渔业开发价值。为促进该项资源的增殖,作者进行了产卵场调查,并对黄尾密鲴的繁殖生物学搜集了若干资料。调查分析结果:(1)千岛湖的黄尾密鲴产卵场共有8个,分散在四周峡谷山溪中,其中以临歧产卵场规模最大;(2)产卵期集中在5月中旬至7月中旬(水温22～28℃),参加产卵的雌雄亲鱼以体长200～300mm,体重100～300g为主,雌性个体较大,性成熟年龄为2龄;(3)集中产卵的条件多在雨后晴天,溪水猛涨、乱石飞流,形成“泡漩水”的区域,选择这样的条件有利于受精卵的散布和粘着在石块上。

A dominant population of Xenocypris davidi Bleeker was naturally formed in Thousand—isles Lake(Xinanjiang Reservoir), and the yield of this species in 1984 reached as high as 410 tons, valuable for fishery exploitation. In order to accelerate the propagation of the fish stock, investigation on its spawning ground was conducted and some data on its reproductive biology were collected. The results showed: (1) There were 8 spawning grounds of this species in the lake, scattering around the streams in valleys, of which the largest located in Linji. (2) The spawning period lay between mid May to mid July(22～28℃ in water temperature). The body length and weight of most of the parent fish were 200～300mm and 100～300 g respectively. The female was a little bigger than the male and the fish reached their first maturity at 2 years.old. (3) Spawning mainly occured on the fine days after raining and in the aera where rolling and upwelling water current existed, resulting from the rapid increase of water level in the streams and from the rolling of pebbles in the water. Such conditions were favourable for the ease distribution of the fertilized eggs and for their sticking to the stones.