长江口及邻近水域夏季鱼卵、仔鱼数量分布特征

Abundance distributions of pelagic fish eggs and larva in the Changjiang River estuary and vicinity waters in summer

根据2001～2003年间，每年8月共3个航次对长江口及其邻近水域20个定点测站（30°05’～31°15’N；121°30’～122°50’E）鱼卵、仔鱼调查的资料，着重就该水域鱼卵、仔鱼的数量时空分布的年际变化特征以及有关的水文生物环境影响因子做了分析和探讨。结果表明，鱼卵、仔鱼的数量3a的年际变化较大，2002年数量为高峰期。平面分布主要集中于长江口和舟山渔场内，杭州湾相对较少。种类以中华小公鱼（Stolephorus chinensis）的卵和仔鱼的分布最多，其变动直接影响总量的变化。盐度相对水温对鱼卵、仔鱼所产生的效应更为明显，降盐以及径流量的加大对鱼卵、仔鱼总量的增加产生一定的影响。而浮游桡足类的数量变动对鱼卵、仔鱼产生一定的作用。调查区内经济性鱼类资源量的日益减少，低值鱼类比例的增加成为资源结构的变动趋势。

According to the Qiantang river and Changjiang river bringing a lot of nutriment, making a good breeding condition, the Changjiang estuary became a place of many larvae breeding. However, the supplement resource, fish eggs and larvae had descended seriously as the human catch to excess in past decade. The ecological investigations of fish eggs and larvae were very important to holding fishery resource variation and protecting present resource. Based on the measured results from three cruises of oceanographic survey carried out in the Changjiang estuary and vicinity waters in the August of 2001 to 2003 （30°5＇-31°15＇N; 121°30＇ -122°50＇E）, the interannual features of abundance distributions of the fish eggs and the larvae were studied, and the relationship between hydrologic and biological factors had been analyzed. The results showed that： the variation abundance of three years was very conspicuous; the peak abundance appeared in 2002. Abundance was mainly distributed in the Changiiang estuary and Zhoushan fishing grounds. The fish eggs distribution showed the west less than the east on the limit of 122°E, the south more than the north on the limit of 30°30＇N as larvae. The dominant species was Stolepkorus chinensis （Gunther）, its distribution mainly determined the abundance distribution. Today, resource composition was different from the past, the economical fish became less and less, the low value fish became more and more in this water area. Impaction of water sa linity on the abundance was more obvious than water temperature. The copepods abundance impacts on the abundance distributions of pelagic eggs and larvae. The decline of water salinity and the addition runoff were important factors to impact the distributions of the fish eggs and the larvae.