浙江北部沿岸春夏季凤鲚鱼卵及仔、稚鱼分布特征

2008年4-6月，在浙江北部沿岸禁渔区线内（28°30’-30°45’N，121°30’-123°15’E）进行了产卵场生态调查，共设置45个调查站位，鱼卵和仔稚鱼的采集分别使用水平和垂直浮游生物拖网，结果表明：凤鲚卵占该海区各种鱼卵总数量的第四位。表层网和垂直网采集到的凤鲚卵占同网型鱼卵总量的6．08％和2．56％，凤鲚卵出现在5-6月，以5月数量最多，5月份平均分布密度4．82粒／网（表层网），最高密度值150粒／网，6月平均分布密度3．02粒，网（表层网）、0．11粒／m2（垂直网），最高分布密度110粒／网。产卵场主要在杭州湾水域，表层水温17．23℃，表层盐度13～31．5，最适表温21～23℃，最适表盐13～26，水深15m以内，透明度0．02～0-3m。凤鲚仔稚鱼在表层网的4-6月和垂直网的6月均采集到，分布面较广，其中表层网采集的凤鲚仔、稚鱼累计居各鱼种仔稚鱼首位，最高分布密度值分别为4月8尾／网、5月2尾／网、6月696尾／网（表层网）和5．9尾／mS（垂直网）。仔、稚鱼分布的表层温度和盐度分别为14．23．5oC、13。33，透明度0．05～1m。

Distributions of Ichthyoplankton of Coilia mystus in the Coast of North Zhejiang Province in Spring and Summer

This paper is the outcome of a spawning ground survey from April to June 2008 in the Coast of North Zhejiang Province. In the investigated area,where were 121°30＇-123°15＇ E, 28°30＇-30°45＇ N, 45 sampiing stations were set up respectively. The abundance of fish eggs and larvae were investigated by horizontally towing with zooplankton net （mouth diameter 80 cm, 280 cm in length, mesh size 0.505 mm） and vertically towing with zooplankton net （mouth diameter 50 cm, 145 cm in length, mesh size 0.505 mm）. Percentage of the eggs of Coilia mystus in horizontally net and vertically net were 6.08% and 2.56% respectively. The eggs of C. mystus occur from May to June, more abundantly in the months of May. The average density of eggs in the May were 4.82 egg/net（horizontally net）, maximum density were 150 egg/net（horizontally net）, and 3.02 egg/net（hori- zontally net）, 0.11 egg/m2 （vertically net）in the June, maximum density were 110 egg/net（horizontally net）. The primary spawning ground is Hongzhou Bucht water, where the surface temperature and salinity are respectively 17-23 ℃, 13-31.5, the optimum surface temperature and salinity for spawning are respectively 21-23℃; 13- 26, depth of water below 15 m, transparence of water 0.02-0.3 m. The larvae of C. mystus were captured from April to June by horizontally net, and merely captured in June by vertically zooplankton net, maximum density were respectively 8 ind/net in April, 2 ind/net in May and 696 ind/net（horizontally net） and 5.9 ind/m2（vertically net） in June. The surface temperature and salinity of the larvae distribution were 14-23.5℃; 13-33 respectively, transparence of water 0.05-1 m.