东海北部和黄海南部鳀鱼卵和仔稚幼鱼数量、分布及其与环境条件的关系

Abundance and distribution of eggs and larvae of Engraulis japonicus in the Northern part of East China Sea and the Southern part of Yellow Sea and its relationship with environmental conditions

1999年夏季鳀鱼卵和仔稚幼鱼主要分布于黄海南部,122°00′～123°45′E、34°00′～35°15′N与122°15′E以西海域分别为鳀鱼卵与鳀鱼仔稚幼鱼的密集分布中心,其表层水温和盐度分别为25.5～26.9℃和27.11～31.81与26.4～27.0℃和31.31～32.05。鳀鱼卵和仔稚幼鱼分布的最适表层水温分别为25.5～26.4℃和25.9～27.0℃;全长为20mm以上的鳀鱼稚鱼已初步形成广盐性分布的习性,鳀鱼卵和仔稚幼鱼的分布对盐度的要求并不非常严格,水温是影响鱼卵和仔稚幼鱼分布的主要原因之一。鳀鱼卵和仔稚幼鱼的分布与叶绿素a的分布也有密切的关系,鳀鱼卵和仔稚幼鱼的密集分布中心正是叶绿素a的高值区。随着季节的变化,黄海南部鳀鱼产卵场由青岛外海逐渐向深水区转移。黄海南部鳀鱼活卵所占的比例为45.76％,胚胎发育状况良好。

The eggs and larvae of Engraulis japonicus were mainly distributed in the Southern patr of the Yellow Sea in summer, 1999. The center of dense egg concentration was located in the area 122°00' - 123°45'E and 34°00' - 35°15'N, while dense larvae aggregation was found in the waters west of 122°15'E; its surface water temperature and salinity were 25 . 5-26. 9° respectively. The optimum surface water temperature for egg distribution ranged from 25 .5 to 26.41, while that for larva ranged from 25.9 to 27.0°; E. japonicus larvae larger than 20mm total length was already euryhaline. The water salinity was not so critical to the distribution of E. japonicus eggs and larvae, while water temperature was an important influential factor. Close correlation was also found between the egg and larval densities and the chlorophyll-a content of the surface water, and the area of dense egg and larval concentration coincided with that of high chlorophyll-a content. As the season progressed, the spawning ground of E. japonicus in the Southern part of Yellow Sea gradually shifted from the waters off Qingdao to deeper waters. In the Southern of Yellow Sea, 45.76 % of E. japonicus eggs were found alive, and their embryos were in good development condition.