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zhou shan yu chang dong xun xun zhao dai yu qun de jing yan ( xia )
Author(s): 
Pages: 21-22
Year: Issue:  19
Journal: China Fisheries

Keyword:  鱼群密度水层外界条件风暴表层水温规律透明度舟山渔场带鱼移动;
Abstract: <正> (五)带鱼群进入渔场后,其棲息回游、垂直活动,也因外界条件而经常变化,掌握其规律,正确地摸到鱼群棲息的水层,对于渔捞意义也很大。(1)检查网具判断鱼群所在水层。带鱼从裤网翼网网目中跃出,必然留下新鲜的鳞白,如鳞白多在上纲(浮子纲)边则鱼群在上层,需收短曳纲和减轻沉石;鳞白在下纲(沉子纲)则鱼群在底层,需放长曳纲加重沉石;鳞白在翼网中衣,是放网水层正合鱼群棲息水层;如整片翼网上中下都粘满鳞白,证明鱼群密度很大很厚。在起网时要仔细观察这些现象,并将发现的鳞白随手抹掉,以免影响下次观察。(2)光照强弱和透明度大小直接影响到带鱼群的棲息水层,带鱼喜弱光,畏强光,早晨和傍晚多棲于上中层,中午前后(晴日从上午九时到下午三时)则
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