9-10月秘鲁外海茎柔鱼摄食习性的初步研究

Preliminary study on feeding behavior of jumbo flying squid (Dosidicus gigas) off Peru during September and October

茎柔鱼(Dosidicus gigas)是大洋性重要经济头足类之一,在食物链中起着重要作用。通过对2009年9-10月秘鲁外海采集的383尾茎柔鱼胃含物进行分析与研究,以了解调查期间茎柔鱼摄食习性的时空变化特性。研究认为,摄食等级在9-10月份间存在极显著差异(P<0.01),其摄食等级9月平均值高于10月。雌雄个体间和昼夜间摄食等级差异不显著(P>0.05)。但昼夜消化水平差异极显著(P<0.01),当地时间19:00时(以下类同)为最低,平均为1级,03:00时达到最高,为6级。捕食主要发生在19:00时至21:00时。个体中基本不存在连续性摄食的现象。空胃现象仅在胴长为25～50 cm的个体中发现;20～25 cm胴长组中未发现鱼类,25～60 cm各胴长组中鱼类的比例均最高,胴长大于50 cm的胃含物仅为鱼类;同类残食主要在25～35 cm、40～45 cm胴长组中发生;甲壳类仅在25～40 cm胴长组中发现,但食性选择差异不显著(P>0.05)。

Jumbo flying squid（Dosidicus gigas） was one of the important economic oceanic cephalopods,playing an important role in the food web.According to the analysis of 383 samples of stomach contents caught by squid jigging fleet in waters off Peru from September to October in 2009,the temporal and spatial variation of feeding behavior was analyzed.It was found that the difference of the monthly degree of stomach fullness was significant（P〈0.01）,and the mean value in September was higher than that in October.But the difference between male and female was not significant（P〈0.05） as well as the diurnal variation.However,the day and night difference of the level of digestion was significant（P〈0.01）,and the level dropped to the lowest at local time（19：00,the following similar）,the average value was 1,up to the highest,grade 6 at 03：00.Predation mainly occurred during the 19：00 and 21：00,almost no continual feeding behavior has been found.The empty stomach was only found in the 25-50 cm mantle length（ML） individuals.There was no fish found in the stomachs of 20-25 cm ML individuals,but the highest proportions of fish appeared in 25-60 cm ML groups.There was only fish debris in the stomach content of larger individuals,which were longer than 50 cm ML.Cephalopods and crustaceans were mainly fed by 25-35 cm ML,40-45 cm ML and 25-40 cm ML individuals,respectively.However,diet selection had no significant difference（P 0.05）.