北部湾鲔（Euthynnus affinis）的摄食习性及其随生长发育的变化

摘要

To study the mackerel tuna (Euthynnus affinis) feeding habits and its ontogenetic diet shifts, 435 mackerel tuna were collected for an annual research from September 2008 to September 2009 in the main fishing ports such as Beihai, Basuo, Sanya and Jianghong of the Beibu Gulf, South China Sea. Results showed that the mackerel tuna of the Beibu Gulf was omnivorous and it predated not only the small pelagic fish but also the benthic fish, crustaceans and cephalopods. Pisces were dominant in the diets with the percentage of Index of Relative Importance (IRI%) of 98.57%. Among these, 21 species were identified. As indicated with IRI%, Bregmaceros rarisquamosus (45.50%), Stolephorus zollingeri (11.81%), Theyssa setirostris (5.89%), and Sardinella aurita (5.87%) were principal in the food cons-ituent. The main species changed monthly and it was Sardinella aurita in January; Bregmaceros rarisquamosus in February, March, November, December; Unidentified Pisces from April to July;Sardinella aurita in August; Leignathus riviulatus in September; Stolephorus zollingeri in October. The prey weight and numbers increased when body size of mackerel tuna was less than 340 mm (SL<340 mm), but there were decreased when body size of mackerel tuna was from 341 to 520 (341-520 mm). The spawning periods of the mackerel tuna were spring and summer, mainly from April to August. There were two spawn peaks, June and August, which were recognized by the female gonad somatic index (GSI) that maintained strong feeding intensity during the reproduction periods. Moreover, the peak periods were consistent with the water temperature of pelagic layers provided by France CATSAT fisheries remote sensing system.%基于2008年9月-2009年9月在北部湾逐月采集的435尾鲔(Euthynnus affinis)生物学数据，对鲔生长、摄食习性及其随生长发育的变化进行了分析。结果显示，北部湾鲔属于广食性鱼类，主要摄食中上层小型鱼类，另外还包括底栖鱼类、甲壳类和头足类等。少鳞犀鳕(Bregmaceros rarisquamosus，45.50%)、青带小公鱼(Stolephorus zollingeri，11.81%)和长颌棱鳀(Theyssa setirostris，5.89%)为鲔优势饵料生物种类，并且其主要饵料生物种类随采样时间的不同而有所差异，如金色小沙丁鱼(Sardinella aurita，1月)、未能鉴定鱼类(4-7月)、长颌棱鳀(8月)、条鲾(Leignathus riviulatus，9月)、青带小公鱼(10月)、少鳞犀鳕(11–翌年3月)。体长小于340 mm 的鲔个体随体长的增加其平均摄食饵料生物的个数与质量呈上升趋势；体长在341-520 mm 范围内的鲔个体，随着体长的增加其平均摄食饵料生物的个数与质量总体上呈现下降趋势。鲔产卵主要集中在4-8月，根据雌性GSI(性腺成熟度指数)分析，具有两个产卵高峰期(6月、8月)，产卵高峰期和中上层水温的升高有密切关系。鲔的摄食强度在性腺发育过程中波动较大，但在产卵期间，其摄食强度并未明显降低。