印度洋中南部大眼金枪鱼生物学特性研究

根据2008年9月~2009年4月在印度洋中南部金枪鱼延绳钓渔场调查期间收集的大眼金枪鱼生物学数据,对其基本的生物学特征进行了研究。结果表明:(1)叉长范围为57~184 cm,优势叉长组为101~110cm和121~130 cm,约占总数的41.7%,平均叉长为119.5 cm;(2)不分性别大眼金枪鱼叉长(FL)与加工后重(DW)的关系可表达为:DW=2.407 6×10-5FL2.931 6,雌雄个体差异不显著(F=0.207,P0.05);(3)调查期间,大眼金枪鱼雄性比例为56.55%,当叉长大于140 cm时,雄性占优势;调查期间,该海域大眼金枪鱼的繁殖期为10月~翌年4月,繁殖峰期为10月~翌年1月;(4)摄食种类中柔鱼、帆蜥鱼和虾类所占比重较高,分别占36.0%、20.1%和18.0%;各月份摄食等级1~4级分布呈显著性差异(χ2=191.20,P0.01),各叉长组大眼金枪鱼摄食等级变化无显著性差异(χ2=41.08,P0.05)。

Biological characteristics of bigeye tuna (Thunnus obesus) in southern and central Indian Ocean

Based on the biological data collected by Chinese tuna longliner operating in the southern and central Indian Ocean from September 2008 to April 2009,the paper analyzed the biological characteristics of bigeye tuna(Thunnus obesus).Results showed:(1)fork length(FL) ranged from 57 to 184 cm with the dominant ones from 101 to 110 cm and 121 to 130 cm(41.7%),and mean FL was 119.5 cm;(2)the relationship between fork length and dressed weight(DW) for unsexed bigeye tuna could be expressed as DW=2.407 6×10-5FL2.931 6,and the difference between two sexes was not significant(F=0.207,P>0.05);(3)the sex ratio of male to female was 56.55% during the survey period,and the male individuals dominated when the FL exceeded 140 cm and the reproduction months were from October to January,but the main reproduction period was from October to January;(4)flying squid,Alepisaurus ferox,shrimp were the main diet items for the bigeye tuna,accounting for 36.0%,20.1%,18.0%,respectively;the distribution difference in feeding stages from 1 to 4 in each month was significant(χ2=191.20,P<0.01),but the difference of feeding stages in each fork length class was not significant(χ2=41.08,P>0.05).