印度洋黄鳍金枪鱼生物学特性的初步研究

根据2003-2004年1-6月印度洋中西部海域金枪鱼延绳钓所捕获的黄鳍金枪鱼数据,对其基本的生物学特征进行了研究。结果表明,2003年和2004年渔获物中黄鳍金枪鱼加工后体重分别为7~81 kg和20~78kg,优势组分别为20~50 kg和30~60 kg。叉长范围分别为70~180 cm和110~170 cm。2003年渔获物雌雄性比的平均值为0.71,月间性比组成差异较小;2004年渔获雌雄性比的平均值为1.00,月间性比组成差异较大。2003年各月的摄食等级以1-2级为主,月间差异较小;2004年摄食等级以一级为主,并且月间各等级组成差异大。当渔获个体的叉长小于100 cm时,其性比组成波动较大;当渔获个体的叉长范围在100~150 cm之间时,性比组成的变化相对较小,基本上维持在0.5左右,也就是说雌雄个体数量大体保持平衡;当渔获个体的叉长大于160 cm时,所有样本个体均为雄性。体长与体重关系为W=2×10-5L2.9269。

Preliminary analysis on biological features of Thunnus albacares, based on observer's data in the west-central Indian Ocean

Based on the catch data of yellowfin tuna captured by Chinese tuna longline fleet in the west-central Indian Ocean from January to June in 2003 and 2004, the basic biological characteristics of catch composition of yellowfin tuna captured were investigated. The result indicated that the processed body weight of yellowfin tuna captured varied between 7-81 kg (2003) and 20-78 kg(2004) respectively, and the dominant processed body weight varied between 20-50 kg (2003) and 30-60 kg (2004) respectively. The fork length of yellowfin tuna captured varied between 70-180 cm and 110-170 cm in 2003 and 2004 respectively. Mean sex ratio remained some 0.71 and 1.00 in all months in 2003 and 2004 respectively. Monthly sex ratio had an insignificant difference among all months in 2003, however, the ratio varied remarkably during 2004. To frequency of monthly feed fullness, grade 1 and 2 dominant in every month of 2003 and insignificant difference existed among all months. Grade 1 dominant in every month of 2004, and large differences existed in 2004. The sex ratio fluctuates remarkably at a LJFL of less than 100 cm. The variation on sex ratio is insignificant and maintaining to some 0.5 when LJFL falls into 100-150 cm. All samples are males at LJFLs larger than 160 cm. The processed body weight and fork length of yellowfin tuna captured had the relationship curves W=2×10-5L2.9269 between them.