【作者】 戴小杰； 许柳雄； 宋利明；

【Author】 DAI Xiao-jie XU Liu-xiong SONG Li-ming (College of Marine Science and Technology,Shanghai Fisheries University,Shanghai 200090,China)

【机构】 上海水产大学海洋学院；

【摘要】 本文根据2003年7月至11月在东太平洋热带海域的金枪鱼延绳钓渔业的实际调查,调查范围是03°S～17°S,96°W～146°W。大眼金枪鱼钓获深度的确定采用公式计算方法和微型深度和温度记录仪器测定,大眼金枪鱼的性腺调查采用肉眼观察和性腺称重方法,并计算性腺指数(GSI)。结果表明,公式计算的深度与仪器测定的深度相当吻合,延绳钓钓具投放的深度范围在90～320m。钓具各部分构成是浮绳长30m、支绳长45m、两支绳间隔数为45m、两浮子间支绳数量17枚,大眼金枪鱼的捕获钩位为3～9,其深度为150～320m。80%的大眼金枪鱼渔获物个体来自为5～9钩位的水层,即深度为200m以深的海域。分析表明,东太平洋的温度跃层上界一般位于100～120m的水层,大眼金枪鱼的栖息水层位于温度跃层的下方。钓获的大眼金枪鱼叉长范围为64～203 cm;全重范围为4.5～170kg,平均个体重量为45kg。性别统计表明,大眼金枪鱼的性比符合1:1。对性腺重量的测定表明,雌性性腺最大重量达到4400g,性腺指数达到4.19,雄性性腺最大重量达到1000g,性腺指数为0.97。观察表明雌性大眼金枪鱼的最小产卵叉长为120cm,全重为29kg。性腺指数达到3.90,其主要特征是卵巢内的卵粒呈游离状态。产卵场主要集中在10°S～15°S,120°W～130°W公海海域,产卵高峰期为10～11月份。同时发现,该海域部分成熟大眼金枪鱼完成产卵,卵巢明显变小,卵巢内具有残留物。成熟个体长度测定表明同期产卵个体大小具有一致性。性成熟繁殖个体栖息深度为200～270m水层,栖息水温17.74～12.00℃,盐度范围35.30～34.80。文章讨论了在东太平洋大眼金枪鱼产卵集中的渔期和渔区,采取保护产卵亲体的管理措施,以利于增加大眼金枪鱼的补充量,持续利用东太平洋大眼金枪鱼的资源。更多还原

【Abstract】 During July-November,in 2003,pelagic fish survey was conducted by Chinese longliner coveting areas of 03°S-17°S,96°W-146°W.Hook depth was determined by two methods formula calculation and Mini DST record,which could precisely measure depth and temperature.Eye observations were conducted on gonads.Gonad weights were measured by scale and OSIs were calculated.Results showed that hook depth by formula calculation was almost identical to that by Mini DST record.Hook depth situated at between 90-320 m.Under the condition of fishing gear float line 30m,branch line 45m, distance between two branches 45m and 17 branch line per basket,hooked bigeye tuna position was between No.3-No.9,with depth 150-320m.About 80% of bigeye tuna catch came from hook position of No.5-No.9,with depth of exceeding 200m.Result also showed that upper layer of thermocline in the eastern Pacific Ocean was 100-120 m and generally bigeye tuna habitat was under the upper layer of thermocline.Fork length of bigeye tuna catch covered 64-203 cm,with weight range of 4.5-170kg.Average individual weight was 45kg. Statistics showed that the ratio of sex for bigeye tuna was fitted 1:1.Maximum ovary weight reached 4400 g and was 4.19.Maximum testis weight amounted to 1000 g and corresponding GSI 0.97. Observation indicated that minimum female spawning size amounted to fork length 120 cm,with weight 29 kg and GSI 3.9.Eggs in the ovary was free.Spawning grounds concentrated on the 10°S～15°S,120°W-130°W,with the spawning seasons Oct.-Nov.Meanwhile,parts of reproductive bigeye tuna catch had completed spawning process,with smaller ovaries and some remains in the ovaries.Spawning individuals tended to same size.Result showed that reproductive individual situated at depth of 200～270m,with temperature 17.74-12.00℃and salinity 35.30-34.80.The paper discussed management measures were probably determined in the bigeye tuna spawning areas and seasons in the eastern Pacific Ocean in order to increase recruitment of bigeye tuna and to exploit sustainable stocks.更多还原