A study on catch rate, sex ratio and fork length of blue shark (Prionace glauca) in longline fishing in Western and Central Pacific Ocean
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摘要: 大青鲨 (Prionace glauca) 是一种分布广泛的大型中上层远洋性鲨鱼,在以金枪鱼等经济鱼种为目标的延绳钓渔业中渔获率较高。根据中国远洋延绳钓渔船2015—2018年在中西太平洋 (Western Central Pacific Ocean, WCPO) 海域共51个航次采集的兼捕大青鲨数据,分析了该海域兼捕到的大青鲨渔获率、性别及叉长 (Fork length, FL) 特征。结果显示,大青鲨兼捕的捕捞努力量渔获量 (Catch per unit effort, CPUE) 在170°30'E—124°50'W、33°30'N—34°40'S范围内分布较高;2015—2018年间大青鲨兼捕CPUE波动较大,以2017年最高,兼捕CPUE与月份之间无显著性差异 (P>0.05);大青鲨的雌、雄个体分布范围基本一致,优势叉长区间均为160~220 cm,各自所占比例为89.26%和85.19%,雌、雄个体的叉长分布存在显著性差异 (P<0.05),雌雄比例为1.75。Abstract: Blue shark (Prionace glauca) is a widely distributed pelagic species with relatively high catch rate of longline fishery targeting tunas. Based on the 51-trip observer data for the blue sharks collected in the Western Central Pacific Ocean during 2015–2018, we anayzed their catch rate, sex proportion and fork length. The results show that higher catch per unit effort (CPUE) was found in the area of 170°30'E−124°50'W and 33°30'N−34°40'S. It is noted that the CPUE fluctuated greatly during 2015−2018 (highest in 2017). There was no significant difference between CPUE and month (P>0.05). The distribution range of male and female was basically the same. The sex ratio for female and male was 1.75. The dominant fork length (FL) for both male and female ranged from 160 cm to 220 cm, accounting for 89.26% and 85.19%, respectively. There was significant distribution difference between male length and female length by t-test (P<0.05).
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Key words:
- Prionace glauca /
- Longline fishing /
- Catch rate /
- Sex proportion /
- Fork length /
- Western and Central Pacific Ocean
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表 1 2015—2018年中西太平洋延绳钓渔业观察员观察航次表信息
Table 1. Observation voyage data of longline fishery in Western and Central Pacific Ocean during 2015-2018
开始时间
Start time结束时间
End time航次
Voyage经度范围
Longitude range纬度范围
Latitude range观察钩次
Observed hook times样本数量
Sample size2015/9 2016/3 8 107.93°W—157.37°E 7.42°N—27.40°S 547 95 2016/7 2017/3 14 105.47°W—161.70°E 30.25°N—33.82°S 1 247 756 2017/1 2018/3 15 130.15°W—158.07°E 37.33°N—24.80°S 1 476 2 279 2018/4 2019/3 14 143.38°W—144.18°E 36.53°N—36.48°S 1 728 823 表 2 不同海域大青鲨优势叉长和雌雄比例
Table 2. Comparison of dominant fork length and proportion of female-male blue shark in different sea areas
海域
Sea Area雌、雄优势叉长
Dominant forks of male and female/cm雌雄比例
Ratio of male to female参考文献
Reference印度洋西南部海域 Southwest Indian Ocean Sea 150~229.9、150~250 0.89 [18] 北大西洋海域 North Atlantic Ocean 180~220、190~230 0.99 [19] 南加州湾水域 Southern California Bight 75~95、75~95 1.01 [15] 加勒比海水域 Caribbean Sea 180~260、180~260 – [1] 中西太平洋 Western and Central Pacific Ocean 160~220、160~220 1.75 本研究 -
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