• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Hydrobiologia >Effects of fishing methods on deep water shark species caught as by-catch off southern Portugal
【24h】

Effects of fishing methods on deep water shark species caught as by-catch off southern Portugal

机译：捕捞方式对葡萄牙南部以外海域捕获的深水鲨鱼种类的影响

获取原文
获取原文并翻译 | 示例
       
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Deep water sharks are commonly caught as by-catch of longlines targeting bony fishes and trawlers targeting crustaceans in deep water off the southern Portuguese coast. Due to low or no commercial value, these species are most of the times discarded at sea, with only the larger specimens of some species commercialized at very low prices. In this study we present size distributions, maturity distributions, and sex ratios of 2,138 specimens belonging to four different species, namely the lantern sharks Etmopterus pusillus and Etmopterus spinax and the catsharks Galeus melastomus and Galeus atlanticus, caught with these two gears. Trawls generally caught smaller-sized specimens, in a wider length range than longlines. Trawls caught mostly immature specimens of all species, namely 83.7% immature of E. pusillus, 84.3% of E. spinax, 89.5% of G. melastomus, and 95.5% of G. atlanticus, while longlines caught mostly immature E. pusillus (69.2%) and G. melastomus (78.6%) and mostly mature E. spinax (88.2%) and G. atlanticus (87.2%). Trawls tended to catch more males than females of all species except E. spinax, while longlines caught more females than males of E. spinax and G. melastomus and more males than females of the other two species. The main conclusion of this work is that trawls are catching smaller-sized and mostly immature specimens when compared to longlines, meaning that they are probably having a more detrimental effect on these shark populations. The data presented here have significant implications for the conservation of these shark populations since sizes, sexes, and the immature and mature components of the populations are being affected differently by these two fishing gears.
机译：深水鲨通常是作为延绳钓的副渔获物，这些延绳钓针对的是骨鱼类，而拖网渔船针对的是葡萄牙南部沿海深海中的甲壳类动物。由于商业价值低或没有商业价值，这些物种大多数时候在海上被丢弃，只有某些物种的较大标本以非常低的价格商业化。在这项研究中，我们介绍了2138个标本的大小分布，成熟度分布和性别比，它们属于四个不同物种，即灯笼鲨Etmopterus pusillus和Etmopterus spinax以及Catsharks Galeus melastomus和Galeus atlanticus，被这两个齿轮捕获。拖网通常捕获较小尺寸的标本，长度范围比延绳钓更大。拖网捕获的大多数物种均为未成熟的标本，即不成熟的大肠杆菌（E. pusillus）为83.7％，菠菜（E. spinax）的为84.3％，黑变种（G. melastomus）和大西洋化种（G. atlanticus）的为95.5％，而延绳钓则捕获的大部分不成熟的E. pusillus（69.2） ％）和黑变种G. melastomus（78.6％）以及大部分成熟的E. spinax（88.2％）和G. atlanticus（87.2％）。在所有物种中，拖网捕捞的雄性往往比雌性多，而延绳钓捕捞的雌性多于棘金枪鱼和黑变种的雄性，而雄性则多于其他两种。这项工作的主要结论是，与延绳钓相比，拖网捕捞的是小型且大多为不成熟的标本，这意味着它们可能对这些鲨鱼种群造成更大的不利影响。此处提供的数据对这些鲨鱼种群的保护具有重要意义，因为这两个渔具对种群的大小，性别以及种群的未成熟和成熟组成部分的影响不同。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号