Philopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the US and Bahamas
Philopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the US and Bahamas
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DOI：
10.3389/fmars.2017.00003
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发表时间：
2017-01-01
影响因子：
3.7
通讯作者：
Gruber, Samuel H.
中科院分区：
文献类型：
--
作者：
Guttridge, Tristan L.;Bergmann, Maurits P. M. Van Zinnicq;Gruber, Samuel H.
彻底了解物种的运动模式对于设计有效的保护和管理举措至关重要。然而，为大型海洋脊椎动物生成这样的信息是具有挑战性的，因为它们通常活动距离很长，生活在隐蔽的环境中，在后勤方面很难捕获，而且作为上层营养的捕食者，它们的丰度自然较低。体型大、分布广泛的热带鲨鱼通常局限于沿海和大陆架栖息地，大锤头鲨Sphrna mokarran就是这种挑战的缩影。其鳍的价值很高(在目标和附带渔业中)，副渔获物死亡率高，加上繁殖力保守的生活史，因此容易受到过度捕捞和种群枯竭的影响。尽管现有的特定物种数据非常少，但由于缺乏最近的渔获量记录，人们怀疑其范围内的渔获量大幅下降。在这里，我们使用生物遥测技术(声学和卫星)、常规标记、激光摄影测量和照片识别来调查大锤头鲨在巴哈马和美国沿海地区的地点保真度/居留水平，以及大锤头鲨在美国和巴哈马之间的活动和连接程度。结果显示，大规模的返回迁徙(3030公里)，季节性居住到当地(有些为期5个月)，地点保真度(许多人每年返回比米尼和木星)和许多国际流动。这些发现加强了对大锤头鲨运动生态学的了解，并有可能有助于改善保护和管理。
A thorough understanding of movement patterns of a species is critical for designing effective conservation and management initiatives. However, generating such information for large marine vertebrates is challenging, as they typically move over long distances, live in concealing environments, are logistically difficult to capture and, as uppertrophic predators, are naturally low in abundance. Large-bodied, broadly distributed tropical shark typically restricted to coastal and shelf habitats, the great hammerhead shark Sphyrna mokarran epitomizes such challenges. Highly valued for its fins (in target and incidental fisheries), it suffers high bycatch mortality coupled with fecundity conservative life history, and as a result, is vulnerable to over-exploitation and population depletion. Although there are very little species-specific data available, the absence of recent catch records give cause to suspect substantial declines across its range. Here, we used biotelemetry techniques (acoustic and satellite), conventional tagging, laser-photogrammetry, and photo-identification to investigate the level of site fidelity/residency for great hammerheads to coastal areas in the Bahamas and U.S., and the extent of movements and connectivity of great hammerheads between the U.S. and Bahamas. Results revealed large-scale return migrations (3030 km), seasonal residency to local areas (some for 5 months), site fidelity (annual return to Bimini and Jupiter for many individuals) and numerous international movements. These findings enhance the understanding of movement ecology in great hammerhead sharks and have potential to contribute to improved conservation and management.