Department of Biology, Dalhousie University, Halifax NS, B3H 4R2, Canada.
J Fish Biol. 2012 Apr;80(5):1844-69. doi: 10.1111/j.1095-8649.2012.03246.x.
Many elasmobranchs have experienced strong population declines, which have been largely attributed to the direct and indirect effects of exploitation. Recently, however, live elasmobranchs are being increasingly valued for their role in marine ecosystems, dive tourism and intrinsic worth. Thus, management plans have been implemented to slow and ultimately reverse negative trends, including shark-specific (e.g. anti-finning laws) to ecosystem-based (e.g. no-take marine reserves) strategies. Yet it is unclear how successful these measures are, or will be, given the degree of depletion and slow recovery potential of most elasmobranchs. Here, current understanding of elasmobranch population recoveries is reviewed. The potential and realized extent of population increases, including rates of increase, timelines and drivers are evaluated. Across 40 increasing populations, only 25% were attributed to decreased anthropogenic mortality, while the majority was attributed to predation release. It is also shown that even low exploitation rates (2-6% per year) can halt or reverse positive population trends in six populations currently managed under recovery plans. Management measures that help restore elasmobranch populations include enforcement or near-zero fishing mortality, protection of critical habitats, monitoring and education. These measures are highlighted in a case study from the south-eastern U.S.A., where some evidence of recovery is seen in Pristis pectinata, Galeocerdo cuvier and Sphyrna lewini populations. It is concluded that recovery of elasmobranchs is certainly possible but requires time and a combination of strong and dedicated management actions to be successful.
许多鲨鱼物种经历了强烈的种群减少，这主要归因于开发利用的直接和间接影响。然而，最近活体鲨鱼因其在海洋生态系统、潜水旅游和固有价值中的作用而越来越受到重视。因此，已经实施了管理计划来减缓甚至扭转负面趋势，包括针对鲨鱼的（例如反鱼翅法）和基于生态系统的（例如禁捕海洋保护区）策略。然而，鉴于大多数鲨鱼物种的枯竭程度和缓慢的恢复潜力，目前还不清楚这些措施的成功程度或效果。本文回顾了当前对鲨鱼种群恢复的理解。评估了种群增加的潜力和实际程度，包括增长率、时间表和驱动因素。在 40 个种群中，只有 25%归因于人为死亡率的降低，而大多数归因于捕食压力的释放。还表明，即使是低捕捞率（每年 2-6%）也可以在六个目前根据恢复计划进行管理的种群中阻止或逆转积极的种群趋势。有助于恢复鲨鱼种群的管理措施包括执法或接近零的捕捞死亡率、保护关键栖息地、监测和教育。在来自美国东南部的一个案例研究中强调了这些措施，在那里可以看到 Pristis pectinata、Galeocerdo cuvier 和 Sphyrna lewini 种群的一些恢复迹象。结论是，鲨鱼的恢复当然是可能的，但需要时间和一系列强有力的、有针对性的管理行动才能成功。
