Frederiksen Morten, Jensen Henrik, Daunt Francis, Mavor Roderick A, Wanless Sarah
Centre for Ecology and Hydrology, Hill of Brathens, Banchory AB31 4BW, UK.
Ecol Appl. 2008 Apr;18(3):701-10. doi: 10.1890/07-0797.1.
Fisheries management across the world is moving toward an ecosystem-based approach, implying that fishery effects on nontarget species should be taken into account. However, such effects are often not well understood, partly because, they can be difficult to distinguish from impacts of environmental fluctuations. We evaluated the effects of an industrial sand lance (Ammodytes marinus) fishery off the North Sea coast of the United Kingdom, which has been opened and closed in a quasi-experimental fashion, on sand-lance-dependent breeding seabirds. Controlling for environmental variation (sea surface temperature, abundance of larval sand lance, and size of adult sand lance), we found that, when the fishery was operating, breeding productivity in the intensively studied seabird colony on the Isle of May was significantly depressed for one surface-feeding seabird species, the Black-legged Kittiwake (Rissa tridactyla), but not for four diving species. Analyzing Kittiwake data from 12 colonies inside and outside the closure zone in a replicated before-after control-impact design, we again found that breeding productivity was significantly depressed in the closure zone when the fishery was active, whereas no effect was found in the control zone. Furthermore, Kittiwake breeding productivity was negatively correlated with fishery effort during the fishery period in the closure zone, but not in the control zone. The contrasting findings in the two zones could be related to environmental differences or to the fact that only one study colony in the control zone was exposed to high fishery effort within the typical foraging range of Kittiwakes during the breeding season. The strong impact on Kittiwakes, but not on diving species, could result from (1) inherently high sensitivity to reduced prey availability, (2) changes in the vertical distribution of sand lance at lower densities, (3) sand lance showing avoidance behavior to fishery vessels, or a combination of some or all of these factors. These findings indicate that local fishery closures can benefit sensitive predators and should be considered as a tool for future ecosystem-based fisheries management.
全球渔业管理正朝着基于生态系统的方法发展，这意味着应考虑渔业对非目标物种的影响。然而，这种影响往往没有得到很好的理解，部分原因是它们可能难以与环境波动的影响区分开来。我们评估了英国北海沿岸以准实验方式开放和关闭的工业玉筋鱼渔业对依赖玉筋鱼繁殖的海鸟的影响。在控制环境变化（海面温度、玉筋鱼幼体数量和成年玉筋鱼大小）的情况下，我们发现，当渔业作业时，在梅岛经过深入研究的海鸟繁殖地，一种表层觅食海鸟——黑脚三趾鸥（Rissa tridactyla）的繁殖生产力显著下降，但另外四种潜水海鸟的繁殖生产力并未下降。在一个重复的前后对照影响设计中，分析了封闭区内外12个繁殖地的三趾鸥数据，我们再次发现，当渔业活跃时，封闭区内的繁殖生产力显著下降，而对照区没有发现影响。此外，在封闭区的渔业期间，三趾鸥的繁殖生产力与渔业努力呈负相关，但在对照区则没有。两个区域的对比结果可能与环境差异有关，或者与以下事实有关：在繁殖季节，对照区只有一个研究繁殖地在三趾鸥的典型觅食范围内受到了高渔业努力的影响。对三趾鸥有强烈影响，但对潜水海鸟没有影响，可能是由于（1）对猎物供应减少的内在高敏感性，（2）玉筋鱼密度较低时垂直分布的变化，（3）玉筋鱼对渔船表现出回避行为，或者是这些因素中的一些或全部的组合。这些发现表明，局部渔业封闭可以使敏感的捕食者受益，应被视为未来基于生态系统的渔业管理的一种工具。
