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首页> 外文期刊>Conservation Biology >Shifting elasmobranch community assemblage at Cocos Islandan isolated marine protected area
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Shifting elasmobranch community assemblage at Cocos Islandan isolated marine protected area

机译：科科斯岛孤立的海洋保护区中不断变化的弹性支流群落

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摘要

Fishing pressure has increased the extinction risk of many elasmobranch (shark and ray) species. Although many countries have established no-take marine reserves, a paucity of monitoring data means it is still unclear if reserves are effectively protecting these species. We examined data collected by a small group of divers over the past 21 years at one of the world's oldest marine protected areas (MPAs), Cocos Island National Park, Costa Rica. We used mixed effects models to determine trends in relative abundance, or probability of occurrence, of 12 monitored elasmobranch species while accounting for variation among observers and from abiotic factors. Eight of 12 species declined significantly over the past 2 decades. We documented decreases in relative abundance for 6 species, including the iconic scalloped hammerhead shark (Sphyrna lewini) (-45%), whitetip reef shark (Triaenodon obesus) (-77%), mobula ray (Mobula spp.) (-78%), and manta ray (Manta birostris) (-89%), and decreases in the probability of occurrence for 2 other species. Several of these species have small home ranges and should be better protected by an MPA, which underscores the notion that declines of marine megafauna will continue unabated in MPAs unless there is adequate enforcement effort to control fishing. In addition, probability of occurrence at Cocos Island of tiger (Galeocerdo cuvier), Galapagos (Carcharhinus galapagensis), blacktip (Carcharhinus limbatus), and whale (Rhincodon typus) sharks increased significantly. The effectiveness of MPAs cannot be evaluated by examining single species because population responses can vary depending on life history traits and vulnerability to fishing pressure.
机译：捕捞压力已增加了许多弹性bra（鲨鱼和鱼）物种灭绝的风险。尽管许多国家已经建立了禁止捕捞的海洋保护区，但缺乏监测数据意味着尚不清楚保护区是否能有效地保护这些物种。我们检查了过去21年中一小群潜水员在哥斯达黎加可可岛国家公园（Cocos Island National Park）上世界上最古老的海洋保护区（MPA）中收集的数据。我们使用混合效应模型来确定12种受监测的弹枝物种的相对丰度或发生概率，同时考虑观察者之间的差异和非生物因素的变化。在过去的20年中，十二种中的八种显着下降。我们记录了6种相对相对丰度的下降，包括标志性扇贝锤头鲨（Sphyrna lewini）（-45％），白鳍礁鲨（Triaenodon obesus）（-77％），mo（Mobula spp。）（-78％） ）和蝠ta（Manta birostris）（-89％），其他2个物种的出现几率降低。其中一些物种的家园范围较小，应通过MPA更好地加以保护，这强调了MPA中海洋巨型动物的数量将继续减少的观念，除非有足够的执法力量来控制捕鱼。此外，在虎（Galeocerdo cuvier），加拉帕戈斯（Carcharhinus galapagensis），黑鳍（Carcharhinus limbatus）和鲸鱼（Rhincodon typus）鲨的科科斯岛上发生的可能性显着增加。不能通过检查单个物种来评估MPA的有效性，因为种群响应可能会根据生活史特征和对捕鱼压力的脆弱性而变化。

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