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首页> 外文期刊>Marine ecology progress series >Diet shift and site-fidelity of oceanic whitetip sharks Carcharhinus longimanus along the Great Bahama Bank
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Diet shift and site-fidelity of oceanic whitetip sharks Carcharhinus longimanus along the Great Bahama Bank

机译：大巴哈马河沿岸的海洋白鳍鲨Carcharhinus longimanus的饮食变化和部位保真度

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摘要

Identifying the driving forces behind oceanic pelagic shark movements is key to a better understanding of their life history. Some oceanic pelagic shark species have been shown to aggregate in specific regions to mate and/or exploit abundant food resources. The oceanic whitetip shark Carcharhinus longimanus, a subtropical, ectothermic, oceanic pelagic shark that has experienced severe population declines, aggregates seasonally around Cat Island (CI) in The Bahamas. Large pelagic teleosts (e. g. billfish, tunas, and dolphinfish) are abundant in this region and oceanic whitetips are anecdotally reported to feed heavily on recreationally caught teleosts. However, it was unknown whether feeding habits at CI substantially differ from longer-term feeding habits. We used tag-recapture to assess site-fidelity of adult oceanic whitetips to CI and stable isotope analysis (SIA) of 2 different tissues (blood plasma and white muscle) to compare short-and long-term feeding patterns. The relatively high recapture rate (20.3%) confirmed that individual whitetips exhibit site-fidelity to CI. The aggregation consisted of adult individuals; females were more common, more than half were gravid, and no physical or behavioral evidence of mating or parturition was observed at CI. SIA-based Bayesian mixing model estimates of short-term (near CI) diets showed more large pelagic teleosts (72%) than in long-term diets (47%), showing a spatiotemporal difference in oceanic whitetip feeding habits. This suggests that availability of large teleost prey is a possible mechanism underpinning site-fidelity and aggregation of whitetips at CI. These results provide insight into the function of one of the last known aggregations of this once-abundant top predator.
机译：确定海洋远洋鲨鱼运动背后的驱动力是更好地了解其生活史的关键。已显示一些海洋中上层鲨鱼物种聚集在特定区域，以交配和/或开发丰富的粮食资源。海洋白鳍鲨Carcharhinus longimanus是一种亚热带，吸热，海洋中上层鲨，经历了严重的种群减少，在巴哈马的Cat岛（CI）附近季节性聚集。该地区大量中上层硬骨鱼（例如比目鱼，金枪鱼和海豚鱼）丰富，据报道，海洋上的白鳍to大量捕食以休闲方式捕获的硬骨鱼。但是，尚不清楚CI的喂养习惯是否与长期喂养习惯大不相同。我们使用标签捕获技术来评估成年海洋白鳍到CI的位置保真度，并通过两种不同组织（血浆和白肌）的稳定同位素分析（SIA）来比较短期和长期的喂养方式。相对较高的捕获率（20.3％）证实了单个白尖对CI表现出部位保真度。聚集包括成年个体；女性更常见，超过一半的人妊娠，并且在CI上没有观察到交配或分娩的身体或行为证据。基于SIA的贝叶斯混合模型对短期（接近CI）日粮的估计显示，大型远洋硬骨鱼（72％）比长期饮食（47％）多，表明海洋白鳍鱼的喂养习惯在时空上存在差异。这表明，大型硬骨猎物的可用性是支撑CI上站点保真度和白鳍聚集的一种可能机制。这些结果提供了对这种曾经丰富的顶级捕食者的最新已知集合之一的功能的了解。

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