Laboratoire BOrEA MNHN-SU-CNRS-IRD-UCN-UA EcoFunc, Aviv, Muséum National d'Histoire Naturelle, Paris, France.
Laboratoire d'Excellence CORAIL, Perpignan, France.
PLoS One. 2021 Oct 5;16(10):e0253867. doi: 10.1371/journal.pone.0253867. eCollection 2021.
Sharks have declined worldwide and remote sanctuaries are becoming crucial for shark conservation. The southwest Indian Ocean is a hotspot of both terrestrial and marine biodiversity mostly impacted by anthropogenic damage. Sharks were observed during surveys performed from April to June 2013 in the virtually pristine coral reefs around Europa Island, a remote Marine Protected Area located in the southern Mozambique Channel. Observation events comprised 67 1-hour scientific dives between 5 - 35m depth and 7 snorkeling inspections, as well as 4 dinghy-based observations in the shallow lagoon. In a period of 24 days, 475 sharks were tallied. Carcharhinus galapagensis was most encountered and contributed 20% of the abundance during diving, followed by C. albimarginatus (10%). Both species were more abundant between 11-14h, and on the exposed sides of the island. Numbers of Sphyrna lewini were highest with 370 individuals windward and leeward, mostly schooling. S. lewini aggregations in the area are hypothesized to be attracted to the seamount archipelago offering favorable conditions for deep incursions and of which Europa Island forms part. C. amblyrhynchos, Galeocerdo cuvier and S. mokarran were uncommon, while there was an additional observation of Rhincodon typus. The lagoon of Europa was a nursery ground for C. melanopterus where it was the only species present. A total of 8 species was recorded, contributing to the shark diversity of 15 species reported from Europa since 1952 in the scientific and gray literature. Overall, with the occurrence of several species of apex predators in addition to that of R. typus, large schools of S. lewini, fair numbers of reef sharks and a nursery of C. melanopterus, Europa's sharks constitute a significant reservoir of biodiversity, which contributes to preserve the functioning of the ecosystem. Our observations highlight the relevance of Europa Island for shark conservation and the need for shark-targeted management in the EEZ of both Europa and Bassas da India.
鲨鱼在全球范围内数量减少，偏远的保护区对于保护鲨鱼变得至关重要。西南印度洋既是陆地生物多样性的热点地区，也是海洋生物多样性的热点地区，主要受到人为破坏的影响。在 2013 年 4 月至 6 月期间，在位于莫桑比克海峡南部的偏远海洋保护区欧罗巴岛周围几乎原始的珊瑚礁中进行了调查，观察到了鲨鱼。观测事件包括在 5-35 米深度进行的 67 次 1 小时的科学潜水和 7 次浮潜检查，以及在浅泻湖进行的 4 次小艇观测。在 24 天的时间里，共记录了 475 条鲨鱼。最常见的是加拉帕戈斯鲨，在潜水时占丰度的 20%，其次是白边真鲨（10%）。这两个物种在 11-14 小时之间以及岛屿迎风面和背风面更为常见。斜齿鲨的数量最多，有 370 条在迎风面和背风面，主要是成群游动。该地区的斜齿鲨聚集可能是被提供了有利的深海入侵条件的海山群岛吸引而来，而欧罗巴岛就是群岛的一部分。窄头双髻鲨、无沟双髻鲨和乌翅真鲨较为罕见，但也有另外一个尖吻真鲨的观察记录。欧罗巴岛泻湖是黑鳍礁鲨的育雏场，是唯一存在的物种。共记录了 8 个物种，这使得 1952 年以来在科学文献和灰色文献中报告的 15 个欧罗巴岛鲨鱼物种的多样性增加。总的来说，除了尖吻真鲨之外，还出现了几种顶级掠食者、大群的斜齿鲨、相当数量的礁鲨和黑鳍礁鲨的育雏场，欧罗巴岛的鲨鱼构成了一个重要的生物多样性储备库，有助于维持生态系统的功能。我们的观察结果强调了欧罗巴岛对于鲨鱼保护的重要性，以及需要对欧罗巴岛和印度巴萨斯群岛的专属经济区进行有针对性的鲨鱼管理。
