Dataset Information

Movements of scalloped hammerhead sharks (Sphyrna lewini) at Cocos Island, Costa Rica and between oceanic islands in the Eastern Tropical Pacific.

ABSTRACT: Many species of sharks form aggregations around oceanic islands, yet their levels of residency and their site specificity around these islands may vary. In some cases, the waters around oceanic islands have been designated as marine protected areas, yet the conservation value for threatened shark species will depend greatly on how much time they spend within these protected waters. Eighty-four scalloped hammerhead sharks (Sphyrna lewini Griffith & Smith), were tagged with acoustic transmitters at Cocos Island between 2005-2013. The average residence index, expressed as a proportion of days present in our receiver array at the island over the entire monitoring period, was 0.52±0.31, implying that overall the sharks are strongly associated with the island. Residency was significantly greater at Alcyone, a shallow seamount located 3.6 km offshore from the main island, than at the other sites. Timing of presence at the receiver locations was mostly during daytime hours. Although only a single individual from Cocos was detected on a region-wide array, nine hammerheads tagged at Galapagos and Malpelo travelled to Cocos. The hammerheads tagged at Cocos were more resident than those visiting from elsewhere, suggesting that the Galapagos and Malpelo populations may use Cocos as a navigational waypoint or stopover during seasonal migrations to the coastal Central and South America. Our study demonstrates the importance of oceanic islands for this species, and shows that they may form a network of hotspots in the Eastern Tropical Pacific.

SUBMITTER: Nalesso E

PROVIDER: S-EPMC6413943 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Publications

Movements of scalloped hammerhead sharks (Sphyrna lewini) at Cocos Island, Costa Rica and between oceanic islands in the Eastern Tropical Pacific.

Nalesso Elena E Hearn Alex A Sosa-Nishizaki Oscar O Steiner Todd T Antoniou Alex A Reid Andrew A Bessudo Sandra S Soler Germán G Klimley A Peter AP Lara Frida F Ketchum James T JT Arauz Randall R

PloS one 20190312 3

Many species of sharks form aggregations around oceanic islands, yet their levels of residency and their site specificity around these islands may vary. In some cases, the waters around oceanic islands have been designated as marine protected areas, yet the conservation value for threatened shark species will depend greatly on how much time they spend within these protected waters. Eighty-four scalloped hammerhead sharks (Sphyrna lewini Griffith & Smith), were tagged with acoustic transmitters a ...[more]

PMID: 30861051

Similar Datasets

Project description:Scalloped Hammerhead shark (Sphyrna lewini) is an endangered species which its populations have been declining globally including in Indonesia, the world's top shark fishing country. However, there is a lack of information on the recent population structure of this species to promote proper management and its conservation status. This study aimed to investigate the genetic diversity, population structure, and connectivity of the S. lewini population, in three major shark landing sites: Aceh (n = 41), Balikpapan (n = 30), and Lombok (n = 29). Meanwhile, additional sequences were retrieved from West Papua (n = 14) and the Western Indian Ocean (n = 65) populations. From the analyses of the mitochondrial CO1 gene, a total of 179 sequences of S. lewini, with an average size of 594 bp, and 40 polymorphic loci in four and eight haplotypes for the Indonesian population and the Western Indian Ocean population were identified. The overall values of genetic diversity were high (h = 0.717; ? = 0.013), with the highest values recorded in Aceh (h = 0.668; ? = 0.002) and the lowest in Papua (h = 0.143; ? = 0.000). On the contrary, the overall value was fairly low in the Western Indian Ocean (h = 0.232; ? = 0.001). Furthermore, AMOVA and FST showed three significant subdivisions in Indonesia (FST = 0.442; P < 0.001), with separated populations for Aceh and West Papua, and mixed between Balikpapan and Lombok (FST = 0.044; P = 0.091). In contrast, genetic homogeneity was observed within the population of the Western Indian Ocean (FST = -0.013; P = 0.612). The establishment of a haplotype network provided evidence of a significantly different population and a limited genetic distribution between the Indonesian and the Western Indian Ocean populations (FST = 0.740; P < 0.001). This study showed the presence of a complex population of S. lewini with limited connectivity only in Indonesia separated from the Western Indian Ocean and requiring specific management measures based on the population structure at the regional level.

Dataset Information

Movements of scalloped hammerhead sharks (Sphyrna lewini) at Cocos Island, Costa Rica and between oceanic islands in the Eastern Tropical Pacific.

Publications

Movements of scalloped hammerhead sharks (Sphyrna lewini) at Cocos Island, Costa Rica and between oceanic islands in the Eastern Tropical Pacific.

Similar Datasets

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