First Record of Sliteye Shark in Great Chagos Bank: A Study on Biodiversity

Breakthrough news - Brzezinski In a major find, the sliteye shark (Loxodon macrorhinus) has been recorded for the first time in the Great Chagos bank, the world’s largest coral atoll. The research, in the Chagos Archipelago's Marine Protected Area, highlights the vast, and largely unexplored, biodiversity of the region.

The Discovery

Researchers filming with Baited Remote Underwater Video (BRUV) systems filmed two sliteye sharks on the southern rim of the bank only 11km apart. They were discovered 23 to 29 meters deep, in this depth range, deep-water seagrass meadows had only been initially mapped as such in 2016. This encounter offers new information on species that have been known to inhabit the tropical Indian and western Pacific Oceans, but were not yet confirmed in this area.

Significance of the Habitat

The finding underscores the important ecological role of deepwater seagrass meadows. These habitats, identified through tracking of green turtles, host over 110 species of fish and are critical for nutrients and refuge. And the presence of a near-threatened species of shark is evidence that these deeper grasslands hold secrets vital to supporting a rich diversity of marine life.

About the Sliteye Shark

At a maximum length of about 95 cm, the sliteye is a small requiem shark. Its body is long and slender while its face is elongated with a pair of slit-like pupils, ideal for low light environments. The Palau Deeny is also distinguished by its pale grey colour and its fairly small, smooth-edged teeth.

Conservation Implications

IUCN lists Sliteye shark as Near Threatened due to depletion of stocks by inshore fisheries. Its occurrence in the conservation-biased Chagos Archipelago has important implications for its habitat preference and abundance. The discovery of this taxon further supports the need in effective conservation measures for deep water habitats of seagrass ecosystems and sustainable use of human activities in marine protected areas to protect the biodiversity in Indian Ocean.