On a recent expedition to this remote group of islands in the British Indian Ocean Territory, biologists from the Zoological Society of London (ZSL) joined colleagues from the University of Western Australia (UWA), and used video technology to document the status of the Archipelago’s diverse range of sharks and other fishes.
Baited remote underwater video systems (BRUVS), used extensively by the UWA team to study the ocean’s diversity, were placed in over 200 locations around the Chagos marine reserve. And it was a number of these cameras which captured life on the newly discovered ‘Sandes Seamount’, named after the expedition Captain who navigated the vessel to the area for the first time.
Rising tall from the surrounding seabed, the seamount hosts congregations of sharks and schooling fishes. These important marine habitats are undersea mountains whose summits rise more than 1000m above the surrounding seafloor. ZSL’s Dr Chris Yesson used bathymetry data to calculate the presence of 86 seamounts within the Chagos marine reserve. This emphasises the importance of this reserve as only 1.5% of the estimated 33,452 seamounts globally are currently protected, even though they are often the targets for fishing activity.
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Video Copyright: University of Western Australia
ZSL’s Dr. Heather Koldewey says: “It was a truly extraordinary experience to see life on the Sandes Seamount for the first time. Most remarkable was to observe a seabed that had not been decimated by trawlers and the associated abundance of fish . The Chagos archipelago gives us an insight into what our oceans should look like”.
The footage shows the Sandes Seamount to be a hotspot for marine life, supporting a rich underwater ecosystem including hammerhead sharks, silvertip sharks, and grey reef sharks, as well as large groupers, and schools of many other fishes.
Professor Jessica Meeuwig from UWA says: “One of the highlights of our survey throughout the Archipelago was finding a previously unexplored seamount, an underwater pinnacle that was just teeming with animals, including sharks that are heavily exploited elsewhere”.
Marine reserves are becoming more and more important as one solution to the global depletion of fisheries resources are due to poor management practices and increasing fishing pressure. It is therefore of utmost importance that the Chagos MPA creates an opportunity to demonstrate how this large area is beneficial, and ensure species that were once targeted by fisheries and caught as by-catch are now protected and thriving in the region. By using BRUVS on the seabed, and extending the technique to the open ocean, researchers can make certain these species receive the best management and protection in this near-pristine part of the ocean, important when only 3 percent of Chagos has been explored. Demonstrating the benefits of protection in Chagos will support implementation of large MPAs in other parts of the world.
ZSL, together with UWA, are now progressing this approach as part of a long-term monitoring programme in Chagos, to support the protection of this extraordinarily rich area of marine biodiversity.