Undersea features provide best protection targets for oceanic sharks

Underwater footage of sea life from one of the world’s most remote marine parks has shown protected areas must include a range of ocean features to maximise marine biodiversity protection.

The footage was recorded as part of an international expedition, which included researchers from The University of Western Australia, working in collaboration with National Geographic’s Pristine Seas project, to help find and inspire the protection of the ocean’s last wild places.

The research, published in Frontiers in Marine Science, examined the effect of various geographical ocean features, including seamounts, islands and oceanographic fronts, on marine wildlife at Ascension Island, a remote and recently protected UK territory in the tropical Atlantic.

The researchers found these ocean features had a significant influence on the distribution, diversity, abundance, size, and composition of the marine communities observed there.

The types of marine life varied markedly among different physical and oceanographic features. 

The waters close to the island were most important for turtles, dolphins, and smaller fishes, while seamounts – underwater mountains formed by volcanic activity – were particularly important for ocean predators, including several threatened species such as silky sharks.

In particular, two shallow seamounts in the south of the territory harboured large groups of sharks and large pelagic fishes like tuna and wahoo, making up more than 99 per cent of the amount of animals in that area. 

These congregations may be driven by opportunities to forage, clean and socialise.

Lead author, Research Fellow Christopher Thompson from UWA’s Marine Futures Lab, said the results showed that including multiple features in conservation efforts increased biodiversity protection.“Our findings highlight the value of including features like seamounts and islands in our marine protected areas,” Mr Thompson said.

“Much of Australia’s marine parks network is located in offshore deep waters and it is important that we ensure that productive shelfs, canyons and seamounts are also protected.

“The marine park at Ascension Island sets a great example for marine protection efforts worldwide and our work provides a benchmark of marine wildlife status which can be used to track the changes moving forward.”