The Olive sea snake, which is closely related to the two species rediscovered. Richard Ling/Flickr. CC BY-NC-ND 2.0
Josh Davis 21 Dec 2015, 22:41

Surveying off the coast of Western Australia, researchers have discovered two species of rare and endangered sea snakes, thought to have become extinct 15 years ago. The venomous reptiles, which are adapted to spending their entire lives at sea in and around coral reefs, were only previously known from one site, and were last spotted there in 2000. This new finding gives hope that the two species, the leaf-scaled sea snake (Aipysurus foliosquama) and the short-nosed sea snake (Aipysurus apraefrontalis), have persisted, surviving over a much larger region than formerly thought.

“This discovery is really exciting, we get another chance to protect these two endemic Western Australian sea snake species,” explains Blanche D’Anastasi, lead author of the study published in Biological Conservation, in a statement. “But in order to succeed in protecting them, we will need to monitor populations as well as undertake research into understanding their biology and the threats they face.”

Researchers were first alerted to the possibility that one of the species of sea snake, the critically endangered short-nosed sea snake, was still present off the Western Australian coast when a pair of the reptiles were photographed on the Ningaloo Reef. The image was sent to D’Anastasi, who was “blown away” when she saw it. “These potentially extinct snakes were there in plain sight,” she said.

The Ningaloo Reef is a World Heritage Site in the north-west of Australia and is home to a wealth of marine life. The reef is famous for its annual whale shark migration, but is also an important stopping off site during the winter months for dolphins, humpback whales, dugongs, and manta rays as they move along the coast. The reef stretches for around 260 kilometers (160 miles), and yet is less than half a kilometer (0.3 miles) from shore, making it the largest fringing coral reef in the world.  

Interestingly, the Ningaloo Reef is actually 1,700 kilometers (1,056 miles) south of where the snakes were last recorded, which was on the Ashmore Reef in the Timor Sea. This means that not only have the researchers rediscovered the species, they’ve also massively extended their range. In addition to that, the scientists also found the snakes living in sea grass, whereas previously it was thought that they lived exclusively on coral reefs. This, coupled with the expansion of their range, means there could be more suitable habitat for the snakes than previously thought.

Despite these positive findings, the researchers note that sea snakes in general are actually faring quite poorly. The reptiles are declining in many marine reserves, and scientists are at a loss as to why. Many are caught as by-catch from trawling for prawns, but this doesn’t explain the decline of the snakes in the Ashmore Reef, for example, as fishing is banned there.   

Main image: Richard Ling/Flickr. CC BY-NC-ND 2.0

Image in text: Full picture of the two short-nosed sea snakes, which is the original photo that alerted D'Anastasi to the species surving on the Ningaloo Reef. Grant Griffin/W.A. Dept. Parks and Wildlife

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