Nature

Thought to Be Extinct, Rare Sea Snakes Found Again in Australia

December 21, 2015 | Joanne Kennell

Two yellow snakes in the water
Photo credit: Grant Griffin/W.A. Dept. Parks and Wildlife

They had not been seen alive since 2000.

If you are a snake-lover like me, then you will be thrilled about the news coming out of Australia.  Scientists from James Cook University (JCU) discovered two members of a critically endangered species of sea snake off the coast of Western Australia — marking the first time this species has been seen alive since 2000.  These snakes disappeared from their only known habitat on Ashmore Reef in the Timor Sea more than 15 years ago and were thought to be extinct.

“This discovery is really exciting, we get another chance to protect these two endemic Western Australian sea snake species,” said lead author Blanche D'Anastasi from the ARC Centre of Excellence for Coral Reef Studies at JCU.  “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.”  The discovery of the short-nosed sea snake was made by Australia Parks and Wildlife Officer, Grant Griffin, who sent a photo of the snakes on Ningaloo Reef to D’Anastasi to identify.  

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Short-nosed sea snakes grow up to 60 centimeters long and are a shade of brown with purple and brown patterns.  They are usually found 10 meters below the surface and can spend up to two hours under water due to cutaneous respiration which allows them to absorb oxygen in the sea water through their skin. Additionally, they can store large amounts of air in a single lung that runs nearly the entire length of their bodies.  

The lifespan of the snakes is typically eight to ten years, and they have a gestation period between six and seven months.  Populations of the snakes began to decline, most likely due to climate change and accidental capture of the snakes by commercial prawn fishing, and they had not been spotted, until now, since the year 2000.

“We were blown away, these potentially extinct snakes were there in plain sight, living on one of Australia's natural icons, Ningaloo Reef,” said D'Anastasi.  “What is even more exciting is that they were courting, suggesting that they are members of a breeding population.”

The researchers also made another very unexpected discovery — a population of critically endangered rare leaf-scaled sea snakes in Shark Bay — about 1,700 kilometers south of the snakes’ only previously known habitat on Ashmore Reef.  “We had thought that this species of sea snake was only found on tropical coral reefs. Finding them in seagrass beds at Shark Bay was a real surprise,” said D'Anastasi.

Although it is fantastic to find these two species of rare sea snakes, snake numbers have been declining in several marine parks, and scientists have no idea why.  “Many of the snakes in this study were collected from prawn trawl by-catch surveys, indicating that these species are vulnerable to trawling,” said Dr Vimoksalehi Lukoschek from the Centre of Excellence for Coral Reef Studies.  “But the disappearance of sea snakes from Ashmore Reef, could not be attributed to trawling and remains unexplained.”

Currently, there are no specific plans to address the decline of these sea-snakes, however, Ashmore Reef has been a nature reserve since 1983.  Not only that, commercial prawners have reduced the number of fishing vessels in hopes to reduce the impact on the populations.  “Clearly we need to identify the key threats to their survival in order to implement effective conservation strategies if we are going to protect these newly discovered coastal populations,” Lukoschek said.

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