Sea snakes thought to be extinct show up in Australian waters

The short-nosed sea snake was discovered recently in Western Australia. Photo / Grant Griffin, W.A. Dept. Parks and Wildlife via Washington Post

Humans haven't seen a living short-nosed sea snake in 15 years. But there they were, two such snakes swimming along in the waters of the Western Australian Ningaloo Reef. Luckily, a park ranger snapped a photo of the pair and submitted it to scientists.

Researchers published the discovery of living Aipysurus apraefrontalis snakes, along with another thought-to-be-extinct snake species, in the journal Biological Conservation on Monday.

"We were blown away, these potentially extinct snakes were there in plain sight, living on one of Australia's natural icons, Ningaloo Reef," study lead author Blanche D'Anastasi said.

"What is even more exciting is that they were courting, suggesting that they are members of a breeding population" added D'Anastasi, a scientist with the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Australia.

The short-nosed sea snake has been listed as critically endangered since it disappeared from its only known habitat, the Ashmore Reef in the Timor Sea. "This species has gone from being the third most commonly recorded sea snake in the 1990s to no individuals being recorded in intensive surveys since 2000, indicating a decline of at least 90 per cent in the past 15 years," according to the International Union for Conservation of Nature.

Researchers also discovered a group of leaf-scaled sea snakes, or Aipysurus foliosquama, living in Western Australia more than 1600km away from their only known habitat, 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," D'Anastasi said.

The leaf-scaled snakes went from making up half of the recorded sea snakes on the reef flats in the 1990s to no individual sightings since 2001. Like the short-nosed snake, threats to its viability "are largely unknown, however, declines are possibly due to habitat degradation from coral bleaching and decline of ecosystem health", according to the IUCN.

The study authors note that their data "significantly increases the known geographic range and habitats" of the leaf-scaled sea snakes.

While sea snakes can be vulnerable to trawling, a method of fishing, "the disappearance of sea snakes from Ashmore Reef could not be attributed to trawling and remains unexplained", Vimoksalehi Lukoschek of the Centre of Excellence for Coral Reef Studies said.

"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.