Two species of water snakes listed as critically endangered in 2009 and presumed extinct have been found. Aipysurus foliosquama and Aipysurus apraefrontalis are two species of venomous sea snakes found only in the waters surrounding Australia.
Surveys between 2001 and 2009 failed to find any individuals of A. foliosquama or A. apraefrontalis, but dead specimens found in 2010 and 2012 prompted biologists to perform another extensive survey.
The team, from James Cook University in Australia, surveyed several locations in West Australia for the two species of sea snakes. They used a variety of methods including scuba and snorkeling in addition to counting snakes caught inadvertently by trawlers. The snakes were identified by both their appearance and genetics. In total, about 200 hours were spent searching for sea snakes.
Sixteen A. foliosquama snakes were found in various locations around Australia and seven A. apraefrontalis snakes were found including a courting pair indicating a mating population. Many of the snakes reported were seen outside of their natural habitats. The finding of these snakes suggests that they may not be at risk of extinction but are still endangered.
Different haplotypes were found in A. foliosquama snakes at different locations. A haplotype is set of alleles passed on to offspring, so the fact that different haplotypes were found suggests a mating population. This is encouraging because it shows that these snakes may be part of a healthy breeding population.
The reason for the decrease in the numbers of these snakes is still unknown but could be due to incidental catching by trawlers. However, this alone cannot account for the large decrease because trawling doesn’t occur in all of the new habitats they now live in. Habitat loss or decrease in prey could also be contributing factors. More research into what is causing the decline of these snakes will be needed to determine the exact causes.
The study was published in the journal Biological Conservation.