Short-nosed sea snake
With no sightings since 2000, short-nosed sea snake populations are in serious decline
AUSTRALIAN CONSERVATION STATUS (EPBC Act)
The short-nosed sea snake is estimated to occupy a combined area of 10 sq.km, and is restricted to the Ashmore Reef and Hibernia Reefs off the coast of northern Western Australia.
Short-nosed sea snake, Sahul Reef snake
The species is mostly found in water more than 10m deep, and can be found both on the flat and around the edge of coral reefs. The snake will often rest during the day under coral overhangs in water depths of 1-2m.
The short-nosed sea snake grows up to 60cm long, is relatively slender and has a small head. The species is brown in colour with purple to brown patterns, and scales on the body overlap one another. The sea snake sheds its skin every two to six weeks, and rids excess salt from the sea water through a gland that is located under the tongue.
Like other sea snakes, the species must come to the surface to breathe; however, it can spend up to two hours under water. Gas (oxygen/carbon dioxide) exchange is managed by the snake’s single lung, which is nearly the length of its body.
In addition, the snake is capable of cutaneous respiration, where tiny blood vessels in the skin absorb oxygen from the sea water and diffuse out carbon dioxide. The nostril valves open inwards, and are held shut while underwater by erectile tissue.
It is thought the species has a life span of 8-10 years, with a generation length of around five years. The snake gives birth to live young, with a gestation period of six to seven months. Eels and small fish make up the sea snake’s diet.
Threats to the short-nosed sea snake
Populations of short-nosed sea snakes are declining at rates of around 90 per cent; however, the demise of the species has not been attributed to one particular cause. Global warming has certainly affected the species’ habitat, with coral bleaching occurring in reefs due to the warming of the ocean. In addition, there is a possibility that the ocean temperature has exceeded the snake’s tolerance level, which is believed to be 36°C.
Commercial prawn fishing is also believed to affect sea snake populations. The Northern Prawn Fishery operates in the vicinity of reefs that sea snakes inhabit, and accidental capture of sea snakes often results in death or injury to the species. The low reproduction rate adds to the species’ vulnerability.
Recovery plans for the short-nosed sea snake
There are no specific plans to address the decline of the short-nosed seas snake. Nevertheless, Ashmore Reef has been a nature reserve since 1983, and a marine bioregional plan has been developed for the north-west region. From 2007 onwards, the Northern Prawn Fishery reduced the amount of fishing vessels from 96 to 56, which is expected to reduce the impact of commercial trawling on sea snake populations.