Highly venomous yellow-bellied sea snake found in Doubtless Bay

A highly venomous sea snake has washed up on a Northland beach - but experts say it's no cause for alarm, as they're known to show up in New Zealand from time to time.

The reptile, identified by the Department of Conservation (DoC) as a yellow-bellied sea snake, was discovered on Tokerau Beach in Doubtless Bay over the weekend.

Sightings of the snakes are somewhat of a rarity in New Zealand. While they are technically native to Aotearoa and drift towards our shores on ocean currents occasionally, they breed in the tropics and are only spotted here between six and 10 times a year.

The person who found the snake, Samantha Cooper, posted footage of it to Facebook on Sunday, saying she didn't even know Aotearoa had snakes.

"We tried to put it back in the ocean but it kept swimming back on to the sand. The tide is on its way out and I was worried about kids and dogs safety," she wrote.

"Also cars drive on Tokerau so it was most probably [going to] get squished. I gave the snake to DoC."

DoC says like this one, most sightings of the snakes are in the north-eastern parts of the country - though they have been seen as far south as the Cook Strait.

"Unlike banded sea snakes and kraits, yellow-bellied sea snakes are entirely oceanic and complete their entire lifecycle far from land, even giving birth to live young at sea," explains DoC marine species technical advisor Clinton Duffy.

"The nearest population to New Zealand is believed to be in the northern Tasman Sea."

The reptile, identified as a yellow-bellied sea snake, was discovered on Tokerau Beach in Doubtless Bay over the weekend.
The reptile, identified as a yellow-bellied sea snake, was discovered on Tokerau Beach in Doubtless Bay over the weekend. Photo credit: Facebook / Samantha Cooper

While their potent venom is likely to cause a scare - a single bite is so toxic it can cause paralysis or even death - no one is known to have been bitten by one in New Zealand, and they are unlikely to lash out without provocation.

"A bite from one is likely to be fatal without access to snake antivenom. However, bites from them are extremely rare because their fangs are small and located at the back of their mouths," Duffy said.

"In addition, yellow-bellied sea snakes are not adapted to life on land and those found ashore are usually injured or moribund from thermal shock."

Even so, Duffy recommends anyone who spots a sea snake keep well away.

"Anyone finding a sea snake should avoid handling it, and if possible photograph and report it to the Department of Conservation."

Unfortunately for this particular snake, it's highly unlikely it will survive as it's pelagic, so can't live on land. DoC says any yellow-bellied sea snake that beaches itself will "almost certainly be dead or dying".

A spokesperson for the Ministry for Primary Industries' biosecurity department said it hadn't been notified about this particular detection.

"Sea snakes (including the yellow bellied sea-snake) are carried to New Zealand waters on warm currents from Australia and the Pacific Islands," a Biosecurity NZ spokesperson told Newshub.

"They do not represent a biosecurity risk as they are considered native species under the Wildlife Act 1953. As native species, they fall under the jurisdiction of the Department of Conservation.

"MPI receives two or three notifications about sea snakes each year. Most of these records represent snakes washed ashore after heavy storms. We pass on this information to DoC for their records."