Yellow-bellied Sea Snake

The yellow-bellied sea snake is a highly venomous oceanic snake that reaches New Zealand naturally on warm currents. Its sharply divided dark upper surface and yellow belly identify stranded animals on northern beaches. The body is dark above and yellow below, with the two colours meeting sharply along the sides, and the tail is flattened into a swimming paddle. Banded sea kraits, which also drift to New Zealand, come ashore in the tropics, whereas this species spends its whole life at sea.

It breeds in tropical waters north of New Zealand and arrives here as an occasional ocean-current visitor. About 12 are reported annually, mainly from the north-east North Island, with records south to Cook Strait. The snake remains at sea throughout its life, feeding on small fish. It can dive to about 50 m and remain submerged for 3–4 hours depending on water temperature.

The yellow-bellied sea snake is classed as Not Threatened (NZ Threat Classification) and is protected by the Wildlife Act 1953. New Zealand water is too cold for long-term survival, and live beach-stranded animals are usually hypothermic and unlikely to recover. Sightings are rare and unpredictable, mostly on north-eastern North Island coasts after warm-water conditions. Keep people and dogs well away from any stranded snake and contact DOC immediately.