Creatures and Features: Tuna/Eels

Tuna (the Māori word for eels) are important to Māori, but pressure on some species is resulting in their decline.

There are two main types of eel – the shortfin and the longfin. There are fewer eels today because of the loss of wetlands and historical commercial fishing practice. Currently the commercial eel fishery is managed by the Ministry for Primary Industries under the Quota Management System.

Eels migrate up streams as elvers to find suitable adult habitat. After many years (15-30 years for shortfins, 25 years for longfins, and sometimes up to 80 years) they migrate to the Pacific Ocean to breed and die. The new elvers migrate back to New Zealand and return to the rivers and streams of their ancestors.

Eels are secretive, mainly nocturnal and prefer habitats with plenty of cover.

The longfin eel is one of the largest eels in the world and it is found only in the rivers and lakes of New Zealand. Longfin eels are considered ‘At Risk, Declining.’

Longfin eels are quite susceptible to pollution, their health is also an indication of the health of the ecosystem in which they live. Tuna are examined for disease on the skin, fins, and mouth. In times of very poor water quality the lips of the tuna become completely covered with fungal growth, which may prevent it from feeding. This sometimes results in the death of tuna.

Find out more about these amazing animals here: www.doc.govt.nz/nature/native-animals/freshwater-fish/eels/