Shortfin eels are one of the three Anguillidae species found in New Zealand. They differ from longfin eels in the length of their dorsal fin. In shortfin eels, the dorsal and anal fins are the same length so the ends are almost adjacent when the fish is viewed side-on.
In longfin eels the dorsal fin is longer and extends well forward towards the head. Shortfin eels usually have a silvery belly compared to a yellowish one on longfins, but colours can vary considerably. Even pure yellow shortfin eels have been caught!
Shortfin eels are found throughout New Zealand and on Chatham and Stewart Island. However, they are not unique to this country and also occur throughout the South Pacific – in Australia, New Caledonia, Norfolk and Lord Howe Island, and perhaps Fiji. Generally shortfin eels are found at lower elevations and not as far inland as longfin eels, but they are still able to climb large obstacles such as waterfalls when they are young. They are often very numerous in lowland lakes, wetlands, and streams, and shortfin eels form the basis of the commercial eel fishery that has existed for over 20 years in New Zealand.
Shortfin eels are our most tolerant native fish species. They survive environmental hazards like high water temperatures or low dissolved oxygen concentrations. That means they can live in habitats where other species cannot survive. Their ability to live almost anywhere might explain why eels are so familiar to New Zealanders and why they were such an important food resource for Maori.