Long-finned eels (Anguilla dieffenbachii) and short-finned eels (Anguilla australis schmidtii) are the common freshwater eels called tuna by the Maoris. They are much alike except for the relative length of the dorsal fin. New Zealand can claim to have the world's largest freshwater eels, for specimens over 5 ft long and weighing up to 46 Ib are on record. These extra large eels are senile creatures that have ceased to obey the breeding urge to migrate and have stayed behind putting on weight.

The remarkable migrations of European and American eels to breeding grounds in the West Indies is now well known, but it is not generally realised that our own species indulge in a similar migration. The actual site of the oceanic breeding ground for the New Zealand eels is not known precisely, but is presumed to be somewhere near Tonga. Many people are loath to believe that our eels proceed to the open sea to breed, but the fact remains that the leaf-shaped larvae of our eels have never been taken in local waters.

by Arthur William Baden Powell, Assistant Director, Auckland Institute and Museum.