There are two main types of eel – the shortfin and the longfin. 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. 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. When eels begin life, they are a tiny 1 mm in length.
During their life, they can grow up to 2 metres long. The biggest longfin eels reported
have weighed as much as 40 kg, but today you’ll seldom find an eel heavier than 10
kg. Eels eat "live" food. Small longfin eels living amongst the river gravels will
feed on insect larvae, worms and water snails. When they get bigger, they begin to
feed on fish. They will also eat fresh-water crayfish and even small birds like ducklings.
Eels hunt by smell rather than sight. Longfin eels have a well-developed sense of
smell. They have tube nostrils that protrude from the front of their head, above
their upper lip. They also have a very large mouth with rows of small, sharp, white
teeth. The top teeth form an arrow shape on the roof of the eel’s mouth.