Eel (Longfin) Anguilla dieffenbachii
Species: A. dieffenbachii
Binomial name: Anguilla dieffenbachii
Common name: Tuna
Longfin eels (Anguilla dieffenbachii) live mainly in rivers and inland waterways. They are probably the world's largest eel and they can grow up to 2 metres in length and up to 40 kg in weight. The New Zealand longfin eel is one of the 15 species of eel in the family Anguillidae and is found only in New Zealand including the Chatham Islands. They breed hundreds of kilometres away from New Zealand, probably in deep ocean trenches somewhere near Tonga. The larvae are called leptocephalus and they look nothing like an eel, being transparent, flat, and leaf-shaped. They reach New Zealand by drifting on ocean currents. Before entering fresh water the leptocephalus change into the more familiar eel shape, although they remain transparent for up to a week after leaving the sea. These tiny "glass" eels enter fresh water between July and November each year, often in very large numbers. Eels take many years to grow and it could be decades before an individual is ready to undertake the long migration back to the tropics. The adults never return as they die after spawning. Females eels are typically twice as long as males and contain huge numbers of eggs, and are thus important in sustaining the population and should be put back if caught. They are an iconic species and are a traditional Maori food in New Zealand. Despite being listed as at risk of extinction and desperate calls (from Māori and environmental groups) to stop fishing, the species is still commercially caught. In the pastr eeling has been a part of our New Zealand heritage. Traditional traps (hinaki) made of climbing fern (mangemange) or aerial roots of kiekie were one of the many and varied fishing methods used for eeling.
The difference between Longfin and shortfin eerls
The eels in the photo below are female, between 85 and 100 years old. They weigh approximately 20kg and are up to 2 metres in length. The eel grows very slowly at a rate of 15-25mm per year. Photographed at the the National Kiwi Centre, Hokitika, Westcoast.
Longfin eels photographed at night in the shallows of the Te Henui stream