DOC's Threatened Species Ambassador, Nicola Toki, talks about the New Zealand longfin eel, or tuna.
She says the eels are "incredible, incredible animals with such an incredible life history".
Toki says that all of the eels we see in New Zealand are "virgins", who might live in a freshwater waterway here for 50-60 years.
But they then head 1000kms into the ocean, mate with other eels, die, then their tiny larvae swim back to New Zealand.
The longfin eel is also considered to be taonga to Māori, and as Toki says any eel that is taken out of our waterways will never breed - and they are in gradual decline.
DOC is also running a Threatened in New Zealand drawing competition , for children up to the age of 13, which finishes on Monday.