A documentary due to screen later this month about the plight of the longfin eel features Whangarei's Millan Ruka and his campaign to clean up Northland waterways.
For years, Mr Ruka has been paddling muddy streams in his kayak, documenting pollution caused by cattle allowed to defecate - and thedroppings left to rot - in tributaries draining into the Kaipara Harbour.
He is one of the people interviewed in Saving Tuna, on Maori Television at 8.30pm on October 27, about the lifecycle of the longfin eel and those helping the threatened species survive.
Saving Tuna also looks at how iwi, from Lake Ellesmere in Canterbury to the "Tuna Town" of Moerewa in the Far North, are trying to regenerate stocks; while Ngati Hine's Tohe Ashby tells how the eel inspired the design of the legendary Ruapekapeka pa, just south of Kawakawa, and site of the final battle in the northern land wars.
Co-producer Gary Scott, of the Gibson Group, said the eel was an "awesome fish. The first time you learn the story of the eel, you get hooked, which is what inspired us to start the production."