A new study has found that increased pressure from agriculture and dairy farming is mostly to blame for the slow death of native freshwater fish populations.
In a report published in the New Zealand Journal of Marine and Freshwater Research, reseachers say that 67% of native fish are in serious trouble.
The threat status of 74 freshwater fish was studied. Fifty-one of them were ranked as threatened or at risk of becoming extinct.
One species, the New Zealand grayling, which has not been seen since the 1920s, was ruled to be extinct.
Most of the threatened species, such as torrent fish and bluegill bully, live in Otago and Canterbury waterways.
One of the report's authors, Professor Jonathan Waters, from the Department of Zoology at the University of Otago, says dairy farming has had a major impact on native fish.
He says some introduced species of trout are also contributing to the downfall of native freshwater fish.