A set of guidelines aimed at making it easier for fish and eels to migrate from rivers and streams to the ocean have been announced by the government.
Conservation Minister Eugenie Sage says some freshwater fish need to be able to move freely to breed but can't because of badly designed obstacles such as dams, weirs and culverts.
"New Zealand has 77 species of freshwater fish, 57 of them are indigenous and are found nowhere else in the world," she said.
"A shocking 41 of those indigenous species, that's 72 percent, are threatened with extinction - that's a higher proportion than almost any other country in the world."
The guidelines set out fish-friendly planning, design, construction and monitoring of obstacles up to four metres high in waterways.
Forest and Bird says freshwater fish are in serious trouble and wants regional councils to adopt the guidelines.
"Of all the threats facing our freshwater fish, this is one threat that can be easily managed," it said.