Eels, whitebait among NZ freshwater species most threatened by climate change - NIWA study

A new study on the vulnerability of New Zealand freshwater fish species has found that eels and whitebait are among those most threatened by climate change.

A file image of a longfin eel in a stream. Source: Supplied:Donna Sayers

Research was carried out by Te Wai Māori Trust and NIWA looked at the vulnerability of 10 species, according to an internationally-recognised method known as a Climate Change Vulnerability Assessment.

The method determines vulnerability by examining how exposed the species are to changes in temperatures and rainfall, as well as whether their unique characteristics allow them to cope with those changes.

Each species is then given one of four designations, based on their vulnerability - low, moderate, high or very high.

According to the assessment, New Zealand's longfin eels (tuna) and lampreys (piharau/kanakana) were ranked as having very high exposure.

Longfin eels are also already classified as "at-risk declining" due to habitat loss, commercial fishing, migration barriers and hydro-electric structure deaths.

In the 'high' category, there were several whitebait species - īnanga/inaka, banded kōkopu and kōaro.

The shortfin eel and freshwater mussels were also classified as having a high vulnerability.

Freshwater crayfish and giant kōkopu were ranked as being moderately vulnerable, and only the yellow-eye mullter was ranked as being low-level.

NIWA chief scientist Erica Williams said the study provides valuable awareness around the emerging climate change-related threated to our freshwater species.

"This approach provides us with insights into how some of our freshwater taonga species' exposure to climate change may vary nationally, and how each species may respond differently depending on where they are located and their unique life cycle requirements," Williams said.

"It also highlighted that there are still some major gaps in our knowledge of these species, and their interactions with the ecosystems they are dependent on to survive and thrive."

Te Wai Māori Trust chair Lisa te Heuheu said local and central government must invest in climate change mitigation for freshwater ecosystems.

"We are seeing the effects of climate change on our freshwater species right now, and no-one has a plan to address it," she said.

"Most of our existing legislation is not fit for purpose to provide for the aspirations of tangata whenua for their freshwater species."