Habitat restoration bigger key to whitebait’s survival than fishing, researcher finds

Tuesday, 16 June 2026

University of Canterbury School of Biological Sciences researcher Ben Crichton with a giant kōkopu.

Restoring rivers and streams could be just as important as fishing restrictions in preventing the collapse of New Zealand’s threatened whitebait species, new research suggests.

University of Canterbury School of Biological Sciences researcher Ben Crichton compared West Coast waterways open to whitebaiting with those where fishing was prohibited.

According to the Department of Conservation, all six species of whitebait are threatened or at risk of extinction, mainly due to spawning habitat damage and loss.

University of Canterbury School of Biological Sciences researcher Ben Crichton spent two years monitoring eight streams from Westport to Harihari on the West Coast.

Crichton’s research on the five diadromous galaxiids species, published in the New Zealand Journal of Marine and Freshwater Research, showed that while unfished streams had more juveniles migrating upstream, adult numbers were similar across both fished and unfished streams.

While more young fish reached streams closed to whitebaiting, adult kōkopu numbers were often similar because the habitat was already full, he said, which showed the quality of adult habitat could be just as important as the number of juveniles arriving each year.

Adult shortjaw kōkopu (Galaxias postvectis) are nocturnal freshwater fish endemic to New Zealand.

Threats to habitat include sedimentation, vegetation clearance, stock access and migration barriers such as weirs and culverts that prevent juvenile fish reaching upstream habitat.

Humans had an “astronomical” impact on habitat decline for whitebait, which used to be abundant throughout New Zealand, Crichton said.

But the farming sector, regional councils and community catchment groups were making strides to protect and restore habitats with riparian planting, he said.

Crichton monitored numbers and collected data on growth and survival rates.

West Coast Whitebaiters Association president Rob Roney said the findings were interesting, if not unexpected.

“A basic tenet of wildlife management is ‘if you can look after the habitat, the species will look after themselves’. Whitebait are no exception.”

Crichton says the West Coast is a stronghold for whitebait habitat.

Crichton’s study found current management strategies, which focus heavily on protecting one species - īnanga - through a network of 22 no-take areas on the West Coast, do not adequately account for the differing vulnerabilities of other whitebait species.

Cobden Aramohana Sanctuary and Recreational Area in 2012 and then in 2016 after whitebait habitat was restored. (Composite image)

Īnanga make up almost 90% of the national whitebait catch and are considered particularly vulnerable because of their annual life cycle and dependence on successful yearly recruitment.

Crichton said īnanga had continued to survive despite significant habitat loss, indicating that restoring waterways could help increase whitebait populations.

The whitebait fishing season runs from September 1 to October 30, but some rivers are closed to fishing all year round.

The study also found that shortjaw kōkopu in unfished streams grow significantly larger than those in fished streams, while īnanga in fished streams are larger than those in unfished areas.

Crichton said many existing closed areas were in degraded catchments or above migration barriers, meaning young fish could still struggle to reach quality habitat and breeding grounds even where fishing was prohibited.

He called for closed areas to be redesigned to cover the full range of habitats each species needs across its life cycle, and for conservation efforts to be spread across multiple regions rather than concentrated on the West Coast.

He said the most effective management would combine targeted fishing regulations with the protection and restoration of high-quality adult habitats.

All species relied on quality habitats to survive, grow, and spawn, Crichton said.

“If the management of these species only focuses on the whitebait stage and ignores adult habitats upstream, juvenile fish may swim upstream into rivers that can’t support them.”