Can the crayfish closure stop kina barrens? – Reto Blattner de-Vries
Opinion by
Reto Blattner de-Vries
Northern Advocate·
4 mins to read
Reto Blattner de-Vries was raised and educated in Rawene, South Hokianga, and has previous experience in Māori land law and Māori fisheries. He is currently a legal advisor for the Environmental Law Initiative, based in Hokianga. He has worked on both of ELI's legal cases against the Minister for Oceans and Fisheries regarding catch limits of crayfish in Northland.
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A 2025 survey found kina barrens now occupy 36% of rocky coastline across northeastern New Zealand.
A 2025 survey found kina barrens now occupy 36% of rocky coastline across northeastern New Zealand.
Aotearoa New Zealand’s principal fisheries law should have prevented the overharvesting of kōura (crayfish) and the related collapse of rocky shore ecosystems on the east coast of Te Tai Tokerau, Northland.
Yet it didn’t. In my view, the loss of kelp forests and spread of kina barrens across Northland areindicators of systemic failure.
How did fisheries management get it so wrong? And will the approaching east coast crayfish closure finally address it?
A 2025 survey found kina barrens now occupy 36% of rocky coastline across northeastern New Zealand.
What were once rich coastal ecosystems have been decimated. Reefs have been stripped bare.
Scientific research has linked the explosion of kina barrens with the dwindling populations of the primary kina predators – crayfish. The link is clear: overfish the predator and the whole ecosystem can be affected.
Over the past five years, the Environmental Law Initiative has partnered with three Te Tai Tokerau hapū to seek accountability and change in Fisheries NZ management practices.
The Fisheries Act 1996 was designed to balance the health of marine ecosystems with how we extract from them. The purpose of the Act is to allow the use of fisheries resources while ensuring sustainability.
The Act requires the minister to decide the total allowable catch for a stock, based on what is known as the maximum sustainable yield.
Despite this, kōura stocks and kelp habitat have steadily declined, as documented in areas such as the Hauraki Gulf and Mimiwhangata. These declines did not occur overnight. Since the Act took effect in 1996, up to 30 catch decisions will have been made.
The law requires decisions to be made on the “best available information”. Yet community observations of ecosystem decline and science suggesting a link to crayfish abundance were ignored.
In our first court case, alongside Te Uri o Hikihiki ki Whangaruru, the court found the minister relied on outdated and misleading scientific summaries that downplayed the relationship between kōura depletion and kina barrens. This failure rendered the decision unlawful.
Although the minister reduced the total allowable catch, spatial closures were not considered as a serious option. The best available science indicated that only substantial predator recovery – achieved fastest in closed areas – could reverse barrens.
We won the case, but we did not see sufficient change from Fisheries NZ or in ministerial decision-making. And so, in 2023, alongside Ngāti Kaharau me Ngāti Hau ki Hokianga, we returned to court, challenging the 2023 total allowable catch.
The court found the minister’s revised decision once again failed to use the best available information and that none of the options presented would make a meaningful difference to the degraded ecosystem.
Reto Blattner de-Vries has experience in Māori land law and Māori fisheries.
The court said that the small, fishery-wide reduction “bore no rational link” to reducing kina barrens.
It said spatial closures were the only tool capable of addressing the kina barren problem.
The court also criticised the failure to consider far stronger recreational controls, despite recreational fishing being a significant pressure along the east coast. Even though the Government is appealing the decision, it is already driving change.
When the Government announced in December 2025 the closure of commercial crayfish fisheries along the east coast of Northland, from Pārengarenga Harbour to Te Ārai Pt, we were cautiously optimistic. The decision finally mirrored the same ecological grounds for action advanced by scientists, hapū and community for years.
The new settings, which also include reduced recreational limits, take effect from April 1, 2026. For this closure to succeed, it must be supported by rigorous, transparent ecosystem monitoring and remain in place for as long as science indicates. Existing studies indicate this is likely to take many years.
However, last week, the Government introduced an amendment to the Fisheries Act, which contains a raft of concerning changes, including significantly constraining the ability of hapū, communities, or individuals to seek judicial review of fisheries decisions.
Had these restrictions been in place when we began our efforts, our legal challenges would have been curtailed, and the shift in Fisheries NZ’s approach may never have occurred.
The two High Court rulings that forced the agency to confront the kina barren crisis were only possible because the law protected the right to challenge unlawful decisions.
Northland’s kōura closure is a long-overdue step towards repairing a broken ecosystem. But if we undermine the public’s ability to hold decision-makers to account, we risk repeating the same mistakes – and allowing the next crisis to unfold in silence.
