Overfishing, poor water quality and habitat destruction are contributing to declining numbers of whitebait, a Forest & Bird advocate says.
The Department of Conservation is consulting on improving the management of whitebait, habitat and species conservation, attracting more than 11,500 submissions.
Whitebaiters have previously expressed concern that some rivers may be closed as part of the consultation that will go to the new Minister of Conservation, Kiri Allan, while conservationists say the species and its habitat are at risk and need protecting.
New research sent to the Department of Conservation says already healthy rivers are the best candidates for closure because they could support greater numbers of whitebait.
Forest and Bird freshwater advocate Annabeth Cohen said four whitebait species are at risk or threatened with extinction and she is calling on the government to strengthen the fishing regulations before the start of the West Coast whitebaiting season next year.
The West Coast whitebaiting season has finished; it finishes on 30 November for the rest of New Zealand.
The Department of Conservation has released its summary of submissions on their whitebait consultation, in which they acknowledged strong support from both fishers and non-fishers for a licence and catch limit to manage and monitor the whitebait fishery, Cohen said in a statement.
Forest & Bird's submission also called for a licence requirement, a catch limit on both commercial and recreational fishing, and a data collection method.
"Native fish species in New Zealand are experiencing death by a thousand cuts. Overfishing is a pressure that we can alleviate right now.
"We need the government to prioritise our incredible native fish and ensure they will be here for future generations.
"It is now up to the Minister of Conservation and the Minister for the Environment to save our whitebait species from overfishing, water pollution, and habitat destruction, so they can thrive and be enjoyed by future generations.
"They travel through a largely unregulated fishery at the start of their lives and go on to live in habitats where bottom lines for pollutants like nitrogen and phosphorus are still not good enough," Cohen said.
Forest & Bird said kōaro, shortjaw kōkopu, banded kōkopu, giant kōkopu, and īnanga are the five migratory galaxiid fish in the whitebait catch.
Common smelt is also a native fish that is part of the whitebait catch.
The West Coast Whitebaiters Association said the 2020 season was reported by fishers as one of the best in decades.
The association does not agree with Forest & Bird's submission that some species are on the brink of extinction and claim some of the data underpinning the science is unreliable.
Its president Rob Roney said the association is unsure which data Forest & Bird have used and claim "absence of evidence" has been translated into "evidence of absence".
"...DOC's review recommendations list many West Coast rivers as possibilities for closure, causing considerable angst for West Coast Whitebaiters particularly when they know that the West Coast already has 23 rivers closed to fishing.
"Similarly, the spate of regulation changes proposed, leave West Coast whitebaiters bewildered, as they already endure a shorter season and harsher regulations than the rest of the country."
Freshwater ecologist Dr Mike Joy from Victoria University of Wellington said evidence shows there are fewer adult whitebait and four of the five species are threatened.
"Some people feel really bad about eating or fishing threatened species.
"The adults are at serious risk, if you don't have adults you don't have juveniles. These are the young, the larvae, returning from the ocean to take up the habitat where the parents live in. They're totally dependent on adults.
"It's very clear there has been a decline [in adults].
"There's very clear consensus that there is a problem and that habitat loss is a big problem, water quality, damage done to our rivers ... plenty of scientific consensus around that. Where the consensus is possibly not there is just how much impact whitebaiting is on that....It's not to say that whitebaiting caused the problem, the cause of the problem is our failure to protect the habitat and the water quality but it doesn't take away from the fact that whitebaiting is harming the adults, the future of the population, because they're declining and their replacements are being taken out by whitebaiters."
Whitebait spend part of their life in freshwater and part of their life in the sea.
Each species grows to a different size, has a different lifespan, and a different breeding pattern. If allowed to grow, some species can reach up to almost 60cm long, while others can live for over a decade.