File photo. Photo: RNZ / Rebekah Parsons-King
Marine experts are at odds with Fisheries New Zealand over a proposal to increase the commercial crayfish catch limit in the Eastern North Island.
Fisheries New Zealand has proposed to increase the commercial catch limit for the CRA2 area, including the Hauraki Gulf, Coromandel, Bay of Plenty and East Cape, from 80 tonnes to either 90 or 100 tonnes.
The crayfish population was now at a sustainable level following cuts to the catch limit in 2018, it said.
But independent surveys of the Hauraki Gulf and Coromandel found populations were still severely depleted, and its authors believed Fisheries New Zealand had overestimated the species' recovery.
Fisheries New Zealand's main measure of the health of the fishery is the catch per unit effort (CPUE) - the amount of crayfish commercial fishers catch per pot.
But a marine scientist with the University of Auckland, Nick Shears, said that didn't show the full picture.
Dr. Nick Shears of the University of Auckland Photo: Tauihu Media / Riki Reinfeld
"Our concern is that they haven't taken into account some of the Fishery's independent data. So survey work we've been doing over the last five years that actually shows the population has remained at relatively low levels in the Hauraki Gulf."
When the catch limit was slashed in 2018, many of the commercial boats dropped out of the area, leaving less competition for crays, Shears said.
"The concerns that we've raised is this increase in CPUE was more related to a reduction in overall catch and therefore less competition among fishers, versus a large increase in the population which is what it's been touted as."
Fisheries estimated that cray numbers in the CRA2 area were 60 percent lower than in unfished areas.
But Shears' research in the Hauraki Gulf and Coromandel found the numbers in fished areas were over 90 percent lower than in marine reserves.
Director of Fisheries Management at the Ministry of Primary Industries, Emma Taylor, said they were aware of the results of the University of Auckland surveys but were confident in their own data.
"We're always open to new information and we're discussing with the university how we can better understand the methodology they've used.
"But at the time being we're really confident that we're using the best information on the state of the fishery and that comes from the stock assessments that we've done."
That led them to propose a 10 to 20-tonne increase in the commercial catch limit.
"The information we've got shows a significant increase in the amount of rock lobster in the fishery over the last few years. So we're proposing either to keep the status quo or small to moderate increases."
Crayfish are one of New Zealand's most important predators for marine reefs, Shears said, and have a crucial job keeping kina under control.
"Historically these abundances were much higher, snapper were larger, crayfish were larger, and they were able to keep kina numbers under control.
"So what we've seen around lots of the northeastern coast and other parts of New Zealand with the loss of those large predators, we've seen an increase in Kina barrens."
Fisheries New Zealand has also proposed closing the whole inner Hauraki Gulf to crayfishing, an area stretching from Cape Rodney in the north to Port Jackson at the tip of Coromandel.
Great Barrier boatie John Bakunin fears this could put more pressure on the outer Hauraki Gulf where people will still be able to fish.
"There will be a huge amount of pressure on Great Barrier, Little Barrier and the Mokohinaus. Because that's basically all that's left."
"It's quite accessible, a 20-foot boat with an outboard and good weather forecast - you can be on the Great Barrier, have a couple of hours diving, get some crayfish and be back in time for beer o'clock in Auckland."
However, Taylor said that was already happening due to the low levels of crayfish in the inner gulf.
Fisheries New Zealand will be going through submissions on the proposal in the coming weeks and then providing advice to the Minister of Oceans and Fisheries, Shane Jones.
Any changes will be put in place from 1 April.
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