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New research sent to the Department of Conservation (DOC) showed already healthy rivers were the best candidates for closure, because they could support greater numbers of whitebait.
That had some coasters worried that yet another natural asset was about to be taken away from them.
Des McEnaney has fished for whitebait on the West Coast for the past 68 years.
"When we were boys, we used to wander down to a local creek and we'd look to fish them out with a tin on the end of a stick and a few nail holes in the bottom of the tin. And you could get them coming up in the shallows."
McEnaney, who was included on a working party looking at the sorts of changes that might help boost flagging whitebait numbers, said compared to the rest of the country, stocks in his region had been relatively stable over the years.
That was why news their rivers may be top of the list for closure was so hard to take.
"The West Coast whitebaiter has been dealing for years and years on tighter regulations that have never been introduced elsewhere and suddenly they become the fall guy for the rest of the nation on an assumption that this may help. Not a good look."
After consulting with whitebaiters and environmentalists this year, DOC began drawing up recommendations to go to its minister.
While it was doing this, Canterbury University released new research which found closing degraded rivers with a limited ability to support larger numbers of whitebait was a waste of time.
Ecologist Mike Hickford, who led the study, explained why this was the case.
"Without some habitat restoration, improving the water quality, improving the food availability and possibly even reducing the predator numbers, the chances are that a lot of those whitebait going through in a river closure will either not grow very well, they'll get eaten by something else or they'll just starve to death."
The healthy rivers on the West Coast stood the best chance of supporting the larger populations of whitebait resulting from closures, and should be at the top of the minister's list for being shut down, he said.
He passed on his findings to the DOC officials drawing up the changes and was hopeful they would listen to the science when deciding which rivers should be closed.
"Healthy rivers which still have reasonably intact catchments, good forest cover and riparian margins, my expectation is that a lot of those rivers would be on the list. But when you get to some of the particularly eastern areas, your Canterburys and Hawke's Bays, we may be struggling to find rivers to go on the list that satisfy those criteria."
An estimated 20 to 30% of whitebait - the juveniles of six native fish species - are netted from rivers each season.
Forest & Bird freshwater advocate Tom Kay said the minister should also consider other measures to help reduce the impact.
"We actually think there should be a catch limit like you would have in any other fishery, a licensing system, and some way of collecting data so that we actually know where these fish are being caught and which places should be being managed more intensely than others."
In a statement, DOC said the whitebait review was still under "active consideration".
When asked about Dr Hickford's research, it said DOC considered "all available academic research on whitebait" when developing recommendations for changes to whitebait management.