The scientist who took on John Key over the '100 percent pure' tourism slogan is now calling for the end of the whitebait industry.
The current fishing season began with a Department of Conservation warning that some whitebait species are as endangered as the kiwi. The catch has been so bad, fishers have called it the worst season in living memory.
Ecologist Dr Mike Joy says it's because we have failed to look after New Zealand's fresh water.
"It's coming home to roost for us now we're seeing freshwater fish disappear," he told Newshub.
"We've got 74 percent of our species listed as threatened, and that's just a really clear indicator that we're trashing our rivers."
Whitebait is an umbrella term for the juveniles of several different species of native fish. There are already limits on net sizes and fishing hours, but Dr Joy wants it limited further to recreational fishers only.
"Give our whitebait, our native fish, the same protections that we give to introduced trout and salmon.
"If we have the same law that says you cannot sell them, a huge amount of pressure that's on the fish at the moment would disappear, because all the people that do it for money wouldn't do it anymore."
Dr Joy has previously predicted whitebait, and other migratory fish, will disappear from New Zealand waters by 2050 if steps aren't taken to limit catch.
A report by the Ministry for the Environment and Statistics NZ last year painted a mixed picture of freshwater quality.
Dr Joy caused furore in 2011 when he criticised the Government's environmental record, leading to a tough interview in which Mr Key infamously compared scientists and academics to lawyers.
"He's one academic, and like lawyers, I can provide you with another one that will give you a counterview," he told the BBC's Hardtalk.
Unitec senior lecturer Dr Stephane Boyer says he doesn't believe whitebait fishing practices in New Zealand are sustainable. He says the big issue is that it's not known which of the species are being caught because they look similar.
"Among these five species, three are declining and one is recognised as a threatened species," he said. "Yet we fish, sell and eat them all without distinction."
Canterbury University research associate Dr Mike Hickford said comprehensive catch information was needed to give an idea of longer-term trends.
"We have no idea if fluctuations in the whitebait catch are even related to fish stocks, let alone whether the whitebait catch is in decline," he said.
Dr Hickford said the whitebait fishery had always been regionally patchy and varied enormously from year to year.
"It's also the case that whitebaiters have notoriously short and fluid memories," he said.
"Many of the people who describe this year as yet another lacklustre year conveniently forget that last year (or the year before), they had a great whitebaiting season."
NZN / Newshub.