The closing of a reportedly 'lacklustre” whitebait season has New Zealand scientists speculating on whether the industry is sustainable.

They've called for whitebaiters to be licensed and the banning of commercial harvesting.

'There is no doubt that freshwater fish populations in New Zealand are declining,” says Dr Mike Hickford, research associate at the University of Canterbury's marine ecology research groups.

'But there is no evidence to link this to whitebaiting.”

He says the main problem with addressing the issue is no-one has comprehensive catch data so no one has an idea what the longer term trends are.

Mike suggests a whitebaiting licence much like a Fish and Game Sports Fishing Licence.

'Whitebaiters would buy a licence for a set number of days and would have to nominate rivers and regions.”

The fee would support research and compliance. But the major benefit would be data on people fishing and when and where – basic data crucial for managing a fishery.

Dr Stephane Boyer, senior lecturer Environment and Animal Sciences at Unitec says white baiting practices aren't sustainable.

'One of the big issues is we don't know what species we catch. There are five species of fish but as babies they all look alike. Three of the five species are declining and one is recognized as threatened. Yet we fish, eat and sell without distinction."

Stephane says it's certain we are not getting any less effective at catching whitebait. 'So a drop in the total catch can reasonably be imputed to a drop in the population of juveniles.”

There's a dire warning from Dr Mike Joy, senior lecturer in environment science/ecology at Massey University.

'Whitebaiting is a really important thing for New Zealanders. If we don't fight to save this right, if we don't do anything about the habitat loss and pollution and commercial harvesting, then we're going to lose it.”

Stephane says we do know the number of adults is declining and their distribution is reducing.

'We should give native fish the same protection as trout and, in the short term, ban commercial harvesting in order to reduce the pressure on juvenile whitebait.”