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Polluted rivers and streams are being blamed for the disappearance of whitebait.
Massey University researcher Mike Joy has found whitebait have disappeared from about 75 per cent of their expected habitats in Manawatu and Horowhenua.
Dr Joy said the national group that monitored the fate of the adult whitebait (galaxiids) had reported a similar level of disappearance.
The dwindling numbers were further affected by the number of fishers who caught juvenile whitebait, and sold them for up to $150 per kg, Dr Joy said.
"Not enough galaxiids are able to return to the streams because of the whitebaiting. Two of those species have the same threat ranking as a kiwi yet selling whitebait is a crucial incentive to get people out there."
Dr Joy said his computer modelling, which focused on the greater Manawatu catchment, showed him where the whitebait should be, including the upper Oroua, upper Pohangina and upper Manawatu rivers.
Dr Joy said a few simple measures could protect what is left of the stocks, including prohibiting the sale of whitebait in the same way trout is protected, minimising high-country erosion and cleaning up waterways.
- NZPA
