The whitebait fishing season opens on 15 August, so expect to see folks down at the river mouth every day until 30 November. Fishing is only permitted between 5:00 am and 8:00 pm or between 6:00 am and 9:00 pm when New Zealand Daylight Saving is being observed.

Whitebait are the juveniles of five species of fish: giant kĹŤkopu, banded kĹŤkopu, shortjaw kĹŤkopu, inanga, and kĹŤaro. They are part of a group called galaxiids.
Unfortunately 3 of the species are threatened and one is declining. Forest and Bird say:
Predictions based on different models show that all four of these species will be extinct by 2050, including the most common species in the whitebait catch: the īnanga.

They go on to say:
Although whitebaiting removes thousands of juvenile fish and is one cause of their decline, our degraded waterways are a much bigger limitation on the size of the adult populations.
And that’s a particular problem at Waikawa Beach, where last summer’s water quality monitoring by Horizons showed our river is sometimes very polluted. That must reduce the numbers of whitebait growing around here.