Council bid to increase whitebait numbers

When Environment Southland surveyed local whitebaiters last year, the main thing respondents wanted was more whitebait.

Now the organisation has begun a project to try to achieve just that. Beginning with land the council owns along Invercargill waterways, council staff are trying to protect the riverbanks where inanga - the most common species of whitebait - lay their eggs.

Marine and freshwater scientist James Dare said inanga mothers laid their eggs in a specific zone at the ''salt wedge'', the point where salt water merged with fresh water but where the waterway was still tidal.

Because the eggs were exposed to the air for about a month between high tides, the council had decided to try to protect spawning areas by keeping the vegetation long.

A 150m-200m stretch of the Kingswell Creek in south Invercargill and an area on the banks of the Waihopai River in north Invercargill were not being mowed this summer, while staff were also monitoring the more remote banks of the Waikiwi Stream where it entered the Oreti River.

Contractors had also been asked to stop weed-spraying along the banks of the Otepuni Creek, which runs through central Invercargill, and coconut husk matting would be anchored to the banks to give inanga eggs a chance of surviving.

Mr Dare said riverbank rejuvenation in other parts of the country, including work carried out by the Waiau Trust in Western Southland, had resulted in increased numbers of whitebait.

The project was the first on urban riverbanks.

''We think it is an easy and reasonably low-cost way to get a large benefit,'' Mr Dare said.

''We will be monitoring these areas to see if it makes a difference ... but we think there is a high potential to get more whitebait back into these streams.''

The next step was to encourage farmers to do the same on rural waterways, he said.

One hundred responses to last year's whitebaiting survey were received. Most respondents had been whitebaiting for more than 10 years, with almost 30% whitebaiting for more than 30 years.

From the responses, Environment Southland estimated the average whitebaiter spent 149.9 hours fishing per season.


New Zealand whitebait
• The juvenile form of five species of the fish family Galaxiidae.
• Only the spawning habits of inanga are fully understood. In late summer/autumn, eggs are laid in estuary vegetation around the high-water mark on a very high tide. Eggs are exposed for some weeks until the next very high tide. Eggs hatch and falling tide carries them out to sea. In spring, juveniles (whitebait) make their way back upriver to live in freshwater habitats.
• On the east coast, the whitebait season is open between August 15 and November 30.


- allison.rudd@alliedpress.co.nz

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