$350k project to boost spawning
A new $350,000 upgrade at Lake McGregor will help to restore the spawning area for brown and rainbow trout to its natural state.
Over the past six years the Lake Alexandrina Conservation Trust has cleared and relaid the fish spawning area.
Trust chairman Alister Clarke said the site along the creek that runs from Lake Alexandrina into Lake MacGregor had been overrun with weeds and willows over the years.
‘‘It’s a big process (recreating the site) with a big 20 tonne digger digging out half a metre then lining the space with rocks so the (trout) don’t get in the silt and spawn.’’
Two hundred tonnes of spawning shingle was then placed on top of the 300 tonnes of rock.
It was cheaper to purchase the spawning shingle from Pleasant Point than Tekapo so it was carted up.
Shingle allowed oxygen to penetrate where the female have laid their eggs, he said.
What was a 90 square metre spawning area before the work started was now 900sqm, allowing the fish to spread out more, Clarke said.
The trout fishing season is from November 1 to the end of May, but a major difference in the amount of fish may not be noticed for a few more years.
However the number of redds has doubled from 20 three weeks ago to 40 last week.
Redds are the mounds on the shingle floor created by the female trout burrowing about 35mm to protect the laid eggs.
They also made it easy for the trust volunteers to estimate how many fish would likely hatch, with a 50 per cent success rate anticipated from every redd.
‘‘The lake is spring fed so there are no floods. What we do will stay intact for the next 20 years,’’ Clarke said.
The cost of the project was funded with $150,000 from the Mackenzie District Council, $27,000 from Pub Charities and the remainder through trust fundraising activities.