Trout spawning race given upgrade

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A makeover for a Waitaki trout spawning race should lead to a huge increase in future fish numbers.
The Aviemore spawning race, an artificial stream channel below the Aviemore Dam, has been refurbished for the first time since it was created in 1968. Because the dam destroyed natural spawning grounds, the race was built to provide new ones and was used by brown and rainbow trout and sockeye salmon.
The 1km race had gravel beds 0.5m deep, suitable for spawning for up to 2000 0.9kg trout.
After 48 years, encroaching vegetation had shrunk the race from 5.5m wide to between 2m and 4m. Trout had also displaced gravel as they dug their redds (nests). Central South Island Fish and Game has groomed the gravel beds regularly and removed weeds every year, as a service to sports fishing licence-holders.
In April, it joined forces with the race’s owner, Meridian Energy, which spent more than $30,000 on the refurbishment. It took seven days to remove vegetation, widen the channel to 5m, sieve and de-silt the gravels, and add 450 cubic metres of new gravel.
Last month, a Fish and Game survey showed about 300 trout were already spawning in the upgraded race.
The improvements were clear to see, Fish and Game officer Jayde Couper said.
“At a glance the works have resulted in a five-fold increase in spawning area, which should result in a significant increase in the number of juvenile fish being produced in the spawning race. In two to three years, when these fish reach maturity, anglers should catch more fish.”Meridian environmental strategy manager Jeff Page said it was pleasing to see the “excellent outcome” so soon.
“By working in partnership with Fish and Game we’ve been able to preserve and enhance fishing stocks, as part of ensuring the ongoing efficient operation of the Waitaki hydro lake.”According to Niwa angler use surveys, 3000 to 5000 anglers visit Lake Waitaki each year.