A ''very trying year'' raising salmon to release in the Waitaki River has had some good news, as the first fish released in an attempt to boost numbers returned to the river this year, the Waitaki Riparian Enhancement Society has reported.
The society was set up to improve the Waitaki River salmon population and established a hatchery at Welcome Stream and rearing pens at Bell's Pond.
In January, the society lost about 32,500 of 40,000 fingerlings, virtually all of this year's release, when didymo blocked the intake of the rearing pens at Bell's Pond, water levels dropped and an alarm failed to activate.
This year, the society hatched 42,000 eggs at its Welcome Stream hatchery, which would have been released in June next year from the rearing pens.
However, publicity officer Linn Koevoet said yesterday flooding in Welcome Stream caused problems with the hatchery filters and a good number of eggs were lost. Welcome Stream then dropped during winter, but that was rectified before causing any major problems.
As a result, the society had 16,300 fry, of an average 4.56g weight, left to transfer to the rearing pens on October 23.
Since then, they had put on about another 5g, Mr Koevoet said.
The larger fish meant larger screens could be used at the intake for the rearing pens, reducing the chance of their being blocked by didymo.
The society expected salmon from its first release in 2010 to start returning to the river this season.
''The numbers will not be great, but will be a huge milestone in our development,'' he said.
Anglers can identify fish by a clipped adipose fin. The society is offering a $500 prize, to be drawn from anglers who report a catch.
Mathematically, about 30 fish should return and anglers should land about 10.
