Fishers, Restaurants Prefer Sterilized Trout

Although biologists are still experimenting with sterilizing trout for stocking in public fishing lakes, fish farmers have no doubts about the merits.

Sterile trout do not suffer the rigors of developing reproductive organs. Therefore, their flesh stays firm as they enter the mature sizes prized by restaurants - and anglers.

State permits for fish farms on the Columbia River stipulate the fish cannot be capable of breeding with native stock.

Fishermen are primarily interested in sterile trout because they can live twice as long and grow to nearly twice the size of normal hatchery trout.

The sterile fish raised in Rufus Woods Lake net pens as well as those being tested in some Washington lakes, such as Amber, are “triploid” females.

The triploid females are produced in a several-stage process at Trout Lodge hatchery near Moses Lake. The hatchery begins with genetically altered male rainbows. Those fish, when mated, produce only female trout.

When the resulting females are sexually mature, they are stripped of their eggs, which are then subjected to pressure or immersed in hot water.

Instead of being diploid - having two sets of chromosomes - the heat-shocked eggs become triploid, and the fish are sterile.

, DataTimes