Triploid rainbows have the genes for success

Not all rainbows stocked in Washington lakes before the April 30 season opener are created equal.

Some hatchery rainbows called “triploids” have been genetically altered to make them sterile, a technique that lets the fish put all their energy into growing large.

A heat process administered to the fish in the egg stage leaves the resulting fish with three sets of chromosomes (triploid) instead of the standard two. Consequently, most of their food and energy goes toward growth, rather than reproduction.

In addition to normal hatchery fish scheduled for stocking before the opener, the Fish and Wildlife Department plans to stock additional triploids running 11/2 pounds apiece in each of the following area lakes:

West Medical, Clear and Badger will get about 1,250 apiece while about 2,380 are going into Williams, 1,800 into Fishtrap, 850 into Loon and 827 into Diamond.

Other Eastern Washington lakes scheduled to be stocked with triploids include Blue (Sinlahekin), 1,000; Spectacle, 1,350; Bennington, 400; Dusty, 1,000, and Railroad, 170.

Indian tribes also stock some of their lakes and the Columbia River with triploids and the Colville Confederated Tribes release additional thousands of tripliods into Lake Rufus Woods downstream from Grand Coulee Dam.