Staff from the Colville Tribes Resident Fish (CTRF) program released approximately 5,700 “triploid” rainbow trout ranging from two to three pounds each into Lake Rufus Woods July 31.

The fish, which can be identified by the absence of the adipose fin, are part of a supplementation effort of the Rufus Woods Net Pen Project, which the program’s staff oversees. The CTRF program purchases these fish from a local commercial aquaculture facility. Since 2011, some 118,100 triploid rainbow trout have been released into Lake Rufus Woods. Approximately 48,000 will be released this year alone.

“Normally, fish are diploid and have two sets of chromosomes (one from each parent),” Hatchery Manager Jill Phillips said, explaining the word triploid. “When a treatment of heat or pressure is applied to a fertilized egg prior to a certain egg development stage, the results are triploid or three chromosomes within the cell.”

She said, “Triploid rainbow trout females do not develop eggs. Male triploid rainbow trout sperm is not viable. Basically, both sexes are sterile. Utilizing triploid rainbow trout to supplement fisheries allow managers to mitigate impacts on native fish species.”

“Our overall goal of the CTRF program is to provide a subsistence and recreational fishery on Lake Rufus Woods which remains a popular fishing attraction,” said Bret Nine, resident fisheries manager for CTFW.

All non-members fishing by boat on the boundary waters of the Colville Indian Reservation or from the shore of Lake Rufus Woods at a Designated Fishing Area must have either a valid Colville Indian Reservation Fishing Permit, or a valid fishing license issued by the state of Washington, a tribal press release states. Tribal members must possess a Colville tribal identification card, which is a legal permit to fish.