Keeping Deschutes coho from disappearing

The unexpected result of a habitat study has inspired a new coho supplementation program in the Deschutes River.

Several years ago, the Squaxin Island Tribe attempted to conduct snorkel surveys in the Deschutes to determine where coho were feeding and rearing. Unfortunately, there weren’t enough young coho to count.

“Only during one out of three years was there a return of coho to the Deschutes that was sustainable,” said Scott Steltzner, environmental program manager for the tribe.

After discovering there were too few coho to count, the tribe began annual releases of 100,000 young coho into the river. Tribal researchers then followed up with snorkel surveys.

“We didn’t want to guess what sort of habitat coho want, so the best way was to get out there and find out first hand,” Steltzner said. “But we needed to put some coho in the river first.”

The salmon for the study were fitted with unique coded-wire tags, small slivers of metal inserted into their snouts that allow individual fish to be tracked when they return as adults.

A couple of years into the study, the tribe found that the tagged fish released for the study were returning at a high rate.

“A significant portion of coho we saw in returning runs, up to 50 percent, were study fish,” Steltzner said. “We realized that by trying to study the coho that we were actually helping them out.”

This year, the tribe and the state Department of Fish and Wildlife released 100,000 juvenile coho into the river to supplement naturally produced fish.

“If we don’t do something to help these runs now, we could see them totally disappear,” Steltzner said.

In the past, the Deschutes River was the largest producer of coho in deep South Sound. Coho have been returning in low numbers for more than 20 years since a landslide sent tons of sediment into the river.

“The landslide wiped out coho in their main stronghold on Huckleberry Creek and they haven’t been able to sustain themselves,” Steltzner said. Because coho salmon spend an extra year in fresh water before heading out to the ocean, they are more dependent on that habitat than other salmon species.

The tribe plans to continue releasing coho each spring. “Most coho spawning occurs in an area of good habitat in the upper watershed,” Steltzner said. “When there aren’t enough fish coming back to the upper watershed, or if high flows destroy salmon egg nests, we’ll expand our efforts and put juvenile coho in the upper watershed. Otherwise we will only distribute coho in the lower part of the river.”