Spring mornings carry a certain apprehension when Cole Rivers Hatchery Manager David Pease scans the watery fish-rearing troughs inside the "Hatch House."

About 66,000 tiny rainbow trout destined for places such as Hyatt Lake and Union Creek fin in thick masses waiting for the electronic feeder to go off. As usual, a few dead trout are pinned against the fish screen, the daily cost of the fish business.

But Pease knows he could walk in tomorrow and find 1,000 dead rainbows, victims of a natural water-borne bacteria that annually kills off enough young rainbows and steelhead bound for the Rogue and other rivers to regularly fall short of annual release goals.

It's the hatchery-production version of death by 1,000 cuts, incrementally chipping away at Cole Rivers' ability to grow fish for area anglers.

"We deal with death a lot here," Pease says. "But it still makes you wonder, Are we going to make it? Are we going to make production?' "

Pease and others hope the answer lies in a revamping of the Hatch House's waterline, troughs and filtration systems meant to curb what's known as "cold-water disease" and prevent other pathogens from sneaking into the fish-rearing process.

Pease is awaiting final word on a $89,920 grant from the state's Restoration and Enhancement Program to go with more than $93,000 supplied by the U.S. Army Corps of Engineers for this project, which is the first of two phases planned for the facility built by the Corps but run by the Oregon Department of Fish and Wildlife.

Phase 2 would come next year with replacement of the water line from the Rogue to the Hatch House. The current line is corroded and cannot be fully cleaned. The new one is expected to cost about $30,000, Pease says.

It will be the first major project at the Hatch House since work was done in the early 1990s to safeguard infant salmon and trout from another natural disease, called IHN, which killed hundreds of thousands of baby salmon during outbreaks in 1989 and '91.

The new filters will stop the cold-water bacteria before it reaches the troughs where young fish spend two months of their early lives before getting shipped to large, outside raceways where they stay until they are released.

The current set of 12 bowing and worn troughs will be replaced by 16 deeper ones that will reduce fish densities, thereby reducing stress and the spread of disease from fish to fish.

When the repairs are complete, cold-water disease should join IHN as a regular worry, but not a regular problem, at Southern Oregon's main aquaculture facility.

"We've been very successful with IHN," Pease says. "Now it's time for cold-water disease."

Named for the Rogue's most famous early fish biologist, Cole Rivers Hatchery was built by the Corps to mitigate for the loss of natural salmon and steelhead spawning grounds from the building of Lost Creek and Applegate dams.

It produces and releases 2.67 million fish annually to meet mitigation goals, and those are paid for by the Corps. ODFW covers the cost of growing more than 500,000 steelhead and chinook for Coos River and Tenmile Creek, as well as another 529,000 rainbow trout for the far upper Rogue and coastal lakes.

The facility went online in 1974 and almost instantly was hit with disease outbreaks, with cold-water disease being the latest.

Named because it attacks fish in cooler water temperatures than other diseases, the bacteria is very invasive and attacks everything from a young fish's fins to its kidneys, says Craig Erwin, Cole Rivers' hatchery coordinator.

It hits steelhead and trout far harder than coho and chinook salmon, and usually during that trough-rearing phase, when it takes 200 of the inch-long fish collectively to weigh a pound, Erwin says.

When the bacteria hits, samples are sent to the ODFW's pathology lab in Corvallis for confirmation, which generally takes three to five days, Pease says. The diagnosis allows the hatchery to get a prescription for Aquaflor, a chemical that's added to fish feed to treat for the bacteria, he says.

"We're talking a good two weeks before we can start treating them," Pease says. "That can turn into a lot of fish."

The Hatch House's corroded water line, a well and an aeration tower have all been tapped as potential sources from which pathogens can enter the Hatch House, Pease says. Ultraviolet filters will be fixed to the water lines going into the new troughs, which should zap any impurities that sneak by improvements to those other parts of the water system, Pease says.

When both phases are done, the crucial two months in the Hatch House troughs won't be met with so much trepidation among hatchery workers, who often feel tied to the fish they rear.

"We're looking at them and thinking, OK, guys, it's time to pull through,' " Pease says. "This will help them."

Reach reporter Mark Freeman at 541-776-4470 or mfreeman@mailtribune.com.


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