Algae overload and an aging Cole Rivers Hatchery infrastructure are being blamed for the deaths of 360,000 Rogue River spring chinook salmon eggs and newly hatched fry in the past week, but the loss may not impact future salmon returns.
The loss represents about 15 percent of this year’s spring chinook egg fertilization at the 45-year-old hatchery, with 1.9 million eggs remaining, according to the Oregon Department of Fish and Wildlife.
The hatchery releases about 1.7 million spring chinook smolts annually. This year’s batch is due for release as smolts next August, September and October as well as March 2020, the bulk of which would return to the Rogue as adults in 2022.
“It’s really unfortunate,” said Ry ODan Couture, the ODFW’s hatchery coordinator. “It depends upon what happens in the next month or so, but we’re still hopeful we’ll meet our smolt production.”
It was not immediately known what caused the algae build-up in the small trays loaded with incubating spring chinook eggs covered with running water siphoned from the Rogue and run through several filters.
Hatchery employees and fish-health experts were inspecting the water system today for possible breaches, Couture said.
The dead eggs and algae build-up were first noticed Dec. 7 by hatchery workers in the hatch house where eggs are incubated, Couture said.
The facility has had other egg die-offs, and over the years, the hatch house water system has been altered and cobbled together.
Cole Rivers Hatchery was built by the U.S. Army Corps of Engineers to provide hatchery fish as mitigation for reduced spawning and rearing habitat for salmon and steelhead lost by the construction of Lost Creek dam.
The ODFW has asked the Corps for a complete replacement of the hatch house’s water supply, estimated in 2016 to cost about $500,000, Couture said. The Corps currently has the project listed in its 2020 fiscal year budget but with no money requested for it, Couture said.
The ODFW has battled disease problems at Cole Rivers almost since it opened in 1974. The most recent disease die-off came in 2014, when half of the winter steelhead bound for release into the Rogue and Applegate rivers died in the hatch house.