Algae blamed for Rogue River salmon egg deaths

MEDFORD, Ore. — 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 in 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 buildup 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 for possible breaches, Couture said.

The dead eggs and algae buildup were first noticed Dec. 7 by hatchery workers in the hatch house where eggs are incubated, Couture said.