Water is warming up at the Klawock River Hatchery on Prince of Wales Island, a Southern Southeast Regional Aquaculture Association facility that fertilizes and incubates 5 million coho eggs each year using Klawock River water.
Hatchery manager Troy Liske said water flowing by the hatchery in 2023 was warmer by an average of 3.6 to 5.4 degrees Fahrenheit than in years past. Warmer water temperatures are speeding up the salmon development process and changing the dynamics of hatchery work, which could pose future challenges, Liske said.
SSRAA has operated the Klawock River facility since 2016. The state founded the hatchery in the 1970s to rear steelhead and chum salmon. In the 1980s, an infectious viral disease that causes necrosis spread among the wild sockeye salmon in the Klawock Lake system.
In 1993, the state turned over the hatchery to the cities of Craig and Klawock. The Prince of Wales Hatchery Association operated the facility for 20 years after it was organized in 1996.
Liske said the past four years have been “pretty rough years” for the hatchery as warmer temperatures are heating up water in the Klawock Lake system from the end of July through September, when mature salmon are returning to the hatchery, ready to reproduce.
“We’re getting up to 18 degrees Celsius (about 64 degrees Fahrenheit) in the river system and lake system,” Liske said. “And really anything over 15 degrees Celsius (59 degrees Fahrenheit) starts really stressing out cold water fish.”
“Once they start getting stressed out and you see problems in the adults with egg development, you see problems in the fry up on the lake (being) more susceptible to bacteria and other diseases,” he said. “Just because they’re already stressed out with the water temperatures being as warm as they are.”
Liske said the warmer water is damaging the “fecundity rate” for mature female salmon, or the number of eggs that each fish is able to create.
“Going back six, seven years ago, we used to average about 2,800 (eggs per mature female coho),” Liske said. “I’m guessing, in the last three years for sure, we’ve been more around 2,600 (eggs per mature female). We’re seeing a 200-eggs-per-female drop.”
Meanwhile, warmer water in the Klawock River system is “speeding everything up” for the salmon rearing process. Liske said coho eggs late last year were already showing quick development.
“We’re about three weeks ahead of schedule (already),” Liske said Dec. 7. “Maybe even four weeks ahead with how warm the water has been this winter.”
Liske said the hatchery’s coho eggs are needing to be “picked” weeks earlier than usual. Fish technicians use a machine to “pick” or sort eggs. The machine removes the dead eggs so that fungus can’t spread and kill healthy eggs.
“Generally, we don’t pick our first lot of eggs until right around Christmas week,” he said. But this year, hatchery technicians began picking the first lot of coho eggs during the week of Halloween.
Warm water is accelerating the coho growth cycle so much that the hatchery technicians may need to transport coho fry to Klawock Lake a month earlier than usual. “What I can see happening is we’re gonna have to try to pond in March instead of April,” Liske said.
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