FAIRBANKS — The state Fish and Game Department has suspended its fish stocking program after hundreds of rainbow trout and Arctic grayling died when they were put into warm lakes.
Temperature shock is being blamed for the deaths of hundreds of fish that were stocked early this week in Ballaine Lake in Fairbanks, the Fairbanks Daily News-Miner reported. Fish also were reported dead at two other Interior lakes.
About 2,000 trout and 370 grayling were raised in at the Ruth Burnett Sport Fish Hatchery, which has a water temperature of about 42 degrees. They were transported to the Ballaine Lake at about the same temperature, but the lake itself was about 76 degrees. Dead fish started showing up Tuesday after they were stocked.
“We went out and we picked up quite a few,” Alaska Fish and Game sport fish biologist April Behr said. “It was temperature shock basically, going from the cool hatchery truck to a warm lake.”
When placed in warm lake, fish usually seek cooler temperatures in deeper parts of the lake. “But when you stock them you can’t get those fish down into the deep areas right away,” she said.
A lack of oxygen also was a likely contributor to the deaths of the fish, which measured anywhere from 9- to 12-inches.
“You get down about 1 meter and the temperature drops a little, but the oxygen levels are really low,” she said. “The fish don’t have anywhere to go, basically.”
Officials also found dead fish at North and South Twin Lakes on Fort Greely, near Delta Junction, said Fish Game sport fish information officer Nancy Sisinyak.
“I don’t think it was as bad as Ballaine Lake but there were some dead fish in there,” Sisinyak said.
Fish and Game has decided to suspend its fish stocking program until temperatures cool off later this summer, hatchery manager Gary George said. That includes nearly 7,000 Arctic grayling.
The late breakup left ice on lakes into June, and then temperatures rose quickly into the 90s earlier this week.
Officials said warm lake temperatures were a concern, but the fish were outgrowing their hatchery tanks.