Extreme Heat Is Killing Off Thousands Of Fish In Alaska

First published on ClimateProgress.org, a project of the Center for American Progress Action Fund, which was recently named one of Time magazine’s Top 25 blogs of 2010.

Unusually hot, dry weather in Alaska is wreaking havoc on fisheries, as thousands of fish perish in overheated waters. Last month, 1,100 king salmon died on their way up to the Crystal Lake hatchery due to water temperatures around 80 degrees Fahrenheit and lack of oxygen. That’s the bulk of the 1,800 adult salmon that were expected to return to the hatchery this season.

Earlier in the summer, another hatchery lost hundreds of grayling and rainbow trout in a Fairbanks lake where water temperatures reached 76 degrees. Alaska’s heat wave broke records last week, with 14 days straight above 70 degrees in Anchorage and 31 days of 80 degrees in Fairbanks.

Officials cited a number of factors affecting the fish, but observed that the die-off coincided with the hottest weather of the season. While die-offs are not uncommon, Doug Fleming, a sportfish biologist for the Alaska Department of Fish and Game, suggested the magnitude of the die-off was surprising.

“And so, getting through till Wednesday which appeared to be the hottest day, then on Thursday I was conducting an aerial survey just to get a grip on how many fish may have been killed by the warm water, not expecting to see a large die-off but some, and I was shocked to see the numbers of fish that we lost,” he told the Associated Press.

Besides the sheer heat, lack of rainfall is also contributing to the die-off. Many streams are too low to accommodate the fish waiting at the mouths, which essentially suffocate as more fish get backed up. The enormous salmon die-off in July was partly because large numbers of fish were trapped at the shallow Blind Slough rapids.

Alaska’s commercial fisheries are among the largest in the world. Salmon is the state’s largest export product after oil and natural gas.

While Alaska’s heat wave is expected to subside soon, the state has warmed up twice as fast as the rest of the nation in the past 50 years, and climate change is worsening extreme weather. Wildfires raged through subarctic forests as late as Friday, consuming more than a million acres and prompting emergency evacuations across the state. Thawing permafrost is also sinking villages, threatening fish stocks and water supplies that the communities rely on to survive.

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