Study Shows Warming Trends in Alaskan Streams

Six-year temperature profile of Kenai streams raises concerns over salmon health

Water temperatures in Alaska's Lower Kenai Peninsula salmon streams have been teetering above the state-mandated 55° F temperature limits, posting a substantial health risk to salmon habitat, according to a new report published by Alaska's Homer Soil and Water Conservation District.

According to the report, underwater temperature loggers placed in four area watersheds show that water temperature rose above the upper limit on 54 days in 2002, 60 days in 2003 and 86 days in 2004.

The Homer district, in partnership with Cook Inlet Keeper, a watershed-based nonprofit organization, has been collecting water quality data on the region's economically important salmon streams since 1998.

"We monitored the streams to gain better understanding of the frequency and extent of the elevated temperatures," said Sue Mauger, a stream ecologist for Cook Inlet Keeper. " To see these types of temperature increases in the streams in definitely a concern, especially when you consider that many of the communities here depend on commercial and recreational fishing and tourism."

Water temperature plays a critical role in the salmon incubation process, and warmer temperatures have been linked to a higher susceptibility to disease and depletion of available oxygen and nutrients.

According to Paul Gannett, a spokesman for Onset, Computer Corporation, a Massachusetts-based manufacturer of data loggers, stream temperature monitoring is key to understand the impact local and global environmental changes have on stream ecosystems. " By looking at temperature profiles over time, researchers are better able to correlate specific environmental events with their impact on streams."

Mauger added, " It's easy to blame climate change, but we also need to look closely at other things we're doing in the watersheds. For example, in recent years we've lost over a million acres of white spruce forests from bark beetle infestation. There has also been a dramatic increase in logging, road building and real estate development. We don't know what effect this shift from a forested landscape to a more grassland-dominated ecosystem might have on stream temperatures."

A copy of the report is available at

Onset Computer Corporation

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