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Drought Linked to Declines of Unique Bear Lake Fish

Hayley Glassic

Bear Lake, on the Idaho-Utah border, is sometimes referred to as the “Caribbean of the Rockies” due to its turquoise-blue waters. Locally famous for its Raspberry Festival, boating opportunities, and fishing, Bear Lake is also home to several species of fish found nowhere else in the world. In a recent study published in the journal Freshwater Biology, researchers from Utah State University have determined that falling water levels are negatively impacting these fishes.

"My name is Hayley Glassic. I was a master’s student at Utah State University and I am now a Ph.D. student at Montana State University."

According to Glassic, "drought is something that is projected to increase in both frequency and duration and this is especially alarming for the areas of the Intermountain West that already are exposed to droughts that naturally happen on the landscape."

Credit Wiley & Sons, Inc.
Journal cover featuring Glassic's work.

Glassic says that the combination of droughts and human-uses of water have caused water levels in Bear Lake to fall in the past. By creating a map showing how deep different types of fish habitat are, she was able to determine how much of each habitat would be available at different water levels.

"We would be able to say, okay, during 1990 when the lake elevation was, for example, 10 feet below normal, there was less habitat available for the Bear Lake Sculpin," says Glassic. "By working with Idaho Fish and Game and the Utah Division of Wildlife Resources to collect historic data on the Bear Lake Sculpin, we saw that over the past 25 years that drought, and more specifically the lake level fluctuation do have an influence on the amount of Bear Lake Sculpin and also how many fish are hatching and becoming adults."

Bear Lake Sculpin are one of those species unique to the lake and Glassic says they are one of the primary prey of Bear Lake Bonneville Cutthroat Trout – a fish often sought out by anglers.  

She says "it’s important that we understand the dynamics of this population along with drought so that we can better manage the Bear Lake Bonneville Cutthroat Trout population in the future as well."

More about Glassic's work can be found on our Science Utah podcast and at USU's Lake Ecology Lab website.