Thermal Imagery to Identify Cold-Water Refugia in the Deshka Watershed

In 2020, Cook Inletkeeper acquired thermal imagery for 32 miles of the lower Deshka River to map discrete cold-water refugia for migrating and spawning Chinook salmon (the study reach from the Kroto and Moose creeks confluence to the mouth was somewhat shorter than expected). With over 200 inflows mapped, productive conservation actions in the Deshka River watershed can move forward with unique opportunities based on public land ownership (state and Mat-Su Borough) and private landowners.

In recent years, this lower reach has exhibited warm temperatures (above 20o C) and thus presents a potential thermal bottleneck for migrating fish. This high-resolution characterization of water temperatures can guide land conservation and fishery management actions by 1) identifying cold-water refugia used by adult Chinook salmon to avoid stressfully high summer temperatures; 2) identifying areas that are warm during summer where fish are particularly sensitive to disturbances such as catch-and-release angling; and 3) identifying areas that are warm during winter that may serve as important overwintering habitats.