Event Title

Reservoirs as Magnifiers of Climate Change: Effect of Climate-Driven Water Management on Kokanee Salmon (Oncorhynchus Nerka) Habitat and Migrations in Idaho's Island Park Reservoir

Presenter Information

Jack McLaren

Location

Logan Golf & Country Club, Logan, UT

Start Date

3-26-2019 5:00 PM

End Date

3-26-2019 7:00 PM

Description

Climate change affects irrigation storage reservoir drawdown patterns, which in turn alters reservoir thermal and dissolved oxygen regimes and littoral habitat availability, all of which may affect fish survival and productivity. Island Park Reservoir on the Henry’s Fork River in southeastern Idaho is one such irrigation supply reservoir where changes in drawdown patterns result in changes to reservoir thermal, dissolved oxygen, and littoral habitat patterns. Island Park Reservoir supports a population of Kokanee Salmon (Oncorhynchus nerka) which are important for sportfishing and as an annual nutrient subsidy to nutrient-poor tributary streams. We utilized three years reservoir profile data to test whether reservoir drawdown affects kokanee salmon habitat. Reservoir profiles revealed reservoir drawdown increases water temperatures, limiting kokanee habitat moreso than dissolved oxygen depletion and littoral habitat loss. Modeling using the program Qual2K reveals the loss of kokanee salmon habitat in Island Park Reservoir could have substantial effect on nutrient flux in tributary streams. Our results indicate to local fisheries managers the importance of decreasing reservoir drawdown rather than dissolved oxygen loss from nutrient loading. Our results indicate reservoirs can magnify climate change, disproportionately reducing available fish habitat and even affecting nutrient flux in tributary streams.

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Mar 26th, 5:00 PM Mar 26th, 7:00 PM

Reservoirs as Magnifiers of Climate Change: Effect of Climate-Driven Water Management on Kokanee Salmon (Oncorhynchus Nerka) Habitat and Migrations in Idaho's Island Park Reservoir

Logan Golf & Country Club, Logan, UT

Climate change affects irrigation storage reservoir drawdown patterns, which in turn alters reservoir thermal and dissolved oxygen regimes and littoral habitat availability, all of which may affect fish survival and productivity. Island Park Reservoir on the Henry’s Fork River in southeastern Idaho is one such irrigation supply reservoir where changes in drawdown patterns result in changes to reservoir thermal, dissolved oxygen, and littoral habitat patterns. Island Park Reservoir supports a population of Kokanee Salmon (Oncorhynchus nerka) which are important for sportfishing and as an annual nutrient subsidy to nutrient-poor tributary streams. We utilized three years reservoir profile data to test whether reservoir drawdown affects kokanee salmon habitat. Reservoir profiles revealed reservoir drawdown increases water temperatures, limiting kokanee habitat moreso than dissolved oxygen depletion and littoral habitat loss. Modeling using the program Qual2K reveals the loss of kokanee salmon habitat in Island Park Reservoir could have substantial effect on nutrient flux in tributary streams. Our results indicate to local fisheries managers the importance of decreasing reservoir drawdown rather than dissolved oxygen loss from nutrient loading. Our results indicate reservoirs can magnify climate change, disproportionately reducing available fish habitat and even affecting nutrient flux in tributary streams.