state of the resource
Extensive climate-related impacts on freshwater ecosystems are a reality. The increased frequency and intensity of droughts, prolonged heat waves, and wildfires impact water temperatures, flow, and quality. Many freshwater systems witness the expansion of alien-invasive species, aquatic plant and wildlife disease outbreaks, and increased vulnerability of native species, ecosystems, and local and global economies.
Many of these changes are and will be irreversible. As with marine fisheries, there is the need to address freshwater fisheries on an ecosystem-by-ecosystem basis. Regardless, however, delaying action to stop the underlying causes of climate change will increase the economic, environmental, and societal consequences.
Some Evidence
Climate change impacts on flow regimes, including both increased droughts and low-flow periods, and increased flooding impact native species with narrow ranges of flow requirements and allow expansion of alien-invasive species that affect the recreational and commercial harvest of fishes and clog waterways.
Higher temperatures and precipitation runoff have increased harmful algae blooms, which can hurt fish, mammals, birds, and even humans.
Organisms dependent on snow melt and glacial streams are declining or shifting their distribution.
Climate change is linked to emerging and re-emerging disease outbreaks in freshwater wildlife and plant species.
Temporal shifts in seasonal cues, such as spring runoff or monsoon seasons, affect the spawning success of fish, resulting in poor survival.
Water issues are at the core of climate change impacts in the western United States. Communities and managers will continue to face future challenges like drought and shifts in seasonal water cycles.
Participants’ understanding of and response to climate change is driven more by their background (stakeholder group) than their location (watershed).
By addressing water issues like availability and quality in future climate adaptation work, we stand to have positive impacts on myriad other conditions, including wildlife habitat, fisheries health, and the economy of local communities.
Primary Sources:
CONVERGENCE, a Conservation Hawks film, explores fly fishing, climate change, and family & friends through the eyes of some truly incredible anglers.
Coldwater Fisheries
Recent years have been the hottest ever recorded. The western United States suffers under heat domes, with much of it experiencing a “megadrought.” Meanwhile, reduced winter snowpack, earlier runoff, and lower summer flows are impacting iconic coldwater fisheries. The wildfire season expands in duration and intensity while the country also registers more extreme rainstorms and more frequent flooding.
Winter snowpack keeps Western rivers flowing cold in the summer. When there is less snowfall and earlier melts, that means less water when downstream fish need it.
Drought means increased water demands for communities and irrigators and less water for fish.
As water temperatures rise and streamflows decline, streams have less dissolved oxygen, and trout have less suitable habitat—fewer places to go during summer heat spells and dry periods.
When heavy rains hit landscapes disturbed by fires, streams fill with sediment. For fish that spawn in the fall, wintertime flooding can scour eggs from redds, imperiling the next generation.
As Trout Unlimited makes clear, Trout and salmon need large, complex, cold, and healthy habitat to thrive. Persistent drought, massive wildfires, and catastrophic flooding are just three of the most obvious signs that climate change is not waiting for us in some distant time. It’s here now and demands, as anglers, our complete and immediate attention.
Primary Source: Trout Unlimited
The Response
Science and research
Climate adaptation and mitigation
Climate Advocacy and policy
give me more!
Running Dry in the American West. Shawn Reagan, National Review (2022)
Greater Yellowstone Climate Assessment, Past, Present, and Future Climate Change in Greater Yellowstone Watersheds (2021)
Warm water has overlooked importance for cold-water fish, like salmon and trout. Oregon State University, Science News (March 2021).
Effects of Climate Change on Cold-Water Fish in the Northern Rockies. Michael K. Young, et al. In Climate Change and Rocky Mountain Ecosystems (pp.37-58). Research Gate (2018)
Cold-Water Fishes and Climate Change in North America. Williams, J.E. et al, Reference Module in Earth Systems and Environmental Sciences (2015).