Please select your home edition
April May June Leaderboard Q2 2023

Streams rich in baseflow are important for Atlantic salmon

by NOAA Fisheries 3 Sep 2022 18:19 UTC
Atlantic salmon parr swimming © Nick Hawkins

Atlantic salmon are an endangered species in the United States with the only remaining populations in the state of Maine. Atlantic salmon need access to a wide variety of habitats during their lives as they move from rivers to the ocean and back again.

In rivers, they also need relatively cool freshwater, ideally below 70 degreesF. As the climate continues to warm, stream habitat that remains cool enough for Atlantic salmon during the summer may become increasingly rare.

Atlantic salmon are among the most vulnerable species to the effects of climate change in the Northeast, partly because of their temperature sensitivity. With expected rises in stream temperature, the amount of suitable habitat will likely decrease. This makes it critical to focus conservation and restoration efforts in areas that the fish are most likely to favor.

Cool streams make for good habitat

Stream temperature is affected by many factors including air temperature and shading from vegetation. Another important factor is how much of a stream's flow comes from underground sources rather than land surface runoff. Streams with a high proportion of groundwater tend to be cooler than those with greater quantities of surface water because surface runoff is exposed to sunlight and land surface air temperature as it travels to the stream. Areas along a stream network that are rich in groundwater, or "baseflow", are important for coldwater fish like Atlantic salmon and brook trout. They can buffer the effects of increasing air temperature. These areas also usually have more flow, and therefore more habitat, during periods without significant rainfall.

Predicting to help prioritize

To help identify stream reaches likely to be favored by coldwater fish, the U.S. Geological Survey, NOAA Fisheries, and the Maine Department of Marine Resources identified environmental attributes that can be used to predict stream reaches that are rich in baseflow. We developed a model to predict where these reaches are likely to occur across the freshwater range of Atlantic salmon in Maine.

"Atlantic salmon are like a canary in a coal mine. If they can't complete their life cycle, it tells us that something is wrong with their habitat. We are concerned that there is not enough cool water for them. Our partners were critical in helping to start to identify areas that will sustain Atlantic salmon and other temperature-sensitive species like brook trout in the future," said Rory Saunders, fisheries biologist with NOAA Fisheries' Greater Atlantic Regional Fisheries Office. Using maps derived from these predictions, we can identify and prioritize conservation actions like fish passage projects that ensure Atlantic salmon can access baseflow-rich stream sections.

For more information about this project, contact Pam Lombard (USGS) or Matt Collins (NOAA).

Related Articles

Alaska aquaculture opportunity area identification
NOAA has determined it to be environmentally, socially, and economically appropriate NOAA Fisheries has chosen Alaska as the next region in which to look for Aquaculture Opportunity Areas. Posted on 3 Jun
Gear up for the Summer Snapper Season
Summer is around the corner! Gulf of Mexico offshore anglers: prep for summer reef fish seasons with gear, training, and giveaways to help fish survive. Posted on 30 May
Pollock, Cod in the Northern Bering Sea
DisMAP displays changes in distribution over time for hundreds of marine species Recent updates to the Distribution Mapping and Analysis Portal (DisMAP) include additional years of data, new filtering features, and data from a new region—the Northern Bering Sea. Posted on 29 May
A Conservation Challenge
Climate-driven changes are affecting the health of marine animals Climate-driven changes such as higher ocean temperatures and extreme weather events are affecting the health of marine animals—and their ability to survive. Posted on 28 May
Increase access for U.S. Vessels to Swordfish
Swordfish, prized in upscale markets, can now be caught with deep-set buoy gear A new West Coast fishery will take advantage of the deep-diving habits of swordfish to reduce the risk of catching other species. Posted on 14 May
Can Pacific Salmon keep pace with climate change?
A recent study showed unpredictable changes in juvenile salmon migration timing A recent study — the largest of its kind — showed unpredictable changes in juvenile salmon migration timing in response to climate change. Posted on 6 May
Survival of juvenile salmon expected to increase
Spring surge to benefit spring-run Chinook and fall-run Chinook that support fisheries Researchers from NOAA Fisheries and University of California Santa Cruz will tag several groups of juvenile salmon in the Sacramento River system. Posted on 2 May
Lifeline for salmon in Central Valley, California
Before the Gold Rush, somewhere between 1 and 2 million salmon a year came up Central Valley rivers Following the Gold Rush and throughout the 1900s, dams and other water diversions for human development have blocked access for salmon to more than 95 perent of their high-elevation spawning and rearing habitat. Posted on 1 May
New study: Atlantic Highly Migratory Species catch
Recreational fishery data reveals climate-driven shifts A new study by NOAA Fisheries has identified shifting distributions of Atlantic Highly Migratory Species catch, including tunas, billfish, and sharks, off the northeastern United States. Posted on 22 Apr
Video: The science of restoration
Research proves restoring habitat works for salmon Juvenile salmon grow strong where water slows down and weaves across floodplains, with lush vegetation that provides refuge and fosters food for their journey to the ocean. Posted on 15 Apr