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The Challenges and Successes of Restoring Atlantic Salmon (Part 1 of a 5 Part Series)

Atlantic salmon. Photo credit: NOAA Fisheries

Salmon smolt.  Photo credit: NOAA Fisheries

Over the next several months, we will be posting a series of feature stories on Atlantic salmon, the “king of freshwater fish” on our website.

This remarkable fish once supported vibrant commercial, recreational and subsistence1  fisheries throughout New England. Today, Atlantic salmon are so rare that they are considered endangered under the US. Endangered Species Act.

Penobscot River Home to Last Remnant U.S. Population

The last remnant population in the U.S. includes several rivers in Maine, most notably the Penobscot River. Historically, the Penobscot River held Maine’s largest population of Atlantic salmon. Annual salmon runs were estimated at upwards of 100,000 adults prior to the construction of the larger scale dams on the river in the 1830’s. Today, the number of fish making the annual run is only a fraction of its historic levels.

Threats to Survival

Today, Atlantic salmon face a variety of threats including dams and other  barriers blocking them from spawning grounds, low marine survival, climate change, non-native fish species, habitat destruction, and water quality degradation. 

What is being done to restore Atlantic salmon?

NOAA Fisheries and our partners have taken significant steps to help restore this iconic fish species and its habitat, including:

On the Penobscot River

  • Several major dams have been removed and/or fish passage has been improved recently, such as at the Veazie and Great Works dams.
  • Still over 470 dams that impair or block access to approximately 90 percent of freshwater habitat on the Penobscot necessary to support Atlantic salmon spawning and rearing of juveniles.  
    • We need to remove and/or improve fish passage at the remaining dams that block access to critical habitat on numerous streams and ponds that feed into the Penobscot. 
    • These waterways may be even more critical to Atlantic salmon spawning and long-term survival.
    • NOAA Fisheries is developing a General Conservation Plan for Atlantic salmon to reach out to owners of small, privately owned dams along the watershed to help them improve fish passage and better comply with federal laws.


Looking Ahead

In future stories, we will discuss some of the continuing challenges facing the species (e.g., fish passage maintenance, survival in the ocean, international management, climate change, etc.) and ongoing efforts to address them. We will also focus on some of the research by NOAA staff, academic scientists and other partners that is helping us understand more about Atlantic salmon and what we can do to better protect them. In particular, we will explore the role of Atlantic salmon in the ecosystem including its relationship with other fishes like alewife, blueback herring, sea lamprey, American shad and rainbow smelt. All these species have a similar life cycle in that they are “diadromous” (i.e., they spend a portion of their lives in fresh and salt water). Restoring the co-evolved suite of diadromous fishes may be necessary for the successful recovery of Atlantic salmon.The work that is underway is also benefiting commercially valuable species such as river herring, American eel and rainbow smelt.  In the future, continued restoration (at the scale envisioned by the Penobscot River Restoration Project) may also benefit commercially valuable species such as cod, haddock, and striped bass by restoring important components of their prey base (most notably river herring).

  1. Where the fish caught are eaten by the fishermen’s family