Does the Penobscot River host the largest population of Atlantic salmon in the U.S.? | Fact brief

The Penobscot River hosts the largest remaining population of wild Atlantic salmon in the United States. Federal agencies and academic research describe it as the country’s last remaining stronghold for the species.

In the U.S., Atlantic salmon once spawned in rivers as far south as Connecticut, but the species now survives naturally in only a handful of Maine rivers. The Gulf of Maine population was listed as endangered in 2000.

During the 19th and 20th centuries, salmon runs collapsed as dams blocked migration routes and rivers were altered by logging, industry and development. Recent restoration work in the Penobscot watershed — including dam removals and fish-passage improvements — aimed to rebuild the population.

Canada still has far larger numbers of Atlantic salmon, with hundreds of rivers across eastern provinces supporting runs. But many populations there are also declining, according to Fisheries and Oceans Canada and conservation groups.