ATLANTIC SALMON


For inquiries contact Stephen D. McCormick, Conte Anadromous Fish Research Center, Biological Resources Division, USGS, Turners Falls, MA


Atlantic salmon are known as the "king of fish," an appropriate title for many reasons. Atlantic salmon make a tremendous journey during their lifetime, migrating from the fresh water streams of their youth to feeding grounds in the north Atlantic Ocean and back again to spawn. Their capacity to return back to the same stream where they were hatched has captivated and mystified biologists for hundreds of years. Salmon are among the most beautiful of fish; stream-lined, silver and graceful. They are powerful, too, among the greatest fighters in the fishing world. And perhaps most important of all, Atlantic salmon are a symbol of clean, unspoiled waters that run wild to the sea. For those of us who live near the Connecticut River, Atlantic salmon are also a symbol of clean and wild waters reclaimed.

Spawning female Atlantic salmon build nests (called redds) in the fall. They excavate gravel from the stream bed by turning sideways and lashing up and down with their powerful body and tail. With the encouragement of a male they lay their eggs in the redd. The eggs remain in the gravel through the winter and hatch the following spring. Newly hatched "fry" will stay in the gravel and continue to develop using the energy stored in their yolk and begin to feed.

Salmon fry just after hatching.

Atlantic salmon spend their first few years in small streams and rivers feeding on aquatic insects and other drift' that is brought into their sight by the current. At this time in their life they are known as "parr" and are mostly solitary creatures that defend their feeding territories from other fish that might intrude and compete for food. After reaching a size of about 4 inches, the fish become "smolts" in the spring and begin migrating to the ocean.

Stream-resident parr (below) and seaward-migrating smolt (above).

In southern New England where the growing season is long it may take only two years to become a smolt, but farther north it takes longer: up to 3 years in Northern Vermont, 4 in Nova Scotia and 5 in Newfoundland! During their downstream migration smolts become more sociable, begin schooling and develop the salinity tolerance they will need when they enter the ocean.

Once in the ocean, salmon take advantage of abundant food resources and grow rapidly. Feeding while they migrate, the salmon move toward their major feeding grounds in the North Atlantic near Greenland and Iceland. While in the ocean salmon must avoid many predators such as seals and larger fish in order to survive. After spending one or two years at sea, salmon begin their homeward journey. It is generally thought that salmon use a magnetic or sun compass to find their way to the coast of their natal river, though this is not known for certain. They then use olfactory (smelling) cues learned as smolts to find the river and tributary of their birth. Salmon may reenter fresh water in spring, summer or fall, but spawning occurs in the fall, and the life cycle of the salmon begins anew.

Adult Atlantic salmon on their upstream spawning migration.

Atlantic salmon have been in trouble in New England for many years. Once abundant, populations of Atlantic salmon went extinct on the Connecticut and Merrimac Rivers in the 1800s as result of dam building which blocked access to spawning grounds. More recently, Atlantic salmon in the downeast' rivers in Maine have experienced substantial population declines. It is thought that these recent declines are part of a widespread decline in Atlantic salmon populations that may be caused by poor conditions in the ocean that are related to cyclical temperature patterns. Whatever the reason, these Maine populations have now been classified as threatened. But there is hope for Atlantic salmon too. Twenty-five years ago state and federal fisheries agencies joined forces to restore Atlantic salmon to southern New England. Two to five hundred salmon have been returning to the Connecticut River for each of the last twenty years, though all involved hope these numbers will increase. Last year the first natural spawning of Atlantic salmon in Massachusetts in over 150 years occurred on the Westfield River, a tributary of the Connecticut. In the coming years we can hope to see even more of the "king of fish" returning to the restored waters of the Connecticut.

For more information on Atlantic salmon:

Mills, D. Ecology and Management of Atlantic Salmon. New
York: Chapman and Hall, 1989.

For more information on Pacific salmon:

Groot, C. and Margolis L. Pacific Salmon Life Histories.
Vancouver: UBC Press, 1991 (pp. 1-564).

For more information on migratory and anadromous fish:

Dadswell, M. J., Klauda, R. J., Moffitt, C. M., Saunders, R. L.,
Rulifson, R. A. And Cooper, J. E. Common Strategies of

Anadromous and Catadromous Fishes. Bethesda: American

Fisheries Society, 1987 (pp. 1-561).