Atlantic Salmon

Common Names: Sea Salmon, Black Salmon, Kelt

Atlantic SalmonDistribution: The Atlantic salmon is native to the north Atlantic Ocean. It spawns in coastal rivers south to Portugal in Europe and south to Connecticut in North America. Native populations were extirpated from New Hampshire in the 1800’s. Until recently, Atlantic salmon were stocked throughout the Merrimack and Connecticut River watersheds as part of the Atlantic Salmon Restoration Program.

Description: The Atlantic salmon is a streamlined fish with a powerful, slightly forked, caudal fin built for swimming upstream in fast current and leaping over small waterfalls. Adults have silvery sides with dark green backs and scattered x-shaped spots above the lateral line. Atlantic salmon are sometimes confused with brown trout as juveniles, but they may be distinguished by their jaw, which extends to the rear edge of the eye in the salmon and well past the eye in the brown trout. Males develop large hook shaped jaws during the spawning season. Juvenile salmon have a series of oval shaped dark markings, called parr marks, along their sides.

Species commonly confused with: Brown trout, rainbow trout 

Habitat: Atlantic salmon migrate from wintering areas in the North Atlantic, off the coast of Greenland, to spawn in cold freshwater rivers and streams with gravel substrate and riffle/pool habitat.

Life History: Atlantic salmon spawn in gravel nests, or redds, which the female excavates with her tail in rivers or stream with cool clear water and moderate current. Spawning occurs in late fall and the eggs overwinter in the gravel, emerging as fry in early spring. The fry survive with yolk sacs until they are able to forage for themselves. Juvenile salmon, called parr, remain in freshwater for 1 to 3 years depending on their growth rate. As they approach a size of between 6 and 8 inches, usually in their second spring, salmon parr begin their transformation into the smolt phase to prepare for life in the ocean. During this phase the salmon take on a more silvery appearance as their bodies undergo changes to deal with the transition to salt water. Smolts migrate for hundreds of miles to reach their wintering grounds, where they will grow rapidly to an average size of about 28 to 30 inches and 10 to 12 pounds, with a few individuals reaching weights over 30 pounds. The Atlantic salmon is an anadromous fish that spends one to three years in freshwater streams after hatching before migrating to the sea. Following a period of one to three years at sea, the adult salmon returns to spawn in the river where it was born.

Origin: Native

Man holding atlantic salmon Conservation/Management: Atlantic salmon were extirpated from New Hampshire with the construction of dams on the mainstreams of the Merrimack and Connecticut Rivers in the early 1800’s. An attempt to restore Atlantic salmon to the Merrimack River using salmon from the Penobscot River in Maine achieved moderate success until the program was ended in 1896. Interest in restoring Atlantic salmon to the Merrimack River was renewed in 1969, with the formation of an inter-agency cooperative to restore anadromous fish to the Merrimack River. The cooperative includes representatives from the U. S. Fish and Wildlife Service, New Hampshire Fish and Game Department, the Massachusetts Division of Fish and Wildlife, The Massachusetts Bureau of Marine Resources, the National Marine Fisheries Service, and The U. S. Forest Service. Another inter-agency cooperative was formed in 1983, when the Connecticut River Atlantic Salmon Commission was established by Congress with the goal of restoring Atlantic salmon and other migratory fish species to the Connecticut River.

Modern restoration strategies involved stocking salmon at different life stages. Millions of salmon fry have been raised in fish hatcheries and stocked in suitable river and stream habitat throughout New Hampshire. Some salmon were held in the hatchery until they were large enough to be released as smolts, just in time to imprint on the river and migrate to the ocean. Other salmon have been released as parr. Returning adult salmon were captured at the first mainstream dams of the Merrimack Connecticut Rivers and taken to National Fish Hatcheries, where they were used as broodstock to provide fertilized eggs for the stocking program. An average of approximately 160 Atlantic salmon returned to the Connecticut River and 120 Atlantic salmon returned to the Merrimack River over the last 30 years. This was far short of restoration targets, which were projected in the thousands.

In addition to stocking, providing fish passage was an important strategy for Atlantic salmon restoration. Fish ladders and fish lifts built on the dams of the Connecticut River made historical spawning habitat accessible to salmon in the Connecticut River. Radio tagged salmon released at the Holyoke Dam in Massachusetts were located as far north as the Ammonoosuc River in New Hampshire. Fishways have been constructed at the first three dams on the Merrimack River, up to the Hooksett Dam, but access to suitable spawning habitat was not available until the Merrimack Village Dam was removed at the mouth of the Souhegan River in 2008.

The removal of the Merrimack Village Dam made the Souhegan River accessible to migrating salmon for the first time since the early 1800’s. To take advantage of this opportunity, staff at the Nashua National Fish Hatchery began stocking the Souhegan River with salmon smolts marked with adipose fin clips. In 2011, 75 returning adult salmon with adipose fin clips were released into the Souhegan River to spawn naturally. Twenty of these fish were monitored with radiotags. Spawning activity was confirmed in the fall of 2011. Fry were not stocked in the Souhegan River in 2012 so that successful reproduction could be documented with electrofishing surveys for young-of-year (YOY) salmon. Electrofishing surveys in the summer of 2012 documented the first naturally reared juvenile salmon in the Souhegan River since the Merrimack River Salmon Restoration Program began in the late 1970’s. Due to the success of natural spawning in the Souhegan River, adult prespawn salmon releases were continued in 2012 and 2013.

Salmon populations throughout North America are in decline, despite the closing of an ocean fishery off the western coast of Greenland, where Atlantic salmon congregate before migrating back to their home rivers. Poor survival in the ocean has been the main obstacle to salmon restoration efforts throughout the region. Determining the potential cause, or causes, of ocean mortality is a major focus of current research. Remnant Atlantic salmon populations in Maine were found to be genetically distinct and are listed under the Endangered Species Act. Thus far, efforts to restore Atlantic salmon in the Penobscot and other Maine rivers have succeeded only in preventing extinction. Connecticut River Atlantic salmon restoration in New Hampshire effectively ended in 2011, after Hurricane Irene destroyed the White River National Fish Hatchery where the majority of Atlantic salmon were held for the Connecticut River Salmon Program. The U.S. Fish and Wildlife Service ended its participation in the Merrimack River Salmon Restoration Program in 2013 due to budget concerns and shifting priorities. The rivers of Maine now offer the last hope for restoring this iconic species in U.S. waters.