Atlantic Salmon & River Herring

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Atlantic Salmon (Salmo salar) - Native

Atlantic salmon with silver scales and a slightly forked tail shown on a blue background, commonly found in North Atlantic waters. — Atlantic salmon are prized game fish known for their sleek silver bodies and strong upstream migrations.

Wild Connecticut River Atlantic salmon fresh from the sea are typically bright silver with purplish iridescence. CT DEEP Fisheries Division file photo.

Identification. Anal rays 7-11. Adults - Similar to brown trout. Dark spots on a light back-ground. Some spots may be X-shaped, but otherwise tend to be more irregularly shaped than those of brown trout. Few spots if any on tail, adipose or dorsal fins. Mouth smaller than other trouts, jaw extends only to or slightly past the posterior margin of eye. Pectoral fins larger than those of trout. Tail large and squared off at end. No reddish spots or halos around spots. Teeth on center roof of mouth in a single row and more weakly developed than those of a brown trout. Caudal peduncle is narrow and thickens toward the tail (you can “tail” a salmon, i.e. hold it up by its tail). Adult sea-run fish, fresh from the ocean, are usually blue-green on back and bright chrome silver on sides. As fall approaches, fish take on spawning colors that often resemble brown trout — females are bronze to olive on their backs and upper flanks and dusky gray on their lower flanks and belly. Males are a dark, reddish brown with a whitish belly. Stocked broodstock are usually brown on the back and brown to silver on the sides. Breeding males develop a hooked jaw in the fall and can be very dark. Parr - Edge of adipose fin clear, without dark border. 8-11 dark parr marks, with a single reddish spot between most. Spaces between parr marks usually less than width of parr marks. Caudal fin deeply forked. Pectoral fin at least as long as total length of depressed dorsal fin. Jaw extends only to middle or rear edge of pupil. Color variable, typically greenish-brown to gray on the back, fading to tan, silver or white on sides. Smolts - Dark, blackish-green on the back to bright silver on sides. Fin margins black. Eyes large. Most smolts tend to be thin, almost emaciated-looking.

Two brown trout shown side by side on a light blue background—one with silvery coloration and the other with golden hues and darker spots. — Male and female brown trout can vary in appearance, with some displaying silvery sides and others showing rich golden tones with dark spotting.

Comparison of female (top) and male (bottom) hatchery-raised Atlantic salmon. Note worn fins.

Size. Young fish in streams (parr and smolts) typically 3 to 8 inches, rarely to 12 inches. Adults commonly 27 to 30 inches. Conn. max. observed size 36 inches. Max. reported size 4.9 feet. World Record 79.1 pounds.

Distribution. Atlantic salmon make spawning runs up major rivers in North America from Quebec to Connecticut and in Europe from the Arctic Circle to Portugal. They also exist in many northern lakes as a landlocked form. In Connecticut, small numbers of anadromous adults run up the Connecticut River and its larger tributaries. Young salmon are stocked into numerous tributary streams within the Connecticut and Pawcatuck River drainages, where they can be abundant. Surplus broodstock adults are stocked during the fall into stretches of the Shetucket and Naugatuck Rivers.

Map of Connecticut highlighting Atlantic salmon broodstock stocking stretches in dark blue, with red dots indicating key stocking locations along rivers. — Connecticut map showing designated Atlantic salmon broodstock stocking stretches and key river stocking sites for sustainable fishery efforts.

All maps created in 2009. See CT DEEP Fish Community Data for updated distributions.

Habits. Atlantic salmon spend 1 to 4 years at sea, after which they return to their river of origin. Their ability to leap over waterfalls is legendary and reflected in their scientific name (salar means “the leaper”). Spawning runs occur during April to June in Connecticut. Once in fresh water, they cease feeding and rest in deep pools until they spawn in the fall. Adults that survive spawning return to the sea until they are ready to make another spawning run. Young salmon (parr) grow for 1 to 2 years in freshwater streams before migrating out to sea as 6- to 9-inch smolts. Although adults do not feed during spawning runs, they will strike at small lures and flies. Smolts are aggressive and easily caught on bait, lures or flies.

Juvenile Atlantic salmon, also known as a salmon parr, showing distinctive vertical markings along its sides on a light blue background. — Juvenile Atlantic salmon (parr stage) with vertical markings, a key developmental phase before migration to the ocean.

A 4-inch Atlantic salmon parr. Note reddish spots.

Comments. Adult salmon can be very difficult to distinguish from brown trout, with the most reliable distinguishing feature being the nature of the teeth on the roof of the mouth. Native Atlantic salmon runs became extinct in Connecticut by the mid-1800s. In 1967, a major restoration effort was initiated by state and federal fisheries agencies to restore the Connecticut River population. To date, the annual numbers of adult sea-run salmon that successfully return to the river have ranged between 40 and 530 fish. Annual stockings of surplus broodstock (2- to 18-pound hatchery-bred adults that are no longer viable for breeding) have created popular trophy fisheries in two rivers.

Juvenile Atlantic salmon smolt with a shiny silver body and dark fins being gently held in two wet hands. — Atlantic salmon smolt showing its silvery body—an adaptation for ocean migration—during a conservation handling session.

Atlantic salmon smolts are bright silver and tend to be very thin. Steve Gephard photo.

Herrings (Clupeidae)

Silhouette of a fish with a forked tail and a prominent dorsal fin, commonly used for fish identification purposes.

Herring are a large family of schooling fishes with a worldwide distribution. Most species are marine, with some being anadromous and/or freshwater. Many species are extremely abundant, making them important forage for larger predators. Herring support some of the largest commercial fisheries in the world. Many herring species are similar in appearance and can be very difficult to distinguish from each other. Herring are laterally compressed, silvery fish with large, easily detached scales, and a belly with a sawlike keel. They have deeply forked tails, no spines, a single soft dorsal fin and abdominal pelvic fins. Scales are absent from cheeks and opercles. There is no lateral line on the body. The base of the dorsal fin is located over the base of the pelvic fins. There is a small flap of tissue (axillary process) present at the base of the pelvic fin.

There are six native species of herring that commonly enter fresh waters in Connecticut. Three are anadromous (one of these has become landlocked in many lakes); one is freshwater/estuarine; one is estuarine/marine; and one is primarily marine. A seventh, marine species, the Atlantic herring (Clupea harengus), is common in coastal waters of Long Island Sound but rarely ventures into fresh water.

Click on the species' names below to learn more.

American Shad (Alosa sapidissima) - Native

Photo of an American Shad, a silvery fish with a deeply forked tail and large scales, displayed against a light blue background. — American Shad – A migratory fish native to the Atlantic coast, valued for both sport fishing and its ecological importance.

Alewife (Alosa pseudoharengus) - Native

Photo of an Alewife fish, a small, silver, herring-like fish with a forked tail and prominent eye, shown on a light blue background. — Alewife – A migratory forage fish vital to aquatic ecosystems, often found in coastal waters and freshwater rivers during spawning season.

Blueback Herring (Alosa aestivalis) - Native

Image of a Blueback Herring fish with a slender, silver body, blueish back, and forked tail, displayed on a light blue background. — Blueback Herring – A migratory fish species with a blue-green back and silver sides, important for river ecosystems and coastal food webs.

Hickory Shad (Alosa mediocris) - Native

Hickory Shad fish displayed on a blue background, showing a silver body with a greenish back and a forked tail. — Hickory Shad – A coastal and river-dwelling fish known for its deep body and forked tail, popular among anglers during spawning runs.

Gizzard Shad (Dorosoma cepedianum) - Native

Gizzard Shad fish shown on a blue background, featuring a deep, compressed silver body with a blunt snout and a long, thread-like dorsal fin ray. — Gizzard Shad – A freshwater forage fish with a deep body and distinctive long dorsal fin ray, commonly found in lakes and rivers across the U.S.

Atlantic Menhaden (Brevoortia tyrannus) - Native

Atlantic Menhaden fish displayed on a blue background, featuring a deep silver body, forked tail, and a noticeable dark spot behind the gill cover. — Atlantic Menhaden – A vital forage fish with a silver body and signature dark shoulder spot, important to coastal ecosystems and commercial fisheries.

Herring are generally not suitable for home aquariums. They require large circular tanks, preferably with a current. They must be kept in large schools, eat only plankton (such as brine shrimp) and are very fragile and skittish.

Text and images adapted from Jacobs, R. P., O'Donnell, E. B., and Connecticut DEEP. (2009). A Pictorial Guide to Freshwater Fishes of Connecticut. Hartford, CT. Available for purchase at the DEEP Store.