The major difference between Atlantic and Pacific salmon is that Atlantic salmon may spawn more than once while Pacific salmon die soon after one spawn. Long ago, some people made boots out of salmon skin!
The Atlantic salmon's sense of smell is 1000 times greater than that of a dog (Maynor, 1996).
Salmon have a great sense of smell, hearing, and taste which helps them find food and sense danger. Salmon are also able to sense danger by feeling the waves on their body.
Atlantic salmon also use their senses to find and return to their home river. Through imprinting, young fry memorize details about their home streams, and they use this knowledge as adult spawners to find their way back. Scientists are not exactly sure how salmon complete this feat, but some theories are the salmon use the sun and stars as navigational guides, while others claim these fish have stored the taste of their home water in their brain. Most feel that salmon are guided home by the characteristic odor of the parent stream which is imprinted during the smolts' migration (Maynor, 1996).
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; chemical
North America's population of large salmon is at its lowest point in history. Declining numbers and loss of whole stocks in some rivers are causing increasing concern. Habitat destruction, denial of access to spawning grounds by dams and other obstructions, overfishing (including high-seas fishing and poaching), pollution, and especially acid rain are taking their toll. Cooperation and compromise by the major groups harvesting Atlantic salmon are essential if native stocks are to be saved. Scientific research has led to the creation of artificial spawning channels which provide a significant supplement to the production of salmon from natural streams. The Atlantic Salmon Federation is the largest, most effective organization devoted to the conservation of the Atlantic salmon and its habitat. This group has been successful in reducing commercial salmon fishing and some salmon streams have reported encouraging increases in the number of returning sea run fish as a result (Scott and Crossman, 1973; Atlantic Salmon Federation, 1996). Atlantic salmon are listed as lower risk by the IUCN, and they are considered an endangered species by the U.S. Fish and Wildlife Service.
US Federal List: endangered
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: lower risk - least concern
Hatching of the eggs usually occurs in April but the young remain in the gravel until the yolk sac is absorbed and finally emerge in May or June of the year following egg deposition. The newly hatched salmon, called "alevins," remain in rapid water until they are about 65mm long. The fish are now called "parr," and their growth is slow. Parr are called "smolts" when they reach a length of 12 to 15 cm and are ready to go to sea. Salmon grow rapidly while at sea. Some may return to the river to spawn after one year at sea, as "grilse," or may spend 2 years at sea, as "2 sea-year salmon" (Bigelow, 1963; Scott and Crossman, 1973).
The Atlantic salmon is renowned among game fishermen and is a highly prized food fish. Because of the strong market demand, an active aquaculture industry, which involves cage-rearing, hatcheries, and some sea ranching, has been developed all over the world. The commercial yield of the Atlantic salmon is estimated to be in the millions of dollars with expected annual doubling in the future (Scott and Crossman, 1973).
Young Atlantic salmon in streams eat mainly the larvae of aquatic insects such as blackflies, stoneflies, caddisflies, and chironomids. Terrestrial insects may also be important, especially in late summer. When at sea, salmon eat a variety of marine organisms. Plankton such as euphausiids are important food for pre-grisle but amphipods and decapods are also consumed. Larger salmon eat a variety of fishes such as herring and alewives, smelts, capelin, small mackerel, sand lace, and small cod. Prior to spawning, salmon cease to feed; they do not eat after they re-enter fresh water to spawn, despite their apparent willingness to take an artificial fly (Bigelow, 1963).
Animal Foods: fish; insects; aquatic crustaceans; other marine invertebrates; zooplankton
Primary Diet: carnivore (Piscivore , Insectivore , Eats non-insect arthropods)
The Atlantic salmon is native to the basin of the North Atlantic Ocean, from the Arctic Circle to Portugal in the eastern Atlantic, from Iceland and southern Greenland, and from the Ungava region of northern Quebec south to the Conneticut River (Scott and Crossman, 1973).
Biogeographic Regions: nearctic (Native ); palearctic (Native ); atlantic ocean (Native )
The Atlantic salmon is an anadromous species, living in fresh water for at least the first 2 or 3 years of life before migrating to sea. Relatively large cool rivers with extensive gravelly bottom headwaters are essential during their early life. Smolts migrate to sea where they may live for 1 or 2 years before returning to fresh water. The movements of Atlantic salmon at sea are not well understood. Tagging has shown that while some salmon wander, the great majority return to the river in which they were spawned. When at sea, salmon seem to prefer temperatures of 4 to 12 C. They may withstand exposure to temperatures in their lower lethal limit (-.7 C) and their upper lethal limit (27.8 C), but only for a short period of time (Bigelow, 1963).
Habitat Regions: temperate ; saltwater or marine ; freshwater
Aquatic Biomes: rivers and streams; coastal
Range lifespan
Status: wild: 3 (high) years.
Average lifespan
Status: captivity: 3.3 years.
Average lifespan
Status: wild: 5.0 years.
Average lifespan
Status: wild: 13.0 years.
Sea-run Atlantic salmon usually attain a larger size than do landlocked (those living in entirely fresh water) salmon. Sea-run salmon range from 2.3 to 9.1 kg and commercially caught fish average 4.5 to 5.4 kg. The world record rod-caught Atlantic salmon weighed 35.89 kg and was caught in the Tana River of Norway.
The adult Atlantic salmon is a graceful fish, deepening rearward from a small pointed head to the deepest point under the dorsal fin, then tapering to a slender caudal peduncle which supports a spreading and slightly emarginate caudal fin. Atlantic salmon are distinguished from the Pacific salmon because they have fewer than 13 rays in the anal fin. Their mouth is moderately large. The shape, length of head, and depth of body vary with each stage of sexual maturity.
Color varies with age of this fish. Small "parr," older young salmon, have 8 to 11 pigmented bars, or "parr marks," along each side of their body, alternating with a single row of red spots along the lateral line. These markings are lost when the "smolt" age is reached. Salmon in the sea are silvery on the sides and belly, while the back varies with shades of brown, green, and blue. Atlantic salmon also have numerous black spots, usually "X"-shaped and scattered around the body. When spawning, both sexes take on an overall bronze-purple coloration and may acquire reddish spots on the head and body. After spawning, the "kelts" are so dark in color that these fish are also called "black salmon"
(Eddy and Underhill, 1974; Bigelow, 1963; Scott and Crossman, 1973).
Range mass: 2.3 to 35.89 kg.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Atlantic salmon spawn in October and November, the peak of spawning usually occurring in late October. As spawning time nears, males undergo conspicuous changes in head shape: the head elongates and a pronounced hook, or kype, develops on the tip of the lower jaw. The nesting site is chosen by the female, usually a gravel-bottom riffle above a pool. The female digs the nest, called the "redd," by flapping strongly with her caudal fin and peduncle while on her side; the redd is formed by her generated water currents. The female rests freely during redd preparation while the male continues to court her and drive away other males. When the redd is finished, the male aligns himself next to the female, the eggs and sperm are released, and the eggs are fertilized during the intermingling of the gametes. On average, a female deposits 700-800 eggs per pound of her body weight. The eggs are pale orange in color, large and spherical, and somewhat adhesive for a short time. The female then covers the eggs with gravel, using the same method used to create the redd. The eggs are buried in gravel at a depth of about 12.7 to 25.4 cm.
The female rests after spawning and then repeats the operation, creating a new redd, depositing more eggs, and resting again until spawning is complete. The male continues to court and drive off intruders. Complete spawning by individuals may take a week or more, by which time the spawners are exhausted. Some Atlantic salmon die after spawning but many survive to spawn a second time; a very few salmon spawn three or more times.
Spawning completed, the fish, now called "kelts," may drop downriver to a pool and rest for a few weeks, or they may return at once to the ocean. Some may also remain in the river over winter and return to sea in the spring.
Hatching of the eggs usually occurs in April but the young remain in the gravel until the yolk sac is absorbed and finally emerge in May or June of the year following egg deposition. The newly hatched salmon, called "alevins," remain in rapid water until they are about 65mm long. The fish are now called "parr," and their growth is slow. Parr are called "smolts" when they reach a length of 12 to 15 cm and are ready to go to sea. Salmon grow rapidly while at sea. Some may return to the river to spawn after one year at sea, as "grilse," or may spend 2 years at sea, as "2 sea-year salmon" (Bigelow, 1963; Scott and Crossman, 1973).
Breeding interval: Breed once yearly, few breed twice before dying
Breeding season: October and November
Range age at sexual or reproductive maturity (female): 1 to 2 years.
Range age at sexual or reproductive maturity (male): 1 to 2 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
There is no parental investment beyond spawning.
Parental Investment: pre-fertilization (Provisioning)
