Even though Atlantic and Pacific salmon look similar, are characteristically athletic in their ability to avoid predators and leap over waterfalls and rapids on the way back to their spawning grounds, and are in the same family, Salmonidae, along with trout and arctic char, they are classified in different genera. One of the key biological differences between Atlantic and Pacific salmon is that Atlantic salmon are iteroparous, that is, they do not die after returning to spawn in their natal streams and can return to the sea. Pacific salmon and other members of the Oncorhynchus genus are semelparous, with mature members of the population generally dying within a short time of spawning.
These belong to the genus Salmo, and within that genus there is only one species, salar, which means “leaper” in Latin. Mature wild Atlantic salmon average about 10 lb [4.5 kg], are about 30 in [76 cm] long, and are sleek and muscular, with steel-blue backs covered with tiny black crosses. They are silver below the lateral line, with white bellies, and their flesh is firm and deep pink. The range of wild Atlantic salmon once extended from New York’s Hudson River all the way up the North Atlantic and arcing over to Russia’s White Sea and down to the Douro River in Portugal. Many of these runs are now severely reduced or extinct due to industrialization, habitat loss, pollution, and overfishing by commercial fleets. The only wild Atlantic salmon available are those caught by recreational fishermen, though conservationists and marine biologists dedicated to saving wild stocks are working hard to introduce Atlantic salmon back into their native waters. For now and the foreseeable future, all the fresh Atlantic salmon in the marketplace, apart from a minuscule amount of boutique wild Atlantic fish imported from Europe, are farmed.
These belong to the genus Oncorhynchus, but unlike Atlantic salmon, the Pacific genus includes seven species, six of which are native to North America. The seventh, the masu or cherry salmon (O. masou), is found in the western Pacific waters off the coast of Japan, Korea, and parts of Taiwan. It is not detailed in this discussion.
THE CHINOOK (KING) SALMON (O. tshawytscha) is truly the “king” of all the Pacific salmon species, not only for its size but also for its economic value. The flavor and texture of the flesh are incomparable, and the heart-healthy, omega-3-rich fat often exceeds 20 percent, higher than any other wild fish. King salmon can weigh more than 100 lb [45 kg], but most weigh 15 to 20 lb [7 to 9 kg] and measure up to 36 in [91 cm] in length. Hefty in appearance, kings are blue-green on the back and the top of the head, with silvery sides and white bellies. They have black spots on the upper half of their body and tail, plus distinctive black lower gums. Their flesh ranges from off-white to pinkish red. The rarely caught white-fleshed king, whose food source consists of sardines and anchovies as opposed to shrimplike pink krill, have taken on a boutique status in the marketplace, where they are called “ivory salmon.” Kings range from Kotzebue Sound, Alaska, to Santa Barbara, California. Their season begins in mid-April in California; mid-May in Oregon, Washington, and British Columbia; and early June in Alaska. It typically lasts until late September and into October in a good year. Not as popular for farming as other species, farmed kings weigh 5 to 15 lb [2.3 to 7 kg].
COHO (SILVER) SALMON (O. kisutch) come close to chinook in flavor but are smaller, weighing from 8 to 12 lb [3.6 to 5.4 kg] and ranging from 18 to 24 in [46 to 61 cm] in length. Adult cohos are steel blue to pale green, with silvery sides and white bellies. They have white gums, small black spots on their backs, and are only lightly spotted at the top of the tail. The flesh is firmly textured and ranges from deep red to pinkish orange. Coho salmon occur naturally only in the Pacific Ocean and its tributaries, from northern Alaska to as far south as Monterey Bay, California, though the stocks in Oregon and California are classified as threatened under the Endangered Species Act. The best catches are made between July and September, with a peak in August. Coho salmon are also farmed and weigh 6 to 8 lb [2.7 to 3.6 kg] at harvest.
SOCKEYE (RED) SALMON (O. nerka) are long and slender, typically 5 to 10 lb [2.3 to 4.5 kg] at maturity, with most weighing about 6 lb [2.7 kg]. Their large, glassy penetrating eyes distinguish them from coho salmon in the wild. Sockeyes have spot-free forest-green backs, bright silver bellies, and look almost as smooth as glass, like they are set in gel, when freshly caught. They have pale gums that bear no teeth, unlike a king or coho. At the spawning stage, the head of the sockeye turns olive green while the body turns bright red. Although this is one of the reasons sockeyes are sometimes called “reds,” the name is also due to the color of their flesh. They have bright, deep orange flesh with a high fat content that makes them prized, distinctive, and delicious. Sockeye is the premium canned salmon variety and very popular for smoking. The fish range as far south as California, but they are most abundant from the Columbia River northward, with large concentrations in British Columbia and Alaska. The vast Bristol Bay watershed is responsible for 40 percent of all the sockeye salmon caught. Wild sockeyes that make it to market as unprocessed fish are typically available from late May to September.
THE PINK (HUMPBACK) SALMON (O. gorbuscha) is by far the most numerous of the Pacific salmon species, representing a little more than 50 percent of all the salmon caught in Alaska. Pinks are typically 18 to 24 in [46 to 61 cm] long and reach an average weight of 3 to 5 lb [1.4 to 2.3 kg]. They are steel blue to blue-green, with large black dots and silver sides. As the common name implies, the flesh is pale pink, lean, and fine textured, with a milder flavor than the other Pacific species. Pinks are widely used for canning, though those that make it to market unprocessed are typically sold whole—and at bargain prices.
CHUM (KETA OR DOG) SALMON (O. keta) are elongated and slim, usually measuring about 25 in [63.5 cm] in length and weighing about 10 lb [4.5 kg]. Their backs and upper sides are steel blue, without the fine black speckles of the other Pacific species, and they have silvery white bellies. During spawning season, they develop elongated teeth, which is why they were given the common name “dog.” Outside of Alaska, chums are sometimes sold under the label “keta.” The flavor, texture, and fat content of chums vary considerably depending on where and when the fish are caught. If chums are caught in the ocean when they are still actively feeding, their flavor and fat content are at their best. Chum salmon in this condition—silvery skinned, almost like coho, with reddish flesh—are labeled “silver brites” and command a higher price than those tagged “semi-brites” and “darks.” As you might guess from the labeling, semi-brites have darker skin and paler flesh, and darks have the darkest skin and are noticeably paler and lower in fat. Chum salmon are commercially fished from Washington to Alaska, but can be found in the Arctic Ocean, as well as in the Okhotsk and Bering Seas. Japan’s hatchery-based fishery accounts for the world’s largest annual catch of chum salmon. Alaska comes in second, producing about 85 percent of the U.S. chum catch. The remainder are caught in Washington. Although chum salmon is sold fresh in supermarkets, its real market value is when it is processed and sold as salmon burgers or sausages.
STEELHEAD SALMON (O. mykiss) and rainbow trout used to be identified by the Latin name Salmo gairdneri and were considered part of the same genus as Atlantic salmon and various trout of the Atlantic basin. However, scientists have long argued that rainbow trout, and especially steelhead salmon, have anatomical and behavioral traits that more closely match the Pacific salmon. In 1989, the American Fisheries Society approved and adopted this reclassification. Rainbow trout and steelhead are extremely similar. The single major difference is that steelhead are a sea-going fish and rainbow trout inhabit only freshwater. Steelhead salmon are 12 to 18 in [30.5 to 46 cm] in length and usually weigh 5 to 9 lb [2.3 to 4 kg], though recreational fishermen have caught steelhead as large as 36 lb [16 kg]. They are silvery, with a number of small black spots. The flesh is usually bright red and rich or pink to white, depending on the diet. Steelhead and rainbow trout are rated two of the top five sport fish in North America. On Washington’s Olympic Peninsula, the Quinault Indian tribe has spent the last three decades developing a successful hatchery program of wild steelhead stocks and are harvesting a plentiful, commercial supply available in Northwest markets. In other parts of the world, fish labeled “steelhead” are rainbow trout raised on farms in salt water.