Coho Salmon Fishing

Coho Salmon (sea-run phase)

Other names—silver salmon, silversides, hookbill, hooknose, sea trout, blueback; French: saumon coho; Japanese: gin-zake.

A member of the Salmonidae family, the coho salmon is an extremely adaptable fish that occurs in nearly all of the same waters as does the larger chinook salmon (see: salmon, chinook), but it is a more spectacular fighter and the most acrobatic of the Pacific salmon. It is one of North America’s most important sport- and commercial fish, especially to the Pacific coast of North America, where this and other salmonids have long had great cultural and food significance.

By nature an anadromous species, the coho can adapt to an entirely freshwater existence and has done so with remarkable success in the Great Lakes of North America. Like the chinook, it has declined through large portions of its endemic range due to dams, other habitat alteration, pollution, and excessive commercial fishing. Some runs in the Pacific Northwest are threatened or endangered.

Although they are smaller on average than chinook salmon, and in many places less abundant, coho are popular sportfish wherever they are found. Their Pacific coastal range parallels the chinook’s. As with the chinook, coho populations in the Great Lakes are supported almost entirely by hatchery production. Both species are intensively sought by boat anglers in coastal estuaries and bays and in the Great Lakes proper, and by boat, bank, and wading anglers in rivers.

As a gamefish, the coho is a much more suitable light-tackle quarry than the chinook, although it is caught with most of the same tackle and methods. Unlike the chinook, it is a streaky, near-surface, and aerial battler, rather than a deep and dogged fighter, although it, too, has great stamina. The coho’s flesh is red and of excellent quality. It is a significant commercial catch for food markets, and is processed fresh, fresh-frozen, canned, or smoked.

Identification

Coho Salmon (spawning male)

The body of the coho salmon is elongate and somewhat compressed, and the head is conical. For most of its life (in saltwater or lake as well as newly arrived in a spawning river), this species is a dark metallic blue or blue green above, becoming silvery on the sides and belly. There are small black spots on the back and on the upper lobe of the caudal fin. They can be distinguished from chinook salmon (see: salmon, chinook) by their lack of black spots on the lower lobe of the tail, and the white or gray gums at the base of the teeth; chinook have small black spots on both caudal lobes of the tail, and they have black gums.

Spawning adults of both sexes have dark backs and heads, and maroon to reddish sides. The males turn dusky green above and on their head, bright red on their sides, and blackish below. The females turn a pinkish red on their sides. The males develop a prominent doubled-hooked snout, called a kype, with large teeth, which make closing the mouth impossible.

Juvenile coho salmon have 8 to 12 well-developed parr marks evenly distributed above and below the lateral line; the parr marks are narrower than the interspaces. The adipose fin is uniformly pigmented. The **** fin has a long leading edge usually tipped with white, and all fins are frequently tinted with orange.

Size

Coho do not attain the size of their larger chinook brethren and in most places are caught around the 4- to 8-pound mark. The all-tackle world record is a Great Lakes fish of 33 pounds, 4 ounces, caught in the Salmon River, New York, in 1989. Fish to 31 pounds have been caught in Alaska, where the average catch is 8 to 12 pounds and 24 to 30 inches long. All coho are exciting to catch, as they are strong and acrobatic, but coho exceeding 15 pounds are a real handful for most anglers.

Distribution

The coho salmon is endemic to the northern Pacific Ocean and the rivers flowing into it, from northern Japan to the Anadyr River, Russia, and from Point Hope, Alaska, on the Chukchi Sea south to Monterey Bay, California. It has been infrequently reported at sea as far south as Baja California, Mexico. Most sea-run chinook are encountered along the coasts and in spawning rivers.

The coho has been transplanted into the Great Lakes and into freshwater lakes in Alaska and along the U.S. Pacific coast, as well as into the states of Maine, Maryland, and Louisiana; the province of Alberta, Canada; and in Argentina and Chile. Natural successful spawning has not noticeably occurred in these transplanted populations, with the possible exception of the Great Lakes in Michigan; the Great Lakes contain substantial populations of coho, which are sustained through extensive stocking.

Life history/Behavior

Like all species of Pacific salmon, coho are anadromous. They hatch in freshwater rivers, spend part of their life in the ocean, and then spawn in freshwater. Those coho that have been transplanted to strictly freshwater environments (as in the Great Lakes) hatch in tributary rivers and streams, spend part of their life in the open water of the lake, and then return to tributaries to spawn. All coho die after spawning.

Adult male sea-run coho salmon generally enter streams when they are either two or three years old, but adult females do not return to spawn until age 3. All coho salmon, whether male or female, spend their first year in the stream or river in which they hatch.

Generally speaking, the larger the female, the greater the number of eggs produced. Females spawn from 1,500 to 4,500 eggs, but the average production is 2,500 eggs. This number also varies with specific runs.

The timing of runs into tributaries varies as well. Coho salmon in Alaska, for example, enter spawning streams from July through November, usually during periods of high runoff. In California, the runs occur from September through March, and the bulk of spawning occurs from November through January. Streams throughout the Great Lakes primarily receive coho from late August into October. Run timing has evolved to reflect the requirements of specific stocks. In some streams with barrier falls, adults arrive in July when the water is low and the falls are passable. In large rivers, adults must arrive early, as they need several weeks or months to reach headwater spawning grounds. Run timing is also regulated by the water temperature at spawning grounds: Where temperatures are low and eggs develop slowly, spawners have evolved early run timing to compensate; conversely, where temperatures are warm, adults are late spawners.

Coho salmon do not feed during their freshwater spawning migration, so their condition deteriorates gradually during the spawning run as they use stored body materials for energy and for the development of reproductive products. Adults hold in pools until they ripen, then move onto spawning grounds; spawning generally occurs at night. The female digs a nest, or redd, and deposits her eggs, which are fertilized by the male. The eggs develop during the winter and hatch in early spring, and the embryos remain in the gravel utilizing the egg yolk until they emerge. The emergent fry occupy shallow stream margins and, as they grow, establish territories, which they defend from other salmonids. They live in ponds, lakes, and pools in streams and rivers, usually among cover in quiet areas free of current, from which they dart out to seize drifting insects.

During the fall, juvenile coho may travel miles before locating off-channel habitat, where they pass the winter free of floods. Some sea-run fish leave the river in the spring and rear in brackish estuarine ponds, then migrate back into freshwater in the fall. Coho spend one to three winters in streams and may spend up to five winters in lakes before migrating to the sea as smolts. Time at sea varies. Some males (called jacks) mature and return after only 6 months at sea, at a length of roughly 12 inches, whereas most fish stay 18 months before returning as full-size adults.

Little is known of the ocean migrations of coho salmon. Evidently there are more coho salmon in the eastern Pacific and along the coast of North America than in the western Pacific. High-seas tagging shows that maturing southeast Alaska coho move northward throughout the spring and appear to concentrate in the central Gulf of Alaska in June. They later disperse toward shore and migrate along the shoreline until they reach their stream of origin. Although most coho do not seem to migrate extensively, tagged individuals have been recovered up to 1,200 miles from the tagging site.

In the Great Lakes, coho migrate many miles from their natal water as abundance of forage and appropriate water temperature dictate. Thus, as surface levels warm, the colder water preferred by both salmon and their forage is deeper (or shallow but farther offshore, depending on wind and other factors). The fish wander considerable distances, and their location varies regularly.

Food and feeding habits

Juvenile coho in freshwater feed on plankton, then later eat insects. In the ocean, coho salmon grow rapidly, feeding on a variety of organisms, including herring, pilchards, sand lance, squid, and crustaceans. Likewise, coho that live entirely in freshwater feed on plankton and insects as juveniles, and on pelagic freshwater baitfish in the lakes. Alewives and smelt are the pri-mary food items, and, in fact, coho and other salmonids were introduced to the Great Lakes and other inland waters especially to help control massive populations of baitfish, which they consume voraciously and thus quickly grow large, stocky bodies. Like all Pacific salmon, the coho does not feed once it enters freshwater on its spawning run.