Learn About Salmon

There are five species of Pacific Salmon that ply the Northwest waters, three of which we regularly see here at the Issaquah Salmon Hatchery:

Chinook

The chinook (or king) is the largest salmon species, averaging 18 to 24 pounds with up to 127 pounds recorded. Chinook have small black spots on the back, dorsal fin, and tail fin. The gums at the base of the teeth are gray. Fall run chinook are robust and deep bodied, while spring chinook are smaller, slimmer, and not as brightly colored when spawning.

Fall chinook spawn soon after arriving at their spawning grounds, usually large rivers. The fry spend 3 to 4 months in fresh water. Spring chinook migrate earlier, but delay spawning until fall, and they spawn in smaller tributaries. Their fry spend a year or more in fresh water. The Sacramento River hosts a unique winter run chinook, which is now listed as endangered.

Coho

Coho (or silver) salmon are powerfully built, and they can jump falls that most salmon cannot negotiate. They have small black spots on their backs and the upper lobe of the tail fin. The gums at the base of the teeth are white. Although sea run coho have silver sides, spawning males develop bright red sides and greenish backs. Spawning females are paler. The jaws of spawning males often become grotesquely hooked.

Most coho spend 18 months at sea, staying in coastal waters, and they return to their home streams as 3 year olds weighing 8 to 10 pounds. The fry spend more than a year living in streams.

Sockeye

Sea run sockeye have dark blue backs with few spots and bright silver sides. When they enter fresh water after a typical 2 years at sea, both males and females develop bright red bodies and green heads. The males' bodies become laterally compressed, a hump grows behind the head, the jaws become hooked, and sharp canine teeth appear.

Sockeye fry, after emerging from the gravel, migrate to freshwater lakes, where they spend 1 to 2 years before heading out to sea. Some populations, called kokanee, spend their entire lives in freshwater lakes.

Pink

Pink salmon rarely travel far upriver to spawn; they are typically found in shorter coastal streams. When the fry emerge from the gravel, they already have the silvery color of smolts, and they migrate directly to sea. Pinks spend a fixed 18 months at sea; thus, all returning pink salmon were born in the same year, and different year classes do not interbreed.

Pinks average 2 to 5 pounds. Sea run pinks are easily distinguished by the large oval spots on their backs and tail fins. Spawning males develop a large hump on their backs, earning the species its other name, "humpback." Some biologists think the males' conspicuous hump diverts the attention of predators away from the females.

Chum

Chum, also known as "dog" salmon from the large canine teeth of spawning males, are the second largest Pacific salmon, weighing up to 40 pounds. Spawning males develop reddish vertical bars on their flanks; females have a reddish lateral band. Although chum are fast swimmers, they are not good jumpers, and they do not migrate far inland to spawn.

Chum fry migrate to the sea soon after they emerge from the gravel. They spend up to 7 years at sea, but 4 years is typical.

Spawning sockeye salmon

The following is an excerpt from the Adopt-A-Stream Foundation Field Guide to the Pacific Salmon, by Robert Steelquist. We are grateful to Sasquatch Books, 1008 Western Avenue, Suite 300, Seattle, Washington for granting us permission to reproduce this description of salmon spawning.

Salmon spawning is a remarkable phenomenon to behold. Generally, spawning is broken into three types of behavior: redd selection and nest building, courtship and mating, and nest closure. Although individual species differ in certain behaviors, a generalized pattern occurs with all salmon.

Redd selection is the task of the female and is based on a variety of factors. Stream velocity, water depth, and gravel size determine the general suitability of a given site. The ability to claim and defend a redd site and the actual physical strength to excavate the nests vary with each fish.

Female building a redd

The following is an excerpt from the Adopt-A-Stream Foundation Field Guide to the Pacific Salmon, by Robert Steelquist. We are grateful to Sasquatch Books, 1008 Western Avenue, Suite 300, Seattle, Washington for granting us permission to reproduce this description of salmon spawning.

Each species of salmon shows different preferences in terms of optimum spawning habitat. This ensures that available habitat is used efficiently with a minimum of competition.

The redd is the general location selected by a female for laying eggs. Within that site, she may dig several nests and deposit eggs in them over a period of several days. The female begins by "nosing," an act in which she tests the gravel by probing, while cruising slowly over the bottom in the redd area. Having identified a suitable site, she turns on her side and begins flexing her body violently, slapping the gravel with her tail. This process dislodges gravel, which is lifted and carried slightly downstream by the current. After a series of digging motions, she swims to repeat the process. Sometimes the movements include tight circling or swimming over the nest in figure eights. Eventually, this produces a cone-shaped hollow varying in depth from just a few to as much as 15 inches (38 cm), depending on gravel composition and fish species.

The act of digging attracts males, who compete for the privilege of courtship. As a male manages to successfully ward off competitors, he joins the female in the nest in a series of movements that lead to egg and sperm release. The first of these movements is a "quiver," in which the male moves alongside the female and his body undulates slightly. He may follow this by "crossing over" the female near the base of her tail. As the nest develops, the female begins "probing" the gravel with her tail. Gradually, the probing increases and the circling decreases. The female settles lower in the nest for longer periods. As this occurs, the male continues to quiver and frequently opens his mouth in a "gape."

As the female nears egg deposition, she begins to "crouch," a position much like the probe, but with mouth agape. By opening her mouth, she increases her resistance to the current, which forces her deeper into the nest cavity. When the female assumes the crouch, the male quickly moves alongside. Both rapidly vibrate their tails and the eggs and sperm are released. The eggs emerge from the female one or two at a time into water clouded by the sperm, or milt. As this occurs, other males stationed outside of the nest may rush in to try to fertilize the eggs themselves. If the dominant male makes chase, another male may try to occupy the nest.

Laying and fertilizing eggs

The following is an excerpt from the Adopt-A-Stream Foundation Field Guide to the Pacific Salmon, by Robert Steelquist. We are grateful to Sasquatch Books, 1008 Western Avenue, Suite 300, Seattle, Washington for granting us permission to reproduce this description of salmon spawning.

Early in spawning, as many as 1200 eggs may be released into the nest, the number decreasing in subsequent nests. As they are released, current eddies in the depression pull most eggs downward into the nest to less turbulent water where sperm has settled and where they become lodged in the gravel.

Female covering eggs

The following is an excerpt from the Adopt-A-Stream Foundation Field Guide to the Pacific Salmon, by Robert Steelquist. We are grateful to Sasquatch Books, 1008 Western Avenue, Suite 300, Seattle, Washington for granting us permission to reproduce this description of salmon spawning.

As soon as the female has released her eggs, she instinctively covers them by moving upstream slightly and repeating her digging motions. This lifts gravel just above the nest, so that the current carries it into the depression. These "covering digs" increase in intensity until the nest has been filled. Often the males will leave the female, in search of another that is preparing a nest. The female moves upstream slightly and begins digging a new nest. Spawning can last for several days. Once the females have deposited their eggs, they defend their redds until they die, about a week later. Males remain sexually active longer, roaming the stream in search of late females.

Gradually, the scene turns from a frenzied expression of life to a pathetic scene of death. Carcasses beach on the gravel, line the bottom, float downstream, and hang up in roots and limbs. Survivors swim listlessly, often drifting with the current. The scavengers arrive - ravens, crows, eagles, gulls, bears, and others. Footprints appear in the river sand overnight. The smell of rotting flesh rises out of logjams.

As the drama of spawning quiets with the death of the adult fish, the patient observer of salmon can take heart in what the process has yielded. The littered bodies, dragged into the shrubs and partly eaten, feed the entire forest. And underneath those fresh mounds of gravel on the stream bottom, thousands of eggs are already growing. The salmon are very much alive.

Did you know?

• The oldest verified fossil for a freshwater version of the salmon is 50 million years old. Five to six million years ago salmon had fangs, weighed 500 pounds, and were ten feet long. The modern anadromous Pacific salmon emerged about two million years ago in the cold mountain streams of the Pacific Northwest.



• Humans have given many nicknames to salmon. Chum salmon are often called "dogs" because of the large canine teeth they develop during spawning. They are also called "calicos" because of their bright spawning colors. Spawning pink males develop a large humped back and are called "humpies."



• Only 2 - 10% of the eggs deposited in a gravel nest will survive to return to the spawning grounds as adults.



• Salmon do not have ears. Instead they hear low frequency sound waves which vibrate through the water to a row of sensory pores, called lateral lines, on the sides of the salmon. Scientists believe lateral lines also may help salmon navigate in the ocean.



• Salmon in their saltwater phase travel an estimated 18 miles a day, but they are capable of maintaining an average of 34 miles per day over long distances. Salmon often travel much more slowly to feed.



• Salmon have an extremely keen sense of smell. Studies indicate that salmon can smell one part per million which translates to one drop in 250 gallons, hundreds of times more acute than that of dogs.



• Like many fish, salmon have 300 degree vision. It is only the area immediately behind them that they cannot see.



• Young salmon moving to sea travel at night to avoid predators. They also drift backwards facing upstream which may allow them to continue feeding and also may provide better control in the downstream current.



• Salmon display silvery colors at sea and vivid reds, greens, browns, and even purple in freshwater. These freshwater colors may become even more pronounced in males during mating or fighting rituals.



• Salmon need cold, clean, well oxygenated water. Even salmon raised in hatcheries spend some portion of their lives in a river or stream. Without healthy watersheds, salmon cannot survive.