Richard Probert

Steelheader Contributor

Every autumn, millions of salmon on the pacific coast return from the ocean to spawn in their birth stream. The story of how pacific salmon migrate as smolt to the ocean, then return as adults to spawn in their home stream, is one of the most remarkable sagas in nature.

Seven species of salmon inhabit the pacific coast of North America and Asia. Coho, Springs (Chinook) Chum, Pinks and Sockeye inhabit streams from Korea to Siberia in Asia and from California to Alaska in North America. A landlocked variety of Sockeye, called Kokanee, inhabit a few interior lakes in British Columbia. Some pacific salmon species ( Coho, Springs) have been successfully transplanted to the Great lakes of North America, as well as in New Zealand, Tasmania and elsewhere.

In Asia, two other species of salmon, the Masu and the Amago, are found in Korea, Japan, northern China and Siberia. Some Masu stay in freshwater, while some Amago are lake dwelling.

Whether Asian or North American, all sea going salmon spawn in coastal rivers and streams, and lakes for Sockeye. Female salmon deposit 2000 to 5000 orange red eggs in gravel nests on the river bottom, After an incubation period of a few weeks, the eggs become alevin, then fry, then smolt. Different species of salmon stay varying periods in fresh water, before they head for the ocean as smolt.

Of the 2000 to 5000 eggs a female salmon deposits in the gravel, 10 to 15 percent survive to the fry stage, while 10 to 30 percent of fry survive to smolt stage. Only a handful of smolt reach adult size, The rest are eaten by predators, including ducks and other birds, garter snakes, frogs and bigger fish. Of the 100 or so smolt that survive the stage, usually only six or eight reach adult size. From the 2000 to 5000 eggs, only two or three remaining adults return to their home stream to spawn. The rest are eaten by predators, or caught in fisher’s nets and by anglers. Seals, sea lions, whales and sharks all prey on salmon in the ocean. In fresh water, bears eat substantial numbers of salmon, relying on them to store fat for the winter months.

In previous years anglers caught huge numbers of Coho and Springs. Stories of past catches seems almost legendary, considering that Coho and some Spring stocks are now depleted. Even twenty years ago, local anglers caught large numbers of Coho and Springs. These salmon were so plentiful that children easily caught salmon. My last very good day of coho fishing was in 1985, in a local slough near Agassiz, in British Columbia’s eastern Fraser Valley. I arose early that blustery November morning, and within two hours had landed five Coho, the biggest ten pounds, and a two-pound cutthroat trout. Catches like this were common until recently, when Coho numbers plummeted.

South of the border, in Washington, Oregon and California, many salmon stocks have been placed on the endangered species list. Industrial pollution, darns, siltation and debris from logging pesticides and nitrates from fields and lawns, construction projects and urban encroachment, have created havoc in American salmon streams.

To some extent, this is also happening in British Columbia. Many salmon streams have fish only because of hatchery programs and careful regulations. Many of our streams are following the American pattern of declining habitat and productivity. Every stream lost, however small, means the extinction of a salmon stock. Multiply that hundreds of times along the coast, from California to Alaska and the rapid decline of some salmon stocks becomes understandable. Our salmon must also compete with increasing numbers of Atlantic salmon, which have escaped from fish farms along the coast. Tens of thousands of Atlantic salmon have escaped from their pens in recent years and the biologists have determined that some of them are spawning in coastal streams. The long term consequence of this is difficult to assess, but in my opinion, can only be viewed with alarm.

Once in the river estuaries, salmon smolt stay there, until they have become completely adjusted in salt water. They then head for the open sea, where they stay from as little as one and one half years, for Pinks, and up to six years for Springs. In British Colombia, returning seven year old Springs are prized by anglers, since they can reach from 50 to 100 pounds in weight. Every angler dreams of landing these giant Tyee Springs, a true test of an anglers skill, strength and courage.

Once salmon reach the ocean, they travel hundreds, even thousands of miles in the north Pacific Ocean, depending on species. Toward the end of their ocean cycle, their bodies change to activate their homing instinct, and they start to mature sexually. How do salmon travel hundreds of miles in the ocean, far from their birth stream, and yet manage to find their way back to their home stream. Scientists have many theories to account for this mystery. They think salmon use a variety of orientation cues, including gravity, landmarks and celestial clues, current, odor, the earth’s magnetic field, the sun and polarized light. This complicated puzzle is slowly being pieced together.

Once salmon reach their home stream the odor of the current guides them to the part of the stream they were born. The female digs a nest out of gravel using her tail, and when the eggs are deposited, and fertilized by the male, the female covers the nest, again using her tail. After spawning, the bodies of the salmon deteriorate, until they are too weak to hold in the current. Their dying bodies are carried downstream where they catch on gravel bars, near shore, or sink to the bottom. Unlike Atlantic salmon all sea going pacific salmon die after spawning. Even Kokanee, the landlocked Sockeye, die after spawning.

While millions of dead salmon may seem wasteful to the untrained eye, this is misleading for the dead salmon become food for eagles, osprey, Blue Heron, gulls and other birds, as well as racoons, mink and other creatures. Is this enduring cycle of pacific salmon endangered by changing ocean currents and warmer temperatures, due to global warming? Perhaps. If this is so, let us hope we have the wisdom to carefully manage salmon. Otherwise our precious salmon stocks may face unprecedented challenges that could result in a dramatic and precipitous decline.

The life cycle and migration of pacific salmon is one of nature’s most intriguing sagas. All creatures have some homing instincts. For pacific salmon, going home means death, their journey’s end.