Aquafacts / Salmon

Pacific salmon

The Pacific Northwest is known for astounding salmon runs. We’ve compiled some of the most frequently asked questions about these ancient fish and had our biologists answer them. Peruse on.

Quick info

5

Pacific salmon species in B.C. waters

6 million years

Approximate age of the genus

16,000 kilometres

Distance a chinook salmon travels before spawning

2%

Less than this amount live to spawn

What makes a Pacific salmon a Pacific salmon?

Most Pacific salmon are anadromous; they are born in fresh water, spend their adult lives in the saltwater oceans and return to their natal rivers, or lakes, to spawn. They are also semelparous, meaning they die after they spawn. Atlantic salmon (Salmo salar) are anadromous, but they may spawn more than once.

What are the different species of salmon?

There are seven species of Pacific salmon, plus two freshwater species.

Five species are found in B.C. waters: sockeye, Oncorhynchus nerka; pink, Oncorhynchus gorbuscha; chum, Oncorhynchus keta; coho, Oncorhynchus kisutch; and chinook, Oncorhynchus tshawytscha.

Two species of Pacific salmon, masu, Oncorhynchus masou, and amago, Oncorhynchus rhodurus, are only found in Asian waters.

The rainbow trout, steelhead and cutthroat, are part of the Oncorhynchus genus, but are primarily freshwater fish.

What are the stages of a salmon's life cycle?

There are six stages of a salmon's life cycle: eggs, alevin, fry, smolt, adult, and spawners.

The salmon life cycle begins, and ends, as the spawning process in fresh water. The female chooses a site for her nest(s), called a redd, and builds one to several nests in the gravel with her tail. She then deposits her eggs into the nest and one or more males fertilize the eggs. The female then covers the eggs with gravel and repeats the process. Adult salmon guard the redd site until their death.

In late winter, eggs hatch from the redds. Young alevin in the gravel live off the nutritious yolk sac that hangs off their undersides for up to four months. Then they swim up from the gravel to start feeding on live prey. Some species head straight to the ocean as fry, while others remain in the stream for another year.

Next, the smolt stage occurs. The juvenile salmon swim downstream and undergo major physiological changes (smolting) while adapting to salt water in estuaries, where freshwater rivers meet the saltwater seas. Once in the ocean, Pacific salmon migrate to the North Pacific Ocean, travelling in schools. After one to seven years, depending on the type of salmon, they return to their home rivers to spawn where they had hatched.

What physical changes occur with spawning salmon?

Physical changes vary between the species of salmon and are dependent on the amount of time between a salmon's entry into fresh water and spawning. The sleek and silvery body maintains its shape, but the female swells in the abdominal area and her snout slightly elongates. The male develops a prominent fleshy hump by the dorsal fin, the snout becomes longer and hooked, and the upper jaw elongates. Colour changes occur but they differ between species. For example, the backs of the sockeye salmon change to a brilliant, red colour.

Which B.C. rivers are salmon commonly found in?

Salmon are common in most B.C. rivers, but the largest runs occur in the Fraser, Skeena, Nass, Somass, Thompson and Adams rivers.

How do salmon protect themselves?

When migrating, salmon are particularly susceptible to predation, so they seek deep areas to quickly swim into. Salmon school in the ocean for protection, and confuse predators with their flashy sides where they can be mistaken for a large predator.

What do salmon eat?

A salmon's diet depends on the species and region, but typically juvenile salmon eat zooplankton, and larval and adult invertebrates. In the ocean, salmon eat smaller fish, such as herring, pelagic amphipods and krill.

What animals eat salmon in the rivers and oceans?

There are diverse predators of salmon at the varying stages of their lives. Other fishes, members of their own species, snakes and birds eat salmon fry. Once in the ocean, salmon are prey to whales, dolphins, seals, sea lions, other fishes and, of course, humans. Bears and birds often scoop up spawning salmon.

What are farm salmon?

Farm salmon are raised for market in large undersea cages, or net pens, off the B.C. coast. Some escaped salmon, including Atlantic salmon, are able to find spawning areas. Atlantic salmon are the most commonly farmed salmon because they have better growth and survival rates on farms than the Pacific salmon. Chinook and Coho are also raised in B.C. Salmon aquaculture is the name given to raising farm salmon. They are hand-fed fishmeal pellets (a vitamin rich, high-protein diet), for about two and a half years, until they are harvested.

How are salmon commercially fished?

There are three common techniques for commercial fishing: seining, gill netting and trolling. Seining involves setting nets to encircle schools of fish. Once a catch is made, the net is drawn up and brought aboard. Gill netting involves dropping a large nylon net in the ocean like a mesh wall, with orange bobs to keep it afloat, and then scooping up the catch. Trolling involves dragging a series of lines and baited hooks that are attached to long poles that extend from the boat.

Are salmon endangered?

Our lifestyles have strong and often negative impacts on salmon stocks. Overfishing has led to a decline in salmon stocks. We develop land that destroys habitats and build dams that divert salmon runs in order to generate electricity. All of these development methods have led to a decline in salmon populations.

What is the BC Hydro Salmon Stream Project in Stanley Park?

The BC Hydro Salmon Stream Project in Stanley Park is a community project supported by BC Hydro, the Vancouver Park Board and the Vancouver Aquarium Marine Science Centre to provide the public with an opportunity to witness a salmon run. The demonstration stream began development in the fall of 1999, winding its way from the Aquarium through to Coal Harbour, near the Vancouver Rowing Club. In the summer of 1998, 10,000 hatchery-bred Chinook and Coho salmon fry were released in Coal Harbour. A pheromone was released into the water to help the mature salmon to "scent" their way to their home stream in the year 2000.

What is the cultural significance of salmon to First Nations' communities?

Salmon are at the base of many First Nations culture. There are songs, dances, visual arts and legends based on the lives of salmon. First Nations of B.C., including Bella Coola, Nootka, Tlingit and others, have relied on salmon as a primary source of subsistence before the salmon populations began declining.