Every fall, beginning in mid October, thousands of salmon make their way up the Goldstream River to spawn and die.Most of these are Chum Salmon (Onchorynchus keta), just one of the five types of Pacific Salmon.Chinook and Coho Salmon also join the Chum Salmon in the Goldstream River but in smaller numbers. Why are they here? What are they doing? Where did they come from? Follow the lifecycle of a chum to learn the answers to these questions and more!
The Chum Salmon Lifecycle
A Long Journey Home
Starting in the Gulf of Alaska, and at the age of four the Chum Salmon make their way back to the river they were born in.The mechanism by which they find their way home is still somewhat of a mystery, but scientists believe they rely on a combination of methods.Studies have shown that salmon use their keen sense of smell, vision and memory.A small piece of magnetite embedded in their heads acts as a compass along with their use of the sun, moon and stars for navigation.
Every girl is crazy for a sharply dressed…salmon
Once they’ve found their way, salmon spend between a few days to weeks at the mouth of the river: the estuary.Here they undergo some amazing physiological changes needed for spawning in freshwater.Male Chum Salmon grow large, hooked jaws with sharp teeth for fighting.Both sexes change colour entirely.The estuary provides the salmon with a gradual change from saltwater to freshwater; nevertheless, the drastic difference causes the salmon’s kidneys to work overtime to absorb the small amount of salts and minerals from the river while constantly expelling excess water.
Making Whoopee: Spawning at Goldstream Provincial Park
Once in the river, the salmon travel upstream in search of a good place to spawn.The Female will look for gravel which is just the right size and shape for her nest; sometimes building within a meter of the very spot she was born!While she digs her nest by slapping her tail against the substrate, the males fight for dominance. The large jaws and teeth they have recently grown come in handy here and they can inflict serious wounds on each other as they fight for the right to pass on their genetic material. The winning male, often the biggest and with the brightest colours, will then join the female in her nest.The “salmon hug” - the male will vibrate his body against the females as if to say “I’m ready when you are!”.When the female is ready, she will release her eggs into the nest.The male has a very short time to fertilize the eggs, usually from 10-30 seconds before a competitive male will swim in and attempt to fertilize the eggs himself.Once they are done the female will move upstream, and start to build another nest, subsequently covering her downstream eggs with rocks and gravel, protecting them until they hatch in the spring.She will build a number of nests that all together are called a “redd”. The female typically dies within a week of laying her last eggs, while the males will keep spawning as long as they are able to win the battles with other males for spawning rites.
§Both male and female salmon.Males have maroon streaks on the sides of their bodies, whereas females have a horizontal black stripe along their sides.
§Female salmon digging their nests.The flanks of the salmon are easily visible as they turn onto their sides to slap their tails against the riverbed.
§Two males fighting.Chasing, biting, gouging- see it all!It’s the ultimate fighting championship with no holds barred!
§Courtship.Watch for males vibrating their bodies rapidly against the females.
§Other wildlife!Check out the field guide for pictures and information!
Gone but not forgotten: Salmon Forests
By early December the spawn is drawing to a close, and the river is choked with the remains of thousands of salmon. Their lives are over but their contribution to ecosystem has just begun. Death is the beginning of a new cycle connecting a multitude of plants and animals. The postmortem gift of the salmon is so great that the forest is known as a “salmon forest”.Many organisms are the beneficiaries of the salmon’s bounty. The current carries decomposing salmon downstream, creating an irresistible buffet in the estuary which attracts hundreds of bald eagles in December and January. Sea Gulls feast upon the carcasses and, as they fly over head, “lighten their load”, sending nutrient rich salmon poop plummeting into the forest. It’s a good idea to keep your mouth closed when looking up, just in case. Little “Dippers” dive into the stream in search of a meal of roe (salmon eggs). Raccoons, mink, otters and even bears have made a feast of the dead and dying salmon during the approximately 9 weeks of the run. The nutrients contained in the salmon’s body are redistributed as bears carry their meal up to 4-6 kilometers into the forest where, like picky children, they eat only their favorite parts and leave the rest to the recycling crew: billions of bacteria, fungi and insects that break down what is left of the salmon and make it available to the trees and plants. Gone but not forgotten, the salmon feed and sustain many of the plants and animals in the “salmon forest”.
The Cycle Renews
As the warm rains of March fall into Goldstream, the salmon eggs, which have been growing in their gravel nests, hatch. The young fish are called alevin. They continue to live in gravel of the freshwater stream and feed off of their yolk sac which is still attached to their body. When the yolk sac is used up they “button up” or scar over where the yolk sac was attatched. They emerge as Fry. Now they have no choice but to leave the safety of the nest in search of food. The Fry don’t spend much time in the river, but head downstream to where the freshwater of the Goldstream River and the saltwater of the Pacific Ocean meet. This is called the estuary, and it is where the fry will undergo an incredible transformation called smoltification that will allow them to survive in the salt water that will be their home for the next four years. The smolt especially vulnerable to predation during this time, and must find places to hide and eat as they adjust to the salt water and grow in preparation for their ocean journey.
Chum Salmon spend 2-4 years in the ocean before returning to spawn. Factors that affect return number include: ocena predation, commercial and sport fishing, near-shore urbanization, pollution, parasites/diseases and more. In 1971 The Goldstream Hatchery began operations and from 1973-1976 the number of incubation boxes was increased. Continuing good survival rates along with more accurate and consistent salmon counting methods are evident in the graph following 1977.
The Open Ocean
After a few weeks the juvenile chum salmon are ready to leave the estuary and venture into the open ocean. They migrate up the coast to the Gulf of Alaska, where they will spend the next four years growing, eating and trying to avoid being eaten. (Salmon are a tastey treat for orcas, bigger fish, dolphins, seals and humans.)
That Lovin’ Feeling
After four years in the open ocean the adult salmon are compelled to return. The adult chum salmon will make the long, long journey back to the very stream where they were born to spawn…and die. The salmon have travelled a long way to be here, and have a very important job to do. We are very lucky to be able to witness this incredible event at Goldstream Provincial Park. Things are all ready pretty stressful for the salmon. You can help reduce the stress of the salmon and increase your viewing enjoyment by following the
Salmon Viewing Tricks and Tips
§Start your visit at the Nature House. Naturalists are always on hand to answer any of your salmon questions.Plus check out our LIVE underwater salmon cam and warm up with a hot cup of fresh organic coffee! Don’t forget your wallet- there’s a fabulous bookstore and giftshop.
§Avoid wearing bright coloured clothing, especially reds, purple and pinks which salmon see very well.
§Avoid coming on weekend afternoons if you can, the park is very crowded.
§Please car pool if possible, there is limited parking.
§Bring sunglasses with polarizing lenses to cut sown on glare from the water. These are especially good for children. You can also get polarizing lenses for you cameras.
§Try to find viewing sites that are up high (top of banks, bridges) to increase visibility, while staying on the trail. Small children can see better up on your shoulders.
§Avoid moving quickly, and approach the river bank quietly. Find fish that are actively building nests and watch for the spawning behaviour.
§Don't throw anything in the river.
§Leave your dog at home. If you do bring a dog it must be on a leash and kept out of the river.
§Bring your binoculars. Because of changes in the way BC Parks manages the estuary, there are increasing numbers of Bald Eagles and other birds using the salmon round.
§Do not leave your wallet, purse or other valuables in your car.