Chum Salmon

Believe it or not, there are salmon in Douglas Creek. Predominantly chum, but some Coho as well. Although their numbers have substantially declined everywhere, their presence, with human assistance, is making a comeback. Salmon must jump many hurdles to survive; pun intended, and human impact has added to these hurdles making their survival even harder.

Chum is the second largest species of pacific salmon, chinook being the largest, but chum are the poorest jumpers. Obstacles like waterfalls don’t stop other species of salmon but make it difficult for the chum. Often, this can stop their upstream migration resulting in them spawning further downstream. This is in part why you won’t find chum further upstream than Ash Road. Coho can easily make the migration further upstream.

Chum Salmons in Douglas Creek

When baby chum, called fry, leave their gravel nest they spend very little time in freshwater before heading out to sea, sometimes only a few weeks. Their migration to the ocean is second fastest only to pink salmon. Coho may spend a year or more in freshwater.

Before all salmon leave fresh water, they must go through a physical change called smoltification to help them transition to saltwater. Very few fish can go from freshwater to saltwater and back again to freshwater. Their bodies become more silvery and reflective, which acts as camouflage to protect them against predators in open water. There are also hormonal changes which impact the way they breathe and tolerate salt water.

When salmon are in freshwater their bodies need added salt which they get through food. The saltwater, on the other hand, pulls water out of the salmon’s body through its skin. Because of this, they must drink the salt water to replace water that was lost. Any excess salt in the salmon’s body is excreted through its gills and urine. At this lifecycle, stage salmon are called smolts. During this time, they are imprinting on their natal stream, taking in the smells and tastes so that they can navigate their way back in a few years.

After 3-5 years, adults come back to the creek they imprinted on at birth to spawn and die. Chum are generally the last of the salmon to return to their natal stream in the fall. Upon their return to freshwater, they go through another physical change and develop colourful bars on their body, green and purple, and the males grow large canines, and a hook jaw called a kype. Note the lighter patch of gravel. This indicates a redd was dug here.

The females create a gravel nest called a redd by making a depression with her tail in which she will lay her eggs, as the male simultaneously fertilizes them. Salmon will repeat this several times, continuously moving upstream until all the female’s eggs have been laid. The gravel that will cover the eggs, which is washed over them from the upstream redds being dug, protects them from predators and being washed away in heavy stream flow. Out of thousands of eggs each female will lay, only about 1% of them are likely to survive.

Note the lighter patch of gravel. This indicates a redd was dug here.

Salmon spawn in gravel that is pea to peach size so that it is small enough for the salmon to move but large enough to allow gaps for airflow. They prefer shallow sections where the water moves more quickly as the increased water flow keeps the redd oxygenated. Some of the current challenges salmon face relate to their spawning preferences. Chum prefer streams close to the ocean so they tend to be more impacted by watershed corruption.

Human impact, and how we can help.

Due to an increase in non-porous surfaces in our city, when there is a storm, the water is unable to seep back into the ground and be filtered by the earth. It all goes into the storm drain and causes a surge of water which washes out the spawning beds, leaving nothing but clay. Because the storm drains are connected to Douglas Creek, there is also the challenge of coping with contaminants.

Spending time in nature provides peace and tranquillity to people’s otherwise chaotic lives. Natural areas everywhere are seeing an increase in human traffic, and along with them their four-legged friends. The goal is to try and find a balance between humans and nature.

Many aren’t aware that PKOLS – Mount Douglas is not a dog park, especially off-leash. Although your dog may love running through the trees and rustling around in the ferns, this has a very negative impact on the ecosystem. New plant life, some endangered, gets trampled; nesting animals like birds are scared off and potentially killed, and trails created by dogs pack the ground preventing things from growing in the future. If your dog needs some exercise, please take them to an appropriate place that is designed for them to run free without causing damage.

Dog droppings are another problem. Droppings that are left will eventually wash into the
waterways increasing bacteria and degrading the water quality. This is not only harmful to the fish and plants but to humans as well. Please pick up your dog droppings, and don’t leave the bag on the trail or throw it in the bush. There are volunteers who work tirelessly to remove invasive species, helping to restore the ecosystem, and we don’t want them to have to encounter tossed feces.

Another issue natural areas are facing is people going off marked trails. It’s tempting to sneak down through the trees to get up close and personal with the creek, but please don’t. There are trails specifically chosen for human use so that nature and people can coincide. Rooted plants help keep the creek bank from eroding. It may not seem like a big deal but if these plants are trampled and die, and the ground is packed so nothing can grow, it will result in the creek banks eroding and ultimately the death of that area. Not to mention the risk of stepping on a red upon entering the creek and crushing the eggs. Countless hours are being put into restoring the plant life that has been trampled by humans and their pets to repair the creek banks, thus improving the health of the creek and bring the salmon back. Please help us keep up the momentum. We are working on increasing signage to make people aware of designated trails, as this is part of the problem.

There is hope!

Everyone can do a little. You may not realize it but even things you do at your home can impact a creek near you. Anything you wash off your car, using windshield washer fluid, soaps, pesticides and so forth will eventually wash into the storm drain. Some things are unavoidable but just being mindful can minimize the impact. If you can, increase the porous surfaces on your property, perhaps use a downspout disconnect, as pictured below, so that some of the water runoff can be filtered by the earth.

PKOLS – Mount Douglas Conservancy have partnered with some great organizations to release chum fry into the creek in hopes they will imprint and return to spawn as adults. In addition to this, there are also salmon carcasses tossed into the creek annually to mimic the natural lifecycle. This provides nutrients to the ecosystem, therefore improving the health of the creek. There has been extensive work done to repair the creek banks and replace plant life to prevent further erosion, and salmon spawning gravel has also been hauled in, along with large rocks and tree root balls being strategically placed in the creek to minimize the impact of storm surges.


How salmon feed flowers and flourishing ecosystems