Climate Change is impacting Salmon populations in the Pacific Northwest. Here’s Why You Should Care.
My family has a tradition where each time it’s someone’s birthday, they get to choose what meal the family will eat. Every year, I always put in a request for salmon. Salmon is my absolute favorite meal. It reminds me of family and friends.
Unfortunately, salmon populations throughout the Pacific Northwest have been in decline throughout the 21st century. In the Fraser River, located south of Vancouver in British Columbia, Sockeye runs in the 1960’s produced 20 adults for every spawning Sockeye. In the mid-2000’s that number has dropped to three adults per spawner (CBC, 2012). Declining salmon populations have been observed throughout the rest of British Columbia, Alaska, Washington, and Oregon.
One of the suggested reasons behind the decline of salmon is climate change. Salmon rely on stable environments in order to spawn and grow their populations, and climate change destabilizes biotic conditions to which salmon are adapted. Climate change impacts many aspects of salmon’s life-cycle, including the transformation of habitats, rising water temperatures, and decreasing freshwater sources.
Salmon have played an essential role for the inhabitants of the Pacific Northwest since time immemorial. Indigenous groups have depended on reliable sources of salmon for centuries. Studies suggest that the Coast Salish who occupy the Olympic peninsula in Washington and the Salish sea, historically relied on salmon for 89% of their protein. Another study claims that they harvested a staggering 57.6 million kilograms (127 pounds) annually; this is more than the average annual catch of Sockeye in BC during most of the 20th century. The decline of salmon populations represent a degradation of an essential part of the Pacific Northwest’s identity, and while the fight to restore salmon populations is difficult, groups around the Pacific Northwest have been restoring critical river ecosystems that are used as spawning grounds. These efforts to restore salmon habitats are an example of community-based restoration efforts, and should be emulated throughout the Northwest in order to create community understanding of salmon populations, as well as to preserve this fish that has played such an important role in the historical development of the Pacific Northwest.
In order to understand the threats that climate change presents to salmon, it is necessary to first understand their life cycle. Salmon’s life cycle is composed of a series of stages as it develops from an egg to an adult fish. First, during spawning, eggs are deposited by the female fish in redds, which are gravel depressions that are scoured out by adults with their tails. Sperm is then deposited from the male to fertilize the eggs. Eggs take between six to twelve weeks to hatch. Newly hatched salmon are called Alevin. Alevin live in the river gravel and get nourishment from the yolk sac of the egg in which they were born. Over time, Alvein absorbs the egg sac, and they must find a new source of food. At this stage, salmon are called Fry. Fry feed on tiny invertebrates and the carcasses of spawned adults. It is at this stage that salmon learn how to school together and develop other survival skills. Fry live in freshwater for just a few days up to two years, depending on the species. During this stage, salmon go through a physiological change which, when completed, enables them to live in salt water without absorbing salt into its bloodstream. This change is called smolting. Once a salmon has completed smolting, it is time for its next stage of life in the ocean. The salmon swims out into the open ocean and quickly gains weight and grows. After they have finished growing, they are ready to return to the freshwater source in which they were born and to begin spawning. Mature adult salmon pair up and start the process making a redd and laying eggs. Salmon populations are especially vulnerable to habitat destruction, as they will only spawn in the freshwater habitat in which they were born. The spawning process is highly reliant on stable freshwater temperatures because high temperatures increase salmon’s susceptibility to predators, parasites, and disease.
Climate change, overfishing, and the loss of productive freshwater habitats have been cited as the main culprits of the vast reduction in salmon populations. Climate change has been postulated as posing the most significant threat to salmon populations due to its contribution to increased freshwater temperatures and altered hydraulic flows. In the Pacific Northwest, temperatures have warmed by between 0.7 and 0.9°C during the 20th century and has been estimated to increase by 1.5 to 3.2°C by the middle of the 21st century. Increasing temperatures are likely to increase water temperatures, threatening salmon during the spawning, incubation, and rearing stages of their life cycle. In watersheds that receive a significant proportion of winter precipitation from rain and snow, the increased amount of precipitation that will fall as rain can lead to elevated winter peak flows, which scour streambeds and destroy salmon eggs, as well as reduce the amount of hydraulic flow during the summer months due to decreasing amounts of melting snow. A study conducted in 2007 examined the impacts of climate change on salmon, which used temperature models for 2050 in the Pacific Northwest, projected a 30% decline in salmon populations.
Sockeye salmon typically thrive in water that is between 40 and 50 degrees Fahrenheit. When temperatures exceed 60 degrees salmon are more susceptible to infection from viruses and pathogens. Warmer water also has lower levels of oxygen compared to cooler water, causing salmon to burn energy much faster in hotter temperatures. The 2015 run of Sockeye salmon through the Columbia river is an example of the serious impact that increasing temperatures can have on salmon. Of the 507,000 salmon that passed through Bonneville Dam, located west of White Salmon, Washington. More than 235,000 of those salmon died before they were able to spawn. Scientists have cited exceptionally high water temperatures as the main culprit behind the die-off. During the Sockeye run, water temperatures near Bonneville Dam were five degrees Fahrenheit above the ten-year average.
There are some actions that can be taken to directly reduce the impact of warmer water on salmon, but these are usually expensive and time-consuming. One success story occurred this past July at the Warm Spring National Fish Hatchery in Central Oregon. Water temperatures had breached 70 degrees and migrating salmon populations were severely stressed. The US Fish and Wildlife services relocated over 160,000 juvenile Chinook salmon to Little White Salmon Fish Hatchery in the Columbia River Gorge. While this creative and innovative solution accomplished its goal of saving the Warm Spring salmon population, it is not possible to implement this in every river that has abnormally high water temperatures due to the high cost. Many experts have claimed that restoring damaged freshwater ecosystems would greatly benefit salmon populations and reduce the impacts of climate change.
Climate change is an extremely complicated issue that requires a global solution, and it presents a significant challenge to recovering salmon populations. Groups all over the Pacific Northwest are working hard to adapt salmon habitats to increasing temperatures. Studies have shown that reforesting narrow streams may decrease water temperatures by increasing shade coverage. Another adaption being implemented is the construction of new reservoirs and flood-control structures that could mitigate flow impacts. One of the most significant restoration actions that can be taken to improve salmon habitats is to allow streams and rivers to flow across a greater proportion of their historical floodplain and reconnect with freshwater and wetland habitats. This can improve low flows and lessen the negative impact of peak flows.
Dozens of stream restoration projects have taken place around the Pacific Northwest. Many of these projects are examples of community-based restoration efforts. One such example is the ongoing restoration of Douglas Creek in Saanich, British Columbia. Earlier this year, restoration crews resurfaced the creek bed, installed boulders, stumps and logs along the banks. Douglas Creek is surrounded by urban areas and is in close proximity to downtown Victoria. Restoring Douglas Creek is an excellent way of informing the community about salmon ecology and riparian ecosystems. The project has received wide support from the Saanich Parks Department, the Pacific Salmon Foundation, and the Department of Fisheries and Oceans.
Another example of community-based salmon habitat restoration is at Hope Creek on Pender Island. Historically, Hope Creek is believed to have supported a healthy salmon population until the 1980’s. Due to environmental degradation of the creek, salmon spawns have since stopped. The Pender Island Conservancy Association, a group of concerned residents, has been working hard to restore salmon populations to the stream. The Conservancy has been working in collaboration with island residents who live near the stream to raise awareness about the possibility of restoring salmon populations. Similar to Douglas Creek, a restored Hope Creek with healthy salmon populations would be an excellent educational resource to the community, and would help preserve salmon populations in the greater region.
While climate change presents a very real threat to salmon populations in the Pacific Northwest, communities and organizations are banding together to restore valuable salmon habitats and by planting trees along riverbanks so that water temperatures will remain stable. In the face of an unpredictable future, the future of salmon populations in the Northwest remains unclear. If salmon populations continue to decline, I might have to start asking for a different meal on my birthday, and that is something I am not prepared to do, so let’s follow the examples of groups like The Friends of Mount Douglas and the Pender Island Conservancy Association, and start focusing on restoring freshwater ecosystems so that they can support healthy populations of salmon.
Chances are, if you live in coastal areas of the Pacific Northwest, you are likely to live near a stream or river that supports salmon populations, or could potentially support salmon populations. There are hundreds of restoration projects in the Northwest attempting to preserve salmon populations.
If you in the United States and would like to find out more, click here. If you live in Canada, click here
