Dani Bowler is a second year Recreation, Fish and Wildlife students at Selkirk College. Photo: Submitted

Ecological Comment: The effect of dams on salmon

Written by second year Recreation, Fish and Wildlife students at Selkirk College in Castlegar, BC.

A hundred years ago, an estimated 16 million salmon migrated over 20,000 kilometres up the Columbia River basin. Today less than one million are only able to travel part way — 877 km to the Chief Joseph Dam in Washington.

With over 400 dams in the Columbia River basin, it is currently the most dammed river in the world. This has had an unfathomable effect on life all over the basin, but salmon in particular have suffered immensely. Dams have not only blocked the passage of these fish on the Columbia River, they’ve also caused other problems.

In the early years of dam construction, engineers ignored the value of aquatic life. Fish ladders and other passages were only introduced in 1927 but continued to be disregarded for many years. Twenty-eight years later, the Chief Joseph Dam was built, permanently blocking salmon migration to most of the Columbia River. Approximately 55 per cent of all spawning and rearing habitat in the Columbia River basin is now inaccessible due to dams.

Dams have permanently changed ecosystems, changing fast running cold rivers to slow warm pools. The pools have made juvenile salmon defenceless against predators. In addition, dams regularly flood and dry out spawning habitats providing fish eggs and juvenile no chance of survival.

The removal of dams would have several significant benefits. It would allow for fish passage, restoration of nutrients downstream, decrease of water temperature, restoration of river ecosystems, allow for the return of communities to their native land, and countless other benefits. Although it is not realistic to remove all dams, major dams that cannot install some kind of fishway to unblock salmon migration should be destroyed.

Salmon are a keystone species in Canada for which humans, raptors, bears, trees, soils and much more rely upon. They are important for the ecosystems in and along the Columbia and are important economically. A study in 2017 by the Ministry of Agriculture determined wild harvest salmon were valued at over $400 million. In addition, sport fishing in British Columbia was valued at just under $300 million dollars in 2005 by the Environmental Protection Agency, totalling to over $700 million dollars. Finally, Indigenous peoples in Canada have relied on wild salmon for thousands of years for sustenance and livelihood as they are an important part of their culture.

Today, the hydroelectric industry and governments are spending millions in order to try to increase the salmon populations upstream by installing fishways on impassable dams. Some scientists and Indigenous peoples feel it may be best to focus on long-term solutions for repopulating rather than find short-term solutions such as fish ladders, conveyor belts, and fish cannons. These short-term solutions may be more affordable and require less work in the short run, but that comes at a cost. Up to 15 per cent of salmon that are transported beyond the dam die and many juveniles that get moved are weakened.

One long-term solution is the destruction of dams. Although this solution sounds rather drastic, it focuses on restoration, not a temporary fix. Around the United States, 1000 dams have been removed since 1999, many with positive and quick recoveries of aquatic and terrestrial ecosystems.

Dam removal becomes a viable option when they have outlived their usefulness, or when they are beginning to fail. Dismantling dams is a real option, however, with the number of dams on the Columbia, this process would take many years, billions of dollars, and most importantly a lot of cooperation with governments, communities, and individuals.

Although there isn’t one perfect solution for restoring this historic salmon run, there are many viable methods to discuss. These methods come at a cost, but the long-term benefit of bringing wild salmon back outweighs the cost that come with any of the potential solutions.

Dani Bowler and Emma Bowins are second year Recreation, Fish and Wildlife students at Selkirk College in Castlegar, BC.

Trail Daily Times


Emma Bowins is second year Recreation, Fish and Wildlife students at Selkirk College. Photo: Submitted