Eco Issues – Logan Huscroft and Sean Mullin
The Columbia River is 2000 kilometers long and is the largest North American river draining into the Pacific Ocean. The river supports a variety of natural fish species including; rainbow trout, kokanee, sturgeon, bull trout and an invasive species – the walleye.
Walleye originally gained access to the Columbia River through an illegal dump of fish at the Roosevelt Reservoir in Washington around 1945. Once they were in these waters they migrated upstream into Canada. They are ferocious predators, a fact that has resulted in some enormous walleye of up to nine kilograms.
They will prey on any baitfish available to them, including native game fish species such as kokanee, rainbow trout, bull trout, and sturgeon. Walleye are known to prey on sturgeon hatchlings and can be a threat to the long term health of local sturgeon populations.
In the Columbia there are no natural predators of the walleye. This and the abundant forage in the river have led to a very rapid growth in their population.
Hydroelectric power operations have helped the walleye get established in the Columbia River system, too.
The massive flow volume and the steep gradient of the river lends itself well to the generation of electricity. Unfortunately since the first dam was installed in 1932, the Columbia river has changed.
Because the dams trap water, the flow is slowed and the water temperature increases. This leads to a habitat that is ideal for the walleye but damaging to the native species of the river.
Despite the negative impacts on the natural river ecosystem, there are people who benefit from this species being in the river. Walleye are very popular game fish, mainly due to the fact that they make great table fare.
The population in the Columbia River is one of a handful in British Columbia that can withstand liberal fishing pressure. Anglers are able to fish and keep walleye year round.
The reason these fish are now in the Columbia River is likely due to a fishermen trying to create a recreational fishery. People have often introduced new fish to rivers thinking it will help improve the fishing. However, transporting live fish is illegal in Canada and introducing species into a new body of water is not only illegal but it can permanently alter the water body’s natural ecosystem.
Once a population of an invasive species is established, it becomes virtually impossible to remove them from the ecosystem. Just ask any Australian about the introduction of rabbits in 1959. This population has become so established that they cannot be eradicated.
The Columbia River will likely never be free of walleye again, but their numbers are being managed in the hopes that the natural biodiversity of the river can survive with this new player.
Anglers play an important role in keeping the population at a level that allows for sustainability of all fish species. Proper management will help ensure that the natural species of the Columbia River will continue to flourish in their natural habitat.
Logan Huscroft and Sean Mullin are second-year Recreation Fish and Wildlife students at Castlegar’s Selkirk College.