Smallmouth Bass in Cultus Lake

In 2018, Cultus Lake got even busier with the introduction of smallmouth bass. In Canada, these bass are native to the Great Lakes and St Lawrence River System, but due to their popularity as a sport fish, they have been introduced throughout the world. In British Columbia, they were first introduced in 1901 through a legal introduction to boost sport fishing. Since then, they have been spread throughout southern and central BC.

In recent years, all new introductions have been illegal, done without the understanding of the devastating effects these fish can have on the ecosystem. Remember – never move a fish from one body of water to another.

Why should we care?

Cultus Lake has an incredibly diverse fish population, with 19 different fish species – many of which may be impacted by smallmouth bass. There are also two species-at-risk who call Cultus Lake home: Cultus Lake Pygmy Sculpin and Cultus Lake Sockeye Salmon. The Cultus sockeye, exclusively uses the lake for spawning and juvenile rearing.

Smallmouth bass are voracious predators, feeding opportunistically on anything they can fit in their mouths. A major concern is that smallmouth bass are known to feed on both juvenile salmon and sculpin, in addition to other fishes, amphibians, insects, and crayfish. They can also outcompete native species for food, and in other areas, have caused the population of species such as sticklebacks, minnows, and dace to plummet or even disappear from their lake ecosystems. All these native species play a key role in a balanced ecosystem. With the introduction of a new invasive top predator like smallmouth bass, the lake is at risk of losing its unique diversity.

Smallmouth bass also have large ‘spawning grounds’ where they build shallow rock nests and defend the nests fiercely. This spawning may take up habitat that was previously key habitat or foraging grounds for other species.

Once introduced, bass are incredibly adaptive and can flourish in a variety of ecosystems. They can survive in a wide range of temperatures and show little preference to lake size and depth. Smallmouth bass can also thrive in river systems. This is especially concerning considering Cultus Lake is well connected to the Fraser River, where even more wildlife is present.

What is being done ?

With a partnership between Thompson Rivers University, government, and local organizations, researchers at the university are trying their best to learn about the bass and suppress their population. Researchers are conducting diet analysis to study their effects on prey species, and tracking their movements throughout the lake to effectively target bass spawning grounds.