Did you know that goldfish aren’t the only species of invasive fish on our radar in the Sea to Sky region? While very few of them are currently found in our lakes and rivers, they are found throughout the province, and could easily be brought to our region.
At the provincial level, invasive fish species may fall under a few different priority categories.
- If a species has not established in BC yet but poses a high risk for the Province, it is placed in the Prevent category.
- The Early Detection Rapid Response category contains fish species that pose a high risk for BC; the goal is to eradicate them from the Province. The species on this list will typically only have had a few sightings within the province.
- The Regional Containment/Control category contains species only found in specific areas of the province. The goal with these fish is to contain them to the regions where they’re already found, and to prevent their expansion into new areas.
- The Management category includes species that are widespread in the province. The goal for these species is to reduce their local or regional impact, especially in specific situations where we wish to protect high-value assets, e.g. conservation lands, agriculture crops, etc.
You can learn more about all the species found in each priority category on the BC Government’s website.
In this post, let’s ‘dive’ in and take a closer look at some of the invasive fish of concern for the Sea to Sky region.
Early Detection Rapid Response
Photo credit: Manoel Jr., CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
Oriental Weatherfish
Oriental Weatherfish are only known to be in the lower Fraser Valley within BC (so far). These fish cause problems for our native fish by competing with them for food and reducing the diversity of aquatic insects. They also carry parasites and pathogens that can harm other fish, native birds, and humans.
Native to East Asia, the Oriental Weatherfish is now a reasonably common aquarium fish worldwide. These fish are long and narrow, with an eel-like body, and grow up to 25cm long. They have 6 short barbells around their mouth, which look like thick cat whiskers. Oriental Weatherfish are typically yellow to brown, with darker spots on their backs. These fish prefer shallow, low-flowing water with a muddy or silty bottom.
Regional Containment/Control
Larger image: angeluisma, via iStockPhoto; Insert: Pinecrest Lake Association
Goldfish
That’s right, goldfish are invasive in BC! In fact, they are found in many lakes of the Sea to Sky, as well as throughout the Lower Mainland and Vancouver Island. They generally get introduced to new water bodies when pet owners release them – not a good move! These fish grow as large as their environment will allow. A typical goldfish can easily reach the size of a football in a lake – the largest known goldfish was 67 pounds! Goldfish compete with and even prey on our native fish species.
Goldfish are covered in large scales, except for on their head. Not all goldfish are orange: they range in colour from white to olive-green to gold. Their size varies widely, but they are typically 15 – 20cm long. They are extremely adaptable: while they may prefer habitats with underwater vegetation, they can tolerate most temperatures and oxygen levels. In fact, goldfish can live in areas with zero oxygen in the water for months!
Management
Photo credit: Manley L. Rusho
Black, Brown, and Yellow Bullheads
Black, Brown, and Yellow Bullheads are invasive in BC but native to eastern North America. Here, they are known to compete with and prey on native fish species. Due to their feeding behaviour, they also impact other species’ ability to hunt by stirring up silt and making it difficult for other fish to see. Bullheads prefer slow-moving water with lots of underwater vegetation.
None of these species of fish have scales. Their heads are large and flat, with four pairs of barbells around their mouth, similar to cat whiskers. Yellow Bullheads are typically yellow-olive to white, Brown Bullheads are dirty white to brown, and Black Bullheads are light brown to dark brown-black. All three species can grow to 50cm long.
Photo credit: alexmak72427 for iStockPhoto
Tench
Tench are native to Europe and some parts of western Asia. These fish reproduce incredibly quickly, allowing population sizes to increase dramatically in a short time. Tench reached British Columbia from Washington by swimming up the Columbia River – and that’s no small feat! This species thrives in our province, as they are well adapted to colder water and low oxygen levels. They prefer slow-moving water with lots of vegetation to hide in, and a muddy bottom to bury themselves in during the colder months.
Tench are olive-green to almost black, blending out to gold on their belly. This species also has orange-red eyes, one barbell on each side of its mouth and rounded fins (rather than pointed). At maturity, Tench are 20 – 25cm long. They are currently known to have established in Osoyoos, Christina, Skaha, and Okanagan lakes, but have the potential to spread.
Photo credit: stammphoto for iStockPhoto
Largemouth Bass
The Largemouth bass is native to central and eastern North America, with a native range spreading from Quebec down to Mexico. They prey on many of our native fish species, which disrupts the ecosystems where they are introduced. They’re even known to prey on young (juvenile) salmon and negatively impact the production of local fisheries. Largemouth bass also carry parasites that harm native fish species.
Largemouth bass are bright- to olive-green on their backs, and lighter on their sides and belly. These fish grow to be 30 – 40 cm long, and have a mouth that extends further back than their eyes (hence their name). Largemouth Bass prefer shallow, warmer waters and are found in lakes and ponds in the Lower Mainland, Vancouver Island, Okanagan, Thompson, and Kootenay regions.
Photo credit: Bass Fishing Gurus
Smallmouth Bass
The Smallmouth Bass is quite similar to the Largemouth Bass. It has a similar native range, extending from Quebec to Texas. Like the Largemouth Bass, they too prey on many of our native fish and amphibians, reducing local biodiversity. This species also carries parasites that harm native fish species. In BC, Smallmouth Bass is found in southern Vancouver Island, the Beaver Creek watershed (Cariboo region), and the Okanagan, Thompson and Kootenay regions.
Smallmouth Bass are grey-green to brown on their back, and lighter on their sides and belly. They have dark vertical bands on their sides which help to distinguish them from Largemouth Bass. Another distinguishing characteristic is their mouth, which only extends to just below their eyes. This species can grow to 25 – 40cm long.
Take action: report sightings!
There are many more species of fish on the Provincial Prevention List that have yet to become established within BC. We rely heavily on reports from the public to understand which species are present in our area. With that in mind, please report all sightings so that we can continue to monitor the distribution of invasive species within the Sea to Sky region.
Don’t Let It Loose
Releasing pets (like goldfish) into the wild is inhumane, illegal and harmful to the environment.
Never release your plants and animals into the wild or dump aquariums or water garden debris into rivers, streams, lakes or storm sewers! What you can do instead:
- Return: contact the place where you purchased your animal to see if they will take it back.
- Rehome: Local friends, science centres, zoos or aquariums may be interested in looking after your pet for you.
- Dispose: Dry and freeze unwanted aquatic plants and place them in the garbage (not the compost)
- Be kind: As a last resort, euthanasia by a qualified veterinarian is far kinder than letting an unwanted pet fend for themselves in the wild and potentially destroy native habitats in the process.
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