Invasive Species
Goldfish, while often considered harmless pets, pose a significant threat when released into natural water bodies. In Saskatoon, these ornamental fish have become an invasive species, disrupting local ecosystems and threatening native wildlife.
Why Goldfish Are a Problem
- Rapid Reproduction: Goldfish reproduce quickly, leading to overpopulation.
- Competition for Resources: They compete with native species for food and habitat.
- Ecosystem Disruption: Goldfish can alter water quality and vegetation, affecting other aquatic life.
- Disease Spread: They can introduce diseases and parasites to native fish populations.
How Goldfish Enter Our Waterways
Most goldfish end up in local water bodies due to well-meaning pet owners releasing them, not realizing the environmental impact. Storm ponds, lakes, and rivers in Saskatoon are particularly vulnerable.
The Impact on Saskatoon’s Ecosystem
- Decline in Native Species: Native fish and plants struggle to survive amidst the growing goldfish population.
- Water Quality Issues: Goldfish stir up sediment, increasing water turbidity and reducing oxygen levels.
- Altered Habitats: Their feeding habits destroy aquatic plants, which are crucial for the health of our waterways.
What You Can Do to Help
- Don’t let it loose: Never release goldfish or any other pets into the wild.
- Proper Disposal: If you can no longer care for your goldfish, consider these alternatives:
- Return them to a pet store.
- Rehome them through local pet adoption networks.
- Educate Others: Spread the word about the dangers of releasing goldfish into natural water bodies.
Invasive Species Removal Project: Summer 2024
The City of Saskatoon is partnering with the provincial Ministry of Environment to safely apply a natural compound called Rotenone to the storm ponds for the safe removal of the invasive species. Rotenone, a natural fish toxicant, has been very successful in the removal of fish in similar environments. It is derived from roots of plants in the bean family and has been used in fish control practices around the world and in other municipalities and national parks in Canada. It is not dangerous to people, mammals or birds unless ingested in extremely large quantities.
A very low concentration of the compound will be applied directly into the affected water to treat the invasive species. After several hours, City crews will remove the fish from the pond.
This work will be completed in August 2024 at the following ponds:
- Dundonald Pond (Dundonald neighbourhood)
- George H Clare Pond (Kensington neighbourhood)
- Bev M Dyck Pond (Kensington neighbourhood)
There is a very low risk to human and animal life from the prescribed approach. If animals somehow eat any treated fish before they are removed or drink the treated water, rotenone will be broken down by the strong enzymes naturally present in their stomachs and intestines.
This process is essential to protect the ecosystem of your neighbourhood ponds and other waterways like the South Saskatchewan River, and to reduce the negative environmental impact of these invasive species. In 2022, approximately 1,090 lbs of invasive species were removed from the storm pond network during a similar process.
Frequently Asked Questions
How will we know when our neighbourhood pond is being treated?
Dates will be posted to this webpage once confirmed and the affected ponds will be clearly marked with signage during the application.
Is rotenone harmful to humans?
It is not dangerous to people, mammals, or birds unless ingested in extremely large quantities.
Can I still swim in the storm pond during the application?
No, swimming and other water activities are strictly prohibited during the application process and while signs are on display.
What is an invasive species?
Invasive species can be any animal, wildlife, fish or reptile not natural or original to the waterway. An example is the common goldfish released into the pond when a family can no longer care for it. A goldfish can grow up to 30 cm (12 inches) in length and threaten native species by eating available food supplies, eating the eggs of original species and spreading diseases. Strange as it sounds, this small fish has been identified internationally as a problematic, invasive species.
How did they get in our ponds?
These fish were most likely introduced by well meaning members of the public into the ponds. It is important to not release any aquarium species into any natural water bodies including storm ponds. '
How does an invasive species get from a storm pond to a river or lake?
Once an invasive water species is in a pond, eggs can travel on birds and be transported to lakes and rivers. High rainfalls can also cause storm pond water levels to rise, which can then allow the invasive fish to travel to the river and lakes.
How will the invasive species be removed?
A safe required dose of a natural compound (rotenone) will be applied. Rotenone, a natural fish toxicant, has been very successful in the removal of fish in similar environments. It is derived from roots of plants in the bean family and has been used in fish practices around the world and in national parks in Canada. It is not dangerous to humans, mammals, and birds unless ingested in extremely large quantities.
Can we eat fish treated by rotenone?
You are strongly cautioned not to eat fish that have been treated with rotenone because no federal or provincial guidelines are in place for eating fish taken after rotenone treatment. Also, salmonella and other bacteria may grow on any fish that is not properly preserved, such as fish that have been floating in a lake for some time, making them unsafe to eat.
Will pets or wildlife that eat fish and drink water treated with rotenone be affected?
To control fish, rotenone is used in very low concentrations. Rotenone residues in treated fish are generally very low, are broken down quickly, and are not easily absorbed through the gut of the animal eating the fish. Birds, cats, dogs, and other mammals that eat treated fish and drink treated water will not be affected. If animals eat fish or drink the treated water, rotenone will be broken down by the strong enzymes naturally present in their stomachs and intestines.
Birds and mammals that don’t rely predominantly on the invasive fish population may be affected slightly because of the temporary absence of fish, but they usually find other food.
Will the chemical harm other aquatic life?
Animals with gills, such as tadpoles and some aquatic insects, are more susceptible because rotenone is absorbed directly into their bloodstream through the gills. Studies have shown that those animals will naturally repopulate an area after the rotenone neutralizes. The City will mitigate this by treatments in the late summer or early fall when life stages of some aquatic organisms have fully developed making them less susceptible to rotenone exposure
What will happen to the fish after treatment?
During the planning process, arrangements will be made to handle the treated fish. Most of the fish along the pond’s surface will be collected and properly disposed of. Some of the fish will naturally sink to the bottom of the pond where they will decompose and release nutrients back into the water. This process will assist in the production of plankton which will, in turn, help re-establish the invertebrate community in the pond.
Does rotenone smell?
Some report a mothball-like aroma, which often comes from the substances added to liquid rotenone to help it spread through the water. This smell may last for a few days, depending on air and water temperatures and winds. There are no health effects from this smell.