Anders storm pond maintenance – goldfish removal

Environmental Services is undertaking a project to remove non-native fish species (goldfish) from Anders stormwater management pond.

1. Why is The City undertaking this project?The Anders pond was found to have a high population of goldfish, which are a non-native fish species that pose risks to native species and their habitat. The pond is a stormwater pond and connects to the City’s stormwater management system and the Red Deer River.The Fisheries Act specifies that actions must be taken to remove non-native fish species, including goldfish, from natural and artificial waterbodies, including stormwater management facilities, due to potential risks to native species and their habitat. These risks include:
   •   Competition with native species for habitat and resources
   •   Increased turbidity caused by goldfish stirs up sediments and nutrients, leading toincreased algae and plants
   •   Introduced diseases/parasites
   •   Reduction in biodiversity
2. Why are there goldfish in Anders pond? How did they get there?We cannot say for certain how Anders pond became populated with goldfish, but it is most likely due to residents placing unwanted goldfish or aquarium species in the pond or elsewhere in the stormwater system.
3. How will the goldfish be removed?Based on best practices from other communities and approval through Alberta Environment & Parks, The City will use a treatment called Rotenone to remove the goldfish. An experienced contractor has been hired to complete this work, which includes:
   •   Applying/spraying the Rotenone solution to the pond.
   •   Collecting and removing the fish carcasses from the pond.
   •   Ensuring all safe handling procedures are adhered to, according to federal and provincialregulations.
4. What is Rotenone?Rotenone is an organic compound derived from plants which has been used successfully in other municipalities to remove non-native fish species like goldfish from stormwater ponds and other localized bodies of water.
5. Is Rotenone harmful to people or pets?No, Rotenone is a target-specific, fish toxicant. The solution is highly toxic to fish (all species) and low to moderately toxic to birds, mammals, amphibians, and invertebrates. However, the concentration of Rotenone required to treat the invasive species in Anders Pond is lower than that which would cause harm to terrestrial species (land animals). In addition, we will be taking several precautions to ensure the safety of people, pets, and other wildlife, including:
   •   Installing fencing around the pond for the duration of treatment.
   •   Completing the treatment during the fall when amphibians have passed the larval stage.
   •   Completing the treatment outside the breeding/nesting bird activity period.

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6. If the chemical isn’t harmful to people, why are staff members wearing safety gear?Staff members wear safety equipment as a precaution while handling the concentrated formula. During application, there is a chance some of the product could become airborne, which poses a larger risk of exposure to staff handling the concentrated solution. Fences will be in place around the pond to ensure the public remain at a safe distance. Once applied to the water, the Rotenone is diluted and poses a low risk to people.
7. Does Rotenone affect all aquatic animals the same?No, fish are more susceptible. All animals have natural enzymes in the digestive tract that neutralize Rotenone. However, fish and some forms of amphibians and aquatic invertebrates are more susceptible because they are gill-breathing animals, and thus, the digestive enzymes cannot neutralize Rotenone. Although some organisms like aquatic insects are susceptible to Rotenone, studies have shown that these organisms can quickly repopulate an area after treatment.
8. What if animals eat dead goldfish or the drink treated water?Birds and other animals have natural enzymes in their digestive tract that neutralize Rotenone and so they would not be at risk if they ate a dead goldfish or drank treated water. Based on the concentration of Rotenone used, animals would need to eat or drink extreme amounts before ingesting lethal amounts of the chemical. For example, a bird weighing one-quarter pound would have to consume 100 quarts (95 litres) of treated water or more than 40 pounds of fish and invertebrates within a 24 hour period to receive a lethal dose. This same bird would normally consume 0.2 ounces (6 millilitres) of water and 0.32 ounces (9 grams) of food daily.
9. Will the Rotenone cause lasting effects in the pond after treatment?No. Sunlight causes Rotenone to naturally photodegrade, so the pond will return to normal in a short period of time. It takes approximately two weeks for the Rotenone to degrade to non-toxic levels. Should the need arise, staff could deactivate the Rotenone using potassium permanganate.

10. How long will this work take?

Two applications of Rotenone are required, and each application will take approximately one day. The two applications will be spaced about three weeks apart to ensure no goldfish in the egg stage at the time of the first treatment are missed (eggs are not susceptible to Rotenone). For several days after each treatment fish carcasses will be collected by contractor and City staff.

11. Will Anders pond be closed?

We will be fencing off the Anders pond for approximately six weeks to ensure time for two applications and to allow the Rotenone to degrade after treatment. The park and walking path will still be accessible, but the water will not be.

12. I live in the area. What should I expect?

Residents who live in the area or frequent the pond can expect the following:

•   The Anders pond will be closed and fenced off for approximately six weeks during treatment.
•   The park and walking path will remain open.
•   Residents and visitors may notice a minor odour for up to one to two days after treatment.
•   Residents and visitors may notice a temporary water discoloration in the pond.
•   There will be an active working site for several weeks, including staff in safety gear (suits,masks, gloves, etc.)