Frequently asked questions about drug and pesticide deposition under the Aquaculture Activities Regulations

Pests and infectious pathogens can occur in the freshwater and marine environments in both wild and farmed fish, and can affect the health of Canada’s aquatic ecosystems. The use of pesticides and drugs to treat fish inflicted with pests or pathogens is sometimes necessary for fish welfare but also needs to be managed by federal and provincial regulators to minimize the risk of any potential environmental effects.

The Aquaculture Activities Regulations (AAR) clarify conditions under which aquaculture operators may install, operate, maintain or remove an aquaculture facility, or undertake measures to treat their fish for disease and parasites, as well as deposit organic matter, under sections 35 and 36 of the Fisheries Act. The AAR allow aquaculture operators to do so within specific restrictions to avoid, minimize and mitigate any potential detriments to fish and fish habitat. The Regulations also impose specific environmental monitoring and sampling requirements on the industry.

All pesticides and veterinary drugs require pre-market authorization by Health Canada, either through its Pest Management Regulatory Agency or Veterinary Drugs Directorate.

Pesticides are regulated under the Pest Control Products Act. Health Canada’s Pest Management Regulatory Agency conducts rigorous, science-based, pre-market assessments to determine if the risks associated with the use of pesticides are acceptable. Health Canada includes environmental requirements, such as restrictions on use, on its pesticide product labels to mitigate any environmental risks.

Veterinary drugs are regulated under the Food and Drugs Act, and are subject to pre-market assessments to establish their safety, quality, and efficacy. In addition, substances approved for use in products regulated by the Food and Drugs Act may be subject to the New Substances Notification Regulations under the Canadian Environmental Protection Act to assess potential environmental impacts.

For food safety, the Canadian Food Inspection Agency's (CFIA) inspection program routinely monitors commercially sold aquaculture products to verify that the residue limits on registered pest control and drug products, established by Health Canada, have not been exceeded and that the products do not contain illegal chemicals.

Fisheries and Oceans Canada, Health Canada, and Environment Canada also have an interdepartmental agreement in place, under which they work together to regulate the safe use of pesticides and drugs in aquaculture today.

Health Canada’s website includes a list of approved veterinary drug products for use by aquaculturists, a public registry of pesticides registered for use in Canada, and a searchable database of product labels which indicates under what conditions these products may be used.

Further information can be found on Health Canada’s Drugs in Aquaculture and Pesticides and Pest Management pages.

The PMRA evaluates data on the environmental chemistry and toxicology of pesticides as well as their environmental fate (i.e. what happens to the pesticide once it enters the environment) to determine if and how a pesticide can be used in an aquaculture setting without presenting unacceptable risks. Directions and restrictions provided on the product label are based on that evaluation and they instruct how to use the pesticide to prevent unacceptable risk. Restrictions could include label statements outlining buffer zones or advising on factors such as timing and frequency of applications or on the rate at which the product can be applied. Pesticides must be used as directed by the product label.

Health Canada’s regional offices promote and verify compliance with the Pest Control Products Act through investigations, inspections and consultations. They have the mandate to: investigate the use, sale, and importation of products; perform on-site inspections of usage and storage of products; assay products and relevant environmental samples (e.g. sediment, water, and fish); and educate individuals, local officials, and grower groups as to regulatory requirements. When contraventions of the Act or regulations occur, appropriate enforcement measures are taken.

Further information can be found on Health Canada’s Pest Management Regulatory Agency’s website.

Pathogens occur naturally in the freshwater and marine environments. As with all types of farming, the process of raising farmed finfish like salmon includes a number of animal husbandry practices to ensure good animal welfare, and that fish remain healthy throughout the production cycle. Practices include using high-quality nutritional feed, providing a low-stress growing environment and, when diagnostic tests demonstrate the need, veterinarian prescribed antibiotic treatments against bacterial pathogens.

In Canada, antibiotics can only be used when they are required to fight disease, never to stimulate growth. Veterinarians can only prescribe drug products to treat farmed fish that have been approved for legal sale by Health Canada according to the Food and Drugs Act. In the past, most bacterial pathogens affecting farmed finfish were treated with antibiotics. However, the majority of the bacterial diseases may now be prevented using vaccines. This change in practice has drastically reduced the quantities of antibiotics used, which also substantially reduces the risks of bacteria in the wild from becoming antibiotic-resistant. However, there are still some diseases (e.g., Yellow Mouth) where vaccine treatments have not been developed or where vaccine treatments are not always successful or available (e.g. Bacterial Kidney Disease). In these cases farmers still rely on antibiotics to treat infected animals.

Pesticides are designed to either impair pest activity or kill them. Since many pests in aquatic ecosystems, like sea lice, occur naturally, there is always the potential for closely related “non-target” species (i.e., unintended animals exposed to the pesticide) to be impacted (e.g., lobsters, which, like sea lice, are crustaceans). Prior to being authorized for use, pesticides must go through a rigorous risk assessment by Health Canada to determine if there are any human and environmental health concerns. If the risk to “non-target” animals is low compared to the benefit of treating the pest, the product would become available on the market. However, if there is evidence that a product in use causes some form of significant unexpected environmental impact, further use will be restricted or the product banned. There are currently only two fully registered pesticides authorized for use in treating aquaculture pests (i.e., sea lice) in Canada: PARAMOVE^® (stabilized 50% hydrogen peroxide) and Salmosan^® (47.5% azamethiphos, an organophosphate). The hydrogen peroxide-based product does not kill the sea lice but rather causes mechanical paralysis, and the lice to release from the salmon. Analyses have shown that PARAMOVE^® is not persistent in the environment, and quickly breaks down into its component chemicals, which are oxygen and water. Thus, this product was determined not to be expected to result in an impact to lobsters. The organophosphate-based pesticide, when used according to the pesticide label instructions, will kill the sea lice (from muscular paralysis) but will not typically kill non-target species or persist in the environment for any period that results in an impact to local invertebrate populations. For further information on the potential fate and effects in the aquatic environment, refer to the 2013 assessment undertaken by Dr. Les Burridge.