Introduction of "Therapeutants" into the Marine Environment
Industrial production of
farmed salmon inevitably leads to disease and parasite outbreaks, leading the farm operators to treat their
fish with a variety of chemical substances in the form of antibiotics and
pesticides. The widespread use of chemicals raises a range of concerns.
It is standard operating
procedure for farmed salmon in Canada to be treated with emamectin benzoate
(trade name SLICETM), a
parasiticide treatment used to combat sea lice.
SLICE is mixed with feed pellets, but not all the feed pellets are eaten by the farmed fish, and uneaten food will drift down to be consumed by other, wild, marine organisms. Therapeutants such as SLICE thereby enter the marine food chain and potentially impact the survival of other species. SLICE acts by inhibiting the development of chitin (which makes up the shells of marine organisms) and has been found to induce early molting in lobsters, suggesting possible impacts to other crustacean species.[1],[2]
The regular use of therapeutants puts a selection pressure on the disease organism to become resistant. There is recent (2010) concern about SLICE resistance in sea lice in Norway and New Brunswick.[3],[4]
It is also unknown what the impacts are at an ecosystem level. Yet, when SLICE is released into the marine environment, there is no requirement to inform others such as local First Nations and commercial prawners, who depend on a safe marine environment for their food.
In the United States, emamectin benzoate is not on the list of "Approved Drugs for use in Aquaculture" (regulated by the Food and Drug Administration).[5],[6],[7] Canada has not applied precaution in approving the use of the pesticide and not requiring the previous withdrawal period of 68 days.[8],[9],[10]
With the widespread use of antibiotics in open net-cage salmon farms, there is also great concern that the introduction of antibiotics into the marine environment contributes to antibiotic resistance.[11] Antibiotic resistance is an emerging global health issue seriously threatening the treatment of infectious diseases.[12]
[2] Detection of emamectin benzoate in non-target spot prawn (Pandalus platyceros) and determination of biological effects; Sea Lice 2010 Conference
[4] Various studies presented at Sea Lice 2010
[10] "Notice of compliance" 2009-06-29. Click for Source 10.
