(l-r) Gerry Burry, Dr. Diane Morrison, Brad Boyce
Low antibiotic use is the rule, not the exception, at Marine Harvest Canada, and there is data to back it up. Marine Harvest Canada fish harvested in 2007 received an average of 50 grams of antibiotic per metric ton.
If you equate that to what a 5.0 kg fish would have received it’s only the weight of a standard tablet of Ibuprofen, or 0.255 grams per 5.0 kilogram fish. Not a lot.
“Our fish health status is currently very good and our need for antibiotic treatments is low”, says Dr. Diane Morrison, Fish Health Director.
When it comes to antibiotic use, fish aren’t all that different from people in a key way: antibiotics are used solely to treat bacterial infections, not viruses or parasites. For example, we won’t receive an antibiotic prescription from our doctor for a cold but we will for strep throat. At MHC there are two conditions where antibiotic use is sometimes required: mouth rot (a concern for smolts) and BKD (bacterial kidney disease, seen in grow-out fish). In the past antibiotics have been used for furunculosis and vibrosis, however, with the use of effective vaccines this is rarely the case. The majority of antibiotic use occurs in the first six months at sea when fish adjust to the saltwater. All antibiotics have a required withdrawal time, during which the fish cannot be harvested, as with other agriindustries (chicken, beef, pork). This ensures food safety for the consumer.
Avoidance is the key, says Morrison. Solid management all the way through the production cycle, and consistently followed biosecurity procedures go a long way towards keeping the occurrence of disease low. Antibiotic treatments only occur when mortality or productivity warrant it. An essential part of the picture is looking for the why – what caused the outbreak in the first place and how do we prevent it in the future. “No antibiotic use is our long term goal”, adds Morrison.
And based on industry use, which is tracked by the provincial Ministry of Agriculture and Lands, it’s not an unrealistic goal.
In 1995, when MAL began record-keeping, industry wide antibiotic use was 456 grams per metric ton of salmon produced.
In 2007, that had dropped to only 110 grams per metric ton of salmon produced across the industry.
With a focus on continuous improvement we should be able to reduce our antibiotic use even further. Veterinarians need tools in the toolbox (antibiotics) to manage bacterial disease outbreaks, but our priority should be ensuring best management of our fish from egg to harvest.
By Gina Forsyth