Ontario Animal Health Network (OAHN) Aquatic Animal Health Report

This report is a communication for aquaculture producers in the province of Ontario, compiled by the Ontario Animal Health Network (OAHN)  

Aquatic Veterinary Services Summary

There were a number of diagnoses during the period of January to December 2020 in aquaculture production in Ontario. During the colder months, these diagnoses were primarily coldwater disease (Flavobacterium psychrophilum) and bacterial gill disease (Flavobacterium branchiophilum). During the warmer months, these diagnoses were primarily bacterial gill disease, nodular gill disease, Columnaris disease (Flavobacterium columnare) and ich (Ichthyophthirius multifiliis). Most of the concerns observed on fish farms in Ontario have been non-infectious and related to environmental conditions. However, bacterial kidney disease was detected in Ontario farmed fish for the first time in 2020.

Disease Spotlight: Bacterial Kidney Disease (BKD)

Bacterial kidney disease (BKD) is a chronic disease of salmonid fishes caused by the bacterium Renibacterium salmoninarum.  BKD was first described in 1933 in wild salmon from Scotland. Since then, BKD has been reported worldwide where salmonid fishes are present including North America, South America, Europe, Japan and Iceland.

Which species are susceptible?

BKD causes significant mortalities in salmon. It is known to cause up to 80% mortality in Pacific salmon and 40% in Atlantic salmon. Other salmonids have varying degrees of susceptibility. BKD has also been detected in brown trout, rainbow trout Arctic char and grayling.

How is the disease spread?

BKD may be transmitted horizontally, through contact with infected fish or water, and vertically, from infected broodstock eggs. It is thought infected fish shed bacteria in feces. Experimental evidence shows viable bacteria can persist for several weeks in fish feces and in sediment.

What should I look for?

Infected fish display a wide range of clinical signs; however, some are asymptomatic with no signs of disease. Clinical signs include lethargy, skin darkening, protruding eyes (exophthalmia), anaemia, distended abdomens, blood-filled blisters on the flanks and bruising (haemorrhaging) around the vent. Internal signs include presence of fluid in the abdominal cavity, swollen kidneys sometimes with white/grey lesions and diffuse white membranes over the internal organs. Trout often classically present with “spawning rash” a transient infection in scale pockets during spawning season resulting in a diffuse ulcerative appearing rash.

How can the disease be treated?

There is no effective treatment for BKD. Antibiotic medicated feed treatments (e.g. Oxytetracycline) have been used in attempts to minimize the severity of a BKD infection, though this does not resolve the infection. Good biosecurity, health monitoring and avoidance of infection are the most effective means of controlling the disease. There are some protocols for minimizing the risk of vertical transmission in infected broodstock.

National Farm Animal Care Council

The aquaculture sector has initiated the development of Canada’s first Code of Practice for farmed salmonids (salmon, trout, char). The draft Code was developed by a multi-stakeholder committee which was formed in November 2018. The public comment period runs from November 2, 2020 to January 7, 2021 and the projected is expected to be completed in the fall of 2021. More information on Code and the development process is available at https://www.nfacc.ca/codes-of-practice/farmed-salmonids.

Provincial Update

Fish Inspection Program

Effective January 1, 2020, Ontario introduced a new fish processing regulation under the Food Safety and Quality Act, 2001 (FSQA). Fish processors within scope of the new regulation will be required to obtain a licence by January 1, 2021. The new regulation is consistent with current industry standards, while protecting public health and supporting growth in the fish processing industry. Licensed fish processors in Ontario will be able to better brand their business by including their licence number on their packaging, in accordance with the regulation. The full regulation can be found at www.ontario.ca/laws/regulation/r19465.

Animal Health Act

The Animal Health Act (2009) is looking to update O. Reg. 277/12 – Reporting of Hazards and Findings. This list was developed when the Animal Health Act was created and has not been updated since 2009.  Hazards include diseases as well as other threats such as chemical or radiological threats. Hazards are listed as either immediately notifiable when diagnosed by a laboratory in Ontario, or periodically notifiable when total diagnoses are reported each year. There is concern that this list doesn’t reflect current Ontario animal health hazards, emerging diseases and of course, aquatic animal diseases are almost entirely missing from this list. A notice to stakeholders has been sent out and consultations will follow prior to finalizing the list of reportable hazards.

National Update

Federally Reportable Aquatic Animal Diseases

From January to December 2020, the Canadian Food Inspection Agency (CFIA) have confirmed cases of infectious salmon anemia in Atlantic salmon in New Brunswick, Prince Edward Island and Newfoundland. A single case of viral haemorrhagic septicaemia was detected in Atlantic herring in Newfoundland during the same time period. These cases represent both wild and farmed aquatic animals across the country. For more information about federally reportable aquatic animal diseases, please visit CFIA’s webpage tiny.cc/CFIA_Disease.

Infectious Hypodermal and Haematopoietic Necrosis virus

The CFIA was been notified of detections of Infectious Hypodermal and Haematopoietic Necrosis virus (IHHNV) in white leg shrimp populations in Texas, Florida and California in 2019. Import permits for live white leg shrimp originating from the USA remain cancelled. Currently, all shrimp operations in Canada haves ceased due to a lack of disease-free post-larvae. CFIA are working with the governments of the USA and Mexico to negotiate agreements with aquatic animal health authorities to ensure that Canada’s aquatic animal resources are protected and that impacts on trade are minimized.

Congratulations to Dr. Ed Creighton

Dr. Ed Creighton, one of our OAHN members and veterinarian at the Canadian Food Inspection Agency Guelph office is retiring! Ed has been a member of the OAHN aquatic network since it was formed in 2015. Good luck in the future Ed!  

OAHN Project Update

The Ontario Animal Health Network is currently working on developing a biosecurity toolkit for Ontario aquaculture producers to apply to their own farm biosecurity plans. This information will be made available to Ontario farmers for free and will teach you how to identify disease hazards, how to complete a risk assessment, how to identify risk management measures and how to write a standard operating procedure to minimize your risk. We expect this information will be made accessible in 2021, stay tuned for more information!