Dangers of illegal harvesting

Enjoy safe shellfish - check before you harvest

Bivalve molluscan shellfish have two hinged shells and include oysters, clams, scallops, mussels, and cockles. Because bivalve shellfish feed by filtering microscopic plankton from the water, changes in water quality can result in unsafe marine biotoxins, bacteria, or viruses building up in their tissue.

The Canadian Shellfish Sanitation Program (CSSP) is designed to minimize the health risks associated with the consumption of contaminated bivalve molluscan shellfish. The program is delivered by the Canadian Food Inspection Agency, Fisheries and Oceans Canada, and Environment Canada.

The CSSP routinely monitors the level of marine biotoxins, bacteria and other harmful contaminants and closes bivalve shellfish areas when levels of these substances exceed safe limits.

While the CSSP has controls in place to prevent contaminated bivalve shellfish from reaching consumers, harvesters also have a role to play by maintaining safe practices. There can be serious consequences if bivalve shellfish are harvested from an area that is closed for harvesting.

Harvesting shellfish from closed or prohibited areas is illegal

Apart from risks to human health, illegally harvesting bivalve shellfish can also damage the reputation of the Canadian bivalve shellfish industry and harvesters who work hard to provide a safe, high quality product.

Areas that have been assessed and determined to be contaminated are generally clearly marked by signs. However, if you are planning to harvest bivalve shellfish, it is your responsibility to check with the nearest Fisheries and Oceans Canada office to find out whether the area is closed.

Harvesting of shellfish is prohibited within 125 metres (410 feet) of a wharf, aquaculture operation (salmon growing cages) or floating accommodation, such as a float home.

Eating contaminated shellfish can cause potentially serious or fatal illness. Consumers should be aware of potential food safety issues associated with eating bivalve shellfish.

Marine biotoxins

Biotoxins, if present in the water, can accumulate in bivalve shellfish. Paralytic Shellfish Poisoning (PSP), Amnesic Shellfish Poisoning (ASP) and Diarrhetic Shellfish Poisoning (DSP) are the most common illnesses associated with marine biotoxins in Canada. Even cooked shellfish can still contain biotoxins.

Symptoms of PSP include tingling and numbness of the lips, tongue, hands and feet, drowsiness, dizziness, headache and difficulty swallowing. In severe cases, this can proceed to incoherent speech, difficulty walking, muscle paralysis, respiratory paralysis, and death.

Symptoms of ASP include severe nausea, vomiting and diarrhea within six hours, muscle weakness, disorientation, memory loss, abdominal pain, and dizziness.

DSP symptoms include diarrhea, nausea, vomiting and cramps.

Bacteria and viruses

Bacteria and viruses that may be present in the water in which shellfish live are capable of causing illness in humans. These include: Vibrio parahaemolyticus (Vp), Norovirus, and Hepatitis A.

Vp is a naturally occurring bacterium found in our coastal waters. The presence of Vp can increase in warm waters to levels that can make people sick, particularly during the summer months. Symptoms of an infection of Vp include diarrhea, abdominal discomfort, nausea, vomiting, fever, and headache.

Norovirus symptoms include diarrhea, abdominal discomfort, nausea, vomiting, fatigue and fever.

Hepatitis A symptoms can include abdominal discomfort, nausea, fatigue, fever, and jaundice. Persons with liver conditions are at risk for more serious illness.

Ways to ensure safe and legal harvest

• Look for signs that indicate the area is closed to bivalve shellfish harvesting.
• Notices about closures are also communicated to the fishing industry and the public through direct communications with harvesters, processors, local media and the Fisheries and Oceans Canada website.
• Access most up-to-date information using the real-time map of openings and closures of harvesting areas.
• Contact your local Fisheries and Oceans Canada offices.

For more information on shellfish food safety, visit the shellfish food safety page.