What You Should Know About Shellfish Contamination

Check Shellfish Contamination Closures (PSP and ASP)

Gathering shellfish to eat is a favourite pastime, but it can be harmful or even fatal if the shellfish are contaminated. Bivalve molluscs such as clams, oysters, scallops, and mussels feed by filtering the water in their environment. The bivalve shellfish can accumulate any toxins, bacteria, or pollutants, from the surrounding waters. Stringent standards exist for shellfish to ensure human health. Water and shellfish sampling programs are undertaken by DFO, Environment Canada, and the Canadian Food Inspection Agency to ensure that areas are safe for shellfish harvesting.  Areas that exceed the allowable limits of any harmful substances are closed to shellfish harvesting.

For the most current information on the location of bivalve shellfish closures:

• check with the DFO office nearest to where you intend to harvest,
• visit the shellfish table
• For PSP (Red Tide) closures call the Openings and Closures 24 Hour
  Toll Free Line : 1-866-431-FISH (1-866-431-3474) or (604) 666-2828 (Lower Mainland).

 Expect in-season changes.

PARALYTIC SHELLFISH POISON
(PSP/RED TIDE)

AMNESIC SHELLFISH POISON

SANITARY CONTAMINATION

VIBRIO PARAHAEMOLYTICUS

PARALYTIC SHELLFISH POISON (PSP or Red Tide)

Change to Public Notification of PSP (Red Tide) Closures for Bivalve Shellfish *September 2006*

Microscopic marine organisms produce toxin that can accumulate in bivalve shellfish such as clams, oysters, mussels and scallops.  Only bivalve shellfish accumulate the toxin by filter-feeding; however crabs and predatory molluscs such as moon snails may concentrate the toxin in their viscera.  Paralytic shellfish poisoning can occur at any time of the year and may change rapidly in season.

Consumption Risks: This is a serious illness that can cause paralysis or death.

To Reduce the Risks:  Check to ensure that the area that you intend to harvest is open, immediately prior to harvesting.  Discard the viscera of crabs and predatory molluscs if they are harvested in areas closed for PSP.  To reduce the risk in areas that are open to butter clams, discard the siphon (neck), gills, and liquid released during cooking.  In areas open for scallops, discard the roe and viscera.

Be Aware of the Symptoms:  Tingling of lips and tongue which may spread to fingers and toes, headache, or dizziness.  As the effect of the toxin progresses, there could be a loss of muscular co-ordination, paralysis, and inability to breathe.

At the First Sign of Any Symptoms: Induce vomiting, take a laxative, and drink water with baking soda.  Seek medical attention immediately, do not wait to see if symptoms progress.

Myths About Red Tide

AMNESIC SHELLFISH POISON (ASP or Domoic Acid)

Similar to the PSP toxin, ASP toxins come from algae blooms in the marine environment that accumulate in the filter-feeding bivalve shellfish.

Consumptive Risks:  Although there have been no reported illnesses from ASP in BC the toxin has been found in BC shellfish.  In other areas of Canada, people have become ill from eating ASP contaminated shellfish.  The symptoms of this illness are nausea, vomiting, diarrhea and memory loss.

To Reduce the Risks:  Check to ensure that the area that you intend to harvest is open, immediately prior to harvesting. 

SANITARY CONTAMINATION

Shellfish may be contaminated by human or animal faeces that contain bacteria or viruses hazardous to human health.  Pathogens such as Norwalk virus, Hepatitis A virus, or salmonella may be concentrated in bivalve shellfish that live in sanitary contaminated areas.

Consumptive Risks:  Consumption of raw or partially cooked bivalve shellfish from contaminated areas increases the risk of illness, especially for individuals with certain medical conditions or with compromised immune systems. 

To Reduce the Risks:  Check to ensure that the area that you intend to harvest is open, immediately prior to harvesting.  As an added precaution, cooking the shellfish may destroy the common micro organisms of public health concern. 

VIBRIO PARAHAEMOLYTICUS (VP)

A type of bacteria that is naturally found in our coastal waters.  It is more prevalent in the summer with warmer water temperatures, and can concentrate in filer feeding bivalve shellfish.

Consumptive Risks:  Illness such as diarrhea, nausea and vomiting

To Reduce the Risks:  Store bivalve shellfish frozen at -18° C (0° F) or refrigerate at 4° C (40° F) and cook the shellfish for five minutes at 60° C (140° F).