- Why is it important to check for red tide and sanitary closures before harvesting?
- What shellfish and bivalves are affected by red tide and other closures?
- What is red tide?
- What are other types of shellfish closures?
- How to check for red tide and other closures by location
Learning how to check for red tide and shellfish closures in BC is an essential part of harvesting shellfish safely. Every harvester must check for red tide and shellfish closures before they eat bivalve molluscs like oysters, clams, mussels, and scallops that they find in BC.
This article was updated to meet 2020 government regulations.
Why Is It Important To Check For Red Tide and Sanitary Closures Before Harvesting?
It’s important to check for red tide and sanitary closures before harvesting shellfish and bivalves like oysters, clams and mussels because not checking risks the health of anyone who ingests contaminated edibles. Red tide, toxins, and bacteria are legitimately dangerous and must be taken seriously.
Most people, especially visitors to BC and the Sunshine Coast, don’t know about red tide or other shellfish closures that occur in British Columbia – not to mention the dismaying number of people who have no idea they need a fishing license to harvest shellfish here. Knowing to check for red tide and shellfish closures simply isn’t common knowledge.
I often hear from visitors and inexperienced foragers in BC who tell me about how they were surprised to find oysters or clams on the beach, and how much they enjoyed eating them fresh or raw immediately after harvesting them.
While I’m always excited to hear about people eating wild food, these kinds of inexperienced shellfish harvesting stories immediately set alarm bells off in my head. I almost always ask these shellfish harvesters whether they checked for red tide and shellfish closures before they ate them, and I’m almost always dismayed to find that they have no idea what I’m talking about. Red tide, toxins, and other bacteria closures are really not worth the risk.
Read this guide on how to check for red tide and shellfish closures in BC so you can harvest shellfish safely and confidently.
Pictured: Foraged wild scallop, oysters, sea asparagus and seaweed from the coast of British Columbia that I harvested.
What Shellfish and Bivalves Are Affected By Red Tide and Other Closures?
Red tide and shellfish closures typically affect bivalves, but they can restrict the safe harvest of any type of shellfish or bivalve, depending on the type of closure. Here are common definitions you should know before reading about these closures:
- Bivalve molluscs are commonly defined as shellfish that have two shells. For example, oysters, clams, mussels, and scallops are bivalves.
- Types of shellfish that are not considered bivalves include crabs, prawns, and shrimp.
- Finfish and other types of fish are not considered shellfish.
What is Red Tide?
Red tide is common name for a harmful algal bloom, which is made up of a large concentration of aquatic microorganisms (algae, a type of phytoplankton) that multiply rapidly during certain marine conditions. The name stems from the colour of the algae, which can appear to turn the water red or brown in when densely accumulated.
Red tide can contain algae that produce dangerous biotoxins that can contaminate bivalve shellfish in the area, making the bivalves unsafe to eat. In BC, red tide is associated with paralytic shellfish poison (PSP), which can have serious or fatal consequences on humans.
Algal blooms occur most often during the spring and summer months, as sunlight and the warm water temperature can encourage the growth and proliferation of algae. However, algal blooms can occur throughout the year, no matter what the temperature or weather is like.
It’s important to know that some algal blooms do not change the colour of the water and that red tide often cannot be seen from the shore by the naked eye. It’s always necessary to check for red tide and other shellfish closures, whether or not the water looks red or brown coloured.
Cooking shellfish does not destroy the biotoxins associated with red tide or paralytic shellfish poisoning. Cooked shellfish can still be dangerous if affected by this closure. Always check for red tide and shellfish closures in BC before harvesting wild oysters, clams, and other shellfish.
Sources: Monica Bloom, “Red Tide – A Harmful Algae Bloom” (Microbial Life Educational Resources); “What is red tide?” (National Ocean Service); Danielle Hall, “What Exactly Is a Red Tide?” (Smithsonian)
What are Other Types of Shellfish Closures?
There are a number of reasons why shellfish closures could occur in your area, other than just red tide. Canada’s Fisheries and Oceans department tests each tidal area and its shellfish for biotoxins and bacteria to make sure that people can harvest shellfish safely.
Other types of shellfish closures:
- Amnesic shellfish poison (ASP) – bivalve molluscs only
- Diarrhetic shellfish poison (DSP) – bivalves molluscs only
- Domoic acid – shellfish and crabs
- Sanitary closure or contamination
Cooking shellfish does not destroy the biotoxins associated with ASP, DSP, domoic acid, or sanitary contamination. Cooked shellfish can still be dangerous if they are affected by these closures.
How to Check for Red Tide, Shellfish and Bivalve Closures By Location
Follow these steps to check for red tide, shellfish and bivalve closures in BC by location:
1. Search for your location on the Marine Biotoxin Contamination Closures – Pacific Region page on the Fisheries and Oceans Canada government website.Click on your city, town, or landmark and tidal area in the chart at the bottom of the page. If you can’t find your city, town, or landmark, use the search function on the right-hand side.
2. Identify your region on the area map. Click on the area map on the right-hand side of the page. Selecting the area map will open a new page that breaks down your location into tidal subareas. If you’re not sure exactly what tidal subarea you’re in, try opening your Google Maps or Maps app and using GPS to locate where you are on a map. Cross-reference where you are in your app to where you are on the regional tidal subarea map.
3. Check the shellfish closure subarea by returning to the region page and finding the tidal subarea you’re in the shellfish closure chart. Check what shellfish are open for harvesting in the tidal subarea you’re in. All shellfish open to harvesting and shellfish closures will be listed in the chart under your tidal subarea.
4. Check the official Fishery Notices pages here for special notices regarding your area. Search by using either Command + F or Control + F on your computer to search for your tidal area to see if there are any new shellfish closures or important information to know before harvesting in that area.
5. Alternatively, call your local DFO office for assistance. You can find your local DFO contact phone number here. If you aren’t able to check whether there are any red tide or shellfish closures in your area online, you can always call your local Department of Fisheries and Oceans (DFO) office by searching for your local DFO officer. Remember, always check for red tide and shellfish closures in BC before harvesting wild bivalves.
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The post was originally published October 17, 2017 and was updated on November 27, 2020 and on January 2, 2021.