Frequently Asked Questions

What is methylmercury?

Mercury is a naturally-occurring element found in rocks, soils, water and air. Mercury is released into the air naturally, and from household and industrial wastes such as burning coal. Mercury in the air returns to the ground and water with the rain and snow. Once in a lake, mercury is converted to methylmercury by bacteria or chemical reactions.

How does methylmercury get into fish?

Fish absorb methylmercury from water as it passes through their gills, or from the prey they eat. It is likely that all fish contain small amounts of mercury because mercury is a naturally occurring element. However, large predatory fish, like walleye and northern pike, accumulate more methylmercury as they consume smaller fish. This is why we often find high levels of methylmercury in large walleye and northern pike caught in Alberta water bodies.

Methylmercury is found in all fish tissues, including flesh. Methylmercury is easily absorbed by humans when eating fish. There is no method of cooking or cleaning fish which reduces the amount of methylmercury in a meal.

What are the potential health risks of eating mercury-contaminated fish?

Methylmercury builds up in your body over time. Small amounts of mercury can be safely eliminated, but large amounts of mercury in the body may damage the nervous system. An unborn baby is more sensitive to mercury poisoning due to rapid brain development during this period.

What levels of methylmercury are safe to eat?

People generally benefit from eating fish, but young children and women of child-bearing age or pregnant women may be harmed if they eat too much fish containing high levels of mercury. It is important to know the safe amount of fish you can eat.

Health Canada has set a guideline of 0.5 parts per million (ppm) of mercury for retail fish and seafood for people who infrequently eat commercially-produced fish and seafood. For safe consumption amounts of retail fish and seafood, please check the Health Canada website.

For those who eat fish on a day-to-day basis, such as First Nations, Métis and Inuit people, Health Canada recommends limiting fish consumption if the mercury levels in fish are more than 0.2 ppm and under 0.5 ppm.

How can people find out whether the fish they caught is safe to eat?

The Government of Alberta is responsible for issuing and reviewing fish consumption advisories for fish caught from local water bodies. Fish consumption advisories enable people to make informed decisions about what is a safe amount of fish that can be consumed, while balancing the potential health risks and known health benefits of eating fish. Fish consumption advisories can tell the public which fish should be eaten less often or should not be eaten at all depending on the mercury levels in particular species, fish size and water bodies.

Fish consumption advisories are posted in the Alberta Guide to Sportfishing Regulations under “helpful information.” They are also posted on My Wild Alberta, and on the Should I Eat This Fish? page of this website, and the “Should I Eat this Fish?” App.

Who should consider restricting their fish consumption?

In order to balance the benefits and risk of eating fish, consumption limits in the advisories are recommended for Albertans who eat fish caught from local water bodies on a regular basis for their entire life time. These fish consumers, also called a “high intake group,” may include First Nations people and recreational anglers in Alberta.

Different fish consumption limits are provided to four consumer groups: children 1 to 4 years old; children 5 to 11 years old; women of child-bearing age (15 to 49 years old) and pregnant women; and adults, plus children over 12 years old. Because women of child-bearing age and young children are more susceptible to potential health risk posed by exposure to high levels of mercury, they should eat less fish.

How much fish can I eat as posted in fish consumption advisories?

Recommended fish consumption limits are available in tables on the Should I Eat This Fish? page of this website, the “Should I Eat This Fish?” App, and on My Wild Alberta . If mercury levels are over 0.5 ppm, you will see an “avoid” indicator for women of child-bearing age and pregnant women, and young children. Adults and children over 12 years old can eat the recommended amount of fish as posted in the tables.

You can eat certain amounts of fish that have mercury levels less than 0.5 ppm. Please check carefully the location of water bodies, fish species and fish size. For example, a northern pike weighing over three pounds from the Red Deer River (downstream from the mouth of the Blindman River), has consumption limits of four servings per week for women of child-bearing age and pregnant women, two servings per week for children aged five to 11 years, and one serving per week for children aged one to four years . Adults and children over 12 years old can eat northern pike without restricting the serving size.

If you catch northern pike less than three pounds from the Red Deer River (downstream from the mouth of the Blindman River), you can eat more servings than the amounts posted in the tables. If you catch other types of fish (not walleye, northern pike and mountain whitefish) from the Red Deer River (downstream from the mouth of the Blindman River), you can eat fish without restricting the serving size.

How do you estimate the amount of fish being eaten?

One serving equals 75 grams, ½ cup, 2.5 ounces, or a piece of cooked fish that fits into the palm of your hand.

How Can I print My Results?

To save as a pdf click “Save/Print Results”. If you are using the Chrome web browser simply choose ' Save as PDF' as the printer destination. For other browsers you may need to download a PDF saver (Bullzip, CutePDF, doPDF are some third party options) and follow their installation instructions. Once a PDF saver is installed you would select it as the printer destination.

For more information contact:

Health Protection Branch

Alberta Health

P.O. Box 1360, Station Main

Edmonton, Alberta, T5J 1S6

Telephone: 1-780-422-4518

Fax: 1-780-427-1470

Technical Notes

To protect public health, Health Canada has proposed mercury guidelines, and advisories for different fish consumer groups (Health Canada,1979; Feeley and Lo, 1998; Health Canada 2007, Feeley 2008) based on total mercury (THg) or methylmercury (MeHg). These values are expressed either in units of mg THg or MeHg per g of fish flesh or as a Provisional Tolerable Daily Intake (pTDI) in units of mg THg or MeHg per kg of consumer body mass per day:

1. 0.5 mg THg/g for all commercial fish/seafood (Guideline);
2. 1.0 mg THg/g for certain commercial fish species such as fresh and frozen tuna, shark, swordfish, escolar, marlin and orange roughy which are known to be consumed less frequently (Advisory); and
3. 0.2 mg THg/g for subsistence consumers (Advisory)
4. 0.2 mg MeHg/kg bw/d pTDI for women of reproductive age and young children (Guideline);
5. 0.47 mg MeHg/kg bw/d pTDI for the general population (Guideline).

The guidelines for commercial fish/seafood are used as a general screening criterion, with the knowledge that most species of commercial fish usually contain lower levels (< 0.1 mg/g) of mercury. This guideline is enforceable by the Canadian Food Inspection Agency (CFIA) for commercial fish. For example, the CFIA has been monitoring total mercury (THg) levels in commercial fish caught from Lake Athabasca in Alberta since the early 1990s. The recommendation for subsistence consumers proposed by Health Canada was put in place in the 1970s when the Medical Services Branch became aware of long term fish consumption patterns of over 100 g/day (Health Canada 1979). The recommendation is for First Nations and Inuit people relying on subsistence fresh water fishing First Nations and Inuit subsistence consumers should limit their fish consumption if the mercury levels in the fish they are eating are over 0.2 mg THg/g of fish tissue. Consumption of fish containing over 0.5 mg THg/g of fish tissue should be avoided by all consumers. Fish consumption advisories are developed based on these pTDIs. These advisories provide the public with a warning of potential health risk resulting from consuming local mercury containing fish. Fish consumption advisories are designed to minimize the potential health risks to fish consumers who can voluntarily restrict their fish consumption.

The criteria for issuing fish consumption advisories are:

1. If mercury levels are higher than 0.5 mg/kg (commercial fishing guideline), the advisory would be to “avoid consuming fish”;
2. If mercury levels are between 0.2 - 0.5 mg/kg (Health Canada recommendation for subsistence consumers), the advisory would provide “consumption limits”;
3. If mercury levels are less than 0.2 mg/kg, an advisory would not be issued;
4. If the fish sample size is less than 5 fish per location sampled, an advisory would not be issued; and
5. If the lakes are used for commercial fishing, advisories would not be issued until after consulting with the Canadian Food Inspection Agency.

For more information and abovementioned references please see the Mercury in Fish in Alberta Water Bodies 2009-2013.

Disclaimer

Please note that the data presented here is only that which is owned by the Government of Alberta. Additional research and reporting such as the Alberta Health Mercury in Fish reports and fish consumption advisories may be based on data from other government agencies that Government of Alberta does not own nor has the permission to release. The data presented on this website may not be sufficient to generate the results shown in the reports or as the basis for issuing fish consumption advisories.

Some waterbodies not displayed here may still have advisories issued for them. For the latest available advisories, please visit our Should I Eat This Fish? app or the My Wild Alberta website. For technical details and a listing of data sources used to inform the advisories, please consult with the Alberta Health Mercury in Fish reports .