Open Data

Chemical Monitoring in Local Foods: Mercury in Fish


Mercury (Hg) enters the environment through natural processes and human activities. There are three forms of Hg: elemental (metallic) mercury, inorganic mercury salts and organic mercury compounds. Methylmercury (MeHg) is often formed from inorganic mercury during biological processes such as methylation by microorganisms in water and sediment. MeHg can accumulate in aquatic organisms including fish. People are exposed to very low levels of mercury in the air, water and food. Some people may be exposed to relatively higher levels of mercury by eating MeHg-containing fish. MeHg accumulates in the human body over time and because it is a known neurotoxin, it is necessary to limit human exposure to MeHg. To protect public health, Health Canada has proposed mercury guidelines and advisories for fish consumption based on total mercury (THg; all forms of Hg in a sample).

This dataset was collected as part of long-term monitoring of mercury levels in various species of fish in Albertan water bodies (e.g., rivers and lakes). Fish were collected by Alberta Environment and Parks, and the chemical analyses and data quality assurance and control were conducted by Alberta Health. This dataset forms the basis for part of the series of Alberta Health Mercury in Fish reports (found here: ) and is also used to inform or issue local fish consumption advisories on My Wild Alberta website:

Each row in the dataset represents the concentration of THg in a single fish sample for a given species, at a specific location during a particular year. This dataset contains data from 1997 to 2021. The dataset is useful for the general public, specifically for people who rely on local fish for subsistence or recreational anglers. This dataset may also be useful to academic researchers studying Hg in the environment.


March 18, 2024

Country or traditional foods Fish Health Hg Local foods Mercury Mercury Guidelines environmental health environmental public health

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Mercury in Fish

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Mercury (Hg) concentrations represent total mercury (THg) in fish muscle and are presented based on wet weight. Between 1997-2008, 1 g of tissue was digested using 5 mL of nitric acid using microwave digestion, diluted to 100 mL with distilled water and BrCl. Hg was analyzed using a flow injection Hg system and cold-vapour atomic absorption detection. The sample volume used was 500 uL. The method detection limit (MDL) was 0.003 mg/kg.

In 2009, 0.2 g of tissue was digested with 7 mL of 7:3 HNO3/H2SO4 in a vented oven and diluted with 19 mL of distilled water. 1 mL of BrCl was used as an oxidizing agent. A 0.5 mL subsample was diluted with distilled water to 50 mL, and neutralized with 0.04% (v/v) hydroxylamine hydrochloride. Samples were analyzed for THg using cold-vapor atomic fluorescence detection. The MDL was 5.1 x 10-4 mg/kg.

Between 2010-2019, 0.09-0.12 g of tissue was introduced into the Milestone DMA-80 Direct Mercury Analyzer (DMA-80) to be thermally decomposed in an oxygen flow. Combustion products were further decomposed in a hot catalyst bed. Mercury vapours were trapped on a gold amalgamator and desorbed for quantitation using atomic absorption detection. The MDL was 0.005 mg/kg. SRM controls are within ±10% of certified values. The percent difference in concentration in duplicate samples is within ±10%. A percent difference of >10% may be acceptable if the concentration is <LOQ. When there was duplicate analysis of a sample, the first result was reported in this dataset.

For additional information about sampling protocols or analytical methodology, please consult the Alberta Health (AH) series of reports ( The reports and fish consumption advisories may contain data from other agencies that AH does not own nor have permission to release. Therefore the dataset provided here may not be sufficient to generate the results shown in the reports or current fish consumption advisories. Data has been cross-referenced against an internal Alberta Environment and Parks database containing sample collection and fish biometric data.


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Environmental Public Health Science Team, Health Protection Branch, Alberta Health

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