The impoundment of hydroelectric reservoirs leads to the conversion and circulation, in the aquatic environment, of mercury already present in plants and flooded soil. The result is an increase in fish mercury levels for a period ranging from 10 to 35 years, depending on the fish species and reservoir characteristics. From the early 1980s until about 2010, Hydro-Québec conducted an extensive research program designed, on the one hand, to determine the effects of the increase in mercury on fish, birds and mammals, and on the other hand, to manage the potential risk to the health of fish consumers.

The program’s specific objectives were the following:

  • Study the fate of mercury in natural and modified environments in Northern Québec.
  • Determine the effects of increased fish mercury levels on wildlife.
  • Examine the health risks and benefits of fish consumption.
  • Improve the methods of predicting the impacts of hydroelectric projects.
  • Search for ways to mitigate the increase in fish mercury levels caused by reservoir impoundment.

The results obtained from this program show that mercury levels in modified environments are not harmful to populations of fish, birds and mammals that eat fish. The recent monitoring of fish mercury levels in hydroelectric developments and of the peripheral population’s exposure to mercury have shown that, at the levels of mercury observed in Québec’s reservoirs, the health benefits of eating fish far outweigh the mercury-related risks. Hydro-Québec is now focusing its efforts on developing, in close collaboration with regional public health authorities, consumption guides which will allow recreational anglers and subsistence fishermen to continue to benefit from the great nutritional value of fish while avoiding mercury-related risks.

Video: How are fish mercury levels monitored?

Example of the Eastmain-Sarcelle-Rupert complex: In the areas affected by the partial diversion of the Rupert, a team follows the evolution of fish mercury levels. In light of the results, we produce a fish consumption guide in collaboration with the Cree Board of Health and Social Services of James Bay to promote the benefits of healthy fish consumption to Crees.

Specialized documentation

Mercury in reservoirs

Technical reports on the monitoring of mercury in reservoirs

  • GENIVAR. 2012. Aménagement hydroélectrique Sainte-Marguerite-3. Suivi environnemental 2011. Évolution des communautés de poissons et du mercure. (Sainte-Marguerite-3 hydroelectric development. Environmental follow-up 2011. Changes in fish communities and mercury). Report prepared by GENIVAR for Hydro-Québec. 82 p and apps (Report in French) Summary [PDF 47 Kb – in French only]
  • Therrien, J. and Schetagne, R. 2012. Centrales de l'Eastmain-1, de l'Eastmain-1-A et de la Sarcelle et dérivation Rupert. Environmental monitoring during operation phase (2011). Monitoring of fish mercury levels. Joint report by Consortium Waska-GENIVAR and Hydro-Québec Production. 73 p and apps. (Report in French, Executive Summary in PDF format) Summary [PDF 2.4 Mb]
  • Therrien, J. 2011. Suivi environnemental du réservoir Robertson (1990-2010). Évolution des teneurs en mercure dans la chair des poissons. (Environmental monitoring of the Robertson reservoir (1990-2010). Changes in fish communities and mercury). Report prepared by Génivar for Hydro-Québec Distribution. 61 p and apps. (Report in French) Summary [PDF 19 Kb]
  • Schetagne, R., J. Therrien, and R. Lalumière. 2002. Suivi environnemental du complexe La Grande. Évolution des teneurs en mercure dans les poissons. Rapport synthèse 1978-2000. GENIVAR and Hydro-Québec Production. 193 p and apps. Report [PDF 7.8 Mb – in French only]
  • Schetagne, R., J. Therrien, and R. Lalumière. 2013. Environmental Monitoring at the La Grande Complex - Evolution of Fish Mercury Levels. Summary Report 1978-2012. Joint report by GENIVAR and Hydro-Québec Production. 172 p and apps. Summary [PDF 3.0 Mb] Complete Report [PDF 9 Mb]

All these reports are available at Hydro-Québec’s Environment & Communities Documentation Centre.

Monograph: Mercury in northern Québec

  • Lucotte, M., R. Schetagne, N. Thérien, C. Langlois and A. Tremblay. 1999. Mercury in the Biogeochemical Cycle: Natural Environments and Hydroelectric Reservoirs of Northern Québec (Canada). New York, Springer. 334 p Summary [PDF 51 Kb]

This monograph is available for consultation at the following libraries:

  • UQAM’s science library
  • Université de Sherbrooke’s Sciences et Génie (science and engineering) library
  • McGill University’s Schulich Library of Science and Engineering

It is also available at Hydro-Québec’s Environment & Communities Documentation Centre.

Posters and presentations on the mercury issue

Mercury – The Romaine complex

Mercury in hydroelectric reservoirs

Mercury sources

Mercury is found everywhere in the environment. It is in the air, soil and vegetation, as well as in lakes and rivers. It can be released into the air naturally, by volcanoes and forest fires, or as a result of human activities such as coal burning and waste incineration. In the Nord-du-Québec region, it is carried through the atmosphere over long distances, and falls into lakes and forests with dust particles and rain. Mercury that is present mainly in inorganic form is relatively harmless, because it is not readily assimilated by living beings.

The Robert-Bourassa development and its reservoir.

Conversion of mercury

Once it enters lakes and rivers, inorganic mercury is converted by bacteria into a form that is easily taken up by live organisms. This form of mercury (methylmercury) can become toxic in high concentrations. The concentrations of methylmercury increase as it passes through the food chain, from plankton (small plants and animals living suspended in the water) to aquatic insects and on to fish.

Once it enters natural lakes, inorganic mercury from the atmosphere is converted by bacteria into organic mercury. Unlike inorganic mercury, organic mercury is readily assimilated by aquatic organisms. The concentration of mercury increases as it passes through the food chain, from plankton to fish.
Figure 1.2: Fate of mercury in natural lakes

Fish (such as northern pike, walleye and lake trout) that eat other fish contain more mercury than fish (such as lake whitefish and brook trout) that feed on insects. Mercury levels in fish that do not eat fish are generally well within the Canadian marketing standard of 0.5 mg/kg for fisheries products. However, even in natural lakes, levels found in fish that eat other fish often exceed this standard. Mercury accumulates throughout the fish's life, meaning that the older and larger the fish, the higher the mercury level. All the fish in all the lakes and rivers in Québec contain mercury.

Mercury levels vary greatly from one lake to another, depending on each lake's specific characteristics. In the La Grande complex region, for example, average mercury concentrations in 800-mm-long northern pike vary from 0.37 to 1.22 mg/kg. In this case, according to Québec public health authorities, the recommended consumption for adults in general ranges from two to eight northern pike meals per month, depending on the water body from which the fish came. Calculations are based on an eight-ounce portion of fish per meal.

Mercury and reservoirs

In recently impounded hydroelectric reservoirs, the green parts of the terrestrial vegetation (i.e., the ground cover, leaves and moss) provide food for the bacteria that convert the inorganic mercury to methylmercury, which is easily accumulated by living organisms (plankton, insects, fish, animals and humans). Fish in and downstream from reservoirs consequently contain more mercury shortly after impoundment. However, the phenomenon is temporary, since the green parts of the vegetation are quickly decomposed by the bacteria. Submerged tree trunks and branches do not release mercury, as their decomposition is minimal.

The flooded soil and vegetation provide food for the bacteria that convert the inorganic mercury to organic mercury. Reservoir impoundment does not lead to an increase in the quantity of mercury present, but it facilitates its conversion into organic mercury, which intensifies its transfer to—and accumulation in—plankton and fish.
Figure 1.3: Fate of mercury shortly after reservoir impoundment

In the different reservoirs in the La Grande complex, average fish mercury levels increased by factors ranging from 2 to 8, depending on the species and reservoir.

Figure 1.4 shows that mercury levels in lake whitefish (insect-eating fish) from the reservoirs in the western sector of the La Grande complex increased for about 20 years, before returning to levels equivalent to those measured in the region's natural lakes.
Figure 1.4: Changes in mercury levels in 400-mm lake whitefish in reservoirs in the western sector of the La Grande complex
Figure 1.5 shows that mercury levels in lake whitefish from the eastern sector of the La Grande complex returned to levels equivalent to those measured in the region's natural lakes in 10 years.
Figure 1.5: Changes in mercury levels in 400-mm lake whitefish in reservoirs in the eastern sector of the La Grande complex
Figure 1.6 shows that mercury levels in walleye (piscivorous fish) from the La Grande complex reservoirs increased for 20 to 30 years, and then returned to levels equivalent to those measured in the region's natural lakes.
Figure 1.6: Changes in mercury levels in 400-mm walleye in reservoirs in the western sector of the La Grande complex

A temporary phenomenon

Monitoring of reservoir fish has shown that mercury levels in insect-eating species such as lake whitefish return to levels equivalent to those in natural lakes after 10 to 20 years. In fish that feed on other fish, such as walleye, the return to normal levels takes longer and is usually complete after 20 to 35 years. The increase in mercury levels is temporary, because the main mechanisms involved in the production of methylmercury and its transfer to fish are intense shortly after reservoir impoundment but are relatively short-lived. The increased methylmercury production generally ends 8 to 10 years after impoundment, due to the rapid depletion of the readily decomposable elements of the flooded soil and vegetation, which provide food for the bacteria that convert the inorganic mercury to methylmercury. After this time, methylmercury transfer to fish by periphyton, zooplankton and insect larvae is reduced to the level occurring in natural lakes.

The increased methylmercury production generally ends 8 to 10 years after impoundment, due to the rapid depletion of the readily decomposable elements of the flooded soil and vegetation, which provide food for the bacteria that convert the inorganic mercury to methylmercury. After this time, methylmercury transfer to fish is reduced to the level occurring in natural lakes.
Figure 1.7: Fate of mercury several years after reservoir impoundment

Therefore, fish born 8 to 10 years after reservoir impoundment live in an environment where the production and transfer of mercury along the food chain are similar to those of neighboring natural lakes. Also, 20 years after impoundment, non-piscivorous fish of an average length that are about 10 years old have mercury levels equivalent to those of fish in natural lakes.

Mercury and fish consumption

For most people, the main source of mercury exposure is fish consumption. Methylmercury (or organic mercury) is readily absorbed by the human digestive system. It is then carried through the blood to all organs in the body. The highest concentrations are found in the liver, kidneys and brain. It takes from 50 to 70 days to eliminate half the methylmercury ingested. During pregnancy, methylmercury present in the mother's blood passes through the placenta and into the bloodstream of the unborn child.

Fish being prepared in a tepee.

Exposure revealed by the hair

Methylmercury is measured in the hair and blood. Hair analysis is an excellent way to determine a person's exposure to mercury throughout an entire year or a fishing season. Mercury is deposited at the roots of the hair, where it becomes permanently fixed. Because hair grows at a rate of about one centimetre a month, the mercury concentration measured for one centimetre of hair reflects the average concentration over that month (see poster Mercury in the blood and hair [PDF 1.2 Mb]). Therefore, a long strand of hair can be analyzed to obtain a record of a person's mercury exposure over several months or years.

Health risk

As with any chemical, the health risk of mercury depends on its concentration in the organism. All people have a little mercury in their bodies, but the concentrations are generally very low and consequently do not pose any health risk. At higher doses, however, the nervous system, in particular, may be affected by methylmercury.

Most of the studies conducted to date have not reported any health effects associated with methylmercury in individuals who have been exposed over a long period of time and have hair mercury concentrations of less than 14 ppm. Developmental effects could be observed in children born to mothers who had more than 14 ppm of mercury in their hair during pregnancy. However, at levels close to this value, the impact on the child's health appears marginal. In adults, 50 ppm in the hair is the threshold at which symptoms could begin to appear in the most sensitive individuals. The earliest symptom commonly reported is a sensation of numbness in the fingers and toes.

Correspondence between hair mercury concentrations and health effects observed
Hair mercury concentration (ppm) Health effects observed
< 14 No significant effect on the child
15 to 50 No clinical effects
(subclinical effects not confirmed)
50 to 200 Threshold for appearance of the earliest symptoms in adults (paresthesia)
200 to 1,000 Increase in frequency of neurological effects
> 1,000 Serious neurological effects leading to death

Safe exposure in Eastern Canada

In Québec, even the highest fish mercury concentrations are not enough to cause symptoms of mercury intoxication, considering the usual low fish consumption. In the vast majority of cases, mercury concentrations measured in Québec fish consumers are well below levels that lead to health effects in adults or unborn children.

The latest data for Eastern Canada, including those collected in 2002 and 2003 by the Collaborative Mercury Research Network (COMERN) among anglers in Lac Saint-Pierre and the Abitibi region as well as among the Labrador Innu, shows that the average exposure is generally around 1 ppm in the hair (see the following table). This value is well below the threshold at which the earliest mercury-related effects would begin to appear in unborn children; according to the available studies, such effects would occur at 10 to 15 ppm in the mother’s hair.

Methylmercury exposure levels in the Québec population
Population Number of participants Hair mercury concentration
Average
(ppm)
Maximum
(ppm)
Sept-Îles Innu 83 0.9 4.2
Labrador Innu 162 0.4 8.1
Innus of Ekuanitshit 36 0.5 2.0
Havre-Saint-Pierre 94 0.9 4.1
Sept-Îles 56 0.8 2.6
Québec 1,109 0.3 3.7
Oujé-Bougoumou 218 1.6 13.9
Nemaska 97 0.9 8.8
Wemindji 188 1.0 13.8
Eastmain 80 1.6 7.4
Methylmercury exposure levels in Québec recreational anglers
Anglers Number of participants Hair mercury concentration
Average
(ppm)
Maximum
(ppm)
Lac Saint-Pierre 130 0.7 5.8
Montréal* 58 0.2 4.1
Montréal* 40 0.5 4.4
Abitibi 130 0.8 16.1
Matagami 174 2.1 14.6
Baie James 88 3.6 16.4

* Two studies are available for Montréal

Recommendations of public health authorities

Public health authorities are responsible for ensuring that fish consumers do not exceed the mercury exposure level deemed safe for their health. On the basis of the findings of recent epidemiological studies, they recommend a specific maximum number of fish meals per month according to fish mercury levels and catch locations.

A safe process

The following table illustrates the process used by public health authorities to establish their fish consumption recommendations, taking those of the World Health Organization (WHO) as an example.

Process for determining fish consumption recommendations
Step Value adopted by the WHO
Determination of exposure threshold
14 ppm in the hair
Calculation of daily intake
1.5 µg Hg/kg/d
Application of a safety factor
6.4 (from 4.5 to 10, depending on the institution)
Calculation of tolerable daily intake (TDI)
0.23 µg Hg/kg/d
Number of meals per month Depending on mercury level (Hg), body weight and portion consumed

Public health authorities determine an exposure threshold at which the earliest symptoms of mercury intoxication would begin to appear, based on their analysis of recent epidemiological studies. In the example chosen, this threshold is 14 ppm, or micrograms (µg) of mercury (Hg) per gram (g) of hair, in the mother's hair.

Next, the daily intake of mercury is calculated; this is the amount the mother must assimilate on a regular basis to reach the exposure threshold. To reach 14 ppm, the daily intake is 1.5 µg of mercury per kilogram of body weight.

A safety factor is then applied to be absolutely certain to avoid any health risk. The WHO applied a safety factor of 6.4, which takes into account individual variabilities in the rate of mercury assimilation and in the efficiency of its transfer from the blood to the hair.

The tolerable daily intake (TDI) for mercury, that is, the daily intake that should not be exceeded, is then obtained by dividing the daily intake by the safety factor chosen. To protect the unborn child, the WHO recommends that the mother not exceed a daily intake of 0.23 µg of mercury per kilogram of body weight.

The number of fish meals per month that the mother can safely eat is based on the following criteria:

  • a tolerable daily intake of 0.23 µg/Hg/kg of body weight
  • a body weight of 60 kg
  • a portion of 230 g of fish (uncooked)

For the majority of mothers, abiding by this consumption frequency will lead to a very safe exposure level of about 2 ppm in the hair, which is about 6.4 times lower than the 14-ppm exposure threshold at which the earliest symptoms would begin to appear.

The 14-ppm exposure threshold protects unborn children and is intended in particular for women who are pregnant or nursing, or planning to become pregnant, as well as for children, whose nervous systems are still developing. For other adults, the WHO considers that intakes of up to twice the TDI, or as much as 0.46 µg of mercury per kilogram of body weight, would not pose any risk of neurological effects.

Health Canada

Although its interpretation of the findings of the epidemiological studies differs slightly from the WHO's, Health Canada obtains essentially the same tolerable daily intakes for mercury by applying the same process:

For adults

  • exposure threshold of 50 ppm, at which the earliest symptoms would begin to appear
  • daily intake corresponding to 3 to 7 µg of mercury per kilogram of body weight
  • safety factor of 10
  • tolerable daily intake of 0.47 µg of mercury per kilogram of body weight

To protect the unborn child

  • exposure threshold of 10 ppm in the mother's hair, at which the earliest symptoms would begin to appear in the unborn child
  • daily intake of 1 µg of mercury per kilogram of body weight
  • safety factor of 5
  • tolerable daily intake of 0.20 µg of mercury per kilogram of body weight

Health Canada therefore recommends a tolerable daily intake of 0.20 µg/Hg/kg of body weight for women of childbearing age and for children, and 0.47 µg/Hg/kg of body weight for other adults.

Fish on the menu

Despite the presence of small quantities of methylmercury, fish is excellent for health. Among other things, it contains high-quality fatty acids, called omega-3, that are not found in red meat. These fats have a beneficial effect on the development of the unborn child and help prevent cardiovascular disease.

All it takes to avoid any mercury-related risk is to follow the consumption recommendations issued according to fish mercury levels and the tolerable daily intakes determined by Health Canada and the WHO.

Fish consumption guides

To obtain a copy of the guides, call 1 800-363-7443.

Communication tools

A team effort

Because of the potential health risk which the marked but temporary increase in fish mercury levels caused by hydroelectric developments poses to fish consumers, Hydro-Québec works together with public health authorities in the regions where its projects are built.

While responsibility for monitoring mercury levels lies with Hydro-Québec, managing the health of recreational anglers and subsistence fishermen is the responsibility of Québec's regional health and social services agencies. As part of this team effort, Hydro-Québec supplies the data on fish mercury levels. The company is also involved in producing consumption guides based on the tolerable daily intakes recommended by the World Health Organization and Health Canada.

Recommendations regarding the number of fish mealsThis table show color-coded recommendations regarding the number of fish meals to be consumed per month based on mercury levels.
Mercury level in fish
in ppm* (mg/kg)
Maximum number of meals recommended per month
Vert. 0.00 to 0.29 No restriction
Jaune. 0.30 to 0.49 8 meals per month
Orange. 0.50 to 0.99 4 meals per month
Rouge. 1.00 to 1.99 2 meals per month
Bourgogne. 2.00 to 3.75 1 meal per month

*parts per million

Natural lakes
Vert. Lake whitefish
500 mm (20 in.)
Vert. Speckled trout
300 mm (12 in.)
Vert. Landlocked salmon
500 mm (20 in.)
Orange. Pike
800 mm (32 in.)
Orange. Lake trout
600 mm (24 in.)

Colorful guides

The guides indicate the number of meals per month recommended for the different species of fish, based on fishing location. The recommendations are color-coded. For example, a green circle indicates that the mercury levels for that fish are low and it can be consumed without restriction. The red circle indicates that the fish mercury levels are high and a consumption frequency of no more than once per month is recommended.

These guides use maps to show, for each species of fish and each part of the region, the maximum number of meals per month that allows fish consumers to keep their mercury exposure below the values recommended by public health authorities. By following these recommendations, consumers can benefit from the great nutritional value of fish.

Specific recommendations apply to women who are pregnant or plan to become pregnant soon, so that their babies can also benefit from the nutrients in fish that promote brain development, while avoiding any mercury-related risk.

Guides adapted to local communities

The people of Gros-Mécatina, in Basse-Côte-Nord, took part in drawing up the consumption guide for their region by specifying what information they wished to have and how it should be presented. They did not want recipes describing healthy ways to prepare fish, but preferred to have information on the changes in fish populations in Robertson reservoir.

In the La Grande complex, fish mercury levels in the majority of modified areas have returned to levels representative of natural environments in the region. The time is therefore right to promote the health benefits provided by fish consumption.

The most recent communication tools

Two new food guides that present the nutritional value and health benefits of fish were published in 2013: the Northern Fish Nutrition Guide – Baie-James Region (in English and French) and the Guide alimentaire des poissons et fruits de mer de la Côte-Nord (Côte-Nord region fish and seafood guide, in French only). The guides were produced by the Environment department of the Direction – Gestion des actifs et conformité réglementaire, Hydro-Québec Production's regional management units La Grande Rivière and Manicouagan and Hydro-Québec's Direction – Santé et sécurité in close collaboration with the following public health agencies: the Institut national de santé publique du Québec (INSPQ), the CHU de Québec Research Center, the Cree Board of Health and Social Services of James Bay, the Centre régional de santé et de services sociaux de la Baie-James and the North Shore Health and Social Services Agency.

These guides emphasize the nutritional value and health benefits of fish and seafood in an effort to promote their consumption and help allay consumers' concerns about mercury. The guides also contain a wealth of information likely to interest fishing buffs, such as the favorite habitats of the main fish species, their most active periods, the most effective lures, the catch record, what they each taste like and, of course, many recipes to better savor the catch. They are distributed to all Cree households in the Baie-James region, the Innu and Montagnais councils in the Côte-Nord region, as well as to regional departments, municipalities, outfitters and fishing associations.

These guides can be consulted online or ordered by calling: 1 800 363-7443.

Cover of the guide for the water bodies of the Nottaway, Broadback and Rupert region.
Cover of the guide for the Gros Mécatina region.
This figure shows the cover of the guide.
This figure shows the different nutrients in speckled trout, including proteins, vitamins and omega-3 fatty acids.
This figure shows the cover of the guide (in French only).
This figure shows the different nutrients in lobster, including proteins, vitamins and omega-3 fatty acids (in French only).

Research and agreements on mercury

An unknown phenomenon

In the 1970s, at the time of preliminary work for the impoundment of Robert-Bourassa reservoir (the first reservoir in the La Grande complex; impoundment was completed in 1979), the temporary increase in mercury levels in reservoirs was an unknown phenomenon. As well, knowledge on the fate of mercury in natural aquatic environments was very incomplete.

In conjunction with the La Grande complex Environmental Monitoring Network (EMN), fish mercury levels in the region's lakes were measured before, during and after reservoir impoundment. As soon as the EMN findings revealed a significant increase in fish mercury levels, Hydro-Québec developed a research program to shed light on the mechanisms responsible for this phenomenon and determine the risks to the health of not only fish, birds and piscivorous mammals, but also of recreational anglers and subsistence fishermen.

Research partnerships

To carry out its research program, Hydro-Québec secured the cooperation of a number of partners:

  • the Environmental Research Chair set up by Hydro-Québec, the Natural Sciences and Engineering Research Council of Canada and the Université du Québec à Montréal to study the fate of mercury in natural and modified environments in the Nord-du-Québec region
  • the Université de Sherbrooke, for studies on modeling mercury in fish in hydroelectric reservoirs
  • the Université de Montréal's Faculty of Veterinary Medicine, for a clinical study on the effects of mercury exposure on mink
  • the Canadian Wildlife Service, for a study on the effects of mercury on the reproductive success of osprey
  • Fisheries and Oceans Canada's Freshwater Institute, for a study of the rate of mercury methylation in experimental reservoirs
  • the public health research institute at CHUL, Université Laval's hospital centre, to produce fish consumption guides
  • the Cree Board of Health and Social Services of James Bay, to produce a fish nutrition guide for the Baie-James region

These various partnerships have allowed Hydro-Québec to gain an in-depth understanding of the issue of mercury in hydroelectric reservoirs and to remain on the leading edge of research on this topic.

From acquiring knowledge to managing the potential health risk to fish consumers

From 1978 to 1985, Hydro-Québec's mercury-related activities were intended mainly to monitor the changes in fish mercury levels in the La Grande complex reservoirs and conduct complementary studies in order to understand the phenomena revealed by the monitoring.

From 1986 to 1988, Hydro-Québec's research activities were carried out in accordance with the Mercury Agreement (1986), as described below (see Mercury agreements).

From 1988 to 2010, Hydro-Québec established a corporate mercury research program at the same time as it continued its activities related to the mercury agreements (1986 and 2001). The object of this program was to meet Hydro-Québec needs that were not priorities for the other partners to these agreements.

Balbuzard
Pêche au filet

The main activities included in the program were the following:

  • monitoring of fish mercury levels in the La Grande complex
  • modeling of mercury levels in fish of future reservoirs
  • determination of the risk to populations of birds and piscivorous mammals
  • determination of the risks and health benefits associated with fish consumption
  • search for mitigation measures that reduce the increase in fish mercury levels in recently flooded reservoirs

To find out more

To find out more about the lessons learned from these partnerships, you may consult the monograph produced through an initiative of the Hydro-Québec–NSERC–UQAM (Lucotte, M., R. Schetagne, N. Thérien, and A. Tremblay. 1999. Mercury in the Biogeochemical Cycle: Natural Environments and Hydroelectric Reservoirs of Northern Québec (Canada). New York, Springer. 334 p).

A monograph on mercury

This publication is a compilation of 14 scientific articles. The articles cover a variety of subjects, including the increase in mercury levels in lake sediments following atmospheric deposits of anthropogenic origin, the mechanisms responsible for mercury methylation and transfer to the food chain in reservoirs, the reasons why the increase in fish mercury levels is temporary and the risks to wildlife such as mink and osprey.

Monograph cover page.

Hydro-Québec's current activities related to the mercury issue

A research program to manage the potential health risk to fish consumers

Through the implementation of the corporate research program, Hydro-Québec and its partners were able to establish the extent, duration and main mechanisms responsible for the increase in fish mercury levels in new reservoirs. The program also showed that this increase does not endanger populations of fish, birds or mammals that eat fish. Therefore, Hydro-Québec's current activities related to mercury are focused on providing recreational anglers and subsistence fishermen with accurate information on the potential health risk associated with the consumption of fish caught in newly impounded reservoirs.

The activities under way are mainly related to Hydro-Québec's commitments and obligations described in the government authorization certificates for recent hydroelectric developments. They include the following elements:

  • regular monitoring of mercury levels in reservoir fish;
  • improvement of models for predicting fish mercury levels in reservoirs planned by the company;
  • development of methods for analyzing the health risk for consumers posed by the temporary increase in fish mercury levels;
  • technical support to public health authorities in the regions that host Hydro-Québec's facilities (e.g. calculating the number of meals per month for each species of fish, from each developed environment, that can be consumed without exceeding the recommended exposure level to avoid any mercury-related health risk);
  • development, assessment and improvement of tools to provide the public with adequate information on the potential mercury-related health risks associated with fish consumption.
Pêcheuse.

An innovative method for analyzing additional health risk for fish consumers

As part of the impact statement for the development of the Romaine hydropower complex, an innovative method for assessing health risk was developed at the request of Health Canada and the North Shore Health and Social Services Agency (Agence de la santé et des services sociaux de la Côte-Nord). The approach consists of measuring local populations' current exposure to mercury and determining their main dietary sources of mercury, as well as the current level of mercury in these sources. Local populations' future exposure to mercury is calculated based on the future mercury levels of the mercury sources affected by the project (obtained from a simulation model), according to different fish consumption scenarios and based on stated intention to fish in the new reservoirs. Additional health risk for fish consumers is then assessed based on recognized thresholds for health effects (see PDF document available on this subject [PDF 746 Kb – in French only]).

The results of this analysis, approved by Health Canada, show that the development of the Romaine hydropower complex does not lead to any additional health risk related to fish consumption. During the public hearings for the project, Health Canada filed a brief according to which the future levels of mercury exposure in local populations were not a health concern.

Suggested reading to find out more about the results of these research

The following documents are available at Hydro-Québec's Environment & Communities Documentation Centre.

  • BÉLANGER D. and N. LARIVIÈRE. 1997. Développement et validation de biomarqueurs d'effets physiopathologiques précoces chez certains piscivores relativement à leur exposition au méthylmercure (Development and validation of biomarkers of early physiopathological effects related to methylmercury exposure in certain piscivorous fish species). Montréal, Faculté de médecine vétérinaire de l'Université de Montréal in partnership with the James Bay Mercury Committee, Hydro-Québec and the Ministère de l'Environnement et de la Faune. 94 p and apps.
  • BROUARD, D., J.-F. DOYON, and R. SCHETAGNE. 1994. "Amplification of Mercury Concentration in Lake Whitefish (Coregonus clupeaformis) Downstream from Robert-Bourassa Reservoir, James Bay, Québec." Proceedings of the International Conference on Mercury Pollution: Integration and synthesis. Boca Raton, Lewis Publishers. p 369-380.
  • CASTONGUAY, DANDENAULT ET ASSOCIÉS. 2001. Programme mercure – Exposition au mercure des pêcheurs sportifs de la Baie James: enquête de récolte, de consommation et caractérisation du mercure corporel (Mercury program – Baie James (James Bay) anglers' exposure to mercury: investigation on the harvesting, consumption and characterisation of mercury in the body). Prepared for Hydro-Québec Hydraulique et environnement, Direction – Expertise et support technique. Montréal. 55 p and apps.
  • DESGRANGES J.-L., J. RODRIGUE, B. TARDIF and M. LAPERLE. 1994. Exposition au mercure de balbuzards nichant sur les territoires de la Baie James et de la Baie d'Hudson (Mercury exposure of ospreys nesting on the Baie James and Baie d'Hudson territories). Technical report series No. 220. Québec, Canadian Wildlife Service, Québec region. 129 p and apps.
  • HYDRO-QUÉBEC PRODUCTION and SEBJ. 2013. Centrales de l'Eastmain-1-A et de la Sarcelle et dérivation Rupert – Évaluation de l'efficacité des outils d'information sur le mercure et la consommation de poisson (Eastmain-1-A and Sarcelle powerhouses and Rupert diversion – Assessment of the effectiveness of information campaigns on fish consumption and mercury). Corrected version. Report prepared by GENIVAR-Waska for Hydro-Québec and SEBJ. Multiple pagination and appendices.
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Mercury agreements

Fish represents an important traditional source of food for the Crees in the Baie-James region. A study carried out in the mid-1970s revealed that fish accounted for 15% to 20% of the bush food consumed by the Crees. At that time, namely before reservoir impoundment, the discovery of high fish mercury levels in water bodies in the southern part of the Baie-James region, stemming from industrial pollution, prompted the Crees in all communities to alter their fishing and fish consumption practices. Communities in the southern part of the territory reacted more strongly than those in the northern part. Early in the following decade, the discovery of a marked increase in fish mercury levels in the La Grande complex reservoirs heightened the concerns of communities farther north in the territory.

Given the importance of fish in the Cree diet and the high mercury levels in certain species of fish in natural environments and in reservoirs, mercury was a matter of concern to the nine Cree communities in the territory. Families that practised traditional activities, or about 30% of the population at the start of the 1980s, and particularly those that regularly caught piscivorous fish in the lakes and reservoirs, were the most likely to be exposed to high levels of methylmercury.

Initial mercury agreement

That is why, in 1986, the Crees from the Baie-James region, Hydro-Québec and the Québec government signed the Mercury Agreement (1986). The James Bay Mercury Committee, made up of six people representing the three signatories, was responsible for its implementation. The main objectives of this agreement were to minimize the potential effects of mercury on the Crees' health, preserve their way of life and their traditional hunting and fishing activities, and identify any measures to reduce fish mercury levels.

The James Bay Mercury Committee had to deal with a complex issue that had environmental, cultural and public health considerations. While it was of prime importance to reduce health risks, the health benefits associated with fish consumption could not be overlooked either.

Funding for this agreement, $12 million of which came from Hydro-Québec, out of a total budget of $18 million, was guaranteed for 10 years. During this time, the Committee oversaw the program for monitoring fish mercury levels; this was part of the environmental component, Hydro-Québec's responsibility. It was also in charge of the program for monitoring mercury exposure levels in the Crees in the Baie-James territory; this was part of the health component, the responsibility of the Cree Board of Health and Social Services of James Bay. In addition, research was conducted on the environment, health and sociocultural aspects, and mitigation measures were suggested.

Two types of mitigation measures could be considered to reduce health risks while encouraging traditional hunting and fishing activities. The first type was designed to reduce methylmercury production and its accumulation in the flesh of fish. A review of the measures of this first type, as proposed in the scientific literature, was carried out at the beginning of the agreement. It revealed a lack of sufficient knowledge of the mechanisms of methylmercury production and transfer to fish, and an absence of measures that are technically and economically feasible on a large scale.

Starting in 1989, the James Bay Mercury Committee consequently focused its efforts on the second type of measures, which were intended to direct traditional hunting and fishing activities toward fish in coastal environments in the James Bay region and in natural lakes close to the reservoirs, or toward other wildlife resources with low mercury levels. The Committee also financed community fishing in areas where fish mercury levels are low, as well as various enhancement measures promoting the production and harvesting of non-piscivorous wildlife species with low mercury levels. The application of these measures has helped reduce the Crees' mercury exposure while encouraging their traditional fish and wildlife harvesting activities.

A number of posters were produced under this agreement to explain the mercury issue and the health risks and benefits associated with fish consumption:

  • Mercury in the food chain
  • Mercury in wildlife other than fish
  • Mercury in the blood and hair
  • Methylmercury in the human body
  • Consumption recommendations

Information campaigns targeted band councils, local public health officials and the population of each Cree community.

This poster shows the mercury levels in the various wildlife species consumed by the Crees, including beluga, seal, bear, beaver, caribou and ducks.
Figure 2.6: Poster illustrating mercury levels in the main wildlife species consumed by the Crees.

A renewed agreement

The 1986 Mercury Agreement was renewed with a budget of $27 million, giving rise to the Mercury Agreement (2001). A non-profit corporation, the Niskamoon Corporation, was set up to apply this new agreement. The board of directors of the Niskamoon Corporation was made up of five Cree members and three members from Hydro-Québec. This second agreement was in effect from 2001 to 2012, until the available funds were exhausted, as planned.

Its activities included environmental and health research programs totaling $8 million and, above all, measures to restore Cree fishing activities, given the low level of mercury exposure in the great majority of Crees, their low consumption of local fish and the health benefits of fish consumption. A study carried out in 2010 showed that approximately 70% of Crees in the Baie-James region ate local fish less than once a week.

Fishing activities were funded to teach the traditional Cree methods for capturing, conserving and preparing fish, and to allow fish that have particularly low mercury levels, such as anadromous brook trout, to be distributed to the Cree villages. The Niskamoon Corporation also financed the enhancement of fish and wildlife habitats and the development of waterfowl hunting ponds.