ENVIRONMENT YUKON






 

Fish

Mercury levels in fish from Laberge and Kusawa Lakes

Significance

 

Contaminants such as heavy metals can persist in the environment and can have serious health implications for wildlife and for people—especially those who depend on traditional foods. In Canada, mercury is a risk to Canadian ecosystems and human health (Environment and Climate Change Canada, 2016).

Most mercury in Yukon lakes and rivers comes from natural sources such as volcanoes, erosion and forest fires. Industrial sources and fuel burning can also release mercury that can travel to the north from industrial areas in the south through the movement of large air masses (Yukon Department of Environment 2014). Fish may absorb this mercury and pass it on to the humans who eat them.

Climate change can influence mercury concentrations in some lakes. Yukon is experiencing increased runoff and precipitation, some from thawing permafrost. These changes influence how lakes naturally process mercury—either through adding mercury to the water or increasing food sources for the lake bacteria that process mercury (Chételat et al. 2015).

Most fish from Yukon lakes and rivers have mercury levels well below Health Canada’s maximum limit and consumption of these fish does not need to be limited.

 

Profile

Nourishing Our Future: Building on the Kluane First Nation's Community Food Security and Strategy, Youth Engagement in Fisheries, and Fish Health in Kluane Lake

 

Lenita learns how to use a Direct Mercury Analyser. Photo credit: Western University.

 

Project Significance

The overall goals of this project were: to promote the importance of consuming traditional foods; understand contaminant levels in fish from Kluane Lake; and provide base-line information for further monitoring efforts.

This project is a collaborative effort between the Kluane First Nation (KFN), Arctic Institute of Community Based Research (AICBR), University of Waterloo, Dan Keyi Renewable Resources Council (DKRRC), Kluane First Nation Traditional Territory area residents, Elders, and Youth. This multi-partner approach provided for a unique mix of scientific, community-based and Indigenous traditional knowledge collection.

The project assessed the nutrient values (omega-3 fatty acids, selenium, and zinc) as well as contaminant levels (mercury, organochlorine pesticides, and trace metals) in Lake Trout and Whitefish in Kluane Lake. Results from these assessments show that Kluane Lake fish are healthy and safe to eat. Compared to other lakes in Yukon, the Northwest Territories and Nunavut, concentrations of contaminants in Kluane fish are very low and the nutritional value of the fish is high.

Part of this research project included conducting interviews with Kluane First Nation citizens and traditional knowledge experts. The interviews solicited local observations of changes in quality, quantity and health of Kluane Lake fish, and whether there are concerns about contaminants in traditional foods. KFN youth involvement was essential throughout the project; three youth researchers traveled to the University of Waterloo and Western University (both in Ontario) to learn how to do contaminant and nutrient analysis in a research lab, analyzing fish from their own community.

Fish Test Results

None of the Lake Whitefish sampled exceed the Subsistence Consumption Guideline for mercury (0.2 ppm wet weight). Some of the larger Lake Trout (greater than 800 mm fork length) were found to have tissue mercury concentrations exceeding this guideline; however, the mean Lake Trout tissue mercury concentration (0.086 ± 0.091 ppm) did not. Larger trout (>~650 mm) are less likely to be consumed by the community (because smaller trout are considered tastier) and there are conservation measures on Kluane Lake that prohibit non-Aboriginal harvest of Lake Trout over 650 mm total length (Barker et al. 2014), reducing exposure to the higher levels of mercury in the larger Lake Trout. Mean tissue mercury concentrations in Kluane Lake Trout are significantly lower than mercury concentrations reported in other northern lakes (e.g. Lake Laberge and Kusawa Lake) (Stern et al. 2013).

Indigenous Traditional Knowledge Results


Through the collection of community-based and indigenous traditional knowledge there was firm acknowledgement of the importance of fish as a dietary staple for Kluane First Nation (KFN) citizens and community members, historically, as well as in a modern-day context.

Many people have noticed changes in Kluane Lake fish, mostly related to climate change, and are becoming very concerned with the levels of contamination and pollution of the lake and its fish. Concerns surrounding climate change are: species decline, food security issues, warmer water temperatures, fluctuating water levels, and changing weather patterns.

Other changes observed were: where people are fishing, and the types of fish that are available. Changes in climate have affected harvesters’ access to traditional fishing spots. Fluctuating ice quality can make it unsafe to get to common fishing areas that were once accessible. The areas that people fish now have also changed due to shifting fish behaviors. With the warming temperatures, fish are changing spawning behaviors. People reported noteworthy changes to the fish in Kluane Lake including the taste and quality of the fish being consumed and the quantity and species found in specific areas.

Transportation modes, such as motorized boats and snowmobiles, and increased use of technology (such as fish finders) have also altered traditional harvesting methods. Fishing practices, including preparation and preservation techniques, differ from the past. Additionally, who fishes and how the fish are shared within a community has changed over time and circumstances.

 

Interviews with knowledge holders. Photo credit: Nelson Zabel.


Overall Results


This project generated a renewed understanding, especially for youth, of the importance of long term stewardship and protection of the local fishery. The research outputs provide strong baseline data for future monitoring of fish health in Kluane Lake. It also provides reassurances to the Kluane First Nation, other area residents, and other fishers that Lake Trout and Lake Whitefish in Kluane Lake are nutritious and safe to eat.

 

 

 

What is happening?

 

Two lakes are monitored annually by the Northern Contaminants Program for mercury and other contaminants in southern Yukon, Lake Laberge and Kusawa Lake. If mercury levels are high in sampled fish, a fish consumption advisory is issued.

  • Fish mercury concentrations for both lakes are below Health Canada’s guideline of 0.5 µg/g.
  • The monitoring shows a correlation between fish length and mercury concentration, which is why consumption advisories are based on the length of the fish.
Lake Laberge

 

Figure 1: Length adjusted mercury concentrations in Lake Laberge trout (1993-2015).

 

  • The mean mercury level since monitoring started is 0.47 ± 0.21 µg/g for Lake Laberge (n=202).
  • There are no significant trends in Lake Laberge fish mercury levels.
  • Mercury levels exceeded Health Canada's guideline four times in the past 22 years.
  • Fish in Lake Laberge have had consistently higher mercury levels than those in Kusawa Lake.

 

Kusawa Lake

 

Figure 2: Length adjusted mercury concentrations in Kusawa Lake trout (1996-2015).

 

  • The mean mercury level since monitoring started is 0.37 ± 0.22 µg/g for Kusawa Lake.
  • There is some indication of trends for Kusawa Lake fish mercury levels. After a significant drop in 2001, levels increased until 2007. Mercury levels dropped again in 2008 and climbed again until 2012 (Figure 2).

 

 

 

Taking action

 

The Northern Contaminants Program works towards reducing and, where possible, eliminating contaminants in traditional/country foods, while providing information that assists individuals and communities make informed decisions about their food use.

The Government of Yukon provides information in a variety of ways:

Fish consumption advisories:

  • In general, Yukon adults do not need to limit consumption. However, eating lake trout or burbot that are less than 60 cm (24 inches) in length can help limit mercury intake.
  • Women of childbearing age and children under 12 should limit their consumption of large Yukon lake trout and burbot according to the following guidelines:
    • Fish shorter than 40 cm (about 2 lbs): unlimited consumption.
    • Fish measuring between 40 and 60 cm (about 2 to 6 lbs): limit to three to four meals/week.
    • Fish longer than 60 cm (>6 lbs): limit to one or two meals/week.

The AMAP Assessment 2015: Human Health in the Arctic has now been released. This assessment of Arctic human health impacts of contaminants and other stressors was conducted between 2012 and 2014 by an international group of over 60 experts. Recommendations from the report were delivered to Arctic Council Ministers at their meeting in Iqaluit in April 2015.

 

Twin Lakes campground.

 

Data quality

  • The Northern Contaminants Program has monitored fish for mercury and other contaminants since 1993 in both lakes Laberge and Kusawa in order to advise fish consumption levels.
  • This study is long-term so annual sampling is projected for well into the future.
  • The data on mercury concentrations are adjusted for the fish length in order to be able to compare fish. This helps to account for age and body mass differences.
  • The samples include trout.

For more details, or for information on the other contaminants that the Northern Contaminants Program monitors, see their website.

 

Emerald Lake.

 

References

Chételat, J., M. Amyot, P. Arp, J. Blais, D. Depew, C. Emmerton, M. Evans, M. Gamberg, N. Gantner, C. Girard, J. Graydon, J. Kirk, D. Lean, I. Lehnherr, D. Muir, M. Nasr, A. Poulain, M. Power, P. Roach, G. Stern, H. Swanson, and S. van der Veldon. 2015. Mercury in freshwater ecosystems of the Canadian Arctic: Recent advances on its cycling and fate. Science of the Total Environment 509-510: 41-66.

Environment and Climate Change Canada. 2016. Canadian Mercury Science Assessment [modified 2016 Mar 8; cited 2016 Mar 29]. Available from: http://ec.gc.ca/mercure-mercury/default.asp?lang=En&n=A2D7E54F-1#BR-Sec2.

Northern Contaminants Program. 2015. Northern Contaminants Program [modified 2016 Jan 25; cited Mar 3]. Available from:http://www.science.gc.ca/default.asp?lang=En&n=7A463DBA-1

Stern, G. 2013. Trace metals and OrganoHalogen contaminants in fish from selected Yukon lakes: a temporal and spatial study. Pages 247-256 in Aboriginal Affairs and Northern Development Canada. Synopsis of Research Conducted under the 2012-2013 Northern Contaminants Program. Aboriginal Affairs and Northern Development Canada, Gatineau, Quebec, Canada. Available from: http://publications.gc.ca/collections/collection_2014/aadnc-aandc/R71-64-2013-eng.pdf.

Yukon Department of Environment. 2015. Yukon Fishing Regulations Summary. Yukon Department of Environment, Whitehorse, Yukon, Canada. Available from: http://www.env.gov.yk.ca/hunting-fishing-trapping/fishingregulations.php.

Yukon Department of Environment. 2014. Yukon Fish Health Handbook. Yukon Department of Environment, Whitehorse, Yukon, Canada. Available from: http://www.env.gov.yk.ca/publications-maps/documents/FishHealthHandbook_2014_FNL.pdf.