This project studies contaminant levels in lake trout from Kusawa Lake and Lake Laberge in the Yukon to determine if these populations remain healthy in terms of contaminant loads, whether these important resources remain safe and healthy food choices for northerners and to see if contaminant levels are changing over time.
Why is this important?
Mercury in lake trout has prompted Yukon Health to advise that women of childbearing age and children under 12 should limit their consumption of large Yukon lake trout 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.
What are we doing?
This project monitors lake trout from Kusawa Lake and Lake Laberge every year, in collaboration with the Ta’an Kwach’an and Champagne and Aishihik First Nations. Twenty trout are sampled from each lake each year. PBDEs, mercury and other metals (e.g. arsenic and lead) are measured in trout muscle and PFASs are measured in liver. Every second year we measure POPs in trout muscle.
What do we know?
- Mercury in fish is a concern in many places in the world, including the Arctic. Most mercury in Yukon lakes and rivers comes from natural sources such as volcanoes, erosion and forest fires.
- The Yukon also receives mercury and other contaminants from pollution from the south that gets blown to the Arctic by wind. Fish may absorb these contaminants and pass them on to the humans who eat them.
- Older, longer fish have more mercury, which is why health advice is based on the length of the fish.
- Predatory fish have higher levels of mercury than those lower on the food chain. To minimize mercury consumption, eat lower on the food chain. Fish that are low in mercury include whitefish, salmon and grayling.
- Levels of pesticides and flame retardants (PBDEs) in fish are below levels of concern.
How our research is helping the world
Data from this monitoring program were part of the evidence that led the United Nations Environmental Program to create the Minimata Convention. This is a global agreement that will limit mercury emissions to the environment and ultimately reduce the mercury in Arctic caribou. The convention came into force on August 16, 2017, and as of March 22, 2018, 90 countries have ratified thereby agreeing to reduce their mercury emissions. We are making a difference!