Arctic Caribou

This project studies contaminant levels in Canadian Arctic caribou 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?

Cadmium and mercury levels in caribou kidneys and livers from across the circumpolar north, are higher than in domestic animals grown for food consumption.

A study by the Centre for Indigenous Peoples’ Nutrition and Environment recommended that a trend-monitoring program be established to verify that the levels are not rising from local or long-range inputs and that new contaminants be addressed as they arise.

What are we doing?

This project monitors two caribou herds, the Porcupine (YT) and the Qamanirjuaq (NU) every year. Monitoring herds from the eastern and western Arctic gives scientists a better understanding of the distribution of contaminants in the Arctic and the variability of contaminant burdens among herds. Two additional herds are monitored each year, depending on availability of samples and community concerns.

Twenty animals from each herd are sampled, and their kidneys analyzed for a suite of 34 elements, including arsenic, cadmium, lead and mercury. Livers are analyzed for a range of brominated and fluorinated compounds that have previously been found in caribou.

What do we know?

  • Arctic caribou are largely free from contamination and are healthy to eat.
  • Some caribou have high levels of mercury and cadmium in their organs. Some of the cadmium and mercury occurs naturally in the land, but some is brought here by wind from industry down south.
  • Cadmium and mercury in caribou organs fluctuate over time.
  • Mercury is generally higher in the spring than the fall, because the caribou eat lichens through the winter which are higher in mercury than their summer foods of grasses and flowering plants.
  • In the spring, mercury may be lower in cows than in bulls, because some of the mercury is passed to the fetus and then to the calf through milk production.
  • In the fall, mercury concentrations are higher in cows than in bulls, because cows are smaller and eat proportionally more food, therefore more mercury.
  • Mushrooms may provide a pulse of mercury in the fall, because mushrooms can accumulate large amounts of mercury and are a preferred food when they are available.
  • Mercury in the Arctic caribou may be affected by rain, snow, wind, temperature, migration patterns, time of green-up and forage quality as well as mercury emissions coming from industry, forest fires and volcanoes.

How our research is helping the world

More than two decades of contaminant data from the Porcupine caribou 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!

Project leader

Mary Gamberg
Email: [email protected]
Phone: 867-334-3360

Where is this study being done?

Samples for this study are collected from Old Crow, Yukon.

What has been done?

  • Samples have been collected from this herd, every year since 1991. The most recent collection was the fall of 2017 by local hunters in collaboration with the North Yukon Resource Council.
  • Kidneys and liver are being analyzed for a range of contaminants.

What we know so far

Porcupine caribou are largely free from contamination and are healthy to eat.

Cadmium

  • is transported to the north from pollution in the south by wind. It lands on lichens and caribou eat the lichens.
  • concentrates in kidney, and to a lesser degree in liver. It does not accumulate in the muscle.
  • increases with age in caribou, so older animals have more than younger animals.
  •  is declining slightly over time in the Porcupine caribou, likely due to increased controls on pollution
  •  levels are well below those thought to cause toxic effects in caribou

Mercury

  • is transported to the north from pollution in the south by wind. It lands on lichens and caribou eat the lichens.
  • concentrates in kidney, and to a lesser degree in liver.
  • levels are not increasing or decreasing over time; they appear to be cyclic.
  •  Levels are well below those thought to cause toxic effect in caribou

Radioactivity

  • levels in the Porcupine caribou did not increase after the nuclear accident at Fukushima, Japan in 2011

Maximum recommended consumption of Porcupine Caribou for one adult for one year

  • Kidneys: 24
  • Livers: 12
  • Muscle: All you want

Tobacco contains much higher levels of cadmium than animal sources. Reducing or eliminating smoking is the most effective way of limiting cadmium intake.

Where is this study being done?

Samples for this study are collected from Arviat, NU. Although we could sample the herd anywhere within its range, we can be most effective by working with hunters from one community so that the hunters become very familiar with the samples we need.

What has been done?

  • Samples have been collected from this herd, every year since 2006. The most recent collection was the fall of 2017 by local hunters in collaboration with the Arviat Hunters and Trappers Organization
  • Kidneys and liver are being analyzed for a range of contaminants.
  • Additional samples were taken from cows immediately after the rut to see if mercury could be stopping some cows from getting pregnant.
  • Lichen, seaweed and mushrooms from Baker Lake, Chesterfield Inlet, Rankin Inlet and Arviat were analyzed for mercury to see if seaweed was an important source of mercury for caribou.

What we know so far

Qamanirjuaq caribou are largely free from contamination and are healthy to eat. The Government of Nunavut (Department of Health) determined that no health advisory is required for caribou in Nunavut, based on an assessment of data from this herd (and others) by Health Canada.

Cadmium

  • is transported to the north from pollution in the south by wind. It lands on lichens and caribou eat the lichens.
  • concentrates in kidney, and to a lesser degree in liver. It does not accumulate in the muscle, brain or marrow.
  • increases with age in caribou, so older animals have more than younger animals.
  • changes over time, but is not increasing or decreasing over the long term in this herd
  • levels are well below those thought to cause toxic effects in caribou
  • Tobacco contains much higher levels of cadmium than animal sources. Reducing or eliminating smoking is the most effective way of limiting cadmium intake.

Mercury

  • is transported to the north from pollution in the south by wind. It lands on lichens and caribou eat the lichens.
  • concentrates in kidney, and to a lesser degree in liver. It does not accumulate in the muscle, brain or marrow.
  • changes over time but is not clearly increasing or decreasing over the long-term
  • Levels are well below those thought to cause toxic effect in caribou
  • Only two of the cows that were sampled for mercury right after the rut were not pregnant and these were old cows (13 and 16 years old) who had similar levels of mercury as the pregnant cows. Mercury is clearly not keeping the Qamanirjuaq caribou from becoming pregnant.
  • Mercury was higher in mushrooms than in lichen and lowest in seaweed. Concentrations did not differ among communities suggesting long-range transport as a source. Seaweed is not a significant source of mercury for the Qamanirjuaq caribou.

We are continuing to monitor contaminants in the Qamanirjuaq Caribou to keep track of contaminants in their organs, and to try to better understand how and why contaminants accumulate in caribou the way they do.