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Contaminants in Yukon Moose and Caribou - 2005 ( DOC ) |
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| Source: | Mary Gamberg | Date: | June 1, 2005 | |
| This project is part of the ongoing monitoring of contaminants in Yukon wildlife that started in 1992 with a study of the Finlayson caribou herd, continued with a comprehensive look at contaminants in country foods, and is now monitoring temporal and geographical trends using moose and caribou as key species. Yukon hunters were requested to submit kidney, liver and muscle samples, as well as an incisor, from moose and caribou killed during the 2005 hunting season. Each hunter that submitted samples had their name put into a draw, once for each tissue they submitted. The winner, Robbie Morris of Whitehorse, claimed the prize of a charter flight with Alpine Aviation, up to a value of $1000. Samples were submitted from 83 moose, 52 caribou, 5 mule deer, 1 elk and 3 bison. Funding was available only to analyze 20 kidneys from the Porcupine herd. These kidneys were analyzed for a suite of 31 elements at the National Laboratory for Environmental Testing (Environment Canada). All other samples collected under the program were archived for possible future analysis. Levels of arsenic, cadmium, copper, lead, mercury, selenium and zinc found in Porcupine caribou from this study should all be considered normal background levels that should not pose a toxicological concern for the animals. Cadmium in caribou livers and kidneys could pose a risk to people consuming them (if enough were consumed), and Health Canada has issued a health advisory recommending limiting consumption of these organs, based on previously collected data. Copper concentrations measured in the Porcupine caribou are low and may suggest the potential for copper deficiency in some individuals. Analyzing the current data with data collected from the Porcupine caribou herd in previous years revealed that concentrations of renal cadmium, lead, mercury and zinc were significantly higher in spring than in fall, while arsenic and copper concentrations were lower and selenium levels were unaffected by season. This may be related to differential uptake of some elements by lichens and other caribou forage during the summer months, and/or seasonal differences in kidney weights. Concentrations of arsenic, cadmium, copper, lead and mercury were significantly higher in female caribou than in males, while renal concentrations of selenium and zinc were unaffected by gender. This may be related to the higher energy demands of females (due to reproduction), and the resulting higher requirement for food relative to body weight. Age was positively correlated with renal cadmium, selenium and zinc concentrations. Renal As showed a significant decline over time while renal mercury showed a significant increase in female caribou, but not in males. Concentrations of both elements may be varying over time in a cyclic rather than a linear fashion. Continuing to monitor these caribou on an annual basis should help to clarify these apparent trends. In 2006/7, the Yukon Hunter Survey will become part of a larger ‘Contaminants in Arctic Moose and Caribou’ program that will include sampling programs in NWT and Nunavut. Two caribou herds have been selected for annual monitoring – the Porcupine herd in Yukon and the Qamanirjuaq herd in Nunavut. Other caribou herds and moose populations will be monitored on a 5-year rotating basis. In 2006/7, in addition to the two annually sampled caribou herds, the program will include moose from the Deh Cho region of NWT, the Bluenose East caribou herd from NWT, and the Dolphin and Union caribou herd from Nunavut. Copies of the full ‘Contaminants in Yukon Moose and Caribou – 2005’ report may be obtained from project coordinator Mary Gamberg (Ph: 867-668-7023; e-mail: mary.gamberg@northwestel.net). |
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