Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
Organochlorine and Trace Metal Contaminants in Mink (Mustela vison)
and Otter (Lutra canadensis) in the Columbia and Fraser River Systems —
Progress Report
Introduction
L. Harding, 1 C. Stevens 2 and J. Elliott 1
1 Environment Canada
2 Faculty of Medicine, University of British Columbia
Mink (Mustela vison) and river otter (Lutra canadensis) are good indicators of contaminant uptake from aquatic
food webs because they are resident, largely piscivorous, and at or near the top of the food chain (Moul and
Nichol, 1994). Mink and otter suffer reproductive failure and other forms of toxicity at the low parts per million
levels of polychlorinated biphenyls (see reviews by Leonards et al., 1994; Smit et al., 1994 and Elliott et al.,
1996). In this study, otter and mink were collected during 1995 in the upper and lower Fraser River and the
Kootenay and Columbia River systems; in the last, collections were coordinated with those of the U.S. Fish and
Wildlife Service from the U.S.-Canada border downstream to the mouth of the Columbia. Chemical analysis of
liver tissues was combined with biological measurements and pathological examination of various tissues and
organs. The purpose of this study was to repeat collections of mink and otter on these systems that were made in
1991 (Elliott et al., 1996) again during 1995 to determine if there has been a reduction in organochlorine
contaminants following improved regulation of pulp mill effluents in British Columbia.
Methods
Study Design
The sampling design was based on detailed analysis for chlorinated organics of composites of livers from six
to 10 individuals from each species at each location and individual analyses of the same specimens for
metals, pesticides and total PCBs. Five locations were sampled (see maps): Upper Fraser, Lower Fraser,
Upper Columbia (above Arrow Lakes), Kootenay system and Lower Columbia (below Hugh Keenlyside
Dam). A preliminary sample of six mink was selected in March, 1995 to be analyzed individually to assess
variability.
Collections
With the assistance of regional wildlife biologists of the B.C. Wildlife Branch, specimens were obtained
fresh from registered trappers, tagged, wrapped in aluminum foil, placed in a plastic bag and frozen. A
standard sample collection protocol was distributed to each trapper participating in the program. Each
carcass was tagged with information on the trapper, the specimen, the location and the date trapped.
Carcasses were shipped by air freight to Vancouver, or picked up and driven directly to the laboratory. As of
February 6, 1996, 32 otter and 20 mink had been collected, as well as five marten (Martes americana) as a
terrestrial analogue of the mink. Each specimen was sexed, measured and weighed and the head removed for
aging by dental cementum annuli.
Analysis
During March, 1995, six mink were taken to the North Vancouver Environment Canada laboratory for
dissection. The liver and kidneys were excised from each animal with a stainless steel knife and forceps
(washed with hexane between dissections), weighed and placed in separate, hexane-washed, heat-treated
jars. Femurs from each were placed in plastic bags and archived at -40°C. Kidney samples were submitted
for trace metal analysis by ICP, low level cadmium and lead by flameless AA, and mercury by AAS. Liver
samples were submitted to Zenon Environmental Laboratories Ltd. for dioxin/furan (low
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