Heavy metal concentrations, aging techniques and population characteristics of mink in Virginia: with a review of the literature on delayed implantation in the mink

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Virginia Polytechnic Institute and State University

Lead, cadmium, zinc and copper concentrations were determined in bone, kidney and liver samples of mink (Mustela vison) trapped during 1981-83 in Virginia. Ages were determined to obtain population information. The literature on delayed implantation in mink was reviewed.

Lead and cadmium concentrations in all tissues were generally low. Approximately 50% of bone samples and less than 10% of kidney and liver samples had detectable lead concentrations (>1 ug/g). Mean detectable bone lead concentrations (ug/g d.w.) were 2.90 and 2.48 during 1981-82 and 1982-83, respectively. Cadmium was detected (>0.1 ug/g) in all kidney samples. Mean kidney cadmium concentrations (ug/g d.w.) were 1.21 and 1.02 in 1981-82 and 1982-3, respectively. Lead and cadmium accumulated (p < .05) with age. Cadmium concentrations were higher (p < .05) in Southwest Virginia than in other areas. Mean zinc and copper concentrations were comparable to those in other mammals and do not appear to pose any toxic threat.

Bacula, femurs, radiographs of canine teeth, and cementum annuli of second premolars were examined for aging purposes. The first 3 methods were confusing in many samples, apparently due to transition from juvenile to adult characteristics. A systematic method for aging winter-trapped mink was developed. Approximately 60% of mink trapped during both seasons were juveniles. The age-specific survival rate was very low (0.292) for juveniles, increased for 2 year-olds (0.719) and then declined quickly for subsequent years. The male to female ratio was very high (approximately 3:1) probably reflecting trapping bias.