Progress Report on Hudson River Mammals: Polychlorinated Biphenyl (PCB) Levels in Mink, Otter, and Muskrat and Trapping Results for Mink, the Upper Hudson River Drainage, 1998-2000.

Mink (Mustela vison), river otters (Lontra canadensis) , and muskrats (Ondatra zibethicus) were collected from the upper Hudson River drainage during the 1998-1999 and 1999-2000 trapping seasons. Liver samples from 162 animals (102 mink, 40 otter, and 20 muskrats) were analyzed for lipids and PCBs as Aroclors. PCB concentrations were elevated for mink and otters collected from the Hudson River drainage between Hudson Falls and Troy. Ranges (means) for PCB levels were 0.541 to 139 (13.0) and 18.5 to 431 (172) μg total PCBs/g lipid for 35 mink and 4 otter, respectively, collected from the towns located between Hudson Falls and Troy. Maximum PCB levels in mink and otters exceed criteria of Leonards et al. (1994) for reproductive impairment by factors of 2.8 and 8.6, respectively. Maximum PCB levels in mink and otters exceed criteria of Smit et al. (1996) for potential health impairment by factors of 6.6 and 20.5, respectively. Levels of PCBs in mink and otters collected from upstream of Hudson Falls were generally below no-effect levels for adverse toxicological effects as defined by Smit et al. (1996). Levels of PCBs in muskrats were markedly lower than levels in either mink or otters. Levels of PCBs in mustelids were similar to those in a study conducted in 19821984 suggesting that levels have not decreased in the upper Hudson River drainage in the past 16 years. To further refine the assessment of levels of PCBs in mink and otters, liver samples are currently being analyzed for congener-specific levels. Research staff trapped for mink in the upper Hudson River drainage during the 19992000 trapping season. A lower take of mink relative to trapping effort was evident for trap sites located within one home range (6 km) of PCB-contaminated sections of the river between Fort Edward and Troy compared to sites at least one home range from the river or upstream of Hudson Falls. The number of mink trapped per 1000 trap nights for sites near the contaminated sections was 3.5; for upstream or distant sites the number was 26.2. To further investigate the apparent decrease in abundance of mink near the contaminated sections, a more extensive assessment of mink abundance, which uses scent stations equipped with track boards to monitor mink activity, is underway. 1 formerly Lutra canadensis, Wilson, D. E., and D. M. Reeder (eds.) 1993 Mammal Species of the World. Smithsonian Institution Press, 1206 p. 2 “Town” is a political subdivision of county government in New York State