Ranch-reared mink (Mustela vison) were used as a model in an experimental trial to investigate the potential effects of exposure to two petroleum products on sea otters (Enhydra lutris). Mink were exposed either dermally on one occasion 60 days prior to breeding or via low level contamination of their diets daily from 60 days prior to breeding (January 1994) until weaning of kits (June 1994). For dermal exposure, we placed mink in either a slick of Alaskan North Slope crude oil (n = 24) or bunker C fuel oil (n = 24) on sea water or sea water alone (n = 10) for 1 min. For dietary exposure, we fed mink rations containing 500 ppm of either Alaskan North Slope crude oil (n = 24) or bunker C fuel oil (n = 24; control, n = 15). The number of liveborn kits did not differ significantly among mink exposed dermally (5.0 kits/female for crude oil and 6.5 kits/female for bunker C fuel oil) and unexposed controls (5.3 kits/female). However, only 2.3 and 0.7 kits were produced per female for those exposed through the diet to crude oil and bunker C fuel oil, respectively. Females with reduced reproductive success had no clinical signs of toxicosis or behavioral abnormalities. In addition, kits of females exposed through the diet had poor survival to weaning. Once mature, kits born to females exposed to bunker C fuel oil in the diet had significantly reduced reproductive success (3.4 kits/female) although their only exposure to the petroleum products was in utero or during nursing. Therefore, it is possible that sea otter populations consuming contaminated food sources or colonizing previously oiled habitats will have reduced reproductive success.
Aleutian mink disease virus (AMDV) occurs in the American mink (Neovison vison) in wild populations and on mink farms and can cause illness and death. The North American river otter (Lontra canadensis) may be exposed to AMDV because of shared space and habitat with mink. Using serology and real-time PCR, we tested river otters across Ontario for AMDV infection. We found no evidence of infection in otters, a surprising finding given the sympatric distribution, niche overlap, and close phylogenetic relationship of the river otter and the American mink. Our results are consistent with the hypothesis that the major point of spillover of AMDV between mink farms and wildlife is manure and composting carcasses on mink farms. Mink farms in Ontario are generally in agricultural landscapes; it is unlikely that river otter use these habitats and thus are likely not exposed to AMDV. We found no evidence that AMD is an important disease for the river otters in Ontario.