Effects of petroleum on mink applied as a model for reproductive success in sea otters

Ranch-reared mink (Mustela vison) were used as a model in an experimental t rial to investigate the potential effects of exposure to two petroleum prod ucts on sea otters (Enhydra lutris). Mink were exposed either dermally on o ne occasion 60 days prior to breeding or via low level contamination of the ir diets daily from 30 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 f ed 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 live born kits did not differ significantly among mink exposed dermally (5.0 kit s/female for crude oil and 6.5 kits/female for bunker C fuel oil) and unexp osed controls (5.3 kits/female). However, only 2.3 and 0.7 kits were produc ed per female for those exposed through the diet to crude oil and bunker C fuel oil, respectively. Females with reduced reproductive success had no cl inical 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 signifi cantly reduced reproductive success (3.4 kits/female) although their only e xposure to the petroleum products was in utero or during nursing. Therefore , it is possible that sea otter populations consuming contaminated food sou rces or colonizing previously oiled habitats will have reduced reproductive success.