Reproductive and morphological condition of wild mink (Mustela vison) and river otters (Lutra canadensis) in relation to chlorinated hydrocarbon contamination

We assessed chlorinated hydrocarbon contamination of mink and river otters on the Columbia and Fraser River systems of northwestern North America, in relation to morphological measures of condition. We obtained carcasses of m ink and river otters from commercial trappers during the winters 1994-1995 and 1995-1996. Necropsies included evaluation of the following biological p arameters: sex, body mass and length, age, thymus, heart, liver, lung, sple en, pancreas, kidney, gonad, omentum, adrenal gland and baculum masses, bac ulum length, and stomach contents. Livers were analyzed, individually or in pools, for residues of organochlorine (OC) pesticides, polychlorinated bip henyls (PCBs), dibenzo-p-dioxins, and dibenzofurans. Contaminant levels wer e relatively low compared to those documented in other North American popul ations, although they ranged higher than those detected during an earlier s urvey (1990-1992) of these regional populations. Body condition varied slig htly among collection regions, but showed no relationship with contaminant burden. Mink from the upper Fraser River had less fat stores and also had s ome of the lowest OC contamination levels observed. Similarly, a few indivi duals with enlarged livers and kidneys had low contaminant levels. Although a few individual animals with gross abnormalities of reproductive systems did not show high levels of contamination, there was a significant negative correlation between total PCB concentrations (as Aroclor 1260) and baculum length in juvenile mink (r = 0.707; p = 0.033; n = 8). The association of juvenile baculun length with eventual reproductive success is unknown, but further characterization of reproductive organ morphology and relationship to contaminants should be undertaken in a larger subset of these population s.