Serious declines in populations of native European mink (Mustela lutreola) have occurred in Europe. One responsible factor may be infectious diseases introduced by exotic American mink (Mustela vison). In order to investigate a possible role for Aleutian mink disease parvovirus (ADV), we surveyed native riparian carnivores and feral American mink. When serum samples from 12 free-ranging European and 16 feral American mink were tested, antibodies to ADV were detected from three of nine European mink. ADV DNA was detected by polymerase chain reaction in whole cell DNA from four of seven carcasses; two American mink, one European mink and a Eurasian otter (Lutra lutra). Lesions typical of Aleutian disease were present in one of the American mink. A portion of the ADV VP2 capsid gene was sequenced and the results suggested that two sequence types of ADV were circulating in Spain, and that the Spanish ADVs differed from other described isolates from North America and Europe. Future conservation and restoration efforts should include measures to avoid introduction or spread of ADV infection to native animals.

Recent studies show that the availability of prey in¯uences the ecology of otters by regulating breeding, carrying capacity and mortality. Mediterranean habitats experience extreme seasonal variation in water ow ± a stress period can occur in summer when water¯ows and levels are low with long periods of drought, while torrential¯oods usually occur in autumn and spring. Reservoirs can affect this situation by further in¯uencing water¯ow regimes and acting as a barrier. Our data show the close relationship between the amount of food (®sh) available to otters and their use of a stretch of water and the otter density there. The adjustment of the number of individuals (and carrying capacity) in an area can be seen from their mortality, a decrease in their reproductive success, or migration. Our results are consistent with the hypothesis that otters are food-limited. Torrential rains, summer droughts and dams for water management have repercussions for otter populations in as much as they affect their prey-species. Barbels Barbus spp. and, secondarily, nases Chondrostoma spp. are shown to be important to otter ecology and breeding in Mediterranean Iberian rivers. The conservation and management of the otter in these habitats must not ignore the management of food sources. In order not to affect otter populations, the effect of the reservoirs and their dams also must be considered. The release and cessation of¯oodwater from reservoirs must be progressive and mimic more closely the¯ow regime of natural rivers.

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