Polychlorinated biphenyls and reproductive performance in otters from the Norwegian coast

Eurasian otter (Lutra lutra) has shown decreasing population trends in most areas of Europe until recently, when populations in some areas started to recover. For Norway it was postulated that PCB concentrations in the south would be high and that levels in otters will show a geographic pattern that can be related to female otter reproductive health. Concentrations of PCBs (measured as the sum of 30 congeners ranging from 0.58 to 29 mg/kg lipid weight [geometric mean 6.18 mg/kg]) were lower than those found in otters from most other European countries. PCB concentrations did not decrease in otters collected during the period from 1979 to 1990. However, a south-to-north gradient of increasing PCB concentrations in otter livers was found along the Norwegian coast. Actual PCB concentrations had not affected the reproductive health of female otters (implanted embryos, implantation sites, regressive structures). This provides valuable information on PCB concentrations tolerated by Eurasian otters at the population level.