PCBs and organochlorine pesticide residues in otters (Lutra lutra) and in otter spraints from SW England and their likely impact on populations.

PCB and organochlorine pesticide residues were determined in otter (Lutra lutra) spraints (faeces) from nine catchment regions in SW England over the period 1989-1991. Results of analyses of tissues from 22 otters are also presented. Dieldrin occurred in the majority of spraint samples and p,p-DDE and total PCBs in all. Lindane occurred mainly in samples collected in spring. Lindane was not found in otter tissues collected after 1991, but dieldrin, p,p-DDE and PCBs were found in all tissues. Dieldrin and p,p-DDE concentrations were strongly correlated in otter tissues, but there were no correlations with lindane or PCBs. Mean concentrations of contaminants varied widely between catchments. It was considered that PCBs were the compounds of most concern in influencing otter populations and that levels in spraints from one catchment were likely to be sufficiently high to exert a negative effect on populations. While levels of PCBs were elevated above background level in several other catchments and some individual otters had high levels of PCBs, it was considered that they were not sufficient to significantly hinder further population consolidation of otters in SW England.