Analysis of the stomach contents of otters recovered from South West England between 1999 and 2003 revealed that prey items taken were principally species of fish and amphibians, with mammals and birds occasionally taken. The fork length of fish recorded was 30 to 720 mm. Eel Anguilla anguilla was the dominant prey item, with up to five present per stomach. Estimated lengths ranged from 100 to 450 mm. Other common prey items were bullhead Cottus gobio and brown trout Salmo trutta. In addition to these freshwater species, there were recordings of sea bass Dicentrarchus labrax and thick lipped mullet Chelon labosus, indicating foraging in both freshwater and marine habitats. A seasonal peak was observed in the relative frequency of amphibians in diet, as otters took advantage of spawning aggregations. However, there were no seasonal trends in the relative frequency of other species in otter diet, with eel, bullhead and cyprinid species taken regularly in all months.