Very little is known about environmental contamination in most otter species. In the range of the Giant Otter, Pteronura brasiliensis, gold miners discharge a great deal of methylmercury into the environment, and this is known to biomagnify in the food chain. Assays for methylmercury were carried out on fish collected in the Madre de Dios department of Peru, from near gold mining areas, and also from more than 100km away; additional fish were obtained from fish markets. Results show that significant contamination occurs in fish bigger than the normal prey size of the otters, but at present, there are low levels in prey species - this should be monitored closely in future.
