Metazoan parasites in wild fish and farmed salmon from aquaculture sites in southern Chile

Parasitology of cultivated salmonids from southern Chile is currently focussed on the agents causing diseases, whereas little attention has been placed on the vector potential of native fish stocks surrounding aquaculture areas. This study describes the variation of both population and community descriptors for metazoan parasite fauna in seven species of wild native fish and in the farmed Atlantic salmon (Salmo salar) obtained from aquaculture sites in southern Chile. Fish were collected by standard methods, identified, measured and gutted for stomach content determination. Each parasite species was rated for prevalence and abundance, and parasite community richness was determined at the infracommumity and component level. Nine species of ectoparasites and 21 species of endoparasites were found in native fish. Although the diet of S. salar overlapped with that, of some native fish, they only harboured two parasite species. Richness of the component parasite community was higher than in other parts of Chile, and was generally related to host body size and diversity of habitat use. Results suggested that salmon farming affects distribution, feeding habits and ingested food items of native species, and may explain the higher species richness of the component community of native fish inhabiting areas surrounding salmon farms when compared to those of north and central Chile where salmon is absent. Native fish species may infect farmed salmonids with two ectoparasites and one endoparasite. However, the natural patterns of migration of some native fish species may enhance the increase of this number, or may cause outbreaks of parasitic species currently under control. (C) 2003 Elsevier B.V. All rights reserved.