Native sea lice (Copepoda: Caligidae) infestation of salmonids reared in netpen systems in southern Chile

Abstract

A survey of parasitic copepods carried out in three introduced salmonid species in Southern Chile and 5 native fish species commonly found in the vicinity of the fish farm cages yielded 5 caligid species. Caligus flexispina, formerly found in the oceanic islands of the Pacific ocean, is currently the dominant species found in continental waters on native fish species ( Eleginops maclovinus and Odonthestes regia) as well as on cultured trout Oncorhynchus mykiss from the south of Chile. Coho salmon O. kisutch and Atlantic salmon Salmo salar are more resistant to this parasite. Among the native fish species associated with netpen aquaculture, E. maclovinus harbours 4 caligid copepods, namely Lepeophtheirus mugiloidis, C. flexispina, C. teres and C. cheilodactylus (in the same order of ranked abundance). Odonthestes regia only harbours C. flexispina, whereas Paralichthys microps is a host of Lepeophtheirus edwardsi and C. flexispina. It is highly likely that the transfer of C. flexispina to salmonids is mediated by the presence of these native fish species.