Comparison of the susceptibility of sea trout (Salmo trutta L.) and Atlantic salmon (Salmo salar L.) to sea lice (Lepeophtheirus salmonis (Kroyer, 1837)) infections

• Published in: ICES Journal of Marine Science
• Main Authors: Dawson, L. H. J., Pike, A. W., Houlihan, D. F., McVicar, A. H.
• Format: Text
• Language: English
• Published: Oxford University Press 1997
• Subjects: Articles; Atlantic salmon; Salmo salar
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/54/6/1129; https://doi.org/10.1016/S1054-3139(97)80018-5

The relative susceptibility of sea trout ( Salmo trutta L.) and Atlantic salmon ( Salmo salar L.) to sea lice infections was investigated under experimental conditions. Skin damage was described for both sea trout and Atlantic salmon, associated with the accumulation of feeding copepodids and chalimus on the dorsal fin and the settlement patterns of the pre-adult and adult lice, on the head and operculum, dorsal ridge, and behind the anal fin. Attachment and survival of chalimus stages were significantly lower on Atlantic salmon than on sea trout because of non-selective settlement of the copepodids, followed by differential mortality. The survival of pre-adult and adult sea lice declined more rapidly on sea trout than on Atlantic salmon, but ultimately, Atlantic salmon had a lower abundance of lice than sea trout. Two possibilities were considered to explain the differences in skin damage—parasite numbers and distribution of lice between sea trout and Atlantic salmon. A greater antibody response by Atlantic salmon to sea lice infection may indicate an immunological strategy rather than the possible behavioural adaptation of a freshwater return by infected sea trout. Alternatively, differences may reflect the parasite's adaptation to the host's migratory patterns in order to enhance survival of the sea lice population.