THE DEVELOPMENT OF SALMON LICE (LEPEOPHTHEIRUS-SALMONIS) ON ARTIFICIALLY INFECTED POST SMOLTS OF SEA-TROUT (SALMO-TRUTTA)

The developmental rate, distribution on the host, and pathogenicity (s kin damage) of salmon lice (Lepeophtheirus salmonis) were tested on ar tificially infected sea trout (Salmo trutta) post smelts. Male lice de veloped faster than females, taking approximately 29 and 38 days, resp ectively, to reach the adult stage at 10 degrees C. During this time, infection intensity decreased. Less than 40% of the lice reached the a dult stage, and their distribution changed from overdispersed towards a more random pattern. The chalimus larvae of the lice exhibited a pre ference for the gills and fins, especially the dorsal fin, and caused only minor skin damage. When the preadult and adult stages appeared, s kin damage became severe, especially on the preferred head and dorsal areas, causing mortality of the most heavily infected fish.