Sea lice on adult Pacific salmon in the coastal waters of Central British Columbia, Canada

Adult Pacific salmon were captured individually during their coastal migration and examined for sea lice in two marine areas in the central coast area of British Columbia. Virtually all salmon had sea lice. Pink, chum, and sockeye salmon had average intensities ranging from 41.5 to 52.0 sea lice. Chinook and coho salmon had average intensities ranging from 16.1 to 18.5 sea lice. Chinook salmon had the lowest intensities of sea lice and the smallest number of chalimus stages. The prevalence and intensities of sea lice were similar in each study area, one of which had salmon farms and one that had no salmon farms. Lepeoptheirus salmonis were about twice as numerous as Caligus clemensi. Most C. clemensi were in the chalimus stage and most L. salmonis were in the mobile stage. Gravid female L. salmonis represented 33.3% of all mobile stages. Gravid female C. clemensi were rare. In general, two species of sea lice were observed to be a common parasite on five species of Pacific salmon in the area that contained salmon farms and the reference area that had no farms.