Fish gills: important sites of sea lice attachment!

摘要

VARIOUS sampling protocols are used in routine monitoring of sea lice numbers, such as those developed by Marine Harvest in Scotland (Fish Farmer, Vol. 20, No 6,p20-21) and in national louse count programmes, for example in Norway, All of these protocols are non-destructive in sampling and the fish are anaesthetised when counting lice. Several studies have indicated that the highest proportion of attached "chalimus" stages in artificial experimental infection is present on the gills (Bron et al., 1991; Johnson, 1993) (Photo 1). However, gills are not routinely examined in monitoring programmes because of the high economic value of sacrificed fish and because the time required preparing the gills and carrying out detailed counts with a microscope would be excessive. Although experimental studies refer to the gills as the major attachment site for Lepeophtheirus salmonis in challenge, the importance of the gills as an attachment site for sea lice in natural challenges of farmed salmon has not been established.