Experimental infection of turbot Scophthalmus maximus and halibut Hippoglossus hippoglossus yolk sac larvae with Aeromonas salmonicida subsp. salmonicida

Abstract

The suscept~bility of early l ~f e stages of turbot Scophthalmus maximus and halibut Hippoglossus h~ppoglossus to Atvomonas salmoniclda subsp. salrnonicida was studied in challenge experiments. Eggs of both fish specles (and the larvae hatching from the eggs) were exposed to the bactenum. Larvae of both species experienced mortality during the yolk sac stage, apparently as a result of the challenge. Examination of histolog~cal sect~ons revealed degenerative changes in the skeletal muscle of both species of larvae. The bactenum could not be recovered from the larvae by culture, but it was shown to be present in the intestinal lumen of some of the turbot larvae examined using a n imn~unohistochemical techn~que known to be spec~fic for the bactenum. The results indicate that manne fish larvae exposed to A salmonicida subsp salmonicida may become ~nfected and that the bacter~um may persist In the larvae. Turbot larvae seemed to be more susceptible than hahbut larvae