Resistance of Atlantic salmon to Major Bacterial Pathogens of Atlantic Salmon

Specific causes of mortality are multifaceted, differ amongst locales, and even
temporally within the same environment. Many specific factors influence the
resistance of an organism to disease. The natural barrier activity of skin and
mucous proteases are critical in the initial defense against infection.
Bacteriocidal/static properties of blood, number and function of leucocytes,
ingestion and phagocytic clearance of microorganisms, and production of natural
antitoxins are critical elements involved in host defense against systemic
infection. Selection for specific characters may provide a crucial element in
the development of genetic resistance to disease. In fact, successful breeding
programs have been developed in salmonids to select for resistance to
furunculosis, but applications have been limited mostly to non-anadromous
species.