Brian Jones

Immunopathology is broadly defined as the study of immune responses associated with disease, including the study of the pathology of an organism, organ system or disease with respect to the immune system. As other chapters in this book discuss topics such as the immune responses of fish to infectious agents and the effects of stressors on the immune response, this chapter addresses a subcategory of immunopathology. Immunopathology is defined here as the study of pathological changes in organs of the immune system resulting from a variety of aetiologies, including infectious agents (viruses, bacteria, fungi and parasites) and non-infectious conditions (nutrition-related, toxicant-related and neoplasia). Whereas numerous studies on fish have focused on the host response to various stressors, relatively few have investigated immunopathology. This review utilises examples of infectious and non-infectious diseases in teleost fishes to summarise our knowledge of teleost immunopathology. For some diseases, the presence of an infectious agent or toxin may directly or indirectly cause destruction of immune organs. In other diseases, an intense inflammatory response, or conversely, suppression of the immune response, may contribute to disease progression in these organs. Other factors such as the virulence of a pathogen biotype, degree of toxicity or carcinogenicity of an exogenous element or compound, the species and age of exposed fish and environmental conditions such as water temperature and water quality can also contribute to determining the outcome of a disease. Additional research is needed to investigate the mechanisms responsible for immunopathology observed in many diseases.

Samples of pilchards from along the south coast of Western Australia obtained by the Department of Fisheries with the assistance of industry and the Albany Port Authority have established that pilchards from King George Sound are no higher in Selenium than pilchards from elsewhere on the south coast of Western Australia, nor are they different from the selenium levels reported for the same pilchard species caught off South Africa. Levels of Se in pilchards are naturally high, but are not as high as in other pelagic tunas caught in the open ocean.

The aquaculture of pearl oysters is an expanding multimillion dollar industry in the tropical marine environment of many countries, including Australia, French Polynesia, the Middle East, China, Southeast Asia and Japan. Despite the size and extent of the industry there is remarkably little known about the diseases and parasites of the genus Pinctada. There is a growing awareness among the industry that, as with other molluscs under cultivation, disease can be an important constraint and chat translocation of shellfish poses a serious risk. This paper will review the known diseases caused by pathogenic agents as well as those with a non-infectious aetiology. Management techniques, which can be used to minimize the impact of disease, will also be discussed.

Australian aboriginals were trading pearls long before Europeans "discovered" pearls in Australian waters in 1812. By the end of the nineteenth century, fishing for "mother of pearl" shell and the incidental pearls was well established. The industry was heavily affected by the decline in value of mother of pearl after World War II (WWII). Artificial seeding of pearls (Pinctada maxima) began in Australia in 1956, under agreement with the Japanese and production grew until major mortalities in the 1970s affected industry growth. The mortalities were traced to inadequate management practices resulting in Vibrio harveyi infections and, following improvements to shell handling techniques, mortalities were eliminated. The Pinctada maxima industry in Western Australia and Northern Terrirory is the most valuable in Australia and is heavily regulated. Smaller industries exist in Australia farming non-maxima pearl oysters. Though a range of parasites have been identified in pearl oysters, none have caused serious problems for the industry, however, mortalities in Exmouth Gulf in 2006 with an unknown aetiology have forced changes to industry protocols.