Australia is relatively free from many of the major fish and shellfish diseases present overseas. Introduction of new diseases, such as through imported products, can lead to increased deaths in native aquatic species with no previous exposure and little resistance to the exotic disease. For example, the much publicised death of millions of pilchards in coastal waters of southern Australia in May 1995 is thought to have been due to a newly introduced viral disease (see Whittington 1996 (www.int-res.com)).
The primary precursor to disease in wild populations is usually physical or chemical stress such as lowered water temperature, rapid changes in salinity, chronic pollution or crowded conditions. It is often the impact of these stressors on a species’ disease resistance that increases their susceptibility to disease-causing parasites, viruses, microbes or fungi already present in the environment.
If you suspect you have observed an aquatic disease please report it. In all cases, a quick response is essential to enable correct diagnosis of the problem and to allow for appropriate measures to be taken to contain the problem.
Learn more about signs to look for in significant existing and potential aquatic diseases through our aquatic health pages: