Conversely, individuals may be more susceptible to a disease because of poor nutritional status, stress or any of a number of other factors. Population density is a particularly important factor in the spread of fish diseases. Diseases can spread more easily within dense populations simply because of increased opportunities for association of infected fish with uninfected fish. The actual development of a disease and the relevant severity of that disease within a fish population is influenced by a complex interaction of these variables associated with the pathogen, the host and the environment. Diseases in Aquaculture Populations . . .
Infectious diseases pose one of the most significant threats to successful aquaculture.
The maintenance of large numbers of fish crowded together in a small area provides an environment conducive for the development and spread of infectious diseases. In this crowded, relatively unnatural environment, fish are stressed and more susceptible to disease. Moreover, the water environment, and limited water flow, facilitates the spread of pathogens within crowded populations. Control of Diseases in Aquaculture Populations . . . In their self-interest, the aquaculture industry in Maine and elsewhere in North America and Europe places a high priority on the prevention and control of infectious diseases.