Abstract
Many effects of diseases on cultured fish are known; they are less clear in wild fish populations. Cultured fish represent captive populations that can be subjected to intense scrutiny with an increasing range of diverse and powerful tools. Disease represents a spectrum from acute mortality to rather benign or inconsequential syndromes, all sharing the common feature of a deviation from the normal structure or function of the host. Understanding these deviations among cultured and wild fish populations and balancing their implications against ecological, economic, and political concerns are challenges for both fish health scientists and fisheries managers. The severity of a given disease is dependent on the interaction of numerous variables of the host, the parasite, and the environment. To understand diseases and their impacts on fish populations, we must know which variables are important, how we measure them, and finally how we assess the results of our measurements. We have perhaps been most ...