Fish Disease Ecology in the Great Lakes

Disease may be an important variable affecting wild fish population dynamics in the Great Lakes, but a lack of information on the ecology of fish disease currently precludes the prediction of risks to fish populations.  We present a conceptual framework for conducting ecologically-oriented fish health research that addresses the inter-relationships among fish health, fish populations, and ecosystem dysfunction in the Great Lakes.  We propose that assessment models based on the response of key indicators could be used to detect ecosystem dysfunction and population responses to fish disease outbreaks.  Under this paradigm, study designs would describe natural variability in the aquatic community to develop an understanding of key ecological drivers and develop models for prediction of important biological relationships (e.g., the effects of temperature and rainfall on young-of-the-year size).  The comparison of the observed performance of real populations against the predicted performance within the scope of natural or expected variation would define the levels of health, and allow the identification of triggers to inform management decisions.  Such relationships also translate ecological information into currencies relevant for land use planning, natural resource management and impact mitigation.  This approach represents a site-specific approach that requires commitment to baseline monitoring, consistency, and long term planning, where the ability of organisms to integrate responses can be used holistically to evaluate fish population health.