Minimizing the Impacts of Disease Outbreaks in Freshwater Fish

Minimizing the Impacts of Disease Outbreaks in Freshwater Fish

Mohamed Faisal   

In their aquatic habitat, fish are exposed to a multitude of stressors including pathogenic microorganisms. When environmental factors fluctuate aggressively, fish host defense mechanisms become compromised and even the least virulent pathogen can cause substantial losses and long-term impacts at both the population and community levels. In the freshwater environment, three major factors seem to foster the eruption of disease outbreaks: the rising expansion in recreational fishing, transboundary movement of fish, and high stocking density in aquaculture and stock enhancement programs. Worldwide, aquaculture of fish has been growing exponentially and is the fastest growing food production sector, providing an alternative to the rapidly declining fisheries. Unfortunately, fish diseases are considered the major impediment to aquaculture growth from the economic and socio-economic development aspects. Therefore, health issues that inhibit the growth of fish must be addressed by both proactive and reactive programs. One such issue is the increased movement of fish broodstock and fertilized eggs around the globe, which plays a major role in the emergence of new diseases in previously free zones. Efforts to prevent the spread of fish pathogens with sound management practices are essential at the farm, regional, national, and international levels. In this context, many national health plans have been proposed yet only a few have been implemented. Such plans have been confronted with major obstacles, including limited knowledge, shortage of funding, and absence of political will to execute these plans. On the brighter side, vaccines against major bacterial pathogens have become available and sensitive diagnostic assays have been developed. Case studies will be presented showing how best management practices and sound surveillance design can minimize the impact of disease outbreaks in farmed and wild freshwater fish.

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