Transboundary and Emerging Diseases of Freshwater Farmed, Ornamental and Wild Fish

Aquaculture offers a solution to many of the food and nutrition security issues facing the growing human population. It bridges the gap between stagnating yields from capture fisheries and an increasing demand for fish and fishery products. It also offers opportunities to reduce poverty, increase employment and community development and reduce overexploitation of natural aquatic resources, thus creating social and generational equity, particularly in developing countries. Increased focus on aquaculture as solution to the demand and supply gap of aquatic products in the future will undoubtedly increase transboundary movement of live aquatic animals and their products. This carries an increasing biosecurity risk, particularly associated with introduction and spread of pathogens.  

Transboundary aquatic animal diseases are highly contagious with strong potential for rapid spread irrespective of national borders. They pose a significant threat to the aquaculture sector and have major social, economic and environmental implications. These include loss of important animal protein source in human diet; direct and indirect impacts on output, income and investment; increased operating costs; restrictions on trade; impacts on biodiversity; loss of market share or investment; loss of consumer confidence; and in some cases, collapse of the sector. Managing aquatic animal health and biosecurity in aquaculture is particularly challenging because of the great diversity of the sector in terms of species cultured, the range of culture environments, the nature of containment, the intensity of farming practices and the variety of culture and management systems.  

This presentation focusses on two transboundary  and emerging/re-emerging freshwater fish diseases, epizootic ulcerative syndrome (EUS) and koi herpesvirus (KHV), which require focussed attention in the coming years to protect a major freshwater aquaculture sector from biosecurity emergencies. Freshwater aquaculture is the major contributor to “food fish” production; susceptible hosts to EUS and KHV rank amongst the world’s most important aquaculture species. These diseases are also important to the ornamental fish industry. The threats posed by EUS and KHV to freshwater farmed, ornamental and wild fish and freshwater resources are explored in this paper. Institutional responses and biosecurity measures to protect and prevent, two major lines of defence, against pathogen aggression, are also explored in this paper.