Challenges and Solutions to Viral Diseases of Finfish in Marine Aquaculture

Abstract

Aquaculture is the fastest food-producing sector in the world, accounting for one-third of global food production. As is the case with all intensive farming systems, increase in infectious diseases has adversely impacted the growth of marine fish farming worldwide. Viral diseases cause high economic losses in marine aquaculture. We provide an overview of the major challenges limiting the control and prevention of viral diseases in marine fish farming, as well as highlight potential solutions. The major challenges include increase in the number of emerging viral diseases, wild reservoirs, migratory species, anthropogenic activities, limitations in diagnostic tools and expertise, transportation of virus contaminated ballast water, and international trade. The proposed solutions to these problems include developing biosecurity policies at global and national levels, implementation of biosecurity measures, vaccine development, use of antiviral drugs and probiotics to combat viral infections, selective breeding of disease-resistant fish, use of improved diagnostic tools, disease surveillance, as well as promoting the use of good husbandry and management practices. A multifaceted approach combining several control strategies would provide more effective long-lasting solutions to reduction in viral infections in marine aquaculture than using a single disease control approach like vaccination alone.

Keywords: biosecurity; challenges; control; prevention; solutions; vaccines; viruses.

Figure 1

Drivers of emerging infectious diseases in aquaculture. (A) Virus drivers include mutations leading to virulent strains and the ability to infect different host species. (B) Fish host drivers include susceptibility to infection due to low immunity. (C) Anthropogenic drivers include farming practices that include high stocking density and poor feeding regimes that cause fish to become stressed and increase susceptibility to infection. (D) Environmental drivers include adverse conditions such as changes in alkalinity, reduced dissolved oxygen, and increase in nitrites that predispose fish to viral infection.

Figure 2

Disease control policies showing different levels namely, global policies involving institutions such as the OIE, multinational polices such as the European Union (EU), national polices, and local farmers’ management plans. Arrows show that policies developed at local fish farmer level can be adopted to become part of the national fish health policy. Similarly, national fish health policies can be adopted and included in multinational and global policies by organizations such as the OIE. The converse also applies: policies developed at global level can be disseminated for inclusion at multinational, national, and local fish famer levels.