Research pre-empting parasite adaptation is key to sustainable disease management in aquaculture

Abstract

As the aquaculture sector continues to expand, there is likely to be a growing need to combat infectious diseases. The desire for rapid and effective results means that any concerns about longer-term effects of disease controls are often sidelined. In particular, the well-documented capacity for parasites and pathogens to evolve treatment resistance must not be ignored in aquaculture. Outbreaks of resistant parasites pose significant threats to the environment, as well as to farm production. If an industry wishes to avoid treatment resistance, there must first be committed research into the evolutionary biology of the parasite species. Such research should be incorporated into the early phases of developing and implementing a treatment strategy—the sooner the risk of resistance is identified, the sooner its impacts on aquaculture can be mitigated. Here I discuss a research framework that can help guide this process. A combination of theoretical (reviewing the literature), empirical (testing for heritable resistance) and modelling (simulating evolutionary dynamics) studies is recommended. Armed with the knowledge from these studies, parasite management strategies can then be optimised at a regional scale (e.g. with refugia or treatment combinations) in ways that minimise the potential for adaptation. The interaction between salmonid aquaculture and parasitic sea lice is an ideal case study for this topic, and the insights gained from this system should be considered across aquaculture industries. Nevertheless, there is no one-size-fits-all solution to treatment resistance. For each system, dedicated research into parasite evolutionary biology—with a research framework as a guide—is required for aquaculture to home in on the most sustainable disease management strategies for the future.