What is “Normative” for Fish Pathogens? A Perspective on the Controversy over Interactions between Wild and Cultured Fish

In its report, Return to the River , the Independent Scientific Group (now called the Independent Scientific Advisory Board—the scientific peer review arm of the Northwest Power Planning Council) advanced the notion of a “normative river ecosystem” as a new conceptual foundation for salmonid recovery in the Columbia River basin. With this perspective, the sum of the best scientific understanding of how organisms and aquatic ecosystems naturally function should be the norm or standard of measure for how we judge the effects of human activities on aquatic systems. For the best likelihood of recovery, key aspects of altered systems should be brought back toward normative (although not necessarily fully back to the historical or pristine state); new alterations should be judged by how much they move key functions away from normative or what might be considered as normal. In this paper, I ask what “normative” is for fish pathogens and how this concept could help resolve the long‐standing disputes between fish culturists and advocates of wild fish in fisheries management. Through literature review and parallels with the evolution of infectious diseases in human populations, I suggest that the concept can be useful for understanding and controlling pathogens and diseases of fish in aquatic ecosystems. One key to avoiding disease outbreaks appears to be maintenance of normal diversity in fish pathogens, intermediate hosts, and immunological types in fish. I encourage further exploration of the normative perspective as a guide to our research and evaluations of pathogens and diseases of fish.