Spatial patterns of PATHogen profiles in marine habitats and associations with active and fallow fish farms from eDNA sampling (PATHDNA)

Infectious disease is a leading cause of fish mortality in open net pen fish farming and represents a primary threat to the viability of wild salmonid populations. Tracking the transmission of pathogens around fish farms is therefore an important research frontier that will help manage disease outbreaks and mitigate environmental damage. The new PATHDNA project aims to adapt environmental DNA sampling for viruses, bacteria, and parasites to model when, where, and how disease agents are spread to and from open net pen fish farms in western Norway, a hotspot for global fish farming operations. Environmental DNA contains the genetic signatures of both fish and pathogens, providing a molecular genetic trail that can help track the distribution and abundance of species across space. Sampling programs for environmental DNA have helped in the protection of threatened species and in the fight against invasive species and we will help develop this method as a tool for combating infectious agents around fish farms. The project has three objectives; 1) evaluate the effects of fish farm fallowing on persistence and spread of pathogens; 2) assess how well boats that travel between farms contribute to pathogen dispersal; and 3) validate a new real-time hand-held tool for tracking the spread of pathogens around fish farms. The project, led by NORCE Norwegian Research Centre, is a collaborative initiative between the research and industry sectors, with contributions from Fisheries and Oceans Canada, the University of Toronto, and the aquaculture industry. The project will run from 2021-2024 and will involve a detailed sampling regime to track the presence and absence of key salmon pathogens in water samples from aquaculture zones in western Norway. The project aims to deliver actionable advice on management of fish farms including the use of fallowing zones and the operation of well boats as well as new tools for tracking disease transfer and monitoring spillover between farms.