As the PACE (Pathogen, Aquaculture, Climate, and Environment) project, funded by the Norwegian Research Council, nears completion, new findings have emerged about the risks facing wild salmonids in northern Norway due to climate change and fish farm expansion.
Project Overview
The study, conducted by researchers from NORCE, NTNU, and DFO (Canada), explores how wild salmonids like Atlantic salmon, sea trout, and Arctic charr are affected by the increasing presence of pathogens linked to fish farming, and how these effects are being amplified by rising water temperatures. The northern regions, which have previously been protected by colder waters and low farm densities, are now experiencing warming trends and expanded aquaculture production, raising concerns about pathogen spillover to wild populations.
Key Findings
Pathogen Impact on Trout: Across various regions of Norway, researchers found high pathogen diversity among sea trout, but the impact of pathogen richness on trout behavior was more linked to specific rivers and water temperatures than to latitude. Warmer rivers exhibited poorer survival rates for trout, highlighting the importance of local watershed conditions over pathogen diversity alone.
Pathogen Spread Along Latitudinal Gradients: Despite widespread pathogen presence across Norway, there was no significant difference in pathogen-induced behavior in wild fish populations along a latitudinal gradient. However, certain pathogens, especially those linked to sea lice, were more prevalent in southern and central regions, indicating a geographical division in pathogen dynamics between the northern and southern parts of the country.
Climate Change and Pathogen Dynamics: The expansion of aquaculture farms into northern Norway is not expected to introduce new pathogens but may amplify their presence in wild fish populations, especially in warmer waters. This could alter disease dynamics and increase the risk to wild fish in these historically low-pressure areas.
Emerging Research Questions: As the environment and fish farming industry continue to evolve, the study has identified eleven critical research questions that need to be addressed. These include understanding the long-term effects of pathogen exposure on wild populations and improving the methodology for monitoring pathogen spillover in northern Norway.
Implications for Policy
The study underscores the need for cautious marine spatial planning and fish farm management in northern Norway. Policymakers must take into account the uncertainty surrounding pathogen dynamics in these regions, particularly in light of climate change, to protect the unique and vulnerable wild salmonid populations.
As the PACE project wraps up, it provides valuable insights into how we can better manage the interface between aquaculture and wild fish populations, ensuring that conservation and industry growth can coexist in a sustainable way.
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