Introduction
Biosafety in Norwegian salmon farming is heavily regulated and still hard to operationalise. Production is diversifying, land-based flow-through and recirculating facilities, semi-closed and submerged units, large post-smolt sites, and each concept changes where infectious agents enter, concentrate and leave the system. Intake and discharge water is common to all of them, and where practice varies most. The regulation is function-based: it requires a function, but not a documented risk assessment matched to the actual risk. WaterSafe asks which biosafety principles hold across farming concepts, and how water treatment can be verified in a standardised, technology-neutral way.
Materials and methods
Interviews and workshops across the value chain (fish health personnel, land-based and hatchery operators, the wellboat sector, water-treatment suppliers) were combined with a literature review, a review of Norwegian regulation and guidance, and experimental work: storage trials at 4 °C and 22 °C read at 0, 24 and 48 h; screening of more than 100 water samples from production areas PO1–PO10 by 16S rRNA sequencing, with cultivation of candidate indicator organisms; and a comparison of analytical methods.
Results
The material converged on principles holding across every concept and group of respondents- risk-based management, multiple independent barriers, separation of biological and operational systems, no downstream transmission, learning systematically from mortality and incidents, information sharing, and robustness ahead of efficiency- while implementation varied widely. Generic measures meant to fit all facilities were rejected in favour of site-specific risk assessment.
Water treatment recurred as the critical control point, with seawater intake to land-based hatcheries carrying the highest consequence. Weak points run the length of the barrier chain: intake placement, pre-filtration without a knowledge base or risk-assessment requirement, UV dose documented through supplier calculations, and short outages.
Above all, what the barriers deliver often cannot be demonstrated. Biodosimetry is standard in drinking water but rare in aquaculture, no harmonised sampling procedure existed, and the 3-log requirement is a method-approval criterion that cannot be transferred to mixed field samples. WaterSafe therefore aims to deliver a technology-neutral sampling protocol built on ISO 19458 and ISO 5667: standardised points before pre-filtration, after pre-filtration and after disinfection; a minimum monthly frequency with trend-based response tiers rather than a fixed threshold; and the sampling errors behind much of the poor field performance. Storage trials support a 24 h / 4 °C limit for unpreserved samples across all methods. Cultivation, flow cytometry, viability qPCR and ATP are being compared head-to-head.
Discussion and conclusions
Most of what is missing in aquaculture water management already exists in the drinking-water sector: a risk-based guideline for the whole water supply, microbial barrier analysis, biodosimetry at commissioning, and an open forum for operating experience. Biosafety principles can be shared across farming concepts, but only where the barriers they rest on are documented, validated and verified with comparable data.
Acknowledgements: Funded by The Norwegian Seafood Research Fund (FHF), project 902001.