Background
Norway's salmon farming industry is entering a period of fundamental change. A government white paper (Meld. St. 24, 2024–2025) has propsed a new system of lice quotas at the level of each production area, calibrated so that mortality of wild salmon caused by salmon louse stays below 10%. Estimates suggest that, in several production areas, this would require an order-of-magnitude reduction in lice levels at farms compared with current practice (Sandvik et al., 2025). Reaching such targets with today's open-cage technology is not realistic. It may require investments of more than ten billion Euro in shielded production methods such as sea based semi-closed and closed containment systems, and deep or submerged farming – an investment programme of unusually large scale for the sector.
A regulatory framework that drives such a transition must offer companies enough predictability to commit capital, and the regulatory incentive design is critical (Cojocaru, 2024). The underlying biological and environmental processes are highly variable and difficult to measure: lice counts at a single farm fluctuate widely, neighbouring sites infect each other, and the link between counts on farms and mortality of wild salmon must be inferred from incomplete data. The central question is how to reduce lice pressure on wild salmon without imposing risks on companies that are too large for the technology transition to be financed and carried out.
Findings and regulatory designs
Lice quotas, on their own, regulate something that is hard to measure precisely - lice counts on farmed fish - rather than what actually matters for wild salmon - the release of infectious lice larvae and the resulting infection pressure on wild smolts. Counts at a farm are noisy, infection drifts between sites, and the link to lice induced wild-salmon mortality must be modelled with substantial uncertainty. Rather than tightening such a noisy signal, regulators can more effectively reward the physical separation between farmed salmon and lice, which is observable through the choice of production technology and more verifiable through engineering specifications.
We compare different regulatory designs, from lice quotas to incentives for separating farmed salmon and sea lice. A stochastic firm-level optimisation model is developed for a risk averse salmon producer that faces simultaneously a Maximum Allowable Biomass (MAB) cap and a binding lice quota, where the lice population is stochastic.
A firm-level analysis of a salmon producer operating under both a biomass cap and a lice quota, with uncertain lice prevalence and sanctions for breaches, yields several findings. First, even when a company aims at an expected lice level well below the quota, year-to-year variation means that the upper tail will sometimes cross the threshold, generating an expected sanction cost that is invisible in deterministic analyses. Cautious firms therefore stock and grow less than the lice-quota number alone would suggest, providing a firm-level explanation for the substantial production losses the industry would face under tight quotas. Second, a verified low-lice technology reduces both the average lice load and its variability, whereas a tighter lice quota only moves the threshold without addressing the underlying variability. Technology-based regulation may hence be more attractive than emission-based regulation for any firm averse to downside risk: it lowers expected compliance costs and works as insurance against year-to-year variability the industry cannot control.
Policy implications for Norwegian salmon aquaculture
For Norway, analysis indicate that the most promising package may combine a moderate conversion factor with a regional cap so that converted capacity displaces open-cage exposure within each production area, and the existing farm-level lice limits retained as a backstop for open cages. The analysis suggests that regulating verifiable physical separation between farmed salmon and lice is more effective and less risky for the industry than tightening noisy lice counts – and may be essential for a successful transition of the magnitude that Norwegian salmon farming now faces.
Acknowledgment
This work was supported by the Norwegian Seafood Research Fund (FHF) through the HAVREG and Havbruksl��ftet projects, and by the Research Council of Norway.
References
Cojocaru A.L., Jensen F., Misund B., Nielsen R., Pincinato R.B. & Tveter��s R. (2024) A flexible policy instrument to encourage externality abatement technologies in salmon aquaculture. Ecological Economics 224, 108317.
Meld. St. 24 (2024–2025) Future marine aquaculture (In Norwegian: "Framtidens havbruk.") Norwegian Ministry of Trade, Industry and Fisheries.
Sandvik A.D., Johnsen I.A., Myksvoll M.S., Johnsen H., S��vik P.N. & ��dlandsvik B. (2025) Reply to request for scientific advice – Salmon lice regulation (In Norwegian: "Svar p�� bestilling om kunnskapsst��tte – Lakselusregulering.") Institute of Marine Research.