Biological Control Strategies in Salmon Aquaculture

Biological control in salmon aquaculture harnesses natural interactions to mitigate parasitic infestations and support fish health while reducing reliance on chemical treatments. Central to this approach is the use of cleaner fish, such as lumpfish and wrasse, to remove sea lice from farmed salmon. Emerging methods also include immunomodulatory interventions, microbial antagonists and welfare-focused monitoring tools. By integrating ecological, physiological and operational insights, practitioners can optimise stocking densities, deployment timing and species selection to achieve sustained delousing efficacy. Advances in noninvasive diagnostics, such as biofluorescence and hyperspectral imaging, enable real-time assessments of cleaner fish stress levels and welfare status, ensuring ethical and effective application. Complementary strategies explore probiotic fish feeds and selective breeding programmes to enhance innate resistance to ectoparasites. Collectively, these interventions offer a globally significant, environmentally benign framework for sustainable salmon production, balancing animal welfare, farm profitability and ecosystem health.

Research from Nature Portfolio

Recent studies have demonstrated that lumpfish biofluorescent emissions vary in response to a controlled stressor, revealing potential for noninvasive welfare assessment. Hyperspectral imaging across the 400–1000 nm range captured distinct shifts in red and green fluorescence following a freshwater bath, indicating applicability in on-farm monitoring of cleaner fish health and stress.

Investigations into liver colour scoring in lumpfish deployed in salmon cages identified distinct pigment and lipid profiles linked to welfare condition. Bright orange livers corresponded to high carotenoid levels and good health, whereas dark reddish-brown hues signalled depleted lipid reserves and poor welfare. This visual index offers a rapid diagnostic tool for farm managers to gauge cleaner fish condition.

Biological Control Strategies in Salmon Aquaculture publication trend

The graph below shows the total number of articles in biological control strategies in salmon aquaculture across all publications each year (not limited to Nature Index journals).

Technical terms

Cleaner fish: Fish species, such as lumpfish or wrasse, employed to remove ectoparasites like sea lice from salmon by grazing.

Sea lice: Parasitic copepods (Lepeophtheirus salmonis) that attach to salmon skin, causing health deterioration and economic losses.

Biological control: Use of living organisms or their natural interactions to regulate pest populations in place of chemical treatments.

Biofluorescence: Emission of visible light by an organism when excited by specific wavelengths, used here to assess cleaner fish stress.

Hyperspectral imaging: Noninvasive technique capturing detailed spectral data across many wavelengths for diagnostic and health monitoring.

References

1. Biological control of a parasite: The efficacy of cleaner fish in salmon farming. Ecological Economics (2025).
2. Biofluorescent response in lumpfish Cyclopterus lumpus to a therapeutic stressor as assessed by hyperspectral imaging. Scientific Reports (2024).
3. Salmon lice (Lepeophtheirus salmonis) in the stomach contents of lumpfish (Cyclopterus lumpus) sampled from Norwegian fish farms: Relationship between lice grazing and operational conditions. Aquaculture (2023).
4. Liver colour scoring index, carotenoids and lipid content assessment as a proxy for lumpfish (Cyclopterus lumpus L.) health and welfare condition. Scientific Reports (2020).
5. In lumpfish We Trust? The Efficacy of Lumpfish Cyclopterus lumpus to Control Lepeophtheirus salmonis Infestations on Farmed Atlantic Salmon: A Review. Fishes (2022).