New case study: Bioremediation – using sea cucumbers to reduce salmon farm waste

Bridging the gap between fish production and environmental conservation by bringing bioremediation to marine aquaculture

Marine aquaculture must balance fish production with environmental protection. Waste from salmon farms can accumulate on the seabed, creating conditions that can impact marine ecosystems. This project explored bioremediation as a natural solution, using Scottish sea cucumbers (Holothuria forskali) to recycle waste and retain the health of the seabed.

With a total value of almost £245k, the project partners were SAMS, Blue Remediation Ltd and: Mowi. The project was funded by the Seafood Innovation Fund (SIF) and SAIC.

Bioremediation uses living organisms to break down or remove pollutants. In this case, sea cucumbers feed on organic matter, potentially reducing waste beneath salmon pens. The project combines laboratory experiments with computer modelling to quantify this effect and predict its impact at farm scale.

An initial three-month feasibility study tested whether sea cucumbers could survive and thrive on salmon waste. Results were promising: sea cucumbers not only survived but preliminary data suggest they could remove up to 70% of waste in targeted areas. This indicates strong potential for improving seabed conditions and reducing environmental impact.

To scale up, researchers are developing a computer model that simulates sea cucumber physiology and environmental interactions. This model will estimate how many sea cucumbers are needed to process farm waste and predict long-term effects on seabed health. Ultimately, the model will integrate with NewDepomod - the regulatory tool used to assess fish farm biomass - providing farmers and regulators with a practical decision-making tool.

A follow-on full R&D phase (lasting 18 months) focuses on refining the model, conducting additional lab experiments to account for seasonal and size variations, and validating results through in-situ trials on salmon farms.

This project demonstrates how nature-based solutions can support sustainable aquaculture. By turning waste into a resource, bioremediation offers a pathway to reduce environmental pressures, improve benthic health, and enable responsible growth in fish farming.

The full title of this project is ‘Investigating sea cucumbers as bioremediators for salmon farms’.

Read the case study