New case study: tackling tubeworm biofouling in Scottish mussel farming

Development of a system to help mussel farmers optimise shell cleaning strategies

Scottish mussel farms face a persistent challenge during spring and summer: biofouling by organisms such as barnacles and tubeworms. Tubeworms attach to mussel shells and form hard calcareous tubes, making them difficult and costly to remove. While they don’t affect edibility, their appearance and smell after cooking reduce consumer appeal, leading to around 500 tonnes of mussels - about 5% of the annual harvest - being discarded each year. Biofouling may also slow mussel growth, further impacting profitability.

This project aimed to develop a rapid monitoring system to help farmers predict tubeworm settlement and optimise cleaning schedules, reducing waste and improving product quality. Valued at £295k, the project was led by the University of Stirling. The projects objectives included:

• Creating a DNA-based test to detect tubeworm larvae in seawater and on shells.
• Validating sampling methods for accurate detection.
• Using test results to guide cleaning operations and reduce fouling.

Project findings

• Plankton sampling combined with DNA analysis (qPCR) proved the most effective way to detect tubeworm larvae, while shell swabs and artificial substrates were unreliable.
• Environmental DNA (eDNA) analysis showed settlement peaks correlated with sea temperatures above 12°C, suggesting temperature could predict fouling risk.
• Visual identification under a microscope was still needed to confirm DNA results, as extraction and detection were inconsistent.
• Cleaning trials were inconclusive, but the study provided valuable insights for designing future interventions.

The research also highlighted the potential impact of climate change, as rising sea temperatures may increase tubeworm abundance and extend fouling seasons, posing greater challenges for mussel farmers.

Future work will refine DNA testing methods for better reliability and explore temperature-based ‘intervention thresholds’ to help farmers schedule cleaning more effectively. These innovations could reduce economic losses, improve efficiency, and support sustainable shellfish farming.

Although cleaning solutions were not fully achieved, this project marks an important step toward early-warning systems for biofouling, combining molecular tools with environmental monitoring to protect Scotland’s mussel industry.

The full title of this project is ‘Investigating tubeworm biofouling and monitoring strategies in Scotland’.

Read the case study