Study Reveals Over Half Of Scotland’s Coastal Vessels Go Untracked

A recent study by Heriot-Watt University has found that more than half of the vessels operating near Scotland’s coasts are not visible through standard maritime tracking systems.

According to the research, only 43% of vessels within 10 kilometers of the Scottish shoreline were found to transmit Automatic Identification System (AIS) signals, which are used to monitor ship movements around the world.

Researchers warn that this lack of tracking could seriously impact marine safety, conservation efforts, and effective ocean management.

The study was based on more than 1,800 hours of surveys conducted between 2019 and 2024, covering nine of Scotland’s eleven marine regions.

A large portion of the data came from citizen scientists-volunteers from various coastal organisations who were trained to follow standardised procedures in observing and recording vessel movements.

Participants included members of Whale and Dolphin Conservation Shorewatch in Shetland, the Hebridean Whale and Dolphin Trust, and the Community of Arran Seabed Trust.

Their contribution was crucial in providing a detailed picture of actual vessel activity along the coast.

Dr Emily Hague from Heriot-Watt’s School of Energy, Geoscience, Infrastructure and Society, who led the study, discussed how the findings challenge the common assumption that AIS provides a full account of vessel traffic.

“In some parts of the country, over 75% of the vessel activity goes unrecorded,” she noted. The research also revealed major differences in AIS coverage across various regions.

For example, in the Outer Hebrides, only 20% of vessels observed were transmitting AIS data. This is particularly concerning as the area is popular for fishing, aquaculture, and marine tourism.

In contrast, Orkney showed a better rate with 58% of vessels using AIS.

One of the most surprising findings came from the Forth and Tay region, which hosts some of Scotland’s busiest ports.

Despite the heavy traffic, only 8% of the observed vessels in this region were found to broadcast AIS signals.

Smaller boats, such as recreational crafts, fishing vessels under 15 meters and jet skis, were identified as the main types of untracked vessels.

These are not legally required to carry AIS equipment, although they can choose to use it voluntarily.

The researchers discussed the importance of having accurate vessel data, especially for assessing the impact of marine activities on local ecosystems.

Dr Hague explained that AIS data is often used by authorities and conservation groups to understand risks like underwater noise, whale collisions, seabed damage, and greenhouse gas emissions.

“If more than half of vessel movements nearshore are missing from the records, then we’re likely underestimating these environmental impacts,” she said. “This could result in weak or misdirected policies when it comes to conservation and safety.”

Dr Lauren McWhinnie, also from Heriot-Watt talked about the risks to wildlife, stating that Scotland’s coastal waters are home to species like bottlenose dolphins, minke whales, and orca.

But it’s extremely difficult to gauge the risks they face or how to protect them effectively without solid data.

The researchers suggest that in regions where non-AIS vessels are common, the AIS data should be backed up wth alternative tracking methods.

Land-based observations and further engagement with citizen scientists could help fill the gaps.

Dr McWhinnie stated that even if smaller boats aren’t required to use AIS, it would be beneficial if more of them did.

Better data would help local communities manage tourism and marine activities in a way that balances economic needs with environmental sustainability.

Carole Davis, a volunteer from WDC Shorewatch in Shetland who participated in the project, expressed hope that the research would help raise awareness.

“It felt great to contribute, The more information we gather, the better we can understand the potential effects of vessels and the important role that citizen scientists can play,” she said.

The study recommends applying correction factors to AIS-based data to help improve current models and assessments.

These should consider vessel type, location, and season to ensure a more accurate understanding of coastal activity.

The full study was published in the academic journal https://www.sciencedirect.com/science/article/pii/S0308597X25001344?via%253Dihub

References: Heriot-Watt University

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