Arran: Lamlash Bay to undergo study on boat traffic impact on sealife

The impact of marine traffic on sea beds has been a point of discussion across Scotland in recent months with events such as the mass stranding of whales at Traigh Mhor on the Isle of Lewis in late July this year, which was the most lethal such occurrence in recent memory. 

On Arran, species such as seals and dolphins are impacted by the presence of boats in the bay, according to Professor Lauren McWhinnie of Heriot-Watt University. 

Professor McWhinnie explained: “Vessel traffic has potentially wide-ranging impacts on marine life. Boats can damage the seabed by anchoring on sensitive habitats such as reefs or impact protected species like seagrass beds that are found in Lamlash Bay’s waters. 

“Species like seals and dolphins are also sensitive to disturbance from boats. Their physical presence can cause changes to their behaviour, and the noise they emit can impact sea mammals’ ability to communicate with each other”. 

Currently under consultation by the Scottish Government is the proposal of Highly Protected Marine Areas, which would see commercial and recreational fishing banned in at least 10% of seas around Scotland.

Scotland already has around 37% of its seas classed as Marine Protected Areas, which aim to protect biodiversity and other marine conservation sites. 

Read more: Highly Protected Marine Areas need 'radical rethink'

Lamlash Bay stands as Scotland’s only ‘no take’ zone, which means no fish, shellfish, or other marine life can be extracted from the seafloor or shore. 

The policy has already been in place since 2008, and Sophie Plant of COAST says the benefits for the Bay have been notable: “Since the No Take Zone was established almost 15 years ago, researchers have seen significant increases in biodiversity and marine life density has more than doubled. These benefits extend to commercial species such as lobsters and scallops whose size, age and abundance is significantly better. 

"The lack of fishing in the area has allowed it to begin to recover, providing more complex habitats that provide nursery grounds for juvenile fish and benefitting the wider marine environment."

The new research aims to calculate the true volume of traffic in Lamlash Bay - smaller boats under 15m long are not obligated to broadcast their ID, speed, activity and position with an automatic identification system (AIS), and so it is hard to know exactly how many are populating the port.

It is believed these vessels could account for up to 70% of boat traffic in some areas - and hence sea traffic figures could be well below the reality, making it hard to understand exactly how sealife are being impacted. 

Read more: Lewis whales: 'Most lethal mass stranding in living memory'

Professor McWhinnie explained how the research is to work: “In collaboration with COAST we’re installing an AIS receiver for Lamlash Bay. 

“Combining AIS data with land-based vessel counts will give us a more accurate picture of the number and types of vessels coming in and out of this environmentally-important area. 

“Many vessel noise estimates are based primarily on AIS data - potentially not including almost 70% of the traffic, and just one of the reasons this work is important”. 

“This isn’t to say small boats shouldn’t be using Lamlash Bay. We just need a better understanding of exactly how much activity is happening so we can ensure that we are doing enough to protect the bay. 

“It’s also an amazing opportunity to get a better understanding of how we can generate data on vessel traffic in other coastal areas.” 

The project is funded by charity Sea Changers and the Natural Environment Research Council, which will offer an undergraduate student at Heriot-Watt the chance to do a placement on the project.