Real-time Passive Acoustic Mitigation Monitoring during Ardersier Port Expansion
SMRU Consulting’s Coastal Acoustic Buoys (CABs) have been busy listening for dolphins in the Scottish Highlands…
Haventus has been leading the redevelopment of the Port of Ardersier, near Inverness. The goal is to repurpose the existing brownfield site and expand the Port into a key hub for the offshore wind industry, focusing on fabrication, assembly, and deployment of wind farm components. The redevelopment of the Port of Ardersier consists of two project phases. Phase 1 refers to the initial, pre-construction preparation and groundwork stages of the Ardersier Energy Transition Facility project, whilst Phase 2 – for which SMRU Consulting are also leading the Marine Mammal EIA Chapter – consists of continued port development and expansion of port related services for energy related uses.
As a part of the Phase 1 development, a dredging campaign has taken place, whereby the seabed of the inner channel of the port, as well as the area immediately outside the port entrance, has been deepened to facilitate access by vessels. However, dredging can cause disturbance to marine mammals. This can include the physical disturbance from the increased turbidity caused by dredging operations, as well as the disturbance caused by noise pollution. This is especially important to consider as the port lies within the Moray Firth Special Area of Conservation, one that has been designated for the resident bottlenose dolphin (Tursiops truncatus) population there.
Fig 1. Bottlenose dolphin in the Inner Moray Firth. Photo: Ella Marwood.
With an interest in both completing dredging works within regulatory compliance, as well as raising the bar of environmental monitoring, Haventus reached out to us regarding our real-time passive acoustic mitigation monitoring tools. As environmental consultants with a marine mammal focus, and who have contributed to EIAs and pre-consenting work on many marine renewable energy developments around the UK, we hopped on the opportunity to be involved in this project.
Fig 2. CAB schematic, from Palmer et al. (2022), Methods in Ecology and Evolution.
Our work involved deploying our in-house engineered CABs (Coastal Acoustic Buoys) at both dredging and spoil disposal sites. These are autonomous multi-channel passive acoustic monitoring buoys that sample at high rate and can transmit summaries of the data back in real-time. CABs were acoustically monitoring both near where the cutter suction dredger was operating in the Inner Moray Firth, as well as farther out, where the scooped-up mud/sand/silt is dumped, throughout the entire dredge campaign.
Fig 3. Jack and Ella with a CAB lander aboard our deployment vessel, looking out towards a spoil disposal vessel.
Throughout the ~4 month dredging works, our CABs have continuously acoustically monitored the area, including monitoring noise, as well as automatically detecting not only the presence of dolphins, but also their location relative to the mitigation zones. Our CABs provided this information in real-time, allowing PAM Operators to make informed decisions according to the project’s Marine Mammal Protection Plan. If, for example, dolphins overlapped with mitigation zones during critical windows, pauses in dredging/spoil disposal operations were taken until the dolphins had moved out of the area. This approach reduces adverse impacts on the dolphins.
The PAM Operator could be located anywhere with internet access, enabling flexibility in environmental monitoring schemes. A real-time display of a custom-configurable PAMGuard screen allowed them to view click detections, listen to whistle detections, observe noise band levels, and visualize bearing estimations on a map.
Fig 4. Real-time map display of CAB Guardian sites.
This real-time acoustic approach also had the additional benefit of reducing potentially costly operational delays, and allowed for dredging operations to continue during hours of darkness where dolphin presence cannot be visually monitored.
Fig 5. CAB being recovered from the seabed, near Ardersier.
Our real-time work complements simultaneous long-term archival acoustic monitoring to evaluate dolphin behaviour and habitat usage, which is being completed by colleagues at the Lighthouse Field Station. Haventus also produced a fantastic video highlighting both these real-time and archival passive acoustic monitoring aspects of this project.
Figure 6. Screengrab from Haventus video summarizing the PAM associated with the port redevelopment. Chloe, Jack and Maddie preparing a CAB for deployment.
Dredging works have recently been completed, and we look forward to hearing about the green energy projects that are facilitated by the port of Ardersier’s redevelopment.
5 September 2025