IWDG Consulting recently completed two geotechnical surveys in the Shannon estuary.

Two MMOs covered 24/7 for six weeks over Christmas and New Year off Foynes Island for Shannon Foynes Port Company as part of their Vision 2041 development of port facilities. A single MMO worked 12 hour shifts off Money Point Power Station for the ESB. The work off Money Point contributes to the development of the Green Atlantic Hub transition in the estuary to support offshore renewables.

This mitigation is important as the Shannon is a Special Area of Conservation with both bottlenose dolphin and otter as qualifying interests. Sightings upriver around Foynes was limited to otters though bottlenose dolphins are known to use this area of the estuary on as much as 40% of days according to Static Acoustic Monitoring data collected by the IWDG. There were more sightings of bottlenose dolphins around Money Point, which also included a number of seal sightings. Minor delays to start up were recorded but the work went ahead with no significant impacts ion dolphins or other marine mammals.

Both geotechnical surveys were carried out on the barge owned and operated by Causeway GeoTech. We thank them for their support and services to enable smooth operation.

IWDG Consulting would like to thank Andrew Shine, Fiona Cummins and Tess Peters for providing their excellent professional services to the IWDG

An event by IMarESTs Marine Mammal SIG in collaboration with Blue Jobs

https://www.imarest.org/events/event-calendar/careers-in-marine-mammal-science-and-industry-building-skills-for-the-blue-economy.html

North Bull Island, a key feature of the Dublin Bay Biosphere Reserve, is an actively accreting dune system, providing habitats for a rich diversity of protected species and a popular natural space for recreation. The northern end of North Bull Island is a well-known haul out site for grey and harbour seals, Ireland’s two breeding pinniped species, both protected under the EU Habitats Directive.

Sites like these are vital for seals to haul out of the water, especially during breeding and moulting seasons, and to rest and regulate their body temperature. IWDG Consulting have carried out monthly seal surveys of North Bull Island since May 2016, as part of the Marine Mammal Mitigation Plan for the Alexandra Basin Redevelopment and ongoing MasterPlan2 projects for Dublin Port Company. During these surveys, grey and harbour seals were present on 58% and 96% of the time, respectively. Typically, groups of up to 25-30 grey seals are present from May to October, while 10-20 harbour seals haul out year-round. Although not an established breeding site, the area has an important role for seals resting between foraging trips and moving between breeding and moulting sites in Dublin Bay. Over the past eight years, the numbers of grey and harbour seals hauled out on North Bull Island have significantly increased, highlighting its increased importance as a haul out site. Following a wider seal survey from July 2023 to January 2024 funded by Dublin Port it showed that North Bull Island is the second most important haul out site for harbour seals in Dublin Bay and adjacent waters.

Having access to haul out sites with minimal human disturbance is important for supporting healthy seal populations, especially when faced with other anthropogenic pressures, such as elevated noise levels from construction activities in the nearby Dublin Port. In 80% of the surveys, there was at least one incident of disturbance, predominantly from people and dogs. In light of these pressures, the increase in seal numbers is particularly noteworthy. Since 2022, a zoning plan has been in place, which designates the northern end of the island as a “Wildlife Only Area”. If complied with, this could help reduce disturbance to the increasing numbers of hauled out seals and maintain North Bull Island as an important haul out site for the grey and harbour seals of Dublin Bay.

Jo Green

Marine Mammal Ecologist

Clowie Russell has started as the new IWDG Consulting Manager. She took over this role in October 2024. She has worked as the Marine Mammal Ecologist for IWDG Consulting in Dublin Port since April 2018 where she delivered the Marine Mammal Mitigation Plan for the Alexandra Basin Re-development project and more recently the start of MP2. This involved large dredging and piling campaigns, long term static acoustic monitoring including real-time PAM and monthly seal surveys.

She completed a BSc (hons) in Marine Science in NUIG and has been a member of the IWDG since 2012. She has worked in the Shannon Estuary on bottlenose dolphins and in Australia on humpback whales. She is a qualified JNCC Marine Mammal Observer with experience inshore, offshore and land based monitoring for both research and mitigation purposes.

Clowie will be organising MMO and PAM operators for coastal and offshore projects, preparing Method Statements, RAMS and quotes and ensuring compliance with all health and safety obligations.

IWDG Consulting have just successfully recovered the first SAM deployment at two proposed offshore windfarms in the Irish and Celtic Seas. Static Acoustic Monitoring (SAM) is a method of gaining fine scale data on occurrence and habitat use by odontocetes, especially harbour porpoise which can be difficult to survey visually.

SAM can be a challenging techniques especially off Ireland’s east coast as tides are very strong and techniques to deploy, and recovery are paramount.  Through working with fishers who are skilled at these techniques at sea, IWDG Consulting trialled a new system over the last few months which, with some tweaking, proved very successful.

Dr Simon Berrow CEO of the IWDG said “this is very encouraging, given the requirements for offshore wind to obtain acoustic data, not only from dolphins and porpoises but to record ambient noise. If these wind turbines will be operating in a naturally noisy environment caused by strong tides and movement of benthic substrates, the impact of increased noise levels associated with turbine operation will be less than in a quieter environment.”.

This is the the third SAM contract IWDG Consulting have won from the offshore wind industry. The IWDG have recommended that SAM should be collected as part of site investigations to identify and avoid important foraging areas, and to be used two years prior to construction starting and during operation to ensure any displacement that may occur is temporary and activity returns to at least its pre-construction levels, or possibly increase through artificial reef effects.

Recent studies using SAM has shown that bottlenose dolphins and harbour porpoises were not excluded from sites in the vicinity of impact piling or vibration piling; nevertheless, some small effects were detected. Bottlenose dolphins spent a reduced period of time in the vicinity of construction works during both impact and vibration piling. The probability of occurrence of both cetacean species was also slightly less during periods of vibration piling (https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.1793).

Recently a study showed that wind turbine installation using gravity-base foundations had no long-term effects on the occurrence of dolphins or porpoise and may represent an offshore construction methodology that is less impactful to dolphins and harbour porpoise than impact pile-driven turbine installation methods (https://link.springer.com/article/10.1007/s00227-023-04240-1).

IWDG is committed to working with the offshore wind companies to not only ensure impacts from the rollout of offshore wind is minimal but all the opportunities to enhance biodiversity and support restoration projects is fully exploited.