20 years studying the Shannon Dolphins
20 years ago today (2nd May 1993), the first research trip into the Shannon Estuary to try and find bottlenose dolphins was carried out. Myself and Brian Holmes headed west from Carrigaholt, in west Clare to Kilcredaun, Ballybunnion and Leck Point in search of dolphins. We returned five hours later without seeing a single dolphin !! The following day we tried again and this time we located three groups with a total of around 16 dolphins, photographed 10 and identified six from permanent, unique markings on their dorsal fins (a technique called photo-id). These dolphins were given a catalogue numbers CN1 to CN6, the first dolphins in the Shannon Dolphin Photo-ID catalogue. Thus the Shannon Dolphin Project was born. 20 years later six of the dolphins recorded in 1993 (25%) were seen last year in the Shannon Estuary and nine (36%) seen during the last three years.
Boarding the first RIB at Carrigaholt Pier. Photo courtesy Brian Holmes.
How it all started
In July 1991, I had seen bottlenose dolphins during a commercial fishing trip from Carrigaholt. We were steaming out of the estuary with bottlenose dolphins on the bow of fishing boat. Skipper, Joe Aston, said “we usually lose the dolphins as we steam past Kilcloher Head” – and we did. On the way back in after a week at sea, we picked up and lost dolphins exactly where the skipper, Joe said we would “they are always in the estuary” he said. My friend and colleague, Brian Holmes, an oceanographer at University College Cork had a similar experience in the estuary, while transiting from Carrigaholt to Ballybunnion in the early 1990s during an oceanographic survey off the North Kerry town. We both discussed the idea of starting a project on the dolphins.
Brian driving Searider RIB, 2 May 1993. Photo courtesy Simon Berrow.
We obtained funding from Shannon Development Ltd, in collaboration with the West Clare Fishing Co-operative based in Carrigaholt, to carry out a feasibility study to explore whether dolphin-watching was viable in the estuary. I purchased a 5.4m Rigid Inflatable Boat (RIB), an SLR camera and 300m lense and a telescope for the contract – which actually cost nearly three times the value of the funding ! but I was convinced this was a great project and that it was going to be successful and had to invest in the necessary equipment to make it happen.
Simon surveying from back of RIB. Photo courtesy Brian Holmes.
In the first years we surveyed the waters between Carrigaholt, Kilstiffin and Ballybunnion buoys and from Ballybunnion buoy to Ballybunnion town and to Leck Point. We used the navigation buoys as markers as this was before GPS was available and it was the best way to know where you were in the estuary !! During the course of that first summer we carried out 27 trips on the RIB and recorded dolphins on 61% of trips. We photographed 25 individually recognisable dolphins but, as we were using print film donated by Spectra Ltd in Listowel, it would take a week or two before photographs were developed and received in the post ! so you were never sure if you had got a good image of the dolphins you saw. After this sponsorship ended we started using slide film, which was expensive, and every frame cost the project money so dorsal fins had to be in focus and filling the frame before the shutter release was pressed. Modern digital cameras have transformed photo-id and now we can rattle off hundreds of images during each dolphin encounter and just save the best.
The first images. Photo courtesy Simon Berrow.
Shannon Dolphin Project
The Shannon Dolphin Project was an initiative of the Irish Whale and Dolphin Group (IWDG) but in 2000 a new registered charity, the Shannon Dolphin and Wildlife Foundation (SDWF) was formed. The SDWF was a group of interested stakeholders from state agencies and local development groups and tourism providers, including all dolphin-watching operators. In 2000 the SDWF were facilitated in the Scattery Island Visitor Centre in Kilrush but when a cottage on Scattery was refurbished as a visitor centre the centre was going to be sold. However the Monuments Section signed the centre over to the National Parks and Wildlife Service as they had based their local Conservation Ranger in the building. The Shannon Dolphin and Wildlife Centre is open each summer to inform visitors about the dolphins and other wildlife in the region and to accommodate our researchers.
Shannon Dolphin and Wildlife Centre. Photo courtesy Simon Berrow.
The Shannon Dolphin Photo-ID catalogue now contains around 45,000 images of around 230 individual dolphins.
Photo-identification of individual dolphins
Collaboration with the dolphin tour boats is critical as this enables regular access to the dolphins during dolphin trips as well as monitoring the potential impacts of dolphin-watching. Some of the dolphins in the catalogue have died, new individuals are born and in time join the catalogue as they pick up marks and nicks in their dorsal fins. Photographing and monitoring individual dolphins not only enables us to determine their longevity but we can plot where in the estuary they are found, who they are associating with, who has calves and over the years, inter-calf intervals. Around seven calves are born each year usually in July and August. The social system has been shown to be a classic fission-fusion society with dolphins freely associating with most other members in the population. Bottlenose dolphins occur throughout the estuary, regularly occurring upriver as far as Shannon Airport and even at Limerick City and are frequently observed off Loop Head.
Using mark-recapture models with photo-id images we can estimate the abundance of dolphins in the estuary and after a number of surveys have been carried out look at population trends. The last estimate was in 2012 where around 107±12 dolphins were estimated to occur in the estuary. This was the fifth estimate since 1997 and all are around 110-130 dolphins suggesting the population is small but stable.
CN001 - the first dolphin in the catalogue. Photo courtesy Simon Berrow.
Uniquely Shannon dolphins
One of the curious things was the lack of sightings of any Shannon dolphins outside the estuary. The Irish Whale and Dolphin Group have been collecting images of bottlenose dolphins from all around the island of Ireland and frequently record the same individual dolphins off the Mayo, Galway, Cork, Dublin, Donegal and Antrim coast s showing this “inshore population” use the entire Irish coastline. We have even matched some of these individuals to Scotland ! but never have we found a Shannon dolphin outside the Shannon Estuary and Tralee Bay. The furthest away from the estuary a Shannon dolphin has been recorded was 20km west off Sauce Creek in the shadow of Mount Brandon. Recently a genetic study of bottlenose dolphins used samples from stranded and biopsied animals and showed the Shannon dolphins are genetically discrete – confirming the evidence from photo-id. This is remarkable, bottlenose dolphins from the genetically different “inshore population” pass by the mouth of the Shannon Estuary but must not breed with the Shannon dolphins. This must have been happening for hundreds if not thousands of years to create such genetic discreteness. What is the mechanism preventing these dolphins from inter-breeding ? nobody knows, maybe it is the acoustic repertoire – they speak with different accents !!
One of our biggest successes is acoustic monitoring. We have pioneered many acoustic monitoring techniques in the Shannon. The first deployment in Ireland of a self-contained click detector (POD) was off Foynes Island in 2001 as part of the environmental impact study for the Bord Gais Pipeline to the West. Since then we have deployed PODs at 13 sites and have around 6-7000 days of monitoring data. We have deployed hydrophones running from the shore into the sea off Kilcredaun Point near Carrigaholt and from a quarry adjacent to Moneypoint Power Station. This enabled us to monitor these sites day and night and through tidal cycles as well as observe and listen to dolphins simultaneously. Using an old lifeguard hut donated by Clare County Council and fitted with solar panel and wind turbine we could power a laptop and become power independent. In 2012 we even deployed a hydrophone off Tarbert Power Station which enabled real-time monitoring, through the internet, of dolphin vocalisations anywhere in the world and briefly for three months we became part of the Ocean Noise Monitoring Network, wow !
Theodolite tracking dolphins during acoustic detection trials. Photo courtesy Simon Berrow.
If you want to hear and see spectrographs of the recent Shannon dolphin vocalisations from Bunratty Castle go to: http://corkcoast.com/shannondolphin/Bunratty/BR3VP/BR3VP.html
Value of long-term monitoring
The real value of this long-term project is only just revealing itself. The recent appearance of three dolphins at Bunratty was a good example. By comparing images of these dolphins with those in the Shannon Dolphin Photo-id catalogue, we were able to confirm them as Shannon dolphins as two of the three were photographed from dolphin tour boats in the estuary last summer. A similar analysis of dorsal images from a mass stranding of bottlenose dolphins at Fenit, Co Kerry in June 2012 showed these were not Shannon dolphins but offshore bottlenose dolphins, a third population in Ireland, who had got into difficulty on the gentle slopes of Tralee Bay. In June 2012 a live stranded bottlenose dolphin was refloated off Béal strand and one month later photographed from dolphin tour boats during SDWF tour boat monitoring. The dolphin was photographed four times during that summer and in September photographed with a newborn calf. This is the first evidence in the world of a successful refloating of a dolphin that used natural markings and not satellite or other tags.
Stranded Shannon Dolphin. Photo courtesy Joanne O'Brien.
So looking back one of the main drivers of the project was to encourage and support commercial dolphin-watching. Dolphin-watching is now well established at two ports in west Clare- Carrigaholt and Kilrush - and around 400 trips are carried out annually catering for around 10-12,000 people. Dolphin-watching is monitored, including using of photo-id to ensure the dolphins are not being overly disturbed and a code of conduct which is now legally enforceable through inshore Irish waters developed by the tour operators. People are getting to see wild dolphins in their natural habitat which can only make them more interested in the marine environment. The estuary is now a protected site for bottlenose dolphins – the only one in Ireland to date – which means no activity or development will go ahead without considering the impact on the dolphins. The impact of dredging, rock-armour, blasting and pile-driving on the dolphins has been assessed and even a study carried out to look at the impacts of persistent pollutants on the dolphins completed.
Since 1993 we have had 14 research assistants employed by the SDWF, and faciltated 14 visiting scientists and seven postgraduate students. We have published 15 papers in the peer-reviewed literature, four book chapters and presented at ten international conferences. SDWF has run educational programmes for young people – Shannon Dol-fun – and maintain a website www.shannondolphins.ie for those interested to learn about current findings.
Shannon Dolphin in Brandon Bay. Photo courtesy Conor Ryan.
Looking back we feel we should have done much more such as regular boat transects; we would have liked to have deployed the hydrophone in more locations and maintained the real-time acoustic monitoring station at Tarbert. With more funding and support we could have achieved much more but you can only do what is practicable and feasible, and to have kept the project going for 20 years is success in itself and the true value of this long term study is only just becoming apparent.
The Shannon dolphin population is a small, isolated and unique population. The Shannon Estuary is undoubtedly one of the best locations in Europe to see bottlenose dolphins and is a natural laboratory for dolphin research. The estuary has much more potential for tourism and research and undoubtedly offers unique opportunities in Ireland, if not throughout Europe. We are privileged to have such a resource and I hope we can continue the Shannon Dolphin Project for another 20 years.
Dr Simon Berrow
Shannon Dolphin and Wildlife Foundation
Bottlenose dolphins breaching in the Shannon Estuary. Photo courtesy Simon Berrow.
Thanks to all those who have contributed including research assistants: Clare Heardman, Sarah Ferriss, Lisa Groth, Shelia Downes, Joanne O’Brien, Andrew Young, Conor Ryan, Randall Counihan, Janelle Atkinson, Aoife Foley, Paddy O'Dwyer, Sarah Blennerhassett, Enda McKeogh, and Isabel Baker; centre staff Bernadette Brady, Jim Martin, Vanessa Klotzer and Jennifer Houlihan. We thank post graduate students Gareth Duguid, Ronan Hickey, Joanne O'Brien, Dana Miller, Sophie Hansen, Siobhan O'Brien: and Joanna Barker for their contribution. Visting Scientists; Brian Holmes, John Gould, Nigel Griffin, Sophie Hansen, Huan Tan, Joanne O’Brien, Ruth Leeney, Przemek Zielinski, Eugene McKeown, Dave Wall, Kerstin Voigt, Florence Erbs and Lonneke Ijsseldijk have helped us maintain standards and we are delighted to have provided work experience to Finnoula Donovan, Evelyn Whelan, Teresa Prendergast and Eleanor Honan.
Thank you to the SDWF Committee especially John Quinlivan who chaired us so well for many years and all the members over the years; Paul Edson, Ogie Moran, Alison Healy, Siobhán Garvey, Siobhán Curran, Leonard Cleary, Joe Aston, Paddy Farrell, Michael O’Connell, Vincent Flynn, Brid Hedderman, Anne Wilkinson, Tom Carey, Bernadette Kinsella, Enda Mooney, Jimmi Conroy, Barry O’Donoghue, Brian Duffy, Seamus Hassett, David Lyons, Michael Roberts, Zena Hoctor, Martin Looby, Chris O’Grady, Michael Canny, Terry Dunne, Tommy Doyle,Robert Stack, Cathal Blunnie representing themselves or Shannon Development Kilrush Town Council, Clare County Council, Carriagaholt Development Association, Mational Parks and Wildlife Service, Marine Institute and Tuithi, Teo Charaii and especially the tour boat operators Geoff and Sue Magee, Paul, Gerald and Geraldine Griffin without whose support over the years we would not have achieved much at all.