Western English Channel IMMA
Size in Square Kilometres
26,139 km2
Qualifying Species and Criteria
Common bottlenose dolphin – Tursiops truncatus
Criterion B (1)
Marine Mammal Diversity
Criterion D (2)
Tursiops truncatus, Phocoena phocoena, Balaenoptera acutorostrata, Grampus griseus, Laghenorhyncus albirostris, Delphinus delphis, Halichoerus grypus, Phoca vitulina, Balaenoptera physalus
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Summary
Coastal ecotype bottlenose dolphins (Tursiops truncatus) tend to live in small communities and populations and are clearly distinct from the more abundant pelagic populations. They range along coastlines typically remaining close to shore in water less than 50m deep and tend to have strikingly limited ranges. The English Channel is habitat for four separate coastal ecotype populations. There is no evidence of social mixing between these populations of animals despite the proximity of their core ranges and they can be segregated by genetic, stable isotope and social factors. The Gulf of St Malo is habitat for the largest coastal ecotype population in northeast Atlantic waters with three other distinct communities found within the Channel: two close together around the northwest tip of Brittany and a third ranging along the south coast of England. This area is also used by at least six other cetacean species and the two native pinniped species.
Description of Qualifying Criteria
Criterion B: Distribution and Abundance
Sub-criterion B1: Small and Resident Populations
The Western English Channel provides the entire known range for four separate populations of the coastal ecotype of common bottlenose dolphins (Tursiops truncatus) defined as ‘coastal-south’ by Louis et al., (2014). Unlike the pelagic ecotype which occurs in large numbers in shelf waters (Rogan et al., 2018; Hammond et al., 2021) the coastal ecotype tends to range within shallow coastal waters and form small, discrete and separate coastal populations/sub-populations with distinct social, habitat and genetic identities (Mirimin et al., 2011; Louis et al., 2014; Oudejans et al., 2015; Nykanen et al., 2019).
Normano-Breton population
This is the largest population of the coastal ecotype in the Atlantic coastal waters of mainland Europe. The abundance estimate from surveys conducted in 2019 was 608 (95%CI= 540-685) (Couet & Mauger, 2022). This population is resident year-round in the Gulf of St Malo in the area between St Malo, Jersey and Cherbourg, and genetic studies have identified this as a discrete reproductive population (Louis, 2014). Currently no protected area has been designated for this population.
Molene Archipelago population
A population of coastal bottlenose dolphins is resident around the Molene archipelago and is one of two discrete populations found within the Parc Naturel Marin d’Iroise (PNMI). A survey in 2022 estimated approximately 139 (95% CI 105-192) dolphins in this population (P. le Niliot, PNRI, pers. comm.).
Ile de Sein population
A second small population of coastal bottlenose dolphins resides within the PNMI and ranges within a small area around the Ile de Sein (Liret, 1994). Surveys have resulted in estimates of 31 animals in 2017 and 37 animals in 2021 (Buanic, 2018; P. Le Niliot, pers. comm.). This long-term resident population has no observed mixing and/or known reproductive exchange with the Molene population. The 95% kernel density home range area was calculated as 33.5km2 with a core area (kernel density 50%) of just 5.6km2 (Louis et al., 2017).
English Channel coastal population (England)
Estimated at just 40 individuals (CV= 0.18, 95% HPDI= 30-59), this group of bottlenose dolphins is resident along the entire Channel coast of England (Corr et al., in press). They are not protected by a designated MPA and range from East Sussex to St Ives in North Cornwall. They are an OSPAR-recognised assessment unit (AU) as indicators of Good Environmental Status (GES) for the Marine Strategy Framework Directive (MSFD). Photo-id studies (Dudley, 2018; Corr, 2020) show multi-annual sightings of individuals dating back to 2007 with these animals resident but mobile in shallow (<50m) coastal waters throughout their known range. Photo-identification studies have shown these animals to be distinct from animals photographed in pelagic Channel waters and from those belonging to populations resident along the northern coast of France.
Criterion D: Special Attributes
Sub-criterion D2: Diversity
In addition to common bottlenose dolphins, seven marine mammal species are regularly seen within the coastal waters defined in this IMMA (McClellan et al., 2014; Leeney et al., 2012; Pikesley et al., 2012). Regular coastal visual-acoustic surveys conducted in the western extent of the English Channel coast (termed sub-area 1) by the University of Plymouth (Edwards, 2018; McClements, 2023), have regular detections and sightings of minke whales (Balaenoptera acutorostrata), harbour porpoises (Phocoena phocoena), common dolphins (Delphinus delphis), Risso’s dolphins (Grampus griseus) and white-beaked dolphins (Lagenorhynchus albirostris), the only population of which seen in the waters of southern England (Brereton, 2014). Wildlife ecotours also report regular sightings of common dolphins, harbour porpoises and Risso’s dolphins at the western extent of the English Channel coast (de Boer et al., 2018). Grey seals (Halichoerus grypus) are found at various haul out sites throughout the IMMA and telemetry tracks show seals travelling between the tip of northwest Brittany and the Isles of Scilly (Vincent et al., 2017). Small, isolated colonies of harbour seals (Phoca vitulina) use haul-out sites on sandbanks in Poole Harbour and on the Normandy coast. The ferry route between Penzance and the Isles of Scilly in the west of sub-area 1 has the second highest cetacean species diversity of all northwest European ferry routes surveyed by ORCA (ORCA, 2016). The cetacean species listed above are regularly recorded on ORCA surveys from ferries and cruise ships in the area. In addition, fin whales (Balaenoptera physalus) humpback whales (Megaptera novaeangliae) and long-finned pilot whales (Globicephala melas) are also occasionally seen. Fin whale sightings around Cornwall peak in winter months (Pikesley et al. 2012; Seawatch Foundation, unpublished data).
Supporting Information
Araújo, J.N., Mackinson, S., Stanford, R.J., Sims, D.W., Southward, A.J., Hawkins, S.J., Ellis, J.R., and Hart, P.J.B. 2006. Modelling food web interactions, variation in plankton production, and fisheries in the western English Channel ecosystem. Marine Ecology Progress Series, 309: 175-187
Brereton,T., Kitching, M., Davies, R., McNie F., and Walker R. 2014. Photo-identification Analysis of White-beaked Dolphins off South west and North east England 2007-2014. Report to Natural England.
Buanic, M. 2018. Bilan du suivi par photo-identification de la population de grands dauphins (Tursiops truncatus) sédentaires sur la Chaussée de Sein. Report to the Agence Francaise pour la Biodiversite. 11pp.
Corr, S., Dudley, R., Brereton, T., Clear, N., Crosby, A., Duncan, S., Evans, P.G.H., Jones, D., Sayer, S., Taylor, T., Tregenza, N., Williams, R., Witt, M.J. and Ingram, S.N. (in press) using citizen science data to assess the vulnerability of bottlenose dolphins (Tursiops truncatus) to human impacts along England’s south and west coast. Animal Conservation.
Couet, P. and Mauger, G. (2022) Results of GECC studies between 2015 and 2020 on bottlenose dolphins of the Normano-Breton Gulf in the English Channel. GECC (Groupe d’étude des cétacés du Cotentin). 6 pp.
Cox, S.L., Embling, C.B., Hosegood, P.J., Votier S.J., and Ingram, S.N. 2018. Oceanographic drivers of marine mammal and seabird habitat-use across shelf-seas: A guide to key features and recommendations for future research and conservation management Estuarine, Coastal and Shelf Science, 212: 294-310
de Boer, M.N., Jones, D., Jones, H. and Knee, R. 2018. Spatial and Temporal Baseline Information on Marine Megafauna-Data Facilitated by a Wildlife Tour Operator. Open Journal of Marine Science, 8, 76-113. https://doi.org/10.4236/ojms.2018.81005
Dudley, R. 2017. Using citizen science data to assess the social structure, residency and distribution of bottlenose dolphins (Tursiops truncatus) in southwest England. Unpublished MSc thesis, University of Plymouth.
Edwards, W. 2018. Modelling the habitat preferences of the harbour porpoise (Phocoena phocoena) along the southern coast of Cornwall, England, in relation to seabed topography. Unpublished BSc thesis, University of Plymouth.
Evans, P.G.H. and Waggitt, J.J. 2020. Cetaceans. Pp. 134-184. In: Crawley, D., Coomber, F., Kubasiewicz, L., Harrower, C., Evans, P., Waggitt, J., Smith, B., and Mathews, F. (Editors) Atlas of the Mammals of Great Britain and Northern Ireland. Pelagic Publishing, Exeter. 205pp.
Girardin, E. 2021. Caractérisation du domaine vital des grands dauphins (Tursiops truncatus) de l’archipel de molene. Unpublished MSc thesis, University of La Rochelle, 49pp.
Grimaud, M., Gally, F., and Couet, P. 2017. Suivi de la population des grands dauphins sédentaires en mer de la Manche. Rapport de synthèse pour l’année 2017. Rapport GECC. 31pp.
Hammond, P.S., Lacey, C., Gilles, A., Viquerat, S., Borjesson, P., Herr, H., Macleod, K., Ridoux, V., Santos, M.B., Scheidat, M., Teilmann, J., Vingada, J., and Øien, N. 2021. Estimates of cetacean abundance in European Atlantic waters in summer 2016 from the SCANS-III aerial and shipboard surveys. https://synergy.standrews.ac.uk/scans3/files/2017/05/SCANS-III-design-based-estimates-2017-05-12-final revised.pdf.
Leeney, R., Witt, M., Broderick, A., Buchanan, J., Jarvis, D., Richardson, P., and Godley, B. 2012. Marine megavertebrates of Cornwall and the Isles of Scilly: Relative abundance and distribution. Journal of the Marine Biological Association of the United Kingdom, 92(8): 1823-1833.
Liret, C., Allali, P., Creton, P., Guinet, C., and Ridoux, V. 1994. Foraging activity pattern of bottlenose dolphins around Ile de Sein, France and its relationship with environmental parameters. Pp. 188-191. In: European Research on Cetaceans – 8. Proc. 8th Ann. Conf. ECS. Montpellier, France, 25 March 1994. (Ed. P.G.H. Evans). European Cetacean Society, Lugano, Switzerland. 288pp.
Louis M. et al. 2014 Ecological opportunities and specializations shaped genetic divergence in a highly mobile marine top predator. Proceedings of the Royal Society B, 281: 20141558.
Louis, M., Buanic, M., Lefeuvre, C., Le Nilliot, P., Ridoux, V., and Spitz, J. 2017. Strong bonds and small home range in a resident bottlenose dolphin community in a Marine Protected Area (Brittany, France, North-East Atlantic). Marine Mammal Science, 33(4):1194-1203.
McClellan, C.M., Brereton, T., Dell’Amico, F., Johns, D.G., Cucknell, A.C., Patrick, S.C., Penrose, R., Ridoux, V., Solandt., J., Stephan, E., Votier, S.C., Williams, R. and Godley, B.J., 2014. Understanding the distribution of marine megafauna in the English Channel region: identifying key habitats for conservation within the busiest seaway on earth. PLoS ONE, 9(2)
McClements, S. 2023. Using habitat models to assess the environmental drivers of common dolphin (Delphinus delphis) abundance and distribution in southwest coastal regions of the UK: Implications for conservation. Unpublished BSc thesis, University of Plymouth.
Mirimin, L., Miller, R., Dillane, E., Berrow, S. D., Ingram, S., Cross, T.F., Rogan, E. 2011. Fine-scale population genetic structuring of bottlenose dolphins using Irish coastal waters. Animal Conservation,14: 342-352.
Nykänen, M., Louis, M., Dillane, E., Alfonsi, E., Berrow, S., O’Brien, J., Brownlow, A., Covelo, P., Dabin, W., Deaville, R., de Stephanis, R., Gally, F., Gauffier, P., Ingram, S.N., Lucas, T., Mirimin, L., Penrose, R., Rogan, E., Silva, M.A., Simon‐Bouhet, B., and Gaggiotti, O.E. 2019. Fine‐scale population structure and connectivity of bottlenose dolphins, Tursiops truncatus, in European waters and implications for conservation Aquatic Conservation: Marine and Freshwater Ecosystems 29, 197-211
ORCA (2016). State of European Cetaceans. ORCA: Portsmouth. Available at: https://orcaweb.org.uk/images/media/ORCA-The_State_of_European_Cetaceans_2006-2015.pdf
Oudejans, M.G., Visser, F., Englund, A., Rogan, E., and Ingram, S.N. 2015. Evidence for Distinct Coastal and Offshore Communities of Bottlenose Dolphins in the North East Atlantic. PLoS ONE, 10(4): e0122668. doi:10.1371/journal.pone.0122668
Pikesley, S.K., Witt, M.J., Hardy, T., Loveridge, J., Loveridge, J., Williams, R., and Godley, B.J. (2012). Cetacean sightings and strandings: evidence for spatial and temporal trends? Journal of the Marine Biological Association of the United Kingdom 92(8): 1809-1820.
Poncet, S., Mercereau, I., Couvrat, C., Le Baron, M., Francou, M., Hemon, A., Frémau, M.-H., Elder, J.-F., Gicquel, C., Monnet, S., Rault, C., Karpouzopoulos, J., Lefebvre, J., Everard, A., Colomb, F., Diard Combot,, M., Provost, P., Deniau, A., Urtizberea, F., Koelsch, D., Letournel, B., and Vincent, C. 2022. Monitoring seals in France – 2020-2021: Extended summary of the collective report of the National Seal Network. 14pp.
Rogan, E., Breen, P., Mackey, M., Cañadas, A., Scheidat, M., Geelhoed, S., and Jessopp, M. 2018. Aerial surveys of cetaceans and seabirds in Irish waters: Occurrence, distribution and abundance in 2015-2017. Department of Communications, Climate Action & Environment and National Parks and Wildlife Service (NPWS), Department of Culture, Heritage and the Gaeltacht, Dublin, Ireland. 297pp.
Vincent, C., Huon, M., Caurant, F., Dabin, W., Deniau, A., Dixneuf, S., Dupuis, L., Elder, J.-F., Fremau, M.-H., Hassani, S., Hemon, A., Karpouzopoulos, J., Lefeuvre, C., McConnell, B.J., Moss, S.E.W., Provost, P., Spitz, J., Turpin, Y., and Ridoux, V. 2017. Grey and harbour seals in France: Distribution at sea, connectivity and trends in abundance at haul-out sites. Deep Sea Research Part II: Topical Studies in Oceanography 141:294-305.
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