Skip to main content

Trends in cetacean sightings along the Galician coast, north-west Spain, 2003–2007, and inferences about cetacean habitat preferences

  • Graham J. Pierce (a1) (a2), Mara Caldas (a3), Jose Cedeira (a3), M. Begoña Santos (a1), Ángela Llavona (a3), Pablo Covelo (a3), Gema Martinez (a4), Jesus Torres (a4), Mar Sacau (a1) and Alfredo López (a3)...

Since mid-2003, systematic monthly sightings surveys for cetaceans have been carried out in Galicia (north-west Spain) from observation points around the coastline, with the aim of providing baseline data on cetacean distribution and habitat use to underpin future conservation measures. Here we summarize results for September 2003 to October 2007. The most frequently recorded species were the bottlenose dolphin (Tursiops truncatus, seen during 10.7% of observation periods), common dolphin (Delphinus delphis, 3.7%), harbour porpoise (Phocoena phocoena, 1.6%), Risso's dolphin (Grampus griseus, 0.4%) and short-finned pilot whale (Globicephala melas, 0.2%). The three most common species showed different distribution patterns along the coast. In terms of habitat preferences, bottlenose dolphins were seen to be associated with more productive areas (areas with higher chlorophyll-a concentrations) where the continental shelf was wider while both common dolphins and harbour porpoises were seen most frequently in less productive areas where the continental shelf is narrowest. Possible reasons for differences in habitat use include differing diets. In Galician waters, all three main cetacean species feed primarily on fish that are common in shelf waters, and in the case of blue whiting (the most important species in the stomach contents of common and bottlenose dolphins) abundant also on the slope. All three cetaceans feed on blue whiting while scad is important in diets of common dolphin and porpoise. It is also possible that porpoises do not use areas frequented by bottlenose dolphins in order to avoid aggressive interactions. Retrospective evaluation of the sampling regime, using data from the 2500 observation periods during 2003–2007 suggests that the overall sightings rates for all species (taking into account observation time and between-site travel time) would be higher if average observation duration was increased to at least 40 minutes. On the other hand, confidence limits on sightings rates stabilized after around 1000 observation periods, suggesting that the number of sites visited or the frequency of visits could be substantially reduced.

Corresponding author
Correspondence should be addressed to: G.J. Pierce, School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK email:
Hide All
Alonso, J.M., López, A., González, A.F. and Santos, M.B. (2000) Evidence of violent interactions between bottlenose dolphin (Tursiops truncatus) and other cetacean species in NW Spain. European Research on Cetaceans 14, 105106.
Bejder, L., Samuels, A., Whitehead, H., Gales, N., Mann, J., Connor, R., Heithaus, M., Watson-Capps, J., Flaherty, C. and Krutzen, M. (2006) Decline in relative abundance of bottlenose dolphins exposed to long-term disturbance. Conservation Biology 20, 17911798.
Cendrero, O. (1993) Note on findings of cetaceans off northern Spain. Boletin del Instituto Español de Oceanografía 9, 251255.
Charnov, E.L. (1976) Optimal foraging: the marginal value theorem. Theoretical Population Biology 9, 129136.
Evans, P.G.H. and Hammond, P.S. (2004) Monitoring Cetoceans in European waters. Mammol Review 34, 131156.
González, A.F., López, A., Guerra, A. and Barreiro, A. (1994) Diets of marine mammals stranded on the northwestern Spanish Atlantic coast with special reference to Cephalopoda. Fisheries Research 21, 179191.
Hastie, G.D., Wilson, B., Tufft, L.H. and Thompson, P.M. (2003) Bottlenose dolphins increase breathing synchrony in response to boat traffic. Marine Mammal Science 19, 7484.
Lahaye, V., Bustamante, P., Law, R.J., Learmonth, J.A., Santos, M.B., Boon, J.P., Rogan, E., Dabin, W., Addink, M.J., López, A., Zuur, A.F., Pierce, G.J. and Caurant, F. (2007) Biological and ecological factors related to trace element levels in harbour porpoises (Phocoena phocoena) from European waters. Marine Environmental Research 64, 247266.
López, A. and Rodriguez Folgar, A. (1995) Agresión de arroás (Tursiops truncatus) a toniña (Phocoena phocoena). Eubalaena 6, 2327.
López, A., Santos, M.B., Pierce, G.J., González, A.F., Valeiras, X. and Guerra, A. (2002) Trends in strandings and by-catch of marine mammals in north-west Spain during the 1990s. Journal of the Marine Biological Association of the United Kingdom 82, 513521.
López, A., Pierce, G.J., Santos, M.B., Gracia, J. and Guerra, A. (2003a) Fishery by-catches of marine mammals in Galician waters: Results from on-board observations and an interview survey of fishermen. Biological Conservation 111, 2540.
López, A., Cedeira, J.M., Caldas, M., Carril, R., Solla, P. and Llavona, A. (2003b) Monitorización de las poblaciones de cetáceos en la plataforma de Galicia (NW Spain). Thalassas 19, 111112.
López, A., Pierce, G.J., Valeiras, X., Santos, M.B. & Guerra, A. (2004). Distribution patterns of small cetaceans in Galician waters. Journal of the Marine Biological Association of the United Kingdom 84, 283294.
Mattson, M.C., Thomas, J.A. and St Aubin, D. (2005) Effects of boat activity on the behavior of bottlenose dolphins (Tursiops truncatus) in waters surrounding Hilton Head Island, South Carolina. Aquatic Mammals 31, 133140.
Murphy, S., Herman, J., Pierce, G.J., Rogan, E. and Kitchener, A. (2006) Taxonomic status and geographical cranial variation of common dolphins (Delphinus) in the eastern north Atlantic. Marine Mammal Science 22, 573599.
Nowacek, S.M., Wells, R.S. and Solow, A.R. (2001) Short-term effects of boat traffic on bottlenose dolphins, Tursiops truncatus, in Sarasota Bay, Florida. Marine Mammal Science 17, 673688.
Pierce, G.J., Santos, M.B., Murphy, S., Learmonth, J.A., Zuur, A.F., Rogan, E., Bustamante, P., Caurant, F., Lahaye, V., Ridoux, V., Zegers, B.N., Mets, A., Addink, M., Smeenk, C., Jauniaux, T., Law, R.J., Dabin, W., López, A., Alonso Farré, J.M., González, A.F., Guerra, A., García-Hartmann, M., Reid, R.J., Moffat, C.F., Lockyer, C. and Boon, J.P. (2008) Bioaccumulation of persistent organic pollutants in female common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena) from western European seas: geographical trends, causal factors and effects on reproduction and mortality. Environmental Pollution 153, 401415.
Redfern, J.V., Ferguson, M.C., Becker, E.A., Hyrenbach, K.D., Good, C., Barlow, J., Kaschner, K., Baumgartner, M.F., Forney, K.A., Ballance, L.T., Fauchald, P., Halpin, P., Hamazaki, T., Pershing, A.J., Qian, S.S., Read, A., Reilly, S.B., Torres, L. and Werner, F. (2006) Techniques for cetacean-habitat modelling. Marine Ecology Progress Series 310, 271295.
Ridoux, V., Lafontaine, L., Bustamante, P., Caurant, F., Dabin, W., Delcroix, C., Hassani, S., Meynier, L., da Silva, V.P., Simonin, S., Robert, M., Spitz, J. and Van Canneyt, O. (2004) The impact of the ‘Erika’ oil spill on pelagic and coastal marine mammals: combining demographic, ecological, trace metals and biomarker evidences. Aquatic Living Resources 17, 379387.
Santos, M.B., Pierce, G.J., López, A., Martínez, J.A., Fernández, M.T., Ieno, E., Mente, E., Porteiro, C., Carrera, P. and Meixide, M. (2004) Variability in the diet of common dolphins (Delphinus delphis) in Galician waters 1991–2003 and relationship with prey abundance. International Council for the Exploration of the Sea CM 2004/Q:09.
Santos, M.B., Fernández, R., López, A., Martínez, J.A. and Pierce, G.J. (2007) Variability in the diet of bottlenose dolphin, Tursiops truncatus (Montagu), in Galician waters, NW Spain, 1990–2005. Journal of the Marine Biological Association of the United Kingdom 87, 231242.
Sini, M.I., Canning, S.J., Stockin, K.A. and Pierce, G.J. (2005) Bottlenose dolphins around the Aberdeen harbour, north-east Scotland: a study of habitat utilization and the potential effects of boat traffic. Journal of the Marine Biological Association of the United Kingdom 85, 15471554.
Stockin, K.A., Lusseau, D., Binedell, V., Wiseman, N. and Orams, M.B. (2008) Tourism affects the behavioural budget of the common dolphin Delphinus sp. in the Hauraki Gulf, New Zealand. Marine Ecology Progress Series 355, 287295.
Torres, L.G., Read, A.J. and Halpin, P. (2008) Fine-scale habitat modeling of a top marine predator: do prey data improve predictive capacity? Ecological Applications 18, 17021717.
Valavanis, V.D., Pierce, G.J., Zuur, A.F., Palialexis, A., Saveliev, A., Katara, I. and Wang, J. (2008) Modelling of essential fish habitat based on remote sensing, spatial analysis and GIS. Hydrobiologia 612, 520.
Varela, M., Diaz del Rio, G., Alvarez-Ossorio, M.T. and Costas, E. (1991) Factors controlling phytoplankton size class distribution in the upwelling area of the Galician continental shelf northwest Spain. Scientia Marina 55, 505518.
Vieites, D.R., Nieto-Roman, S., Palanca, A., Ferrer, X. and Vences, M. (2004) European Atlantic: the hottest oil spill hotspot worldwide. Naturwissenschaften 91, 535538.
Visser, F., Hartman, K.L., Rood, E.J.J., Hendriks, A.J.E., Zult, D.B., Wolff, W.J., Huisman, J. and Pierce, G.J. (in press) Risso's dolphin alters daily resting pattern in response to whale watching at the Azores. Marine Mammal Science.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of the Marine Biological Association of the United Kingdom
  • ISSN: 0025-3154
  • EISSN: 1469-7769
  • URL: /core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 3
Total number of PDF views: 45 *
Loading metrics...

Abstract views

Total abstract views: 283 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 20th April 2018. This data will be updated every 24 hours.