Skip to main content

First report on abundance and distribution of common bottlenose dolphins (Tursiops truncatus) in the NATURA 2000 area, Istria, North-eastern Adriatic Sea

  • Darja Ribarič (a1) (a2)

The bottlenose dolphin (Tursiops truncatus M.) local population off west Istria in the North-eastern Adriatic has received no prior study of abundance and distribution despite the habitat's relevance for the preservation of this key species in the marine ecosystem. The research area comprises part of the NATURA 2000 network which was predominantly established here for these dolphins. Official data regarding the local population's status in the region are currently marked as deficient. Thus, the aim of the present study was to provide the first population data for the area. Boat-based survey work was carried out from April to September 2012–2015 using a mark–recapture photo-identification method. Prior to this period a random data collection was used to study distribution, since 2001, to cover the area of 927 km2 lying between Umag to lighthouse Albanež in the south. 143 bottlenose dolphins were photo-identified to date with the average group size of 9.27 ± 6.53 animals. Several abundance models were used, from which the Markovian robust model proved the best fit and predicted between 47–142 dolphins along the west Istria coast. A few individuals were also identified in Slovenia, indicating a bigger home range along the 98 km length of the studied area. There is an indication of a regular year round presence of dolphins. The west Istria coast constitutes an important feeding and breeding ground. The region should develop a sustainable plan to manage those human activities negatively impacting the dolphins. Therefore the present study is of relevance for the implementation of management directives for their conservation.

Corresponding author
Correspondence should be addressed to: D. Ribarič, Vivamar – Society for Marine Mammal Research and Sea Conservation, 52475 Savudrija, Croatia email:
Hide All
Balmer B.C., Wells R.S., Nowacek S.M., Nowacek D.P., Schwacke L.H., McLellan W.A., Scharf F.S., Rowles T.K., Hansen L.J., Spradlin T.R. and Pabst D.A. (2008) Seasonal abundance and distribution patterns of common bottlenose dolphins (Tursiops truncatus) near St. Joseph Bay, Florida, USA. Journal of Cetacean Research and Management 10, 157167.
Bas A.A., Öztürk A.A. and Öztürk B. (2015) Selection of critical habitats for bottlenose dolphins (Tursiops truncatus) based on behavioural data, in relation to marine traffic in the Istanbul Strait, Turkey. Marine Mammal Science 31, 979997.
Bearzi G. (1994) Photo-identification: field methods. In Notarbartolo di Sciara G., Evans P.G.H. and Politi E. (eds) Methods for the study of bottlenose dolphins in the wild. European Cetacean Society Newsletter 23 (Special issue), 2226.
Bearzi G. (2002) Interactions between cetacean and fisheries in the Mediterranean Sea. In Notarbartolo di Sciara G. (ed.) Cetaceans of the Mediterranean and Black Seas: state of knowledge and conservation strategies. A Report to the ACCOBAMS Secretariat, Monaco, February 2002. Section 9, 20 pp.
Bearzi G., Fortuna C.M. and Reeves R.R. (2008) Ecology and conservation of common bottlenose dolphins Tursiops truncatus in the Mediterranean Sea. Mammal Review 39, 92123.
Bearzi G., Fortuna C. and Reeves R.R. (2012) Tursiops truncatus (Mediterranean subpopulation). In IUCN 2016. IUCN. Red List of Threatened Species. Version 2016.1. Available at:
Bearzi G., Holcer D. and Notarbartolo di Sciara G. (2004) The role of historical dolphin takes and habitat degradation in shaping the present status of northern Adriatic cetaceans. Aquatic Conservation: Marine and Freshwater Ecosystems 14, 363379.
Bearzi G., Notarbartolo di Sciara G. and Politi E. (1997) Social ecology of bottlenose dolphins in the Kvarnerić (Northern Adriatic Sea). Marine Mammal Science 13, 650668.
Bolger D.L., Morisson T.A., Vance B., Lee D. and Farid H. (2012) A computer-assisted system for photographic mark–recapture analysis. Methods in Ecology and Evolution 3, 813822.
Bouveroux Th., Le Boulengé E., Nowacek D.P. and Mallefet J. (2007) Abundance and distribution of bottlenose dolphins, Tursiops truncatus, in Panama City, Florida. Available at
Burnham K.P. and Anderson D.R. (1992) Data-based selection of an appropriate biological model: the key to modern data analysis. In McCullough D.R. and Barrett R.H. (eds) Wildlife 2001: populations. London: Elsevier Science Publishers, pp. 1630.
Campbell G.S., Bilgre B.A. and Defran R.H. (2002) Bottlenose dolphins (Tursiops truncatus) in Turneffe Atoll, Belize: occurrence, site fidelity, group size and abundance. Aquatic Mammals 28, 170180.
Chapman D.G. (1951) Some properties of the hypergeometric distribution with applications to zoological sample censuses. University of California Publications in Statistics 1, 131160.
Conn P.B., Gorgone A.M., Jugovich A.R., Byrd B.L. and Hansen L.J. (2011) Accounting for transients when estimating abundance: a case study of bottlenose dolphins in Choctawhatchee Bay, Florida. Journal of Wildlife Management 75, 569579.
Culloch R. (2004) Mark recapture abundance estimates and distribution of bottlenose dolphins (Tursiops truncatus) using the southern coastline of the outer Moray Firth, NE Scotland . Master of Science thesis. School of Biological Sciences University of Wales, Bangor, UK.
Diaz Lopez B. (2006) Interactions between Mediterranean bottlenose dolphins (Tursiops truncatus) and gillnets off Sardinia, Italy. ICES Journal of Marine Science 63, 946951.
Državni zavod za zaštitu prirode (2015) NATURA 2000 standard data form. Available at:
Ferretti F., Myers R.A., Serena F. and Lotze H.K. (2008) Loss of large predatory sharks from the Mediterranean Sea. Conservation Biology 22, 952964.
Fortuna C.M. (2007) Ecology and conservation of bottlenose dolphins (Tursiops truncatus) in the north-eastern Adriatic Sea . [cited] PhD thesis. University of St Andrews, UK.
Gaspari S., Holcer D., Mackelworth P., Fortuna C., Frantzis A., Genov T., Vighi M., Natali C., Rako N., Banchi E., Chelazzi G. and Ciofi C. (2013) Population genetic structure of common bottlenose dolphins (Tursiops truncatus) in the Adriatic Sea and contiguous regions: implications for international conservation. Aquatic Conservation: Marine and Freshwater Ecosystems 25, 212222.
Gomerčić H. and Huber Đ. (1989) Istraživanja i zaštita morskih sisavaca Jadrana. Plenarni referati i izvodi saopštenja Četvrte konferencije o zaštiti Jadrana. In Grgić P. (ed.) Savjet Republičke konferencije SSRNBiH za zaštitu čovjekove okoline i Organizacioni odbor Četvrte konferencije o zaštiti Jadrana. Neum, 19 pp.
Gomerčić H., Huber Đ., Gomerčić A. and Gomerčić T. (1998) Geographical and historical distribution of the cetaceans in Croatian part of the Adriatic Sea. Rapp . Commission Internationale pour l'Exploration Scientifique de la Méditerranée 35, 440441.
Gomerčić T., Đuras Gomerčić M., Gomerčić H., Škrtić D., Ćurković S., Lucić H., Galov A., Vuković S. and Huber Đ. (2004) Abundance, population size and distribution of marine mammals in the Croatian part of the Adriatic Sea. In Proceedings Croatian-Slovenian Symposium About Exotic and Wild Animals. Zagreb: Croatian Veterinary Society, pp. 16.
Gonzalvo J., Giovos I. and Moutopoulos D.K. (2015) Fishermen's perception on the sustainability of small-scale fisheries and dolphin–fisheries interactions in two increasingly fragile coastal ecosystems in western Greece. Aquatic Conservation: Marine and Freshwater Ecosystems 25, 91106.
Gonzalvo J., Valls M., Cardona L. and Aguilar A. (2008) Factors determining the interaction between common bottlenose dolphins and bottom trawlers off the Balearic Archipelago (western Mediterranean Sea). Journal of Experimental Marine Biology and Ecology 367, 4752.
Government of the Republic of Croatia (2013) Proposal for tourism development strategy of the Republic of Croatia until 2020. Available at:
Hammond P.S. (1990) Heterogeneity in the Gulf of Maine? Estimating humpback whale population size when capture probabilities are not equal (SC/A88/ID4). In Hammond P.S. (ed.) Report of the International Whaling Commission (Special Issue 12). Cambridge: IWC, pp. 135139.
Hrvatska Agencija za okoliš i prirodu (2016) Bioportal; web portal informacijskog sustava zaštite prirode. Available at:
Institute of Lexicography, Miroslav Krleža (2016) Land and people. Available at:
IUCN (2016) Red list of threatened species Available at:
Jacalyn L.T., Hohn A.A., Able K.W. and Gorgone A.M. (2010) Patterns of seasonal occurrence, distribution, and site fidelity of coastal bottlenose dolphins (Tursiops truncatus) in southern New Jersey, USA. Marine Mammal Science 27, 94110.
Jaiteh V.F. and Allen S.J. (2012) Subsurface behaviour of bottlenose dolphins (Tursiops truncatus) interacting with fish trawl nets in northwestern Australia: implications for bycatch mitigation. Marine Mammal Science 29, 266281.
Karczmarski L., Winter P.E.D., Cockcroft V.G. and Mclachlan A. (1999) Population analyses of Indo-Pacific humpback dolphins Sousa chinensis in Algoa Bay, Eastern Cape, South Africa. Marine Mammal Science 15, 11151123.
Kendall W.L. (2001) The robust design for capture–recapture studies: analysis using program Mark. In Field R, Warren R.J., Okarma H. and Sievert P.R. (eds) Wildlife, Land and People: Priorities for the 21st Century. Proceedings of the Second International Wildlife Management Congress. Bethesda, MD: The Wildlife Society, pp. 357360. Available at:
Kendall W.L. and Nichols J.D. (2002) Estimating state-transition probabilities for unobservable states using capture–recapture/resighting data. Ecology 83, 32763284.
Kolarić A., Đuras M. and Gomerčić T. (2011) Utjecaj antropogenih čimbenika na smrtnost kitova (Cetacea) u Jadranskom moru. Veterinar 49, 515.
Krebs C.J. (2016) Why ecology matters. Chicago, IL: University of Chicago Press. Available at:
Lusseau D., Wilson B., Hammond P.S., Grellier K., Durban J.W., Parsons K.M., Barton T.R. and Thompson P.M. (2006) Quantifying the influence of sociality on population structure in bottlenose dolphins. Journal of Animal Ecology 75, 1424.
McCrea R.S. and Morgan B.J.T. (2015) Analysis of capture-recapture data. Boca Raton, FL: Chapman & Hall/CRC Interdisciplinary Statistics Series.
Narodne novine (Official Gazette) (2014) Odluka o donošenju akcijskog programa strategije upravljanja morskim okolišem i obalnim područjem. 2014/153, 72 pp. Available at:
National Report of the Republic of Croatia to the Convention on Biological Diversity (NR5) (2014) Available at:, 131 pp.
Notarbartolo di Sciara G., Bearzi G. and Bonomi L. (1991) Bottlenose dolphins off Croatia: photoidentification and behavioral observations. In 9th Biennial Conference on the Biology of Marine Mammals. Chicago, Illinois, 5–9 December 1991.
Olsen I.C. (2006) The analysis of continuous mark–recapture data . PhD thesis. Norges Teknisk-Naturvitenskapelige Universitet, Trondheim, Norway.
Otis D.L., Burnham K.P., White G.C. and Anderson D.R. (1978) Statistical inference from capture data on closed animal populations. Wildlife Monographs 62. Lawrence, KS: Allen Press, pp. 1135.
Parra G.J., Corkeron P.J. and Marsh H. (2006) Population sizes, site fidelity and residence patterns of Australian snubfin and Indo-Pacific humpback dolphins: implications for conservation. Biological Conservation 129, 167180.
Pirotta E., Merchant N.D., Thompson P.M., Barton T.R. and Lusseau D. (2015) Quantifying the effect of boat disturbance on bottlenose dolphin foraging activity. Biological Conservation 181, 8289.
Pleslić G., Rako Gospić N., Mackelworth P., Wiemann A., Holcer D. and Fortuna C. (2013) The abundance of common bottlenose dolphins (Tursiops truncatus) in the former special marine reserve of the Cres-Lošinj Archipelago, Croatia. Aquatic Conserv ation: Marine and Freshwater Ecosystems 25, 125137.
Ponti M., Perlini R.A., Ventra V., Grech D., Abbiati M. and Cerrano C. (2014) Ecological shifts in Mediterranean coralligenous assemblages related to gorgonian forest loss. Available at:
Read A.J., Urian K.W., Wilson B. and Waples D.M. (2003) Abundance of bottlenose dolphins in the bays, sounds and estuaries of North Carolina. Marine Mammal Science 19, 5973.
Reed D.H., Julian J., O'Grady J.J., Barry W., Brook B. W., Ballou J.D. and Frankham R. (2002) Estimates of minimum viable population sizes for vertebrates and factors influencing those estimates. Biological Conservation 113, 2334.
Republic of Croatia, Ministry of the Sea, Transport and Infrastructure (2008) Available at:
Ribarič D. (2002) Questionnaire feed back and preliminary observations of the bottlenose dolphins (Tursiops truncatus) in Slovenia. ACCOBAMS Report of the 1st Meeting of the Scientific Committee to Accobams. Monaco, p. 54. Available at:
Ribarič D. (2003) Questionnaire feed back and preliminary observations of the bottlenose dolphins (Tursiops truncatus) in Slovenia. In 17th Conference of the European Cetacean Society, Las Palmas de Gran Canaria, 8 March 2003. Conference Guide and Abstract Book, 251 pp.
Ribarič D. (2013) Bottlenose dolphins (Tursiops truncatus) off Rovinj archipelago (Istria, Croatia). A mosaic stone to a picture in north-east Adriatic. In 27th Conference of the European Cetacean Society, Setubal, Portugal, 8–10 April 2013. Conference Guide and Abstract Book, 245 pp.
Ribarič D. and Herlec T. (2008) A first report about Bottlenose dolphins (Tursiops truncatus) off the tip of Istria, Croatia. In 22th Conference of the European Cetacean Society, Amsterdam, Netherlands, 10–12 March 2008. Conference Guide and Abstract Book, 270 pp.
Ribarič D. and Robinson K. (2006) The habitat use and site fidelity of bottlenose dolphins (Tursiops truncatus) in the Slovenian sea and Bay of Trieste: a first estimation. In 20th Conference of the European Cetacean Society, Gdynia, Poland, 3–6 April 2006. Conference Guide and Abstract Book, 213 pp.
Robinson K.P., O'Brien J.M., Berrow S.D., Cheney B., Costa M., Eisfeld S.M., Haberlin D., Mandleberg L., O'Donovan M., Oudejans M.G., Ryan C., Stevick P.T., Thompson P.M. and Whooley P. (2012) Discrete or not so discrete: long distance movements by coastal bottlenose dolphins in UK and Irish waters. Journal of Cetacean Research and Management 12, 365371.
Pollock K.H., (1982) A capture-recapture design robust to unequal probability of capture. Journal of Wildlife Management 46, 752757.
Scheinin A.P. (2010) The population of bottlenose dolphins (Tursiops truncatus), bottom trawl catch trends and the interaction between the two along the Mediterranean, continental shelf of Israel . PhD thesis. University of Haifa, Israel.
Schwarz C.J. and Seber G.A.F. (1999) Estimating animal abundance: review iii. Statistical Science 14, 427456.
Seber G.A.F. (1982) The estimation of animal abundance and related parameters. London: C. Griffin and Company Ltd.
Severini N. (2013) Management and overfishing problems in the High Adriatic sea and the future policy perspectives. In 2nd AIEAA Conference, Parma, Italy, 6–7 June 2013. Available at:
Shane S.H. (1980) Occurrence, movements and distribution of bottlenose dolphins, Tursiops truncatus, in southern Texas. Fisheries Bulletin 78, 593601.
Shane S.H. (1990) Behavior and ecology of the bottlenose dolphin at Sanibel Island, Florida. In Leatherwood S. and Reeves R.R. (eds) The bottlenose dolphin. San Diego, CA: Academic Press, pp. 245265.
Simoes-Lopes P.C. and Fabian M.E. (1999) Residence patterns and site fidelity in bottlenose dolphins, Tursiops truncatus (Montagu) (Cetacea, Delphinidae) off Southern Brazil. Revista Brasileira de Zoologia 16, 10171024.
Thompson W.L., White G.C. and Gowan C. (1998) Monitoring vertebrate populations. San Diego, CA: Academic Press.
UNEP-MAP-RAC/SPA (2014) Status and conservation of cetaceans in the Adriatic Sea. In Holcer D., Fortuna C.M. and Mackelworth P.C. (eds) Internal report for the purposes of the Mediterranean regional workshop to facilitate the description of ecologically or biologically significant marine areas, Malaga, Spain, 7–11 April 2014.
UNEP-MAP-RAC/SPA (2015) Twelfth meeting of focal points for specially protected areas. Available at:
Urian K., Gorgone A., Read A., Balmer B., Wells R.S., Berggren P., Durban J., Eguchi T., Rayment W. and Hammond P.S. (2015) Recommendations for photo-identification methods used in capture-recapture models with cetaceans. Marine Mammal Science 31, 298321.
Urian K., Hohn A.A. and Hansen L.J. (1999) Status of the photoidentification catalog of coastal bottlenose dolphins of the western North Atlantic. Report of a Workshop of Catalog Contributors. NOAA Technical Memorandum NMFS-SEFSC 1999/425, 22 pp. Available at:
White G. C., Anderson D.R., Burnham K.P. and Otis D.L. (1982) Capture-recapture and removal methods for sampling closed populations. Biometrics 39, 11221123. Available at:
Whitehead H., Cristal J. and Tyack P.L. (2000) Studying cetacean social structure in space and time. In Mann J., Connor R.C., Tyack P.L. and Whitehead H. (eds) Field studies of dolphins and whales. Cetacean Societies. Chicago, IL: The University of Chicago Press, pp. 6587.
Williams B.K., Nichols J.D. and Conroy M.J. (2002) Analysis and management of animal populations: modeling, estimation and decision-making. San Diego, CA: Academic Press.
Williams J.A., Dawson S.M. and Slooten E. (1993) The abundance and distribution of bottlenose dolphins (Tursiops truncatus) in Doubtful Sound, New Zealand. Canadian Journal of Zoology 71, 20802088.
Wilson B., Hammond P.S. and Thompson P.M. (1999) Estimating size and assessing trends in a coastal bottlenose dolphin population. Ecological Applications 9, 288300.
Yazdi P. (2005) Einfluss der Tourismusboote auf das Verhalten und die Energetik der Grössen Tümmler (Tursiops truncatus) vor der Insel Choros, Chile . PhD thesis. Christian-Albrechts-Universität zu Kiel, Germany.
Zolman E.S. (2002) Residence patterns of bottlenose dolphins (Tursiops truncatus) in the Stono River estuary, Charleston County, South Carolina, USA. Marine Mammal Science 18, 879892.
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? *



Altmetric attention score

Full text views

Total number of HTML views: 4
Total number of PDF views: 21 *
Loading metrics...

Abstract views

Total abstract views: 329 *
Loading metrics...

* Views captured on Cambridge Core between 11th August 2017 - 20th November 2017. This data will be updated every 24 hours.