Bearzi, Giovanni

Bonizzoni, Silvia

Genov, Tilen

Tempesta, Milena

Repository of University of Primorska

Long-distance movement of a loneshort-beaked common dolphin Delphinusdelphis in the central Mediterranean Seatilen genov1, giovanni bearzi2,3, silvia bonizzoni2,3 and milena tempesta41Morigenos Marine Mammal Research & Conservation Society, Jarsˇka cesta 36/a, 1000 Ljubljana, Slovenia, 2Tethys ResearchInstitute, Viale G.B. Gadio 2, 20121 Milan, Italy, 3Dolphin Biology & Conservation, Collebaldo 40, 06066 Piegaro PG, Italy,4WWF Italy, Miramare Marine Protected Area, Viale Miramare 349, 34151 Grignano, Trieste, ItalyWhile short-beaked common dolphins are often regarded as highly mobile animals, their movements and ranging patterns arepoorly known and no long-distance movements have been documented through photo-identiﬁcation of individuals. We reportthe long-distance movement of a naturally marked individual, encompassing a minimum of 1000 km across the Ionian andthe Adriatic Seas, and the subsequent behaviour and site ﬁdelity of the same individual, in association with a calf, in andaround the commercial port of Monfalcone, northern Adriatic Sea. This is the longest documented movement for any indi-vidual of this species, worldwide.Keywords: short-beaked common dolphin, Delphinus delphis, movements, behaviour, photo-identiﬁcation, Mediterranean SeaSubmitted 3 October 2011; accepted 22 October 2011I NTRODUCT IONThe short-beaked common dolphin Delphinus delphis (here-inafter ‘common dolphin’) has faced a major decline in abun-dance and distribution in the Mediterranean Sea in recentdecades (Bearzi et al., 2003). In the coastal waters of Greece,a local population of common dolphins inhabiting the InnerIonian Sea Archipelago has undergone a decline fromaround 150 animals in 1996 to only about 15 in 2007(Bearzi et al., 2008), likely due to prey depletion resultingfrom overﬁshing (Bearzi et al., 2010; Gonzalvo et al., 2010;Piroddi et al., 2010). In the northern Adriatic Sea, commondolphins were historically abundant but had virtually van-ished by the 1970s (Bearzi et al., 2003, 2004).While common dolphins are often regarded as highlymobile animals, their movements and ranging patterns arepoorly known (Natoli et al., 2006; Mirimin et al., 2009). Toour knowledge, no long-distance movements have beendocumented through photo-identiﬁcation of individuallyidentiﬁable animals. This paper reports: (1) the long-distancemovement of a naturally marked individual, encompassing aminimum of 1000 km across the Ionian and the AdriaticSeas; and (2) the subsequent behaviour and site ﬁdelity ofthe same individual, in association with a calf, in and aroundthe commercial port of Monfalcone, northern Adriatic Sea.METHODS AND RESULTSIn June 2010, an adult–calf pair of common dolphins—theadult a presumed mother—was observed in the port ofMonfalcone, an industrial town near Trieste (northernAdriatic Sea, 45047′N 13033′E; Figure 1). These dolphinswere repeatedly sighted there between June 2010 andJanuary 2011, in an area of 1.2 km2. High-quality digitalphotographs of the dorsal ﬁn of both animals were taken forindividual photo-identiﬁcation (Wu¨rsig & Jefferson, 1990)and video footage was obtained on some occasions. Theadult appeared in good physical condition, with no evidenceof injuries, malnutrition or skin disease based on images ofits dorsum. The calf—about half the length of the adult—initially appeared in good condition but started showingsigns of emaciation by January 2011. It was estimated to beabout one year old at the beginning of the observationperiod, based on a comparison with photographs of animalsof known age taken in the Ionian Sea. In February 2011, thecalf disappeared. After this, the adult was absent from theport on several occasions and could not be found in the adja-cent waters within a 6 km radius. However, the animalreturned to the port occasionally between February and May2011. In May 2011, the adult was ﬁlmed 4.5 km fromMonfalcone. In June, July and August 2011 it was observedrepeatedly between Monfalcone and the city of Trieste(22 km south-east of Monfalcone), within 1 km of the coast.During some encounters, both inside and outside of theport, the animal was quite active, performing bowriding,leaps, breaches, side-slaps, tail-slaps and carrying jellyﬁshRhizostoma pulmo between its pectoral ﬁns while swimmingbelly-up at the surface. Some of the observed behaviourswere suggestive of foraging and playing.A comparison with a catalogue of 171 naturally markedcommon dolphins from the Inner Ionian Sea Archipelago,Greece (Bearzi et al., 2008), revealed that the adult wasencountered there in August 2008, in a group composed ofeight adults and one calf. Although most photo-identiﬁedanimals in the Inner Ionian Sea Archipelago were sightedCorresponding author:T. GenovEmail: tilen.genov@gmail.com1Marine Biodiversity Records, page 1 of 3. # Marine Biological Association of the United Kingdom, 2012doi:10.1017/S1755267211001163; Vol. 5; e9; 2012 Published onlinehttps://doi.org/10.1017/S1755267211001163Downloaded from https:/www.cambridge.org/core. Open University Library, on 25 Jan 2017 at 20:41:08, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.regularly, this particular animal was encountered in that areaonly once. If moving in a straight line, the animal would havetravelled a minimum of 1000 km between the two sites(Figure 1). This is the longest documented movement forany individual of this species, worldwide.D ISCUSS IONCommon dolphins are generally thought to be wide-ranging.For example, a radio-tagged female common dolphin offthe coast of California travelled at least 500 km in 10 days(Evans, 1982). Genetic studies of common dolphins in theMediterranean Sea and North Atlantic Ocean further supportthe notion that these animals perform long-distancemovements(Natoli et al., 2006). However, such movements have neverbeen documented based on individual photo-identiﬁcation,probably due to scarce application of this method to commondolphins (Neumann et al., 2002; Bearzi et al., 2011).In most mammals dispersal is biased towards males(Greenwood, 1980). Females are usually philopatric whilemales tend to disperse. As revealed by genetics, this alsoappears to be the case in at least some populations ofcommon bottlenose dolphins Tursiops truncatus (Mo¨ller &Beheregaray, 2004), but not in others (Natoli et al., 2005).Genetic studies of short-beaked common dolphins from theMediterranean and North Atlantic showed no marked differ-ences in dispersal between sexes (Natoli et al., 2006, 2008).The observation reported here refers to an individual thatmoved to a part of the Mediterranean Sea—the northernAdriatic Sea—where the species no longer occurs (Krysˇtufek& Lipej, 1993; Bearzi et al., 2004; Genov et al., 2008).Additionally, this particular animal seems to have settled ina port for several months. Such behaviour is atypical for thisspecies. Bottlenose dolphins frequently approach and enterports and a number of single individuals have taken residencein urban areas (Lockyer, 1990; Eisfeld et al., 2010). Commondolphins, however, have rarely been reported to do that. Onecase involved the presence of two long-beaked common dol-phins D. capensis in two small bays on the central coast ofChile for 10 years (Bernal et al., 2003). Given the circum-stances, care must be taken in interpreting and assessing theecological signiﬁcance of the reported long-distance move-ment for Mediterranean common dolphins on the whole.Still, this study indicates the value and the potential ofphoto-identiﬁcation to gain insights into common dolphinmovement and ranging patterns. Comparisons among theexisting common dolphin photo-identiﬁcation catalogueswould therefore be worthwhile and may provide furtherinsight.ACKNOWLEDGEMENTSWe are grateful to Tina Centrih, Tommaso De Lorenzi, SibillaGerin, Ana Hace, Polona Kotnjek and Karin Schlappa for theirFig. 1. Minimum distance travelled by the adult common dolphin, with some of the locations cited in the text.2 tilen genov et al.https://doi.org/10.1017/S1755267211001163Downloaded from https:/www.cambridge.org/core. Open University Library, on 25 Jan 2017 at 20:41:08, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.help with ﬁeld data collection. Annalise Petroselli took photo-graphs of the adult common dolphin in the Inner Ionian SeaArchipelago. David Janiger helped with the literature. AdaNatoli, Bill Perrin, Karen Stockin and Ben Wilson provideduseful comments and suggestions that helped improve themanuscript. We would also like to thank Ana Rita Amaral,Maddalena Bearzi, Simon Berrow, Massimo Celio, SaulCiriaco, Antonio Codarin, Lisa Faresi, Erik Merson, EnricoVinzi, ARPA FVG and the Coast Guards of Trieste andMonfalcone.REFERENCESBearzi G., Agazzi S., Gonzalvo J., Bonizzoni S., Costa M. and PetroselliA. (2010) Biomass removal by dolphins and ﬁsheries in aMediterranean Sea coastal area: do dolphins have an ecologicalimpact on ﬁsheries? Aquatic Conservation: Marine and FreshwaterEcosystems 20, 549–559.Bearzi G., Agazzi S., Gonzalvo J., Costa M., Bonizzoni S., Politi E.,Piroddi C. and Reeves R.R. (2008) Overﬁshing and the disappearanceof short-beaked common dolphins from western Greece. EndangeredSpecies Research 5, 1–12.Bearzi G., Bonizzoni S., Agazzi S., Gonzalvo J. and Currey R.J.C. (2011)Striped dolphins and short-beaked common dolphins in the Gulf ofCorinth, Greece: abundance estimates from dorsal ﬁn photographs.Marine Mammal Science 27, E165–E184.Bearzi G., Holcer D. and Notarbartolo di Sciara G. (2004) The role ofhistorical dolphin takes and habitat degradation in shaping thepresent status of northern Adriatic cetaceans. Aquatic Conservation:Marine and Freshwater Ecosystems 14, 363–379.Bearzi G., Reeves R.R., Notarbartolo di Sciara G., Politi E., Can˜adas A.,Frantzis A. and Mussi B. (2003) Ecology, status and conservation ofshort-beaked common dolphins Delphinus delphis in the MediterraneanSea.Mammal Review 33, 224–252.Bernal R., Olavarrı´a C. and Moraga R. (2003) Occurrence and long-termresidency of two long-beaked common dolphins, Delphinus capensis(Gray 1828), in adjacent small bays on the Chilean central coast.Aquatic Mammals 29, 396–399.Eisfeld S., Simmonds M. and Stansﬁeld L. (2010) Behavior of a solitarysociable female bottlenose dolphin (Tursiops truncatus) off the coast ofKent, south-east England. Journal of Applied Animal Welfare Science13, 31–45.Evans Q. (1982) Distribution and differentiation of stocks of Delphinusdelphis Linnaeus in the northeastern Paciﬁc. In Mammals in theSeas: Small cetaceans, seals, sirenians, and otters, Volume 5. Rome:FAO, pp. 45–66.Genov T., Kotnjek P., Lesjak J., Hace A. and Fortuna C.M. (2008)Bottlenose dolphins (Tursiops truncatus) in Slovenian and adjacentwaters (northern Adriatic Sea). Annales, Series Historia Naturalis 18,227–244.Gonzalvo J., Moutopoulos D.K., Bearzi G. and Stergiou K.I. (2010)Fisheries mismanagement in a Natura 2000 area in western Greece.Fisheries Management and Ecology 18, 25–38.Greenwood P.J. (1980) Mating systems, philopatry and dispersal in birdsand mammals. Animal Behaviour 28, 140–162.Krysˇtufek B. and Lipej L. (1993) Kiti (Cetacea) v severnem Jadranu.Annales, Series Historia Naturalis 3, 9–20.Lockyer C. (1990) Review of incidents involving wild, sociable dolphins,worldwide. In Leatherwood S. and Reeves R.R. (eds) The bottlenosedolphin. San Diego, CA: Academic Press, pp. 337–353.Mirimin L., Westgate A., Rogan E., Rosel P., Read A., Coughlan J. andCross T. (2009) Population structure of short-beaked common dol-phins (Delphinus delphis) in the North Atlantic Ocean as revealedby mitochondrial and nuclear genetic markers. Marine Biology 156,821–834.Mo¨ller L.M. and Beheregaray L.B. (2004) Genetic evidence for sex-biaseddispersal in resident bottlenose dolphins (Tursiops aduncus).Molecular Ecology 13, 1607–1612.Natoli A., Birkun A., Aguilar A., Lopez A. and Hoelzel A.R. (2005)Habitat structure and the dispersal of male and female bottlenosedolphins (Tursiops truncatus). Proceedings of the Royal Society B:Biological Sciences 272, 1217–1226.Natoli A., Can˜adas A., Peddemors V.M., Aguilar A., Vaquero C.,Fernandez-Piqueras P. and Hoelzel A.R. (2006) Phylogeographyand alpha taxonomy of the common dolphin (Delphinus sp.).Journal of Evolutionary Biology 19, 943–954.Natoli A., Can˜adas A., Vaquero C., Politi E., Fernandez-Navarro P. andHoelzel A.R. (2008) Conservation genetics of the short-beakedcommon dolphin (Delphinus delphis) in the Mediterranean Sea andin the eastern North Atlantic Ocean. Conservation Genetics 9, 1479–1487.Neumann D.R., Leitenberger A. and Orams M.B. (2002) Photo-identiﬁcation of short-beaked common dolphins (Delphinus delphis)in north-east New Zealand: a photo-catalogue of recognisable individ-uals. New Zealand Journal of Marine and Freshwater Research 36,593–604.Piroddi C., Bearzi G. and Christensen V. (2010) Effects of local ﬁsheriesand ocean productivity on the north-eastern Ionian Sea ecosystem.Ecological Modelling 221, 1526–1544.andWu¨rsig B. and Jefferson T.A. (1990) Methods of photo-identiﬁcation forsmall cetaceans. In Hammond P.S., Mizroch S.A. and Donovan G.P.(eds) Individual recognition of cetaceans: use of photo-identiﬁcationand other techniques to estimate population parameters. Report of theInternational Whaling Commission, Special Issue 12, Cambridge, UK,pp. 43–52.Correspondence should be addressed to:T. GenovMorigenos, Jarska cesta 36/a1000 Ljubljana, Sloveniaemail: tilen.genov@gmail.comlong-distance movement of delphinus delphis 3https://doi.org/10.1017/S1755267211001163Downloaded from https:/www.cambridge.org/core. Open University Library, on 25 Jan 2017 at 20:41:08, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms.

Long-distance movement of a lone short-beaked common dolphin Delphinus delphis in the central Mediterranean Sea

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Long-distance movement of a lone short-beaked common dolphin Delphinus delphis in the central Mediterranean Sea

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