Cetaceans in Greece: Present status of knowledge

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Reported sightings and strandings There is only one sighting of harbour porpoises recorded in the Greek Seas, but it has to be noted that no dedicated surveys have been conducted in the areas mainly inhabited by this species (Thracian Sea and Thermaikos Gulf). The available information regarding the species comes from 15 strandings (Table 1); of which 13 were recorded in the northern Aegean Sea. Geographic range Until the mid 1990s the harbour porpoise was considered absent or extinct in the Mediterranean Sea (Frantzis et al. 2001). Its presence is now definitely confirmed by 15 strandings and one sighting and it is limited to the northern part of the Aegean Sea. The harbour porpoise is absent from the rest of the Mediterranean basin and has been recorded exceptionally as a vagrant species close to the Gibraltar area (Frantzis et al. 2001). Until 2006 all records of harbour porpoises concerned exclusively the northernmost part of the Aegean Sea and particularly the Thracian Sea. Since 2006 three new strandings were reported further south, on both the west and east coasts of the Aegean Sea. In summer 2006 a harbour porpoise stranded alive in N Evvoia, at about latitude 38°58’ (Pelagos Cetacean Research Institute unpublished data). In October 2006 another specimen stranded in Urla (Turkish Aegean Sea) at 38°21’ of latitude (not represented on the distribution map; Güçlüsoy 2007). Finally, in spring 2008 a third specimen stranded in Kavouri Vouliagmenis in Saronikos Gulf at about a latitude of 37°49’ (Pelagos Cetacean Research Institute unpublished data). This is the southernmost position ever recorded for the subspecies Phocoena phocoena relicta, i.e. some 460 km further south of its previous known range in the northern Aegean and the Thracian Sea. There is no easy explanation of this appearance of harbour porpoises in southern and warmer seas, and it is unknown whether they indicate southern limits for the true range of this species. Recent observations in the area of the Çanakkale Straits (Güçlüsoy 2007, Tonay et al. 2009), both in its Aegean side and inside the straits, have shown that harbour porpoises found in the Aegean may have a continuous range with the harbour porpoises of the Marmara Sea. Habitat The harbour porpoises typically occupie the continental shelf waters close to the coast and seem to prefer lower water temperatures than the average temperatures of the Greek Seas (seldom found in waters warmer than 17°C; Read 1999). The single sighting in the Greek Seas clearly does not allow drawing conclusions about the habitat preferences of harbour porpoises in this area. However, the location of strandings indicates that the Thracian Sea encompasses the core area of its habitat. The Thracian Sea (as well as Thermaikos Gulf) has an extended plateau of shallow waters that present the lowest temperatures and salinities in the Greek Seas (Poulos et al. 1997). The only sighting of a group of 6-10 harbour porpoises occurred at about 100 m from shore (Frantzis et al. 2001). In the Black Sea, harbour porpoises occupy coastal waters up to 200 m deep, although they can also occur in deep offshore waters (Birkun & Frantzis 2006). 54
Abundance The population size of Aegean harbour porpoise is unknown, but likely small as indicated by the limited geographic range and rarity of records. Population trend The population trend of the Aegean Sea subpopulation or population is unknown. Degree of residency and/or isolation According to stranding and sighting data the harbour porpoises seem to be present yearround in the northern Aegean Sea. They have been recorded in all months of the year except April and September. Their small size for their age and genetic signature indicates that they originate from the Black Sea population (subspecies Phocoena phocoena relicta) rather than from the Atlantic, from which they have been reproductively isolated for thousands of years and have genetically and morphologically diverged (Rosel et al. 2003, Viaud-Martinnez et al. 2007). It has been suggested that movements of porpoises out of the the Marmara Sea and into the Mediterranean Sea may occur through the Dardanelles Straits (Rosel et al. 2003). Recent observations all along the Dardanelles Straits as well as at their exit into the Aegean Sea have shown a continuous range (Güçlüsoy 2007, Tonay et al. 2009). The population of P. p. relicta, to which the Aegean harbour porpoises belongs, may consist of three or more subpopulations, e.g. the Azov Sea, northwestern Black Sea, Marmara Sea and northern Aegean Sea (Birkun & Frantzis 2006). However, further work is needed to determine whether the animals found in the northern Aegean Sea represent a separate subpopulation, and which is their degree of geographical and/or genetic isolation from the Black and Marmara Seas (Frantzis et al., 2001; Rosel et al., 2003). Despite the recently confirmed continuous range, the genetic analysis of six samples from the Aegean Sea showed that one of their two haplotypes was shared with the Black Sea, while another was unique. Unexpectedly, all three samples from the Sea of Marmara (located between the Aegean Sea and Black Sea) possessed a single and unique haplotype. Seasonality of reproduction There is no available information regarding the reproductive season of the Aegean harbour porpoises. Reproduction is seasonal in all studied populations of this species (Read 1999). In the UK and the Baltic Sea births occur primarily in June and July. In the western Atlantic (Bay of Fundy and Gulf of Maine) they occur in May (Read 1999). Feeding habits The analysis of stomach contents of a few harbour porpoises sranded in Greece is still pending. Anchovy (Engraulis encrasicolus ponticus) is an important prey species for harbour porpoises of the Black Sea and Azov Sea populations during the cold season. At least 14 fish species have been recorded in stomach contents, of which four are considered 55
Page 1 and 2:
Cetaceans in Greece: Present status
Page 3:
Organisations supporting the Initia
Page 7: ORIGIN AND SCOPE OF THIS REPORT The
Page 10 and 11: According to the distribution maps
Page 12 and 13: not belong to the suborder of mysti
Page 14 and 15: Data collection Available cetacean
Page 16 and 17: from the network was initially cons
Page 18 and 19: Distribution and effort The distrib
Page 20 and 21: Sighting data Ten cetacean species
Page 23: CETACEAN SPECIES COMMONLY OCCURRING
Page 26 and 27: Reported sightings and strandings T
Page 28 and 29: Main threats In the western Mediter
Page 32 and 33: published stomach content contained
Page 36 and 37: the stranding and death of several
Page 40 and 41: IUCN Red List classification Medite
Page 45 and 46: Drawing by Massimo Demma / ICRAM Ta
Page 47 and 48: Degree of residency and/or isolatio
Page 49 and 50: Drawing by Massimo Demma Taxonomy D
Page 51 and 52: a similar abundance. Short-beaked c
Page 53: 2008b). No information is available
Page 58 and 59: important: anchovy, sprat (Sprattus
Page 61 and 62: Megaptera novaeangliae (Borowski, 1
Page 63 and 64: Balaenoptera acutorostrata Lacépè
Page 69 and 70: Steno bredanensis (G. Cuvier in Les
Page 71 and 72: FALSE REPORTS OF CETACEAN SPECIES I
Page 73 and 74: WHAT IS KNOWN, WHAT REMAINS UNKNOWN
Page 75 and 76: ARE THE GREEK CETACEAN POPULATIONS
Page 77 and 78: ACKNOWLEDGEMENTS Many thanks to sev
Page 79 and 80: Bearzi G., Politi E., Agazzi S., Az
Page 81 and 82: García-Martinez J., Barrio E., Rag
Page 83 and 84: Notarbartolo di Sciara G., Demma M.
Page 85 and 86: ANNEX I: Distribution of searching
Page 87 and 88: Balaenoptera physalus FIN WHALE (Π
Page 89 and 90: Ziphius cavirostris CUVIER’S BEAK
Page 91 and 92: Tursiops truncatus COMMON BOTTLENOS
Page 93 and 94: Delphinus delphis SHORT-BEAKED COMM
Page 95 and 96: ANNEX III: Additional references on
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Cetaceans in Greece: Present status of knowledge

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