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Mediterranean and Black Sea Cetacean Red List Assessment Stenella coeruleoalba Summary Documentation Biome Marine Major Habitat(s) Open sea Geographic Range Temperate and subtropical waters of all oceans. Present throughout the Mediterranean Sea but has not been recorded in the Black Sea. Population The most abundant cetacean in the Mediterranean. Population in the western Mediterranean excluding the Tyrrhenian Sea (1991) estimated at: 117,880 (95%CI=68,379-214,800) (Forcada et al., 1994). There is no estimate for the eastern Mediterranean Sea. Population Trend Declined in the early 1990s, current trend uncertain. Detailed Documentation Range and Population Mediterranean population as a designatable unit: Morphological and genetic studies strongly suggest that the Mediterranean and eastern North Atlantic populations are isolated from each other, with little or no gene flow across the Straits of Gibraltar. Maximum body length of eastern North Atlantic striped dolphins is 5-8 cm longer than that of Mediterranean individuals (Calzada and Aguilar, 1995). Skull size is also smaller in Mediterranean specimens than in their neighbouring Atlantic counterparts (Archer, 1997). Mitochondrial Annex 3: Regular Species 59
Mediterranean and Black Sea Cetacean Red List Assessment Stenella coeruleoalba DNA analysis yielded 27 haplotypes, none of which was shared between the two areas, thus supporting differentiation (García-Martínez et al. 1995). Sub-population structure: Inside the Mediterranean there is some clinal variation in body size suggestive of population structure and/or restriction in gene flow between areas (Calzada and Aguilar, 1995); this appears to be confirmed by significant differences in tissue pollutant levels between Spain and Italy (Monaci et al., 1998). Gaspari (2004) considered dispersal range sufficiently limited between populations across the Mediterranean, and possibly between inshore and offshore populations within the Ligurian Sea, to make differentiation feasible. Generation time: Generation time for this dolphin population has been estimated as 22 years for females (Calzada et al., 1996; Calzada et al., 1997) and 20 for males (Calzada et al., 1996). It is therefore appropriate to use the default value for small delphinids of 20 years (see main text of workshop report). Range and population: Although overall the striped dolphin is the most abundant cetacean in the Mediterranean, both in the eastern and the western basins, it is not found at uniform densities. It typically shows a preference for highly productive, open waters beyond the continental shelf (Notarbartolo di Sciara et al., 1993; Forcada et al., 1994; Frantzis et al., 2003; Gannier, 2005). Two strandings were recorded in the Marmara Sea in 1990s (Öztürk et al., 1999). Reliable abundance estimates are available only for the western basin and most of them refer to the period immediately or soon after the 1990-1992 die-off: Western Mediterranean excluding the Tyrrhenian Sea (1991): 117,880 (95%CI=68,379-214,800) (Forcada et al., 1994) Balearic Sea (1991): 5,826 (95%CI=2,193-15,476) (Forcada and Hammond, 1998) Gulf of Lions (1991): 30,774 (95%CI=17,433-54,323) (Forcada and Hammond, 1998) Ligurian Sea (1992): 14,003 (95%CI=6,305-31,101) (Forcada et al., 1995) South Balearic area (1991): 18,810 (95%CI=8,825-35,940) (Forcada and Hammond, 1998) Alboran Sea (1991): 17,728 (95%CI=9,507-33,059) (Forcada and Hammond, 1998) Central coast of Spain (2000-2002): 15,778 (95%CI=10,940-22,756) (Gómez de Segura et al., 2006) Habitat and Ecology Oceanic, with a preference for highly productive, open waters beyond the continental shelf. Particularly abundant in the Ligurian Sea, the Gulf of Lions, the waters between the Balearic Islands and the Iberian Peninsula, and the Alborán Sea. Threats In the past, striped dolphins were hunted for use as bait for shrimp traps and longlines. Despite being prohibited, catches with this aim continue in at least southern Spain and probably other areas. Incidental captures in pelagic drift nets have been a major source of mortality all over the western Mediterranean in the past. These nets are still being used by at least Italian, Greek and Moroccan vessels, resulting in extensive dolphin mortality. The Spanish driftnet fishery in the Alborán Sea reportedly killed 145-183 striped dolphins per season in the early 1990s (Silvani et al., 1999); this fishery was halted in 1995 but the nets were transferred to Moroccan boats, which continue operating and have been estimated to kill more than 3,600 dolphins (striped and common, combined) in the Alborán Sea per year (Tudela et al. 2005). The Italian drift net (spadare) fishery is estimated to have killed thousands of striped dolphins per year through at least the early 1990s (Di Natale, 1992, 1995); although fishing effort has declined, mortality is still observed in Italian waters. The French thonaille drift net fishery has been estimated to take about 180-472 striped dolphins per season (Imbert et al., 2001). Reports from other fishing activities are sparse and collected non-systematically, but they indicate that striped dolphin mortality in at least pelagic purseseines, longlines and gillnets is widespread and likely significant (Di Natale and Notarbartolo di Sciara, 1994). To this should be added a certain number of direct catches for human consumption or for use as bait, which continue in several Mediterranean countries (SGFEN, 2001). In 1990-1992 a die-off devastated the whole Mediterranean population; > 1000 carcasses were examined Annex 3: Regular Species 60
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Published by: The World Conservatio
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Contents Preface ------------------
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Background and Introduction The con
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Results Of the 12 assessed units in
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Acknowledgements Workshop participa
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Annex 1 Workshop Agenda Mediterrane
Page 14 and 15: Blue World Institute of Marine Rese
Page 16 and 17: Fin whale (Balaenoptera physalus) M
Page 18 and 19: Mediterranean and Black Sea Cetacea
Page 28 and 29: Long-finned pilot whale (Globicepha
Page 34 and 35: Risso’s dolphin (Grampus griseus)
Page 44 and 45: Harbour porpoise (Phocoena phocoena
Page 62 and 63: Striped dolphin (Stenella coeruleoa
Page 96 and 97: Annex 4 Visitor Species Species Com
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Annex 5 Vagrant Species Species Com
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Mediterranean and Black Sea Cetacea
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North Atlantic right whale (Eubalae
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Northern bottlenose whale (Hyperood
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Harbour porpoise (Phocoena phocoena
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Indo-Pacific humpback dolphin (Sous
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Annex 6 Introduced Species Species
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Annex 8 Species reported to have oc
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