Dolphins, Whales and Porpoises: 2002-2010 Conservation - IUCN

appears to be limited to dolphins in the Alboran Sea (Natoli
in press). Some authors consider common dolphins in the
Black Sea to be an endemic subspecies (Tomilin 1967;
Heptner et al. 1996). Recent line-transect surveys resulted
in an estimate of about 15,000 common dolphins in the
south-western Alboran Sea, but abundance was not estimated
for the rest of the western Mediterranean due to the
low number of sightings (Forcada 1995; Forcada and
Hammond 1998). No credible information exists on the
abundance of common dolphins (and other cetaceans) in the
Black Sea, but massive directed killing, which continued to
the early 1980s, is believed to have considerably reduced the
population size (Buckland et al. 1992). Currently, the main
threats facing common dolphins in both regions include
accidental killing in fishing gear, reduced availability of
prey due to overfishing and habitat degradation, and the
effects of toxic contaminants. This last threat may have
increased the population’s susceptibility to epizootic outbreaks
that resulted in mass die-offs in the Black Sea
(Birkun et al. 1999). In the Mediterranean, epizootics and
reproductive disorders appear to have affected striped dolphins
primarily (Van Bressem et al. 1993; Munson et al.
1998), but common dolphins may also be at risk because of
their similarly high contaminant loads (Fossi et al. 2000).
This project should entail a series of surveys to determine
the distribution and abundance of common dolphins in the
Mediterranean and Black seas and their connecting waters.
Standard methods should be used so that results can be
compared over time and from one region to another. Biopsies
should be collected for genetic and contaminant analyses,
while recognizing that the darting to obtain biopsies is
not without risk to free-ranging dolphins (Bearzi 2000).
Samples should be archived in a central repository, and
collaborative studies should be initiated to better understand
population structure and identify regional differences in
contaminant exposure. Sighting surveys, stranding networks,
and related activities require collaboration among
national scientists, government agencies, and NGOs in the
various range states. ACCOBAMS provides an ideal basis
for coordination and collaboration. This project should result
in a comprehensive assessment of the status of
Mediterranean and Black Sea common dolphins and lead to
appropriate measures for their conservation.
48. Investigate the distribution and abundance of
bottlenose dolphins in the Mediterranean and
Black Seas, and evaluate threats to their
survival
In the Mediterranean and Black seas, bottlenose dolphins
occur in scattered inshore communities of perhaps 50–150
individuals, and the gaps between them appear to be getting
larger (Bompar et al. 1994; Bearzi et al. 1997; Notarbartolo
di Sciara and Gordon 1997; Birkun and Krivokhizhin 1998;
Fortuna et al. 2000; Pulcini et al. in press). Genetic evidence
suggests that there is gene flow between bottlenose dolphins
in the Mediterranean and the North Atlantic (Natoli and
77
Hoelzel 2000). Some authors regard the Black Sea population
to be an endemic subspecies (e.g., Heptner et al.
1996), and although no firm morphological or genetic evidence
has been presented to support this claim, available
information suggests that the population is substantially
isolated from that in the Mediterranean and therefore vulnerable
to depletion and extirpation. Bottlenose dolphins are
common in the Kerch Strait (Birkun and Krivokhizhin
1998) and probably occur at least occasionally in the Sea of
Azov (Birkun et al. 1997). Conservation threats are roughly
similar to those facing short-beaked common dolphins (see
above) and other small cetaceans of the region, except that
bottlenose dolphins in the Mediterranean and Black seas
may be particularly vulnerable to human activities due to
their near-shore occurrence and fragmented population
structure. Recent dramatic changes to the ecosystem of the
Black Sea have generally been attributed to extensive pollution,
coastal development, disturbance from vessel traffic,
overfishing, and the effects of introduced species
(GESAMP 1997). Incidental kills of bottlenose dolphins in
trammel and gillnets occur frequently in some areas (Silvani
et al. 1992; UNEP/IUCN 1994). Overfishing of demersal
fish may have affected the prey base for bottlenose dolphins
in some areas. Sharp declines in the abundance and range of
some fish species have been observed in the Black Sea,
attributed to environmental pollution, blooms of an exotic
ctenophore, and overfishing (Andrianov and Bulgakova
1996). The live-capture of bottlenose dolphins for Russian
and Ukrainian oceanaria, and for export, is believed to be
adding to the pressure on local dolphin communities in the
Black Sea (A. Birkun, pers. comm.). Based on trade data
submitted by member countries of CITES and managed by
the UNEP-World Conservation Monitoring Centre, at least
92 bottlenose dolphins were exported from the Black Sea
between 1990 and 1999. In addition, unknown numbers are
removed from the wild each year by countries bordering the
Black Sea for military purposes, to replace animals that die
in display facilities, and to supply the captive dolphins used
in human therapy programs.
This project consists of a series of intensive population
assessments in areas of the Mediterranean and Black seas,
and interconnecting waters, where bottlenose dolphins are
known to occur, combined with larger-scale but less intensive
surveys to identify previously unknown hotspots of
occurrence (Figure 33). Efforts are also required to monitor
incidental catches (best accomplished through on-board observer
programs)(cf. Silvani et al. 1999) and to investigate
the possible problem of nutritional stress from reduced
availability of suitable prey (cf. Bearzi et al. 1999). A
particular need is for genetic studies of bottlenose dolphins
in the Black Sea to determine the extent to which they are
distinct from other populations. Similar to the common
dolphin project described above (Project 47), this project
requires coordination among various national agencies and
scientists, which may be accomplished under the auspices of
ACCOBAMS.