Marco conceptual

Bottlenose dolphins in the Black Sea are recognized as endemic subspecies possessing morphological differences from Atlantic and Pacific populations. The Black Sea population is also differentiated genetically from other bottlenose dolphin populations in the eastern and western Mediterranean and the northeastern Atlantic.

2.1.4.1. Geographic range

The range of Black Sea bottlenose dolphins (Figure 2.5) includes the Black Sea proper; Kerch Strait along with the adjoining part of the Azov Sea and, probably the Marmara Sea, Bosphorus and Dardanelles straits. The genetic data suggest that the TSS constitutes an ecological barrier between the Black Sea dolphins and those in the Mediterranean, although limited gene flow between the two seas is probable.

Figure 2.5 Range of the Black Sea bottlenose dolphin. Red dots (direct observations) and query mark (eyewitness’s testimony) indicate locations of strandings on the Azov Sea coast (Birkun, 2008b).

The range of the Black Sea subspecies includes the territorial waters and exclusive economic zones of Bulgaria, Georgia, Romania, Russia, Turkey and Ukraine in the Black Sea; internal waters of Ukraine in the Black Sea, internal waters of Russia and Ukraine in the Kerch Strait and Azov Sea; and internal waters of Turkey, including the Bosphorus Strait, Marmara Sea and Dardanelles. In Romania bottlenose dolphins are sighted most frequently in Gura Portitei area and in front of Techirghiol Lake.

There are a few records of bottlenose dolphins entering rivers, e.g. the Danube in Romania and the Dnieper in Ukraine.

2.1.4.2. Principal, secondary and occasional habitats

Black Sea bottlenose dolphins live predominantly in the marine environment, although they may occur occasionally in estuarine and fluvial environments.

Principal habitat: circumlittoral area over the continental shelf (usually more than 6 m but less than 200 m deep).

Secondary habitats: open sea (usually more than 200 m deep) and shallow sea (usually less than 6 m deep; includes sea bays and straits).

Occasional habitats: a few instances of Black Sea bottlenose dolphins visiting big rivers are known. Sightings in some estuaries and coastal saline lagoons are not rare. Few stranded individuals were found on the Azov Sea shore.

2.1.4.3. Critical habitats

Bottlenose dolphins are distributed across the Black Sea shelf although they sometimes occur far offshore. In the northern Black Sea they form scattered communities of some tens to approximately 150 animals in different places around Crimea. Accumulations also are known to form off the Russian Caucasus and close to the Turkish coast. Bottlenose dolphins typically aggregate during autumn, winter and spring in a relatively small area off southern Crimea between Cape Sarych and Cape Khersones. Groups of hundreds of animals migrate every autumn to this area from the eastern and, probably, other parts of the Black Sea. In the Turkish Black Sea, Zonguldak and Sinop areas seem to be the most important areas for bottlenose dolphins whereas they are rare off the eastern coast of Turkey. Bottlenose dolphins migrate to Bulgarian waters annually from the southeast and northeast in spring. The migration routes, breeding, calving, feeding areas of bottlenose dolphin coincide with the fishing grounds where turbot is exploited intensely by bottom-set gillnets.

Bottlenose dolphin critical habitats overlapping with fishing grounds of intense bottom-set gillnet fishery are identified as follows:

Bulgaria: between Kavarna and Cape Cherni; near Krapets (by the Romanian border); to the south of Burgas; EEZ of Bulgaria;

Georgia: uncertain; Romania: EEZ of Romania;

Russia: area from Anapa to Sochi; the Kerch Strait; Turkey: western (European) coast and Prebosphoric area;

Ukraine: Dniester Bank; waters off the Crimea round Tarkhankut peninsula (including Karkinitsky Bay), between Cape Kiik-Atlama and Cape Chauda (Gulf of Feodosia), and in the Kerch Strait; EEZ of Ukraine in the northwestern Black Sea.

2.1.4.4. Population

The total population size is unknown. During most of the 20th century, the bottlenose dolphin was considered the least abundant of the three cetacean species in the Black Sea. During the 1990s, bottlenose dolphins have become prevalent in coastal waters of the northern Black Sea where the sighting rate increased by a factor of five between 1995 and 1997-1998.

There are some abundance estimates from line transect surveys in different parts of the range. These estimates suggest that present population size is at least several thousand but, presumably, not more than ~15,000.

Table B1-3. Bottlenose dolphin density and abundance estimates in selected Black Sea areas and contiguous water bodies

Surveyed area and observation effort Observation platform Research period Uncorrected density estimates Uncorrected abundance estimates References

Turkish Straits System (Bosphorus, Marmara Sea and Dardanelles)

Vessel Oct 1997 Not available 495 (203–2,197; 95% CI) Dede (1999)263

Turkish Straits System (Bosphorus, Marmara Sea and Dardanelles)

Vessel Aug 1998 Not available 468 (184–1,186; 95% CI) Dede (1999)263 Azov Sea in total, 40,280 km2_{/2,735 km aircraft Jul 2001 No sightings Birkun et al. (2002)}107

Southern Azov Sea (the same area), 7,560 km2_{/716 km}

aircraft Aug 2002 No sightings Birkun et al. (2003)108

Kerch Strait, 890 km2_{/353 km Aircraft Jul 2001 0.09 (0.03–0.22; 95% CI) 76 (30–192; 95% CI) Birkun et al. (2002)}107

Kerch Strait, 890 km2_{/353 km Aircraft Aug 2002 0.10 (0.04–0.27; 95% CI) 88 (31–243; 95% CI) Birkun et al. (2003)}108

Kerch Strait, 862 km2_{/310 km Vessel Aug 2003 0.15 (0.08–0.28; 95% CI) 127 (67–238; 95% CI) Birkun et al. (2004a)}109

NE shelf area of the Black Sea, 7,960 km2_{/791 km}

Aircraft Aug 2002 0.10 (0.04–0.26; 95% CI) 823 (329–2,057; 95% CI) Birkun et al. (2003)108 NW, N and NE Black Sea within

Ukrainian and Russian territorial waters, 31,780 km2_{/2,230 km}

Vessel Sep-Oct 2003

0.13 (0.08–0.22; 95% CI) 4,193 (2,527–6,956; 95% CI) Birkun et al. (2004a)109

Ukrainian EEZ within NW shelf area, 22,630 km2_{/388 km}

vessel Sep 2004 0.08 (0.03–0.21; 95% CI) 1,776 (660–4776; 95% CI Krivokhizhin (2009)195

SE Black Sea within Georgian waters, 2,320 km2_{/211 km}

Vessel Jan 2005 No sightings Birkun et al. (2006)105

SE Black Sea within Georgian waters, 2,320 km2_{/211 km}

Vessel May 2005 No sightings Komakhidze and Goradze (2005)110

110 _{KOMAKHIDZE G., I. GORADZE, 2005 - Estimate of distribution and number of cetaceans in coastal waters of south - eastern part of the Black Sea. Workshop on cetaceans surveying} in the Black Sea, 17-18 October 2005, Istanbul - Turkey

SE Black Sea within Georgian waters, 2,320 km2_{/211 km}

Vessel Aug 2005 No sightings Komakhidze and Goradze (2005)110

SE Black Sea within Georgian waters, 2,320 km2_{/211 km}

Vessel Nov 2005 No sightings Irakli Goradze, 2006, pers. comm.

Central Black Sea beyond territorial waters of Ukraine and Turkey, 31,200km2_{/660 km}

Vessel Sep-Oct 2005

Figure 2.6 Geographical extent of line-transect cetacean surveys where bottlenose dolphins were recorded (yellow shaded areas) (Notarbartolo di Sciara and Birkun, 2010).

2.1.4.5. Population trend

In the 20th century, the number of Black Sea bottlenose dolphins was reduced by direct killing for the cetacean-processing industry, which continued until 1983. The numbers of animals taken were not recorded accurately. Nevertheless, it can be inferred that the population size had been reduced by many thousands as a result of these direct kills. It is suspected that during the period beyond 1983 the population had a tendency to increase. However, it is also suspected that recovery was compromised by a mortality event in 1990 and is continuing to be compromised by anthropogenic influences.

↓ – until 1983 (directed killing)

↑? – 1983–2005 (mortality event in 1990 and persistent anthropogenic threats could have compromised recovery)