Tursiops truncatus ssp. ponticushttp://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T133714A17771698.en
|Scientific Name:||Tursiops truncatus ssp. ponticus|
|Species Authority:||Barabasch, 1940|
|Taxonomic Notes:||Bottlenose Dolphins in the Black Sea are recognized as a subspecies possessing morphological differences from Atlantic and Pacific populations (Barabasch-Nikiforov 1960, Geptner et al. 1976). The Black Sea population is also differentiated genetically from other bottlenose dolphin populations in the eastern and western Mediterranean and the northeastern Atlantic (Natoli et al. 2005), and this evidence supports recognition of T. t. ponticus (A. Natoli pers. comm. 2006).|
|Red List Category & Criteria:||Endangered A2cde ver 3.1|
|Reviewer(s):||Brownell Jr., R.L. & Crespo, E.|
The Black Sea bottlenose dolphin, T. t. ponticus, qualifies for listing as Endangered based on criterion A2cde.
Generation time was not estimated for this subspecies; it was assumed to be approximately 20 years, as for the Mediterranean bottlenose dolphin (Taylor et al. 2007 estimated 23 years for the species). Thus, three generations for Black Sea bottlenose dolphins would be about 60 years.
There is no estimate of total population size but information from incomplete surveys suggests that the current population size is at least several 1,000s of animals.
The past 60-year period (1946-2005; three generations) includes events, circumstances and trends that are relevant to Criterion A, as follows:
(1) Large directed takes occurred before the ban on small cetacean hunting was declared in Turkey in 1983. Within the 38-year period from 1946-1983, the total number of bottlenose dolphins killed was at least 24,000-28,000 but certainly much greater (probably by tens of 1000s) because those figures do not incorporate any catch statistics from Romania, or for Turkey before 1976 and after 1981, or for Bulgaria before 1958 (see “Threats”). There are indications of some recent intentional killing and harassment in Ukraine;
(2) Regionally dispersed incidental mortality in bottom-set gillnets from 1946 through the 1980s is roughly estimated at some 100s per year. The scale of this mortality almost certainly increased in the 1990s-2000s owing to the rapid expansion of illegal, unreported and unregulated fishing in the Black Sea;
(3) Hundreds and probably 1,000 bottlenose dolphins have been live-captured in the Black Sea for captivity since the mid 1960s. This does not account for mortality (usually unreported) during capture operations. Live-captures continue in the Russian Federation, with 10-20 animals taken annually from a small area;
(4) A mortality event of unknown cause occurred in 1990;
(5) There has been ongoing degradation of the Black Sea environment overall (including bottlenose dolphin habitat) and declines in many of its indigenous animal populations (including bottlenose dolphin prey) from the 1970s to the present, with a likely peak in the devastation caused by overfishing and habitat deterioration (including pollution and explosive growth of populations of invasive species) in the late 1980s–early 1990s. These processes, taken together, have led to severe declines in prey populations.
The inference of a reduction in population size of 50% was supported by a simple simulation in which the population was assumed to increase at a constant rate of 4% per year and the direct and incidental removals (as indicated by points (1), (2) and (3) above) were estimated realistically. This simulation showed that a decline of more than 50% in the last three generations would be required for the current population size to be about 15,000.
|Previously published Red List assessments:||
The range of Black Sea Bottlenose Dolphins includes the Black Sea proper; Kerch Strait along with the adjoining part of the Azov Sea (Tzalkin 1940, Birkun et al. 1997, Sokolov 1997); and the Turkish Straits System (TSS) (Kleinenberg 1956, Beaubrun 1995, Öztürk and Öztürk 1997) (see Figure 1 in the Supplementary Material). 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. A possible vagrant from the Black Sea population was identified genetically in the western Mediterranean (Natoli et al. 2005).
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 (including the Dnieper-and-Boug Liman, Karkinitsky Bay and Donuzlav Lake); internal waters of Russia and Ukraine in the Kerch Strait and Azov Sea; and internal waters of Turkey, represented by the Turkish Straits System including the Bosphorus Strait, Marmara Sea and Dardanelles. There are a few records of Bottlenose Dolphins entering rivers, e.g. the Danube in Romania (Police 1930, cited in Tomilin 1957) and the Dnieper in Ukraine (Birkun 2006).
Population structure within the Black Sea is likely (Bel’kovich 1996), with several subpopulations or “semi-resident” communities, including those that spend most of the year in geographically and ecologically different areas, e.g. northwestern Black Sea; coastal waters off the southern Crimea; Kerch Strait and adjoining portions of the Black Sea and Azov Sea; shelf waters off the Caucasian coast; Turkish Black Sea; and TSS.[Note: It has been agreed that territorial waters of all six Black Sea countries constitute the 12-mile-wide aquatic strip along the coasts of the sea; marine boundaries of the countries coincide with the external (offshore) border of this strip. However, there are some areas where the sea runs deep inland (gulfs, bays, etc.), and in these places the 12-mile rule does not work. These water bodies are situated quite far from the state boundaries and constitute the so-called “internal [marine] waters” of the Black Sea countries.]
The map shows where the species may occur. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states.
Native:Bulgaria; Georgia; Romania; Russian Federation; Turkey (Turkey-in-Europe); Ukraine (Ukraine (main part))
|FAO Marine Fishing Areas:||
Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The total population size is unknown. Region-wide estimates of absolute abundance, based on strip transect surveys carried out in the USSR (1967–1974) and Turkey (1987), have been discredited by the IWC Scientific Committee due to irremediable methodological and interpretive problems (Smith 1982, Buckland et al. 1992). During most of the 20th century, the Bottlenose Dolphin was considered the least abundant of the three cetacean species in the Black Sea (Tzalkin 1940, Kleinenberg 1956, Geptner et al. 1976, Yaskin and Yukhov 1997). During the last decade, Bottlenose Dolphins have become prevalent in coastal waters of the northern Black Sea (Birkun et al. 2004b). The estimated sighting rate increased by a factor of five between 1995 and 1997–1998. There is an annual autumn accumulation of Bottlenose Dolphins in waters close to the southern extremity of the Crimea (Cape Fiolent – Cape Sarych). Groups of hundreds of animals migrate every autumn to this relatively small area from the eastern and, probably, other parts of the Black Sea (Birkun et al. 2004b, Birkun 2006). Estimates of abundance from recent line transect surveys in different parts of the range (see Table 1 in the Supplementary Material) suggest that present population size is at least several 1,000s.
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; much of the catch data was recorded as numbers of animals undifferentiated to species (all three Black Sea cetacean species were targeted) and by wet weight aggregates (e.g. tons of small cetaceans landed). Nevertheless, it can be inferred that the population size of T. t. ponticus had been reduced by many thousands as a result of these direct kills by the time of the total ban on the Black Sea dolphin fishery (see “Threats” section). It is suspected that during the period from 1983–2005, 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 the persistent and probably increasing anthropogenic influences listed below under “Threats”.
It was assumed that Black Sea Bottlenose Dolphins have a life history similar to T. truncatus elsewhere and therefore that the generation time is approximately 20 years. The interval between births is from two or three to six years (Tomilin 1957), but in captive females the reproductive cycle can be as short as two years (Ozharovskaya 1997). It was assumed that one female is unlikely to produce more than eight calves in her lifetime (Tomilin 1984, cited after: Ozharovskaya 1997). Sexual behaviour can be observed during the whole year with a peak in spring and early summer. The reproductive season (maximum five spontaneous ovulations) extends from March to October with a peak in June; the highest concentrations of testosterone in males were recorded in July and the lowest in January (Ozharovskaya 1997). Gestation lasts 12 months. Lactation can last more than 1.5 years.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Bottlenose Dolphins are distributed across the Black Sea shelf; they sometimes occur far offshore (Beaubrun 1995, Yaskin and Yukhov 1997). In the northern Black Sea they form scattered communities of some tens to approximately 150 animals in different places around Crimea, including the Kerch Strait and coastal waters off the western and southern extremities of the peninsula (Zatevakhin and Bel’kovich 1996, Birkun et al. 2004a, Birkun 2006). Accumulations also are known to form off the Russian Caucasus (Olga Shpak pers. comm. 2005) and close to the Turkish coast (Sergey Krivokhizhin pers. comm., 2005). Bottlenose Dolphins typically aggregate during autumn, winter and spring in a relatively small area off southern Crimea between Cape Sarych and Cape Khersones (Birkun et al. 2006). According to a 2-year photo-identification study, this “winter” accumulation consists of animals from other “summer” concentrations. Mean group sizes varied from 2.0 to 2.9 in different surveyed areas (Birkun et al. 2002, 2003, 2004a).
The peculiarities of cetacean ecology in the Black Sea are conditioned mainly by the high degree of geographical isolation of the sea, its relatively low salinity, significant seasonal fluctuations of water temperature, and the presence of anoxic water saturated with hydrogen sulphide below 100–250 m depth. Bottlenose Dolphins are primarily piscivorous in the Black Sea, taking both benthic and pelagic fishes, large and small. A total of 16 fish species have been reported as prey off the Crimean and Caucasian coasts (Tzalkin 1940, Kleinenberg 1956, Tomilin 1957, Krivokhizhin et al. 2000) including four species of mullet (Lisa aurata, L. saliens, Mugil cephalus and M. so-iuy).
In the past, the population was subject to extensive commercial killing. Bottlenose Dolphins were taken by all Black Sea countries for manufacturing oils, paint, glue, varnish, foodstuffs, medicine, soap, cosmetics, leather, “fish” meal and bone fertilizer (Kleinenberg 1956, Tomilin 1957, Buckland et al. 1992). The total number of animals killed is unknown; however, it is generally acknowledged that all Black Sea cetacean populations, including Bottlenose Dolphins, were greatly reduced by the dolphin fishery (IWC 1983, 1992, 2004). It has been roughly estimated that between the early 1930s and mid 1950s Bottlenose Dolphins constituted only 0.5% of the aggregate numbers of Black Sea cetaceans killed and processed in the USSR (Tzalkin 1940, Kleinenberg 1956) including present-day Russia, Ukraine and Georgia. The statistics of the fishery were commonly expressed as total weight or total numbers of animals in the catch without species differentiation. Using the value of 0.5%, Zemsky (1996) estimated that a total of only 4,279 Bottlenose Dolphins were taken in the USSR (1946-1966) and Bulgaria (1958–1966), with yearly variation from 30 (in 1966) to 656 (in 1959). These figures are very likely underestimated to a great extent for the following reasons: (a) in spring 1946, more than 3,000 Bottlenose Dolphins were caught during a single day in one location close to the southern Crimea (Kleinenberg 1956); (b) in 1961, the Bulgarian cetacean fishery concentrated almost exclusively on bottlenose dolphins and about 13,000 of them were taken (Nikolov 1963 cited in Sal’nikov 1967); (c) in April 1966, a single dolphin-processing factory in Novorossiysk, Russia, processed 53 Bottlenose Dolphins (Danilevsky and Tyutyunnikov 1968).
Thus, taking into consideration the unknown but presumably significant size of the Turkish and Romanian catches, it can be inferred that the number of Bottlenose Dolphins killed before the mid 1960s was sometimes very high. From 1976 to 1981, Bottlenose Dolphins were believed to account for 2–3% of the total catch in the Turkish cetacean fishery, which took an estimated 34,000–44,000 small cetaceans annually (IWC 1983, Klinowska 1991). This would imply 680–1,320 Bottlenose Dolphins per year, or 4,080–7,920 for the six years all told. No reliable information is available on illegal commercial killing of Black Sea Bottlenose Dolphins since the ban on cetacean fisheries in 1983. Isolated cases of deliberate killing and harassment (with pyrotechnic devices and firearms) have been reported in coastal fisheries. For instance, at least two bottlenose dolphins were reportedly shot in Balaklava, Ukraine (S. Popov pers. comm. 2004).
Since the mid 1960s, many hundreds of Bottlenose Dolphins (probably >1,000, not including those that died during capture operations) have been live-captured in the former USSR, Russia, Ukraine and Romania for military, commercial and scientific purposes (Birkun 2002a). The capture operations sometimes cause accidental (but usually unreported) deaths. In recent years, 10–20 animals have been taken annually in May–June from a small area in the Kerch Strait, Russia. During the 1980s–early 2000s the number of facilities for dolphin shows and “swim with dolphins” programmes greatly increased in Black Sea countries. The export of bottlenose dolphins from Russia and Ukraine for permanent and seasonal shows also expanded, for example, to Argentina, Bahrain, Byelorus, Chile, Cyprus, Egypt, Hungary, Iran, Israel, Kuwait, Lithuania, Romania, Saudi Arabia, Syria, Turkey, United Arab Emirates, Vietnam, and former Yugoslavia countries. A few captive animals were exported from Georgia to Yugoslavia and then re-exported to Malta. According to CITES statistics, at least 92 individuals were removed from the Black Sea region during 1990–1999 (Reeves et al. 2003) and Russia reportedly has exported at least 66 for travelling shows since 1997 (Fisher and Reeves 2005).
At present, incidental mortality in fishing gear is probably one of the main threats to T. t. ponticus, although these animals have never been the predominant species in national cetacean bycatch statistics. They constituted no more than 3% of the totals in the reports from Black Sea countries during the 1990s (Birkun 2002b). At least 200–300 Bottlenose Dolphins were estimated as being taken incidentally in Turkish fisheries each year (Öztürk 1999). They are known to be susceptible to capture in a variety of fishing nets, including bottom-set gillnets for turbot (Psetta maeotica), spiny dogfish (Squalus acanthias), sturgeon (Acipenser spp.) and sole (Solea spp.), purse seines for mullet (Mugil spp. and Lisa spp.) and anchovy (Engraulis encrasicolus ponticus), trammel nets and trap nets. However, only bottom-set gillnets are thought to take significant numbers, especially during the turbot fishing season between April and June.
Small-scale coastal fisheries also affect Black Sea Bottenose Dolphins indirectly by depleting their prey populations.Declining trends have been observed in the abundance of indigenous mullets (M. cephalus and Lisa spp.) (Zaitsev and Mamaev 1997). At the same time, the effects of a suspected decrease in cetacean forage resources (Bushuyev 2000) might be offset at least to some extent by the introduced far-east mullet, M. so-iuy, which has become abundant in the northern Black Sea since the 1990s (Zaitsev and Mamaev 1997). In fact, it may be responsible for the relocation of Bottlenose Dolphin groups and the recent marked increases in density along the Crimean coast (see “Abundance”).
According to annual compilations of cetacean stranding records in Crimea (Krivokhizhin and Birkun 1999), there was a prominent peak in T. t. ponticus strandings in 1990 (20 dead animals, representing 44% of all Bottlenose Dolphin strandings reported from 1989–1996). The primary cause and magnitude of that spike in Bottlenose Dolphin mortality remains unclear, although it can be inferred that many more than just 20 animals died. Severe purulent pneumonia was revealed in some cases. The multi-microbial pollution from untreated sewage in coastal waters poses a chronic risk of opportunistic bacterial infections to Bottlenose Dolphins, and there is evidence that they (as well as other Black Sea cetaceans) are exposed to morbillivirus infection (Birkun 2002c). Another ongoing problem (as a potential source of exotic infections and genetic “pollution”) is the poorly managed intentional releases and spontaneous escapes of captive Bottlenose Dolphins and other marine mammals from dolphinaria or oceanaria (e.g., Veit et al. 1997, ACCOBAMS/SC 2005).
The species T. truncatus is listed as Least Concern by IUCN, although the Black Sea population is highlighted as a concern in the IUCN SSC Cetacean Specialist Group's 2002–2010 Conservation Action Plan (Reeves et al. 2003).
Commercial hunting of Black Sea cetaceans, including Bottlenose Dolphins, was banned in 1966 in the former USSR, Bulgaria and Romania, and in 1983 in Turkey. The riparian states assumed international obligations to protect Black Sea cetaceans as contracting parties to the Convention on Biological Diversity (CBD), Convention on the Conservation of Migratory Species of Wild Animals (CMS), Convention on the Conservation of European Wildlife and Natural Habitats (Berne Convention), Convention on the Protection of the Black Sea Against Pollution (Bucharest Convention), Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES, Appendix II), and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS). The 1st Session of the Meeting of the Parties to ACCOBAMS (2002) adopted a resolution to strengthen measures for restricting the deliberate catching, keeping and trade of Black Sea bottlenose dolphins. At the 12th Conference of the Parties to CITES (2002), a quota of zero was established for commercial export of live dolphins wild-captured in the Black Sea. In 2003 the IWC Scientific Committee’s Sub-Committee on Small Cetaceans reviewed the status of Black Sea Bottlenose Dolphins and concluded that this population should be managed for conservation as a distinct entity (IWC 2004).
The Bottlenose Dolphin is included in Annex II of the EC Directive No.92/43/EEC on the conservation of natural habitats of wild fauna and flora. In 1996 the Ministers of Environment of Black Sea countries adopted cetacean conservation and research measures in the framework of the Strategic Action Plan for the Rehabilitation and Protection of the Black Sea (paragraph 62). The Bottlenose Dolphin is included as Data Deficient in the regional Black Sea Red Data Book (1999). However, in 2002 it was listed as Endangered in the Provisional List of Species of Black Sea Importance, an annex to the Black Sea Biodiversity and Landscape Conservation Protocol of the Bucharest Convention. The regional Conservation Plan for Cetaceans in the Black Sea has been drafted in accordance with the ACCOBAMS International Implementation Priorities for 2002–2006 (Notarbartolo di Sciara 2002).
On a national level, Black Sea cetaceans, including Bottlenose Dolphins, are protected by environmental laws, governmental decrees and national Red Data Books. The Bottlenose Dolphin is listed in the Red Data Books of Bulgaria, Georgia, Russia and Ukraine (which do not use the IUCN categories and criteria). In Russia and Ukraine, Red Book inscription means that a species should be monitored and managed by appropriate state/national programmes. Such a programme has existed in Ukraine since 1999 (the Delfin-programme adopted by the Ministry of Environment). Action Plans for the conservation of Black Sea cetaceans were produced in Ukraine (2001) and Romania (2003) but they have no legal effect. The ACCOBAMS Implementation Priorities for 2002-2006 (Notarbartolo di Sciara 2002) envisage the development of a pilot conservation and management project to benefit Bottlenose Dolphins and Harbour Porpoises in the well-defined area between Cape Sarych and Cape Khersones, southern Crimea (Ukraine).
|Citation:||Birkun, A. 2012. Tursiops truncatus ssp. ponticus. The IUCN Red List of Threatened Species 2012: e.T133714A17771698. http://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T133714A17771698.en . Downloaded on 10 October 2015.|
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