(Delphinus delphis ponticus)

Conservation status:
In Bulgaria: Biological Diversity Act – Appendix III; International: IUCN Red list – VU (Vulnerable); Bern Convention – Appendix II; CITES – Appendix II; The Habitats Directive 92/43/EEC – Appendix IV.
The subspecies D. d. ponticus is suggested on the base of  morphological characteristics, later on criticized as insufficient. However, the comparative analyses using skull morphometric measurements and DNA analyses suggest that some diversity exists between the Black Sea and the Mediterranean common dolphins. Up to now it could not be defined with certainty, but it seems that the genetic exchange between the Black Sea and the Mediterranean Sea is rare or almost none. Therefore the subspecies is recognized at this stage.
 
Distribution:
Practically, it is found in all the oceans and seas of the tropics. The distribution area of the Black Sea common dolphins covers almost the entire Black Sea, including the territorial waters and the exclusive economic zones of Bulgaria, Georgia, Romania, Rusia, Turkey and Ukraine, as well as the internal sea waters of Ukraine at Karkinitsky Bay and Turkey, including Bosphorus and Marmara Sea, although for the last two a taxonomic survey and genetic research are needed to confirm that they belong to the Black Sea subspecies. The common dolphins are not found in the Sea of Azov and generally avoid the Kerch Strait, although a single live stranding was recorded there in 1994 during the morbillivirus epizootic. There is no reliable information on the presence of the species in the Dardanelles that connects Marmara and Aegean Sea, as there are no reliable evidences of migrations of common dolphins across the Turkish straits.
 
Population:
Total size of the population in the Black Sea is unknown. It is generally recognized that during the first two-thirds of the 20^th century the numbers of the common dolphins in the Black Sea have been much higher than those of the Black Sea bottlenose dolphins (Tursiops truncatus ponticus) and the harbour porpoises (Phocoena phocoena relicta). The estimates of the population size based on line transect surveys in some parts of the Black Sea suggest that the present size of the population is at least several tens of thousands of individuals as it is possible to reach over 100 000 individuals.
 
Biology and ecology:
The body is elongated, torpedo-shaped. The rostrum (the beak) is clearly distinctive. The dorsal fin is big, triangular, tipped and slightly arched backwards. The coloring of the body is dark grey to black on top, whitish underneath, with light grey, yellowish or white patch on both sides in the form of horizontally hourglass or infinite sign. In his mouth the dolphin has numerous sharp teeth. Their number is 80-120 on the lower and upper jaw. The form is conic as with the bottlenose dolphin, but differs from it in the smaller size and much larger number.
It is found mainly in open water, but sometimes it also enters the coastal waters following the seasonal gatherings and mass migrations of the small pelagic fish species. The Black Sea subspecies is the smallest representative of the species worldwide: the average length is 1,5-1,7 m (maximum 2,0 m) for the adult females and 1,7-1,8 m (maximum 2,2 m) for the adult males. The weight is 50-55 kg, maximum 100 kg. Females reach sexual maturity at the age of 2-4 years, while males at 3-4 years.
The average life span is 20-22 years, with possibility to reach even more (25-30 years). The breeding season usually is in the late autumn or early spring as reaches its peak in July-August. The annual share of pregnant females is calculated on 46-75%, depending on the length of the interval between births, which is 1,3-2,3 years. The pregnancy lasts 10-11 months, giving birth to one infant. The lactation period lasts 14-19 months, but the infants feed on mother’s milk only during the first 5-6 months of their life.
The preferred food consists of small pelagic fish forms large shoals – anchovy (Engraulis encrasicolus ponticus) and sprat (Sprattus sprattus). 11 species of fish in total are registered in the food spectrum: pipefishes (Syngnathidae spp.), whiting (Merlangius merlangus euxinus), mullets (Liza spp.), red mullet (Mullus barbatus ponticus), bonito (Sarda sarda), shad (Alosa spp.), bluefish (Pomatomus saltatrix), scad (Trachurus spp.), garfish (Belone belone), mackerel (Scomber scombrus), wrasses (Labridae spp.), blennies (Blennidae spp.). The daily consumption is about 4-10 kg.
 
Threats:
There are two pathogens known to be the reason for mass mortality resulting in limitation of the population: the lung nematode (Skrjabinalius cryptocephalus) and unidentified morbillivirus. An epidemic, caused by morbillivirus is registered in July-September 1994, going along with washed ashore diseased individuals. Another reason for the decrease of the population is reduction of the food resource, caused by fishing and by the introduced species ctenophore Mnemiopsis leidyi.