Common dolphin Delphinus delphis ponticus
Vulnerable · VU
Image: Sgt. Brandon Anderson, source, Public domain
The most numerous of the three. IUCN page
Three mammals, one sea
Three mammals live in the Black Sea. The seal is gone
A common dolphin, a bottlenose dolphin and a harbour porpoise — about 225,000 of them all, by the 2019 aerial count. In the early 1970s, hunting killed over a hundred thousand a year. Meet all three, measured and counted.
Meet the threeGuess first
How many mammals live in the Black Sea?
A whole sea, with fish, birds and tourists. Pick one before you read on.
Three. The fourth, the monk seal, has not been seen since 1996.
The Black Sea holds the common dolphin, the bottlenose dolphin and the harbour porpoise, each a subspecies found nowhere else. The monk seal lived here too: the last Bulgarian animal was seen alive on the beach in December 1996.
The three
Counted and measured
Pick what the bars show. The numbers come from the summer 2019 aerial count; the lengths are the largest animal of each species measured on Bulgaria's shore between 2010 and 2022.
The bars show at least this many: plenty escape the plane.
The bars show the largest animal measured on shore, not the species' maximum length.
Bottlenose dolphin Tursiops truncatus ponticus
Endangered · EN
The largest and rarest of the three. IUCN page
Harbour porpoise Phocoena phocoena relicta
Endangered · EN
Image: National Park Service, source, Public domain
The smallest, closest to shore: it stays on the shelf, near the coast. IUCN page
The planes flew 7,324 km over 15 good days, between 19 June and 4 July 2019, and logged 1,744 sightings. The estimates were never corrected for missed animals, so the true numbers run higher.
The hunt
Millions killed, hundreds of thousands today
For decades, Black Sea dolphins were hunted for meat and oil. The common dolphin nearly vanished.
The Soviet Union, Romania, Bulgaria and Georgia banned hunting in 1966, Turkey only in 1983. The exact number is unknown: the Soviets killed over one and a half million dolphins, the other states probably over four million.
Turkey alone killed up to 176,000 animals a year, more than half of them porpoises. At least 840,000 common dolphins were killed between 1946 and 1983, and their population fell by about 70% in three generations.
Deliberate killing is now banned everywhere, but dolphins still die in fishing nets, above all in bottom-set gillnets.
Killed in the 20th century, at least 5.5 million
Alive in the summer of 2019, at least 224,811
The two bars do not subtract: one adds up decades, the other shows one summer.
How many dolphins and porpoises did hunting kill in the 20th century?
At least 5.5 million.
Over one and a half million by the Soviets, over four million by the other coastal states. The exact figures will never be known: many catches went unrecorded.
What the shore brings
Strandings: the few that show
Of the dolphins that die, a small share reaches the shore: sometimes barely 8%. Here is what turned up on Romania's and Bulgaria's shores.
Romania's shore, 2010–2012
20102/5/38 · 45
20113/5/80 · 88
201210/7/160 · 177
Number order: common / bottlenose / porpoise · year total.
The Romanian count stopped in 2012: 45, 88 and 177 strandings, almost all porpoises.
Bulgaria's shore, 2010–2022
Porpoise1,031
Bottlenose199
Common97
Delphinid19
Unidentified182
1,528 strandings in 13 years: 1,031 porpoises, 199 bottlenose dolphins, 97 common dolphins.
The Bulgarian peaks came in 2016 and 2022. The first was made of porpoise calves dying in unusual numbers, probably of disease; the second fell with the start of the war, with unusually many live strandings. What caused the May–June 2022 wave was never settled.
On the Romanian shore, 310 stranded dolphins were found from 2010 to 2012. The sum comes from the report's tables: its prose mixes up the yearly percents, so the page set them aside.
Game
True or false?
Eight statements about Black Sea dolphins. Some sound like stories and are true.
The eight statements and their answers:
- True. Three marine mammals live in the Black Sea. The common dolphin, the bottlenose dolphin and the harbour porpoise, each a subspecies found nowhere else. Paiu et al. 2024, Frontiers in Marine Science
- False. The monk seal still lives in the Black Sea. The last Bulgarian animal was seen alive on the beach in December 1996. Nobody has seen one since. Boev 2018, Lynx
- True. The aerial count found more than 100,000 common dolphins. 108,283 common dolphins, 93,808 porpoises and 22,720 bottlenose dolphins, in the summer of 2019. Paiu et al. 2024, Frontiers in Marine Science
- False. The count caught every dolphin. The numbers are uncorrected underestimates: animals under water or missed by observers stay out of the count. Paiu et al. 2024, Frontiers in Marine Science
- True. Twentieth-century hunting killed millions of dolphins. Over one and a half million by the Soviets and probably over four million by the other coastal states. OceanCare 2023, after Birkun et al. 1992
- True. The porpoise and the bottlenose dolphin are endangered. Both subspecies are listed Endangered by the IUCN; the common dolphin is Vulnerable. IUCN 2012, Mediterranean and Black Sea volume
- False. Most dolphins stranded in Bulgaria were common dolphins. Of 1,528 strandings, 1,031 were porpoises, 199 bottlenose dolphins and only 97 common dolphins. Popov et al. 2024, Oceans
- True. Few dead dolphins ever reach the shore. The share of the dead that reaches the shoreline can be as low as 8%. What you see on the beach is the tip of the iceberg. Popov et al. 2024, Oceans
What the sources cannot say
Where the measurements end
The sums above run on the 2019 count and on studies read in full. Here is where they may go wrong:
The numbers are floors, not totals.
The plane misses animals under water and ones the observers skip. All three estimates are uncorrected underestimates.
The lengths are shore records.
The bars show the largest animal of each species measured on Bulgaria's shore, not the species' maximum length. For adult maxima no good source turned up.
Romania's shore has been silent since 2012.
The last public count of Romanian strandings is the 2012 one. What happened since, nobody knows from open data.
The 2022 wave has no total.
The all-sea 2022 stranding total lives in a conference abstract that could not be found freely. The page uses only what open studies state.
The Romanian report's percents are tangled.
The Mare Nostrum report's prose fits the 2010 percents to the 2011 table and back. The page uses the table numbers, which add up correctly.
Sources
How we know all this
The numbers come from the summer 2019 ASI/CeNoBS aerial count, published in 2024: three uncorrected underestimates. The 2021 report gives the method, the coverage and the comparison with the 2013 north-western basin count.
Who the three are comes from the 2012 IUCN volume: endemic subspecies, the Vulnerable and Endangered categories, the common-dolphin slaughter and today's nets. The twentieth-century hunt comes from the 2023 OceanCare chapter, the 2006 workshop report and the PNAS genetics study.
Strandings come from the 13-year Bulgarian study and the 2010–2012 Mare Nostrum report. The seal comes from the Lynx paper: the last animal, 8 December 1996.
The count
- Paiu, R.-M., Cañadas, A., et al. (2024). Density and abundance estimates of cetaceans in the Black Sea through aerial surveys (ASI/CeNoBS). Frontiers in Marine Science 11:1248950. full text — 108,283 common, 22,720 bottlenose, 93,808 porpoises — underestimates
- ACCOBAMS (2021). Estimates of abundance and distribution of cetaceans in the Black Sea from 2019 surveys (CeNoBS report). free report — the method, the coverage and the 2013 comparison
Who they are
- IUCN (2012). Marine mammals and reptiles of the Mediterranean and Black Seas (Red List volume). free volume — the VU/EN/EN categories, the endemic subspecies, the common-dolphin slaughter
- Reeves, R. R., Notarbartolo di Sciara, G. (2006). Red List Assessment of Cetaceans in the ACCOBAMS Area (workshop report). free report — at least 840,000 common dolphins killed, the 70% decline, the 1994 morbillivirus
The hunt
- OceanCare (2023). Under Pressure, chapter 5: whaling in Europe. free chapter — over 1.5 + 4 million killed, the 1966 and 1983 bans
- Fontaine, M. C., et al. (2012). History of expansion and anthropogenic collapse in a top marine predator of the Black Sea. PNAS 109. full text — up to 176,000 animals a year killed by Turkey
The shore
- Popov, D., et al. (2024). Cetacean Strandings along the Bulgarian Coast in 2010–2022. Oceans 5. full text — 1,528 strandings, the 2016 and 2022 peaks, the shore lengths
- Mare Nostrum NGO (~2013). Final report on Black Sea cetaceans (ACCOBAMS project). free report — 45, 88 and 177 strandings on Romania's shore, 2010–2012
- Boev, Z. (2018). The monk seal along the Bulgarian Black Sea coast. Lynx 49. full text — the last animal: 8 December 1996