Given their sheer number, assessing all geographic populations of cetaceans (sub-populations, in Red List-speak) is a long-term challenge; only a small fraction have been assessed, with priority given to those suspected of being in the most trouble. Two regions where relatively good progress has been made in recent years are the Mediterranean and Black Seas thanks to a joint effort by ACCOBAMS (the CMS Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea, and Contiguous Atlantic Area) and the Cetacean Specialist Group.
The first subpopulation in the region to have been assessed formally under the modern quantitative Red List categories and criteria was the Mediterranean short-beaked common dolphin, Delphinus delphis, which was redlisted in 2003 as Endangered (A2abc). The assessment was drafted by Giovanni Bearzi, who had become especially motivated when he witnessed the almost complete disappearance of the species from one of his study areas, off western Greece, likely as a result of prey depletion due to overfishing.
In 2008, the assessment produced by Alexei Birkun, Jr. and Alexandros Frantzis of Black Sea harbour porpoises, Phocoena phocoena relicta, was finalised. This subspecies is found in the Black Sea and also occurs in the Marmara Sea and in portions of the Aegean Sea, well inside the Mediterranean. Harbour porpoises in the Black Sea were subjected to very large legal direct takes until 1983, and to continued illegal hunting until at least 1991. They still suffer from extensive incidental mortality in bottom-set gillnets. This history of heavy exploitation, together with ongoing threats, led the subspecies to be redlisted as Endangered (A1d+4cde).
In 2012, several additional Mediterranean sub-population assessments were published, namely:
- sperm whales, Physeter macrocephalus, listed as Endangered (C2a(ii)), assessed by Giuseppe Notarbartolo di Sciara, Alexandros Frantzis, Giovanni Bearzi and Randall R. Reeves;
- fin whales, Balaenoptera physalus, listed as Vulnerable (C2a(ii)), assessed by Simone Panigada and Giuseppe Notarbartolo di Sciara;
- striped dolphins, Stenella coeruleoalba, listed as Vulnerable (A2bcde), assessed by Alex Aguilar and StefaniaGaspari;
- common bottlenose dolphins, Tursiops truncatus, listed as Vulnerable (A2cde), assessed by Giovanni Bearzi, Caterina Fortuna, and Randall R. Reeves;
- Cuvier’s beaked whales, Ziphius cavirostris, listed as Data Deficient, assessed by Ana Cañadas;
- long-finned pilot whales Globicephala melas, listed as Data Deficient, assessed by Ana Cañadas; and
- Risso’s dolphins Grampus griseus, listed as Data Deficient, assessed by Stefania Gaspari and Ana Natoli.
Assessment of the Gibraltar subpopulation of Orcinus orca is not yet completed.