This is a very abundant species, with many available estimates for the various areas where it occurs. In the Pacific, 2,963,000 (CV=24%) was estimated for the eastern tropical Pacific (Gerrodette and Forcada 2002), and an average of 352.000 (CV = 18%) was estimated for the US west coast based on surveys between 1991 and 2005 (Barlow and Forney in press). Off California, common dolphins show seasonal and inter-annual changes in abundance due to shifts in distribution (Forney and Barlow 1998).

In the Atlantic, abundance in European continental shelf waters was estimated at 63,400 (95%CI=27,000-149,000) in 2005 (SCANS-II project; P. Hammond pers. comm.). Offshore, abundance in a block bounded by 53-57ºN and 18-29ºW was estimated at 273,000 (95%CI=153,000-435,000) in 1995 (Cañadas et al. in press). West of the Bay of Biscay, 62,000 common dolphins were estimated in the fishing grounds of the albacore tuna driftnet fishery in 1993 (Goujon 1996). In the western North Atlantic, 121,000 (CV=0.23) were estimated to occur (Waring et al. 2006).

In the western Mediterranean, abundance has been estimated at 19,400 (95%CI=15,300-22,800) in the northern Alborán Sea between 2000 and 2004 (Cañadas 2006). Once one of the most common species in the Mediterranean Sea, the short-beaked common dolphin has experienced a generalized and major decline during the last 30-40 years (Bearzi et al. 2003). Dramatic negative trends were recorded in portions of the central Mediterranean, particularly in the northern Adriatic Sea and in the eastern Ionian Sea (Bearzi et al. 2004; 2006). Recent genetic studies indicate that population structure within the Mediterranean reflects differences in distribution pattern and habitat use by short-beaked common dolphins in the eastern (where the species is predominantly coastal) and western (where it is predominantly pelagic) portions of the basin (Natoli 2004). Genetic exchange between short-beaked common dolphins from the Mediterranean Sea and the Atlantic Ocean, to the extent that it occurs, appears to involve predominantly animals from the Alborán Sea (Natoli 2004).

The population size in the Black Sea is unknown. Line transect surveys have been conducted recently to estimate common dolphin abundance in a few parts of the range. The survey areas are small relative to the total range of the subspecies. Results suggest that current population size is at least several 10,000s, and possibly 100,000 or more (Birkun 2006). By the mid 1960s, the Black Sea subpopulation collapsed due to long-running overexploitation, and a reduction of 70% was inferred. However, directed takes continued until 1983 when cetacean hunting finally ceased. The population has not recovered (Birkun 2006).

Unknown