The vaquita is known to occur only in the northern Gulf of California, Mexico, mainly north of 30º45'N and west of 114º20'W (Gerrodette et al. 1995). The so-called ?core area? consists of about 2,500 km² centred at Rocas Consag, some 40 km northeast of the town of San Felipe, Baja California. This core area straddles the southern boundary of the Upper Gulf of California and California River Delta Biosphere Reserve. There is no evidence to indicate that the vaquita?s overall range has changed in historic times.

Endemic to upper quarter of Gulf of California, extent of occurrence (EOO) >2,000 km², area of occupancy (AOO) (core area) approx. 2,000 km².