DISTRIBUTION AND NUMBERS OF STRIPED DOLPHINS IN THE WESTERN MEDITERRANEAN-SEA AFTER THE 1990 EPIZOOTIC OUTBREAK

A survey was conducted in the summer of 1991 in the western Mediterran ean to map the distribution and to estimate the number of striped dolp hins surviving the 1990 outbreak of the morbillivirus epizootic. The h ighest densities of striped dolphins were found in the Alboran Sea and the Ligurian Sea. Total numbers were estimated at 117,880 (SE: 38,962 ; 95% CI: 68,379-214,800). The mortality resulting from the epizootic is unknown but may have been severe because the mean size of dolphin s chools observed during the epizootic outbreak was significantly smalle r than that before the event. A return to larger school sizes after th e 1990 outbreak is not evidence of a recovery but can be viewed as a r egrouping of individuals into schools of a preferred size. Calves were observed in 24.6% of the schools. They were not seen in schools of te n or less but were present in about half the schools of 30 or more dol phins, a result which suggests segregation similar to that seen in pop ulations of this species elsewhere in the world.