Preliminary observations on abnormal abundance of Cetorhinus maximus (Gunnerus, 1765) in the central and northern Adriatic Sea

During 2000 and in the first months of 2001, numerous records of Cetorhinus maximus (Gunnerus, 1765) were made in the Central and Northern Adriatic Sea along the Italian, Croatian and Slovenian coasts. The collected records include 1) sightings of a single specimen and small groups; 2) reports on some accidental captures. The number of records collected in the last two years has highly increased in relation to the records made of basking sharks in previous years, due to which some considerations on the apparent migratory movement in the Adriatic and comparisons with the data concerning the Tyrrhenian Sea are presented. Some hypotheses about the causes of the unusual basking shark abundance in the area are also presented.