British sharks in Sicily: Records of long-distance migration of tope shark (Galeorhinus galeus) from the north-eastern Atlantic to the Mediterranean Sea

This study presents data of two adult female tope sharks, Galeorhinus galeus (Linnaeus 1758) that were tagged in the northeast Atlantic and recaptured in the central Mediterranean Sea. The sharks were tagged in Scotland in 2009 and Ireland in 2015 and were recaptured off the south coast of Sicily in 2014 and 2017, respectively. The specimen captured in Scotland was a female with an initial total body length of 175 cm, which grew 37 cm and gained about 10 kg on recapture (5.4 years later, or 1967 days). The specimen captured in Ireland was a pregnant female that grew 14 cm between captures (spanning 248 days), with an estimated age of 15-17 years. The growth rate of the two specimens was 6.8 and 7.8 cm year, respectively. This growth rate was faster than the annual increments previously suggested for adults of this species. Previous tope shark recapture records in the Mediterranean Sea were limited to the Alboran Sea, coast of Valencia, and the coast of Algeria. Thus, the records for the two females in the current study provided the first evidence of long distance entrance of the north-east Atlantic tope shark in the Mediterranean Sea. Genetic data are required to establish the connectivity of the population across the north-east Atlantic and Mediterranean, along with the identification of factors driving the migration of females from the north-east Atlantic to lower latitudes.