Age and growth of the blue shark (Prionace glauca) in the North Atlantic Ocean*

The blue shark (Prionace glauca) is a large pelagic carcharhinid that is widely distributed in the world’s oceans. Throughout its range, it is considered the most abundant species of large shark (McKenzie and Tibbo, 1964; Casey, 1982). In the Atlantic, the blue shark is distributed from Newfoundland to Argentina in the west and Norway to South Africa, including the Mediterranean, in the east (Compagno, 1984). There is strong evidence from tagging data and catch records that blue sharks in the North Atlantic constitute a single stock (Kohler et al., 2002). Moreover, mitochondrial DNA d-loop sequence and nuclear microsatellite analyses indicate no differences between blue sharks from the eastern and western North Atlantic (Shivji1). Distribution and movements of the blue shark are strongly influenced by seasonal variations in water temperature, reproductive condition, and availability of prey (Kohler et al., 2002). Blue sharks make frequent trans-Atlantic movements between the western and eastern regions, utilizing the major North Atlantic current systems (Stevens, 1976, 1990; Casey, 1982, 1985; Kohler et al., 2002). Temporal and geographic patterns of size and sexual segregation have been described for this species, and mating areas and pupping areas are reported to be in the western and eastern regions of the North Atlantic, respectively (Casey, 1982; Kohler et al., 2002). Pregnant females are rare in the western North Atlantic, which is dominated by juveniles of both sexes, Age and growth of the blue shark (Prionace glauca) in the North Atlantic Ocean*