A preliminary study on age and growth of the blue shark (Prionace glauca) in the North Atlantic Ocean

Abstract:

The blue shark Prionace glauca, is broadly distributed in temperate and tropical waters of the Atlantic Ocean, and is the main by catch species in tuna long line fishery. A total of 524 (328 males, 196 females) blue sharks were sampled from Chinese tuna long line fisheries in the North Atlantic Ocean(48° to 52°N/15° to 34°W , 3° to 15°N/34° to 40°W) from October 2010 to March 2011. Whole vertebrae of 51 males (104-256 cm) and 52 females (135-211 cm) were used to age for blue shark. Based such information from these samples, the age growth of blue shark was analyzed in this study. The results showed that the relationship between fork length and vertebral radius for both sexes was as follows: LF=192.8 Rv=0.837(n=117，R²=0.91). Males were aged to 11 years (256 cm) and females were 7 years (211 cm). The index of average percentage error (IAPE) ranged from 0-3.58% for 1-11 years. Parameters derived from observed length at age data for males and females were best to describe the growth of the blue shark. The von Bertalanffy growth parameters were:L∞=289.4 cm, k=0.16, t0=-1.61 for males, and L∞=308.3 cm, k=0.13,t0=-1.77 for females; differences in growth were found between sexes. The longevity for males and females were 21.3a and 17.1a, respectively.