The driftnet fishery of Santa Catarina State targeting hammerhead sharks, Sphyrna lewini (Griffith & Smith 1834) and Sphyrna zygaena (Linnaeus 1758).

Abstract

From May, 2005 to October, 2006, the gillnet fleet in Santa Catarina was composed of 245 boats. From these, 194 landed in Itajaí, Navegantes and Porto Belo; 21 in Laguna; and 30 in Passo de Torres. Driftnet activity is higher between Spring and Autumn. The average net height was 18 m (n = 16; s = 7 m), net length 5222 m (n = 16; s = 1929 m) and mesh size 32,8 cm (n = 17; s = 9,3 cm). The average total length of the scalloped hammerheads landed was 171,8 cm (n = 717; s = 43,3 cm), median = 170 cm and there were high quantities of big juveniles landed. Sex-ratio was higher for males (72 %). ANCOVA models showed an average catch decline between 2000 and 2005. The catches increased from winter to autumn. Reference points were established for the sustainable management and conservation of S.lewini: (1) 30 % annual reduction on driftnet dimensions until reaching the size limits of 2500 m length and 10 m high; (2) Closure season from november to march; (3) Closure areas (< 20 m depth) to protect pupping grounds; (4) Mesh-size limit of 40 cm (between knots, stretched); (5) 200 cm as the minimum catch size for the scalloped hammerhead shark.