Biology aspect and parameter population the scalloped hammerhead (Sphyrna lewini Griffith & Smith, 1834) caught from coastal fisheries in the eastern Indian Ocean

Abstract

The scalloped hammerhead, Sphyrna lewini, have a circumglobally distribution in tropical and warm-temperate waters. Generally, in Indian ocean this species is a bycatch of the tuna longline, however, in Tanjung Luar, this species is a target species. The life history from this species is still limited. The study aimed to assess the biology aspect and growth of the scalloped hammerhead in the period February 2013 to December 2016. The result showed that 2449 individuals were caught with size between 43-395 cm TL (average 198,03 cm) for females and males ranged between 47-340 cm TL (average 161.61 cmTL). The sex ratio that was dominated by female sharks was 2.69: 1. The clasper length and total length relationship were positive with a linear regression equation of CL = 0.0902*TL-4.4402 (R2=0.6837). It showed that the length of the claspers increases proportionally with the length of the body. Application of age at length data for produced von Bertalanffy growth model parameter estimates of female L∞ = 397 cm TL, K = 0.27 year−1, for male S. lewini was L∞ = 381 cm TL, K = 0.17/ year. The total mortality rate (Z) the scalloped hammerhead was 1.15/ years, natural mortality (M) is 037/ years and the fishing mortality (F) was 0.78/ years with exploitation rate (E) = 0.68