Biological aspects, exploitation rates, and spawning potential ratio of scalloped hammerhead shark ( Sphyrna lewini Griffith & Smith, 1834) in Lampung Bay waters, Indonesia

Abstract

The scalloped hammerhead shark is an endangered species that is listed in CITES Appendix II. Information on the biological aspects, exploitation rate, and spawning potential ratio of scalloped hammerhead sharks are very limited, especially in Lampung Bay waters. These data were important to find solutions and the best management to sustain the scalloped hammerhead sharks in Indonesia, especially in Lampung Bay waters. The aim of this study is to investigate the biological aspects, exploitation rates, and spawning potential ratios of scalloped hammerhead sharks in Lampung water. Scalloped hammerhead shark samples were collected from the catch of bottom gillnet in Kalianda Fish Landing Place, Lampung Province. Enumerators collected biometric data (length and weight) of 332 scalloped hammerhead sharks from July to November 2020. Biological aspects include distribution of length, length-weight (L-W) relationships, length at first capture, and length at first maturity. The utilization rate was calculated using the exploitation rate (E) and the estimated SPR based on length data. The results show that the length of scalloped hammerhead sharks ranged from 37.5 to 173.0 cm FL. Most of the samples fish had not spawned yet or were immature (Lc =47.1 cm FL; Lm =89.4 cm FL). The growth pattern of scalloped hammerhead sharks was allometrically negative. Scalloped hammerhead sharks have natural mortality of 0.18/year, while fishing mortality was 1.08/year. The fishing status of scalloped hammerhead sharks in Lampung Bay was fully exploited (E=0.85), and the stocks were in a recruitment overfishing condition. These findings indicate that effective management is required to ensure the sustainability of scalloped hammerhead sharks in Lampung Bay waters, such as adjusting mesh size, fishing season, and avoiding capture in the nursery area.