Stock assessment and management strategies for shark fisheries in the Arafura Sea: A length-based analysis of Carcharhinus sealei

Abstract

Increased demand for the production of sharks in the Arafura Sea can lead to the overfishing condition, which resulted in the depletion of fish stocks. Effective management measures are crucial to ensure the sustainability of shark fisheries. The objectives of this study were to investigate the stock status and to recommend some management strategies for shark fisheries in the Arafura Sea. Length frequency data and some life history parameters were used to perform a length-based stock assessment of Carcharhinus sealei in the Arafura Sea. C. sealei has an asymptotic length of 102.25 cm with a growth constant of 0.36 year⁻¹. C. sealei has been exploited heavily, which was indicated by the current fishing mortality (F_cur = 1.2 year⁻¹), which was much higher than its natural mortality (M = 0.29 year⁻¹) and the optimal fishing mortality (F_40%=0.49 year⁻¹). This study revealed that the high fishing pressure of sharks has resulted in the stock overfished condition for C. sealei in the Arafura Sea, with the current spawning potential ratio (SPR_cur = 0.23) less than the reference point 40% SPR. The low selectivity of drift gillnet (current Lc₅₀ = 66 cm) caused the low spawning stock biomass of C. sealei. The stock rebuilding strategy would be required to increase the spawning stock biomass of C. sealei. A minimum legal size of 77 cm, a marine protected area, and effort controls were some management strategies that can be adopted for the sustainability of shark fisheries in the Arafura Sea.