Stock assessment and management implications of three lobster species in Gunungkidul waters, Indonesia

Abstract

The high commercial demand of lobsters caused the intensive fishing of three lobster species Panulirus homarus, P. penicillatus and P. longipes in Gunungkidul waters, Indonesia. Proper management strategies were required to maintain the sustainability of lobster stocks. A stock assessment was conducted to develop proper tools for the sustainable management of the stocks under a data-deficient situation. A length-based analysis was employed to estimate population ecological characteristics and biological reference points for the three species of lobsters. The exploitation rates of the three species ranged from 0.72 to 0.79 year−1, which were higher than the optimum rate of 0.5 year−1. The current length at first capture of P. penicillatus was estimated to be much lower than the optimal length at first capture, which indicated a growth overfishing for P. penicillatus. The current percentages of spawning stock biomass ranging from 22% to 35% were lower than their optimal value of 40% spawning stock biomass per recruit, indicating the recruitment overfishing for the three lobster species. It was recommended that the fishing mortality should be reduced to be 33% of the current fishing mortality to avoid recruitment overfishing. The carapace length for P. penicillatus should be limited to 74 mm as the minimum legal size of catch to increase the yield per recruit. Finally, it is necessary to establish a strong monitoring, controlling and surveillance (MCS) system to effectively manage the lobster stocks in Gunungkidul waters.