Population assessment of the conch Strombus galeatus (Gastropoda, Strombidae) in Pacific Panamá

Abstract

Populations of Strombus galeatus Swainson 1823 have been severely overfished in pacific Panama. In this study, we assessed the status) of the S. galeatus population in Las Perlas and Coiba Archipelagos. Average densities per site were dismal: 0.45 +/- 3.8 ind.ha(-1) and 6.0 +/- 18 ind.ha(-1) in Las Perlas and Coiba, respectively. In Las Perlas, low densities occurred on the southwest coast of Del Rev, the south coast of Chaperas, and Bolanos, whereas intermediate densities were found on the eastern coast of Saboga. In Coiba, high relative densities occurred only on the west coast of Coiba Island and at the north and south of Bahia Damas. Environmental variability and depth did not explain the differences found between densities nor the low abundances in the archipelagos. Shell length of S. galeatus from Coiba ranged from 91.0-213.3 mm (156 +/- 22.2 mm). We fitted a von Bertalanffy growth model to juvenile date using the following parameters: L-infinity = 315 mm, K = 0.029 mo(-1), and t(o) = 0.5 mo. The model suggests that 27-28 mo arc required (on average) before the outer lip begins to form. Two years after the enactment of Decree No. 159 in September 2004, which banned the Strombus fisheries in Panama for five years, the conch populations in Las Perlas and Coiba have not recovered. The Las Perlas population is recruitment limited and we recommend that a program of law enforcement and monitoring should be implemented immediately to protect this species, conducive to increase spawning and settlement in nursery grounds.