Population dynamics of Parastromateus niger in Kuwaiti waters as assessed using length?frequency analysis

Abstract

The population dynamics of the black pomfret, Parastromateus niger, sampled from commercial gill-net catches from Kuwaiti waters of the Arabian Gulf, were investigated from October 2003 to September 2005. Length-based stock assessment using the FiSAT software package showed an asymptotic length of 65 cm TL and growth curvature of 0.34 year−1. Raw data as well as that corrected for probability of capture indicated a recruitment from February to September. The total mortality coefficient was estimated to be 1.20, a natural mortality of 0.68 and fishing mortality of 0.52. The selectivity model based on the running average showed that 25% of 14.0 cm TL fish, 50% of specimens reaching 16.3 cm TL, and 75% of all specimens of 20.2 cm TL encountering the gear were retained. Relative yield-per-recruit analyses revealed a current exploitation rate of 0.43; this is below the maximum sustainable yield index, indicating for sustainable fishery of P. niger that the exploitation rate could be increased to 0.6, provided size of the fish at first capture, i.e. the legal size, is also increased to 32.5 cm TL. These results suggest that P. niger stocks in Kuwaiti waters, contrary to existing views, are moderately exploited. This conclusion, however, is critically dependent on the estimate of natural mortality, which requires further confirmation.