Population dynamics of two squid species, <em>Uroteuthis duvaucelii</em> (D'Orbigny, 1835) and <em>U. singhalensis</em> (Ortmann, 1891) (Family: Loliginidae) in the Trincomalee bay, Sri Lanka

In the Trincomalee bay of Sri Lanka, two species squids, Uroteuthis duvaucelii and U. singhalensis, support profitable small-scale fisheries. The present study is an attempt to assess fisheries these squid using length-based stock assessment methodologies. Length frequency data collected from landings species, during fishing season May October 2003 were analyzed FiSAT II software package. asymptotic length (mantle length) growth constant 31.8 cm 0.90 yr-1 respectively singhalensis 31.2 0.72 respectively. Using mortality coefficient estimates based on parameters, exploitation rates (E) period found be 0.55 0.44 Optimal strategies determined by relative yield-per-recruit (Y’/R) analyses squad indicated that sizes first capture (Lc) E at sub-optimal levels. As both are exploited same gear, optimal values predicted Y’/R cannot achieved. This analysis indicates levels having Lc 15.8 for = 14.3 maintained. It therefore concluded effort in do not require adjustments through fishery regulations sustainability their