Mortality and Recruitment of the West African Fiddler Crab (Uca tangeri) inMbo River of AkwaIbom State, Nigeria

Abstract

Studies on the mortality and recruitment pattern of the crab Ucatangeriin Mbo river of AkwaIbom State, Nigeria, was conducted for 12 consecutive months (April, 2012 – March, 2013). Length-frequency data was analyzed using FISAT software. Using the Shepherd’s method, asymptotic length (L?) was 3.99cm, while the Von Bertalanffy Growth Function(VBGF)  K was 0.10. Meanwhile, Powell-Wetheral plot estimated asymptotic  length (L?) was 3.58cm and Z/K was 0.72yr^-1. The natural mortality(M) ofUcatangeriwas 0.71yr^-1. However, using length-converted catch curve, total mortality (Z) was estimated to be 0.27yr^-1. The instantaneous fishing mortality (F) was calculated to be -0.44yr^-1, indicating that it was not a highly fished species.

Keywords: Mortality, Recruitment and Crab.