Age, growth and mortality of Indian mackerel Rastrelliger kanagurta (Teleostei: Scombridae) in the Egyptian Red Sea coast

Abstract

An increased understanding of fisheries target species population dynamics is a key requirement for successful management. Age, growth, and mortality of Indian mackerel, Rastrelliger kanagurta were estimated based on samples collected from commercial purse seine fishery in the Egyptian Red Sea between October 2019 and September 2020. The age estimates were based on two readers to increase the accuracy of results.  The age estimates, in the period of study, were observed at a maximum age for both sexes at 4 years old and the most sampled occurrences in the second years (2 years old). The von Bertalanffy growth function was estimated for males at L ∞= 343.83 -0.447 (t+0.474) ; for females at L ∞= 367.37 -0.357 (t+0.767) and combined at L ∞= 353.78 -0.406 (t+0.595) . The mortality rate was determined at 1.35, 1.32 and 1.37 year -1 and exploitation ratio at 0.417, 0.511 and 0.492 year -1 for males, females and combined receptively. The length at first maturity (L 50 ) was estimated at 206.9, 208.26 and 207.48 mm for males, females and combined receptively. The updated estimates of these biological parameters, by this study, indicate that R. kanagurta population is more vulnerable to fisheries exploitation than before.