An investigation of age, growth and mortality of the red mullet Mullus barbatus Linnaeus, 1758 in the western Black Sea

Abstract

The aim of this study was to determine the age, growth, length-weight relationship, sex ratio and fishing mortality rates of the red mullet off the western Black Sea coast of Turkey. Age, growth and mortality parameters were estimated for the red mullet, M. barbatus, sampled from commercial landings for the demersal trawl fishery in the western Black Sea between October 2012 and April 2014. The age of 1426 individuals was determined using the sagittal otolith reading technique. The total length ranged from 6.3 to 18.9 cm, while weight varied between 3.62 and 62.42 g for 4928 red mullet individuals (1829 males, 1986 females and 1113 unidentified). 3815 individuals were found mature while 1113 individuals as immature. The length-weight relationship for all individuals was calculated as W = 0.0109 x L-2.9886. M. barbatus has a life-span of 4 years, but over 60% of fish were less than 3 years old. The growth parameters were k = 0.17 yr(-1), L-8 = 24.1 cm, and to = -1.98 years for pooled data. According to age-structured analysis, the total, natural and fishing mortalities were Z = 1.32 year(-1), M = 0.45 year(-1) and F = 0.86 year(-1), respectively. The exploitation rate, E = 0.65, suggests a high fishing pressure on the red mullet stock in the studied area.