Population characteristics and stock assessment of European anchovy (Engraulis encrasicolus L., 1758) in coastal waters of the south-eastern Black Sea of Turkey

Abstract

This study was carried out throughout 10 fishing seasons between 2002 and 2018 to monitor the population and stock variations of Engraulis encrasicolus (L., 1758) on the south-eastern Black Sea coast of Turkey. Asymptotic length (L-infinity), growth constant (K) and growth performance indexes (phi) were calculated to be between 12.86 and 15.79 cm, 0.69 and 0.99, 2.10 and 2.29, respectively. Theoretical birth ages were determined to range between (t(o)) -0.15 and -0.27, the maximum ages (t(max)) ranged between 3.03 and 4.35, total mortality rates (Z) between 2.19 and 2.66, natural mortality rates (M) between 0.93 and 1.26, the fishing mortality rate (F) between 0.93 and 1.47, and the optimum fishing mortality rate (F-opt.) between 0.37 and 0.62. Fishing mortality rates (F) were estimated to be higher than the optimum fishing mortality rates (F-opt). Z/K ratios were determined to range between 1.91 and 3.43. Current exploitation rates (E-curr.) were calculated to range between 0.42 and 0.62. The first recruit lengths (L-r) and first capture lengths (Lc(50)) were estimated to range between from 5.25-7.75 and from 7.66-8.74 cm, respectively. The first maturity lengths (Lm(50)) of E. encrasicolus ranged between 8.57 and 10.53 cm. The maximum sustainable exploitation levels (E-max) were determined to range between 0.72 and 0.83. These data indicate that if current levels of fishing pressure continue, anchovy stocks will collapse in the near future.