مرکز منطقه ای اطلاع رساني علوم و فناوري - Evaluation of anchovy (Engraulis encrasicolus) population dynamics studies (1985-2015) in terms of fisheries management in the Black Sea

Abstract :

In this study, the result on population dynamics of European anchovy (Engraulis encrasicolus) were evaluated from the present to the past 30 years in the Black Sea and is intended to contribute to the creation of the Black Sea anchovy fishery management system. In studies presented catch composition, growth parameters, the average length values in ages, the mean length values in general, mortality rates and exploration rates were evaluated in the fishing seasons and five-years periods. 0 years of age composition of individuals not reached sexual maturity was estimated as 27.4 ± 3.6% (n = 26 studies), and this ratio was calculated as 32.7±9.04% for 1985 – 1990 period (n = 7 studies), 39.6±7.76% for 1990 – 1995 (n = 5 studies), 24.2±3.56% for 1995 – 2000 (n = 7 studies), 14.5±4.55% for 2000 – 2005 (n = 5 studies) and 22.1±21.1% for 2005 – 2010 (n = 2 studies). Zero-year-old age composition was not significantly difference in the five-years periods (one-way ANOVA; P 0.05). The von Bertalanffy growth function (VBGF) parameters; asymptotic length (L∞) values were ranged between 14.1 – 23.5 cm (mean: 17.0±0.38 cm) and brody growth coefficient (K) values were ranged between 0.139 – 0920 year-1 (mean: 0.331 ±0.031 year-1). The VBGF was calculated as Lt = 17.0±0.4(1 – e-0.331±0.031(t+2.344±0.233) (n = 26 studies). A relationship between L∞ and K values was calculated as K = 1105.3L∞-2.8958 (r2 = 0.6224, n = 26). The relationship between natural mortality ratio (M) and K values was determined as M = 0.7171K0.3073 (r2 = 0.2982; n = 26). Regression coefficients of this equations were found to be statistically different from zero (P 0.05). Anchovy grew quickly reach at 1 age of 60-70% in the value of L∞ and Lmaximum length values. The instantaneous mortality ratio (Z) of anchovy was designated by fishing mortality ratio (F). The exploration ratio (E) consistently show an increase from 1985 – 1990 period to 2000 – 2005 period and it was determined as above the optimum value (E 0.5; F M). It has been proposed the creation of the Black Sea anchovy fishery management system for sustainable anchovy fisheries in the Black sea.