Determination of population parameters and stock assessment of european anchovy (Engraulis encrasicolus) in south-eastern Black Sea

SUMMARY Determination of Population Parameters and Stock Assessment of European Anchovy (Engraulis encrasicolus) in South-eastern Black Sea This study was conducted during 1996/97 and 1997/98 anchovy fishing seasons in South-eastern Black Sea (Fatsa-Hopa) and aimed collecting basic data on population parameters and developing stock management strategies of European anchovy {Engraulis encrasicolus). Mean length and weight values were 10.12 and 10.81 cm, and 6.69 and 7.89 g in 1996/97 and 1997/98 fishing season, respectively. Numbers of females in population seems to higher than those of males. Mean growth rates were estimated as 18% and 17% (length), and 63% and 58% (weight) during the first and second seasons, while the mean condition factor remained at 0.59 during the both seasons. Length-weight, age-length and age- weight relationship equations of the population are follow: W=0.0073L290; Lt = 17.00(1 -e^10^2160*);^ = 27.23(1 - ^«k^m»)"» m 1990/97 ^d W=0.0055L303; 4 = 15.57(1 -e^417^1^));^ =22.42(1 -^.4,7(t+I^))3027 in 1997/98. Data shows that mean survival rates (S) for 1996/97 and 1997/98 seasons were 19% and 14%, while total instantaneous, fishing and natural mortality rates were; Z=1.67, F=1.10 and M=0.56, and Z=2.07, F=1.40 and M=0.67 respectively. Fishing rates (E) on the population for the study periods have been estimated as 0.66 and 0.68. According to length based cohort analysis results size of the population has been assessed as 326 thousands tons in 1996/97 and 252 thousands tons. Catch for per unit fishing effort seemed to high for small and medium size vessels and the catch for per unit effort during 1996/97 fishing season was higher than that of the following season. Beverton-Holt's yield for per recruitment (Y/R) and Thompson-Bell approaches indicates that fishing rates were insufficient during both seasons and it seems to possible to reach MSE level with smaller F than actual fishing pressure. Therefore, it appears quite possible that well programmed fishing and rational utilisation of the fishing power may reduce catch, increase fishermen's income and sustain the anchovy fisheries in this area. Key Words: Anchovy, Engraulis encrasicolus, Black Sea, Population Parameters, Cohort Analysis, Bhattacharya, Beverton-Holt, Thompson-Bell Models VI