Length Based Growth Estimates and Reproduction Biology of Whiting, Merlangius merlangus euxinus (Nordman, 1840) in the Southeast Black Sea

Growth pattern and reproductive biology of whiting, Merlangius merlangus euxinus were studied in southeast Black Sea between April 2011 and March 2012. The seasonal von Bertalanffy growth equation parameters, computed from monthly length frequency distributions, were estimated as L-infinity = 18.95 cm TL, K= 0.900 year(-1) for males and as L,= 20.29 cm TL, K= 0.805 year(-1) for females. Seasonal oscillation of growth for males (C = 0.510) were stronger than females (C = 0.197), and the time of the slowest growth period corresponded to May (WP = 0.358) in males and January (WP = 0.040) in females. Fecundity ranged between 11659 and 354204 eggs (mean 70,919 +/- 11,659 eggs) and fecundity - total length relationship was significantly different from zero (P<0.0001). The growth of gonad from stage 1 to stage 4 appeared throughout the year and recently spent gonad was also observed only in August, December and January for both sexes. Spawning continues throughout the year with intensive spawning occurred at last three times in a year; at the end of the summer, in mid-autumn and in early winter. The size at sexual maturity was estimated as 14.6 cm TL for females and 13.9 cm for males. The protection of whiting breeding and for a sustainable whiting fishery with bottom gill nets, the smallest capture size should be applied as 15 cm TL.