İbrahim Okumuş

Population structure, growth and reproduction of introduced Pacific mullet, Mugil so-iuy, in the Black Sea

Population structure (age and sex composition), growth and reproduction of Pacific mullet (Mugil so-iuy) were determined from specimens collected on the eastern Turkish Black Sea coast during May–August 1995. The species has been introduced to Black Sea recently and the age composition of the newly established population varied between 1 and 6, with age group 4 dominant. Total length and weight values ranged from 225 to 667 mm and 101 to 3260 g, and there were significant differences between sexes in favour of the females (P < 0.05). Similarly, mean condition factors of males (0.91 ± 0.091) and females (0.94 ± 0.098) were significantly different (P < 0.05). From the length-age and weight-age data for both sexes combined, the following population parameters were estimated: length-weight relationship, W = 0.0099L2.98; L∞ (cm) = 71.9, W∞ (g) = 3412.7, K= 0.26 year−1, t0 = −1.57 year. The sex ratio was 0.9:1 males to females. Age at first sexual maturity was estimated as 3–4 years for males and 4–5 years for females, and spawning period extends from end of May to beginning of July. Total fecundity ranged from 454,300 to 2,366,574, while mean egg diameter was 0.67 ± 0.136 mm. The total fecundity was highly correlated with total length and the relationship was F = 2.776 L3.26 (r = 0.88). It has been concluded that the newly introduced mullet species appears to establish a self-reproducing population, the growth rates seem to be much better and age at first sexual maturity earlier than that of the native mullet species.