Nadir Başçınar

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.

Quality Changes and Shelf Life of Cultured and Wild Hot-Smoked Mediterranean Horse Mackerel (Trachurus mediterraneus) at Refrigerated (4 ± 1°C) Conditions

ABSTRACT Mariculturing of horse mackerel is not known in the world. Additionally, limited studies exist on quality changes of smoked horse mackerel at refrigerated temperatures. Therefore, in this study, between 1+ and 2-year-old wild and cultured horse mackerels were hot smoked and stored at refrigerated conditions. Chemical, microbiological, and sensory analyses were performed weekly to investigate quality changes and to determine the shelf stability of the products. The results of thiobarbituric acid, trimethylamine, and total bacteria counts were obtained within the acceptable levels. Although the counts of histamine-forming bacteria increased significantly (p < 0.05) during storage, histamine values were well below the permitted limits set by Food and Drug Administration and European Union (EU). Sensory results showed that both storage groups had 3 weeks of shelf life. Total volatile basic nitrogen values supported sensory results. Therefore, the results indicate that culturing of horse mackerel did not alter the quality during storage at 4 ± 1°C.

Comparison of Proximate Composition and Fatty Acid Profile of On-Growing and Wild Mediterranean Horse Mackerel (Trachurus mediterraneus)

ABSTRACT On-growing of horse mackerel is not known in the world. Recently, we have initiated on-growing of the Mediterranean horse mackerel in the Black Sea. Therefore, we aim to compare proximate composition and fatty acid profile of on-growing and wild horse mackerels to evaluate the effect on their nutritional value. Captured horse mackerels less than 13 cm were kept on-growing in sea cages and fed sea bass feed for a year in the southern Turkish Black Sea. Results showed seasonal variations in the proximate contents and fatty acid profile of both on-growing and wild fish groups (p < 0.05). Protein contents of the wild horse mackerel group were significantly higher than the on-growing mackerel group, while the opposite situation was observed for lipid contents (p < 0.05). Despite higher eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels (as fatty acid methyl esters %) of wild horse mackerel in comparison with on-growing group, much higher EPA + DHA contents were accounted for in on-growing fish in the edible portion resulting from higher lipid contents of these samples. The results suggest that lower amounts of fish meat, 50–90 g, from on-growing mackerel would cover the daily suggested value of EPA + DHA; this level is calculated as 51–150 g for wild fish meat.