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Turkish Journal of Fisheries and Aquatic Sciences 2008, Vol 8, Num, 2     (Pages: 321-327)

Diet Composition of Horse Mackerel, Trachurus mediterraneus ponticus Aleev, 1956 (Osteichthyes: Carangidae) in the Bulgarian Black Sea Waters

Maria Hristova Yankova 1 ,Violin Stoyanov Raykov 1 ,Petya Bogomilova Frateva 1

1 Institute of Fishing Resources, P.O. Box 72, 4 Primorski Blvd., 9000, Varna, Bulgaria Viewed : 4130 - Downloaded : 4028 Present analysis was performed on samples of horse mackerel Trachurus mediterraneus ponticus Aleev, 1956 collected at monthly intervals (April - September 2007) off the Bulgarian Black Sea territorial waters. Stomach contents of 1042 specimens were analyzed. Of the total number of examined stomachs, 597 were empty (57.3%). This percentage varied significantly with season, the maximum number of empty stomachs was observed during spring (52.3%) and a minimum number observed during summer (32.4%). The mean weight of stomach contents increased significantly for fish larger than 16 cm TL, while the mean number of prey items significantly declined in the large –size classes. Mean weight of stomach contents and mean number of prey significantly increased in spring-summer period. The stomach content consisted of several major prey groups: Crustacea (Copepoda, Cladocera, Mysidacea, Ampipoda, Isopoda, Decapoda), Polychaeta and Pisces. Mysidacea were the most important ingested prey, especially in small and medium size classes. Sprattus sprattus phalericus L. and Engraulis encrasicholus ponticus L., whose proportion increased in large size classes, were the most important food categories. Cladocera were food category with especially abundant in summer, while Amphipoda, Isopoda, Polychaeta and Decapoda were occasional foods. With fish growth, the proportion of planktonic organisms decreased, while that of fish increased. Feeding intensity varied throughout the year. The lowest feeding intensity was recorded in spring and the highest feeding intensity was recorded in summer. Keywords : Trachurus mediterraneus ponticus, horse mackerel, stomach contents analysis, food composition, feeding intensity, Black Sea