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
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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