Diet Composition and Prey Selection of Flathead Trout (Salmo Platycephalus, Behnke, 1968) in Zamanti Stream of Seyhan River, Turkey

Abstract

Diet composition and prey selection of flathead trout (Salmo platycephalus) were studied in Zamanti stream, Turkey. Stomach contents of 120 specimens were collected between June 2005 and April 2006. Analysis of monthly variations of stomach fullness indicated that feeding intensity was higher between June and August than that of the spawning season in the period from September to November. A total of 18 prey taxa representing Malacostraca, Clitellata, Tricoptera, Hemiptera, Gastropoda, Ephemeroptera, Turbellaria, Coleoptera, Plecoptera, Nematoda, Diptera was identified in the diet. The index of relative importance index (IRI%) indicate that the most important feeding organism of flathead trout specimens in Zamanti stream is Gammarus sp.  and they are more than 90 % of total diet composition. The Shannon-Weinner index, food diversity in the stomach contents are generally high except for reproduction period. Gammarus sp. was the most abundant prey organizm in the Zamanti stream ecosystem, accounting for 81.38 % of Gammarus sp. in the environment samples. However, they made up 87.08% of all prey macroinvertebrates consumed by flathead trout. In terms of diet selectivity index Gammarus sp.has positive selectivity, but selectivity index has not important statistically. The other organism groups have rather low and not significant availability ratios in the diet with Zamanti stream ecosystem (p>0.05).

Keywods: Diet composition, feeding, prey selection, Salmo platycephalus, river Seyhan