Diet and prey selection of pikeperch (Sander lucioperca Linnaeus, 1758) population in Lake Eğirdir (Turkey)

Abstract

The diet and prey selection of pikeperch (Sander lucioperca L., 1758) were assessed by determining the frequency of occurrence, numeric and weight percentages, and the index of relative importance (IRI%) between January 2010 and December 2010 in Lake Egirdir, Turkey. Pearre's index was used to estimate diet selectivity, while the Schoener Overlap Index was utilized to compare diets. The stomach contents of 241 S. lucioperca were analyzed. Pikeperch diet included prey fish, insects and other organisms. The diet was predominantly fish, consisting of Atherina boyeri, Knipowitschia caucasica, Aphanius anatoliae, Seminemacheilus ispartensis and Carassius gibelio. A. boyeri was the most abundant prey fish in the lake; it was a positively selected food item (V= 0.130, X2= 3.359, p> 0.05) and was not statistically significant. C. gibelio also inhabits the lake, but was not preferred by pikeperch (V=0.134, X2= 3.582, p> 0.05). In addition, A. anatoliae (V=-0.223, X2=9.977, p<0.01) and Chironomus sp., (V= -0.297, X2= 17.665, p<0.01) were negatively chosen by pikeperch despite their high abundance in the lake. Stomach fullness was highest in January, while feeding density was lowest in November and >50 cm in length pikeperch. Cannibalism was not evident during a decade, due to there being enough food for pikeperch in the lake.