Diet composition and prey selection of the pike,Esox lucius, in Çivril Lake, Turkey

Abstract

Diet composition and prey selection of pike (Esox lucius) were studied in Ç ivril Lake, Turkey. The lake is eutrophic in character with a surface area of ca. 64 km )2 and mean depth of 3 m. Stomach contents of 409 specimens were collected between October 2003 and April 2005. Pike diet included 10 prey fish species, two Crustaceae, four Insecta, one Hirudinae and one Amphibia. Feeding was homogeneous, with most pike specializing in prey fish and a few pike specializing on miscellaneous items. Feeding activity varied by season and ontogeny. Stomach fullness and the percentage of fish with prey were highest in spring and in small pike, while feeding intensity was lowest in winter and in large sized pike. Diet composition was dominated by fish, including Carasius gibelio, Chondrostoma meandrense, Esox lucius, Gambusia affinis, Gobio gobio, Hemigrammocapoeta kemali, Leuciscus cephalus, and Tinca tinca. Crustacea were also a significant component in spring and in small sized pike. The most important prey items were C. meandrense, Gammarus sp., H. kemali, and L. cephalus. Pike feeding in winter and summer was homogeneous, specializing mainly on fish as prey, while the diet in spring and autumn was heterogeneous with some pike specializing on Gammarus sp. Cannibalism at 8.7% was observed only in the large sized pike (>40 cm). Pike strongly preferred C. meandrense (Selectivity index V = 0.372; v 2 = 27.739; P < 0.01), G. gobio (V = 0.192; v 2 = 7.350; P < 0.01) and T. tinca (V = 0.146; v 2 = 4.257; P < 0.05) despite their low abundance in the lake. Hemigrammocapoeta kemali was the most abundant prey fish in the environment; however, it was a negatively selected food item (V = )0.358; v 2 = 25.642; P < 0.01). Cyprinus carpio also inhabits the lake, but was not preferred by pike (V = )0.056; v 2 = 0.625; P > 0.05). Accordingly, the aims of the study were to (i) describe pike diet composition; (ii) determine seasonal changes in different size groups; (iii) investigate prey selection by pike in Ç ivril Lake; and (iv) compare the results with data from other lakes. Materials and methodsÇ ivril Lake is a large wetland lake (area: 64 km )2 , mean depth: 3 m) located in the Bu¨yu¨kmenderes River basin in western Turkey and also known as Is¸ıklı Lake (Fig. 1).

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“…The percentage of empty stomach (VI%) was lower than in other with 54.5% in The Green River Basin (Tyus & Beard, 1990), 53.5% in Feldberger Haussee (Wysujack et al 2001), 54.3% in Çivril Lake (Alp et al, 2008), while VI% value was similar with previous researches which 32.8% in Lake Trasimeno (Lorenzoni et al 2002), 37% in Karamık Lake (Çubuk, Balık, Özkök, & Uysal, 2006). This may be due to differences in sampling method, climate features of the study field, residence time on nets of fish.…”

“…They provide better understanding of fish niche in the ecosystem, their food preferences, dietary overlaps (Padmakumar, Bindu, Sreerekha, & Nitta, 2009), effective lake fisheries management (Alp et al, 2008), and functional role of the fish within their ecosystems (Osman, Farrag, El Sayed, & Moustafa, 2013). Feeding habits in fish species usually depend on environmental conditions and thus can be different from one habitat to the other.…”

“…According to Polat, Yılmaz, and Yazıcıoğlu (2012), pike represents the most important target species for commercial fisheries in Lake Ladik, because pike is one of the main livelihoods of local fishermen. Since the pike is considered as a top predator in the food web in most freshwater ecosystems that it occupies (Soupir, Brown, & Kallemeyn, 2000), it plays an important role as regulator in abundance of prey fishes in most of the aquatic environments (Alp et al 2008). In addition, pike is used for (improving water quality) biomanipulation (Craig, 2008).…”

Pike Esox Lucius Distribution and Feeding Comparisons in Natural and Historically Channelized River Sections

“…The amount of invertebrates found in pike stomachs increased in hydromorphologically modified river sections, but the correlation is weak (Rs = 0.31, p < 0.01). Nevertheless, just as in this study, others [32]; [33] have shown that pike are flexible with respect to their choice of food -large invertebrate rations and a large diversity of fish species has been noted in pike population. In other studies, however, it has been found that there is a relatively small spectrum of food, and a substantial significance of invertivores in the food [34], [35].…”

“…During the study, a relatively large amount of empty stomachs, average 35 %, was noted both in channelized and natural rivers. The proportion of empty stomachs in recent studies vary between 28 % and 78 % on average, annually (28 % [36]; 50 % [34]; 50 % [32]; 33 % [35]; 54 % [33]; 78 % [37]; 58 % [18]). …”