Abstract
Effects of interaction of season, sex and size on nutrient composition and fatty acid profiles of freshwater crayfish (Astacus leptodactylus) caught from the Eğirdir Lake were investigated on a factorial level. In the factorial analysis; 4 levels of season factors (autumn, winter, spring, summer), 2 levels of sex factor (male, female) and 1 level size factor were available. According to the results of biochemical analysis, effects of seasons were determined on crude protein and moisture levels. Crude ash levels changed depending on sex and season. There were no interactions of these three factors on the crude fat levels. The season and sex affected on LA, α-LNA and ∑HUFA levels. ARA, EPA, DHA, ∑SFA and ∑PUFA levels were affected from seasonal changes. Interaction of season/sex affected to ∑MUFA levels. The crude protein content, DHA, EPA and n-3 contents in tail muscle of A. leptodactylus increased by feeding in summer while these contents decreased by gonadal development in autumn. Therefore, in terms of nutritional protein contents, EPA, DHA and n-3 of this species were higher in summer. EPA, n-3 and DHA contents are important for A. leptodactylus.
Highlights
Astacus leptodactylus is naturally and widely distributed in lakes, ponds and rivers throughout Turkey (Harlioğlu & Harlioğlu, 2004)
Binary or triple interaction was not obtained when crude protein, crude ash and moisture analysis results were evaluated in tail meat of A. leptodactylus
Silva-Castiglioni et al (2007) indicated that total muscle proteins were high during summer in both sexes of Parastacus varicosus and there was no difference between the sexes during the year
Summary
Astacus leptodactylus is naturally and widely distributed in lakes, ponds and rivers throughout Turkey (Harlioğlu & Harlioğlu, 2004). There has been a gradual decrease in the production of crayfish in Turkey from 5000 tons in 1984 to 532 tons in 2015 (Turkish Statistical Institute, 2017). The greatest cause of this decline is crayfish plague fungus (Aphanomyces astaci) seen after 1985 (Baran et al, 1987; Rahe & Soylu, 1989; Harlioğlu, 2008). There is no crayfish culture in Turkey and all production is obtained from wild harvests (Harlioğlu et al, 2012). Culture of crayfish is needed to replenish native stocks of A. leptodactylus. Feeding habits of A. leptodactylus compose bivalves (Dreissena polymorpha), gastropods (Greacoanatolica lacustristurca), crayfish eggs (Acar Kurt, 2016), Nematoda (Capillaria sp.) and sometimes fish Aphanius anatoliae, aquatic plant Ceratophyllum demersum, Elodea canadensis, and Epithemia sp., Cocconeis sp., Amphora sp., Synedra sp., Diatoma sp., Pinnularia sp., Cymbella sp, Navicula sp., Fragilaria sp., Gyrosigma sp (Uysal, 2011)
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