Effects of photoperiod and stocking density on survival, growth and physiological responses of narrow clawed crayfish (Astacus leptodactylus)

Photoperiod and stocking density are critical factors influencing the performance of decapod crustaceans in culture, however, their influence on growth; survival and biochemical physiology of crayfish broodstock have rarely been considered. Analysis of biochemical physiology in crayfish broodstock during the non-breeding season provides information on the energy storage requirements of broodslock for increased si and reproductive output. Growth rate, moulting frequency, survival and biochemical physiology were measured in Astacus leptodactylus broodstock that were cultured at three different photoperiods (18L:6D: 12L:12D: and 6L:18D) and three stocking densities (10, 20 and 40 individuals m(-2)) during non-breeding was highest at 181,:61) (100%) than other survival of crayfish and 2 fie high stocking density was high when combined with 18L:61) photophase, hut Weight. gain (AA() and specific growth rate (SGR) were higher at shorter photophase and lower stocking density. Longer photophase (18L:6D) increased stress responses, characterized by increased haemolymph lactate and glucose levels. Stocking density did not affect proximate composition of crayfish: However, individuals cultured at 181,:61) photo phase had higher lipid content than other photo period treatments. The study demonstrated that culturing A. leptodaelylus at 181,:61) photophase and 10 m(-2) is critical for increased survival of broodstock.