Biological peculiarities of the cultivation of narrow-clawed crayfish astacus leptodactylus Eschscholtz, 1823 (crustacea, decapoda)

Abstract

Crayfish Astacus leptodactylus Eschscholtz, 1823 is one of the largest commercial invertebrate internal waters of Ukraine. At the present time producers are unable to meet the needs of the people in this food. The largest number of crayfish (over 90%) is caught in natural reservoir as a result of illegal (poaching) production. Crayfish with spawn and larvae is caught which undermines the commercial reserves of this aquatic animal in reservoir. The article presents the results of growing crayfish under controlled conditions, taking into account their biological traits. We were investigated strength of currents on the development of crayfish in artificial conditions (closed water supply installation with a volume of 3240 l). We were analyzed the effect of surfactants, insecticides, fungicides, herbicides, and mineral fertilizers (nitrogen, phosphorus, and potassium) that enter natural and artificial reservoirs with wastewater on the organism of A. leptodactylus. We were used crayfish groups of 10 females and 10 males in each experiment. We have developed a methodology for 6 obtaining products in three years, namely keeping of the breeding stock in specialized tanks with temperature control, high landing density, sufficient number of caches, appropriate feeding and use of automatic devices for that, development and application of artificial caches of different sizes. It was found that the most optimal for crayfish was their keeping in closed water supply installation with a water exchange of 27 l/min. Their live weight was greater compared to individuals who grew up in the experiment with a flow rate of 0.5 l/min by 95%, 162 l/min-by 0.3%, and at 216 l/min by 1.3%. Optimal regime for crayfish growing was the dissolved oxygen content 6.0 mg/l, pH 7.3, NO 2-130.03-0.35 mg/dm 3 , NO 3-0.35-0.37 mg/dm 3 , CO 2-13-14 mg/dm 3. A number of integrated studies were also presented to determine the effect of surfactants, insecticides, fungicides, herbicides, and mineral fertilizers arriving into the reservoir with sewage are dangerous for aquatic animals and affecting the survival of experimental crayfish. Laboratory studies have shown that the lethal dose for crayfish is 2.5 g/l of washing powder Lotus. Invertebrates also died with the introduction of 0.05 ml/l of insecticide Bi-58 new. The lethal dose for crayfish are 5 g/l of the fungicide Rydomil and 0.08 ml/l of the herbicide Napalm. The lethal dose of ammonium nitrate, superphosphate and potassium salt are 0.4, 0.6 and 0.5 g/l, respectively.