Identification of optimal conditions for juvenile noble crayfish growth

Akvakultura predstavlja biomanipulaciju životnog ciklusa uzgajanih organizama i uvjeta okoliša. Ona uključuje kontrolu reprodukcije i rasta, te eliminaciju uzroka prirodnog mortaliteta. U ovom istraživanju manipuliralo se temperaturom, gustoćom juvenilnih jedinki i vrstom hrane kako bi se utvrdilo koji su temperaturni i prehrambeni uvjeti te gustoća jedinki najpovoljniji za rast juvenilnih rakova vrste Astacus astacus. U razdoblju od pet mjeseci prikupljani su podaci o masi, dužini i spolu jedinki te temperaturi vode. Uz to su utvrđeni fiziološki parametri uvjetovani zadanim tretmanima, a u tu svrhu su primijenjeni hepatosomatski i mišićni indeksi kondicije. Utvrđeno je da je najveći prirast u ukupnoj dužini i masi tijela postignut u tretmanu: plastenik, hrana životinjskog podrijetla, 25 jedinki / 0,6 m2 te je utvrđena statistički značajna pozitivna korelacija između ukupnog prirasta u dužini tijela i temperature vode. Ustanovljene su statistički značajne razlike među tretmanima u kondicijskim indeksima, a pokazalo se da su za energetski status juvenilnih jedinki najznačajniji čimbenici temperatura i hrana. Aquaculture represents biomanipulation of life cycle of cultured organisms and environmental conditions. It includes the control of reproduction and growth and the elimination of the causes of natural mortality. In this study it was manipulated with the water temperature, density layout of juvenile specimens and type of food to determine which temperature and food conditions are the most favourable for the growth of juvenile crayfish Astacus astacus. In a period of five months, data on weight, length and sex of individuals were collected, as well as water temperature data. In addition, physiological parameters conditioned with default treatments were identified and for this purpose hepatosomatic and muscle indices have been applied. It was found that the largest increase in the total length and body mass was achieved in the following treatment: greenhouse, meat, 25 specimens / 0.6 m2. A statistically significant positive correlation was established between the total increase in body length and water temperature. Also, some statistically significant differences in body indices between treatments were found and it turned out that the most significant factors in the energy status of juvenile specimens were food and temperature.