Under present conditions of depletion of natural resources and introduction of a moratorium for commercial sturgeon fishing there is a need to take urgent and radical steps in order to conserve the Caspian populations of these valuable species. Natural and artificial reproduction efficiency shall be improved in order to restore sturgeon population level in the Volga-Caspian basin. The analysis of the current state of natural sturgeon reproduction in the Volga river unregulated part has shown that due to a variety of reasons its efficiency has been minimized. The role and importance of artificial reproduction is increasing, yet in the last years its efficiency has been negated because of increasing deficiency of sturgeon sires in natural populations. Timely composition of productive stocks in the fish ponds of 6 Astrakhan region sturgeon breeding hatcheries allows to provide artificial reproduction fish-breeding operations with high quality spawns and milters within the conditions of their population’s decline in the natural habitats. The data on the quantity and the biomass of the sturgeon productive stocks at the Astrakhan sturgeon hatcheries prove that the prospects for developing artificial reproduction are possible only due to using stocks available at the hatcheries.

No abstract

It is shown that the leading role in the aquaculture of Iraq belongs to Cyprinids, which account for over 80 % of all fish farming production. The most widespread in the country are four main world species of carp aquaculture: common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). Basically, the traditional technology of growing Cyprinids in ponds is used, which includes the main fish farming processes: care of broodstock to prepare them for spawning, collecting eggs and milt, eggs fertilization and incubation of embryos, raising juveniles and marketable fish. Currently, there are about 2 thousand private fish farms, which have ponds of various sizes from 4 to 100 hectares. Cultivation of Cyprinids in Iraq is carried out mainly by extensive methods: the use of the natural food base of reservoirs with low fish stocking density in polyculture. The fish productivity of ponds varies greatly in different fish farms from 1,5 to 6 t/ha, which is due to economic reasons. The data on changes in the temperature of pond water during the year and hydrochemical indicators are given, which shows favorable conditions for Cyprinids rearing. Information on the use of compound feeds for growing carp in ponds is provided, and data on the composition and nutritional value of the feed used. The fish culture indicators for the main biotechnical processes of the rearing of four Cyprinid species in Iraq are described in detail. In the conclusion, it is indicated that for the effective development of aquaculture in Iraq, government support is needed in the form of a developed long-term program and legislative acts.

A quaculture farmers are concerned with achieving the highest growth rates regardless of the condition of water quality; therefore, the farms set up in areas with unsuitable water parameters have been under-performing in production and are thus unsustainable (Stewart et al., 2013). Furthermore, anthropogenic actions have led to the degradation of freshwater habitats and the concomitant depletion of fish populations (Closs et al., 2015; Gordon et research Article Abstract | The American paddlefish (Polyodon spathula) is one of the most valuable native fish in the united states, china, and several Eastern European countries. Sustainable paddlefish production at a commercial scale is essential for caviar and meat production but requires maintaining high water quality throughout the rearing period. The present study analyzes the paddlefish' biological and physical Caspian environmental data using fuzzy logic control methodology from non-traditional analysis to deliver detailed insight into critical factors that affect the aquatic ecosystems. For this hypothesis, there was one governate station (the Caspian Fisheries Research Institute), including twelve earthen ponds with 850 kg fish per hectare in this study. The fuzzy inference system was performed to predictable solutions for output data (metabolic rate), influencing the selected factors (temperature, dissolved oxygen, pH and oxygen uptake) involved in the system. Through prediction and simulation, each input factor was determined during the breeding season (seven months). Water quality parameters involved in the variation in the paddlefish rearing conditions were classified into four groups, including temperature, pH and dissolved oxygen, along with oxygen consumption. For each rearing condition, a separate fuzzy inference system was defined and the output of each fuzzy system was named F1, F2, F3, F4 and F5. Finally, F1 and F2 were identified as the inputs to a fuzzy model to evaluate the relation between the metabolic rate index's and environmental factors. The results indicated that the decline in the paddlefish metabolic rate rearing index was correlated with the water temperature and dissolved oxygen percentage during the breeding season. In conclusion, improving oxygen flowing and optimum water temperature could reduce environmental stress and improve paddlefish production in this system during the breeding season.

No abstract