Industrial fish-breeding is a promising trend for freshwater aquaculture development. The production of clarid catfish in Kazakhstan has advantages over traditionally grown fish species (trout, sturgeon) due to their valuable edible qualities. Clarid catfish grows very quickly even at high seeding densities, is undemanding to the environment, resistant to diseases, and effectively assimilates food. When growing clarid catfish in water recycling systems it is possible to refuse using oxygen equipment, because the fish species can use atmospheric air for breathing. As a result, the construction of such plants can save up to 40% of capital investments. In the course of the research, the physiological nutritional requirements of clarid catfish juveniles were established. Based on the data obtained there have been developed two extruded starter compound feed recipes for clarid catfish juveniles containing protein/fat 53.5 : 11.4 and 61.85 : 5.82 and energy exchange energy value varying within 16.46 - 17.12 MJ/kg. There have been conducted the production tests on assessing the efficiency of the developed compound feed and their intake by larvae and clarid catfish fry in the fish farms of “Kapshagayskoye NVH-1973”, LLP and “HalykBalyk”, LLP. The feed Aller Agua (Denmark) served as a control feed for comparing the nutritional and consumer qualities of the developed feed for trout. The determined feeding ratio of the developed feed did not exceed 0.93 units, it was insignificantly inferior to the import feed. The fry survival rate made 76% when using both the control and developed feed. The compound feeds for clarid catfish juveniles were developed by extruding, which allowed to obtain increased digestibility, water resistance and extended storage life. Introducing these feeds into the fish breeding practice will help to increase the efficiency of clarid catfish fry growth and expand opportunities of aquaculture facilities.
The results of the cadastral survey of 4 reservoirs located on the territory of the Korgalzhyn State Nature Reserve are presented. The assessment of the main biological characteristics of living fish is given: size, weight composition, linear and weight growth rate. In total, 15 species of fish from 5 families were found in the surveyed reservoirs in 2016-2020. The carp family is most widely represented in the reservoirs of the national park, 9 species are noted, the loach, pike and stickleback families are represented by 1 species, perch — 3 species. According to the results of research fishing, it was found that in the lakes of the Korgalzhynsky SNR, the organization of reclamation fishing in the form of total trapping and research fishing is necessary in 2021.
The article presents the data on linear growth of perch from 35 water bodies in the Nura and Sarysu river basin in Central Kazakhstan obtained using the inverse calculation method. The obtained annual values of linear growth, increments and their variability have been analyzed. The increments were defined as a contribution of annual growth to the obtained length, but not as the initial length increase. At that, in the analysis the maximum age was limited to the most common 6 years. As a result, it has been stated that some populations from small depressive rivers have lower growth rates. Perches from southern parts of the Sarysu River grow more slowly, compared to the populations from the Nura River which is located northward. Studying the scheme of the body length advancing has reviled the distinctive features of samplings from the Ashchisu River, a tributary of the Nura River. Samplings from the Kurgaldzhin lakes are characterized by greater variability of annual growth values against the general background over a long time. Besides, they have a high correlation of the values in subsequent years. Samples from the Ashisuy, on the contrary, have the least correlation. The Kurgaldzhin groups are open for migrants, which evidently explains the discovered features. The populations from the Ashchisu River watershed have been isolated from the indigenous basin for more than 35 years, which may have determined the features of growth. The influence of hydrological and hydroclimatic factors on perch growth has been stated. But the influence of the structure of ichthyocenosis and on the population size has not been found, probably, due to the relatively identical living conditions of the studied samples.
The Tobol River, a nationally significant economic water body, serves various purposes and spans across diverse landscape zones and environmental conditions. An evaluation of the forage base development of the Tobol River was conducted through the survey of six stations along the river in 2019. The investigation revealed a total of 15 species of planktonic invertebrates, including 6 rotifers, 5 cladocerans, and 4 copepods, as well as 28 species of benthic organisms. The survey period of 2016-2019 registered 36 species and forms of benthic organisms within the Tobol River basin, with a high diversity of insect groups. The considerable length and varied landscape zones of the river contribute to the observed high diversity of organisms. In terms of zooplankton development, the Tobol River exhibits a moderate food supply class and, according to S.P. Kitayev's trophic scale, can be classified as a β-mesotrophic water body. Similarly, the river's zoobenthos development indicates a moderate food supply class, designating it as an αmesotrophic type under S.P. Kitayev's trophic classification. The study of the food spectrum of river perch and roach in the Tobol River suggests relatively high food availability for these species, underscoring the importance of understanding the ecological and biological forage base of the river for maintaining ecosystem health.
The reservoirs of the K. Satpayev canal are the important fishery water bodies in the Central Kazakhstan. Some of these reservoirs are inhabited by tench, a fish species relatively widely represented in other water systems of the region. In the reservoirs of the canal this species is not the main commercial one but it has a fairly high commercial value due to its popularity with consumers. As part of the research, the growth indicators of Tinca tinca from 4 reservoirs were evaluated, and the data on its growth from 3 more reservoirs were also provided. These samples differ in efficiency and growth rates. It has been found that there is no sexual or generation variability. Growth rates in successive fish generations strongly correlate with each other, which may indirectly indicate the stability of living conditions. The R. Lee’s phenomenon was not marked. In this regard, the calculation of variables of the von Bertalanffy growth equation was carried out without additional data processing. The highest rates of linear growth were characteristic of Tinca tinca from the reservoir of HS No. 9. However, the effectiveness of its growth scheme was the lowest. Population with a longer age range from the reservoir HS No. 3 did not have high linear growth rates, but its growth efficiency was higher. In this case, it is obvious that any assessment of growth will be relative and depend on the goals set for it. In the reservoirs of the canal there are more or less similar conditions for tench populations living due to the specifics of its functioning. The main limiting factor for the growth rate, in our opinion, will be abundance of the species in the reservoir and related trophic factors with a certain influence of withdrawal (fishing, predators).
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