SPECIES COMPOSITION OF COMMERCIAL FISH CATCHES IN WATER BODIES OF THE STAVROPOL TERRITORY FOR THE PERIOD OF THE LATE XX – EARLY XXI CENTURIES

Aim. The aim of the study is to analyze the species composition of commercial fish catches in water bodies of the Stavropol Territory for two periods from 1986 to the present.Methods. The first period from 1986 to 2003 is conventionally highlighted and the second period from 2009 to 2017. Data on linear and area characteristics of the territorial objects was obtained using Landsat 8 satellite imagery.Results. In 2017, in the fish industry of the Stavropol Territory, 10.8 thousand tons of marketable fish were produced, which was about 70% of the best production level in 1990. The share of common carp production was 58%, silver carp – 34%, white Amur – 5% , other carp fish species – 3%, trout and sturgeon – 1%. In 2017, 1415 tons of fish seeds were produced bringing the total to 19 million units, which is 4 times less than in 1990. The importance of fish catching in providing the population of the region with fish is not so great in comparison with fish farming. In different periods of the last thirty years, the total annual catch in regional state water bodies (reservoirs) ranged from a maximum of 1065 tons (1990) to a minimum of 82 tons (2016). The average annual catch in all state water bodies for the period 1986 – 2003 amounted to 357 tons; fish productivity was 32 kg, with fluctuations from 2 to 113 kg/ha in eleven water bodies. Over the past 9 years, since 2009, the average annual catch in all state water bodies has decreased and amounted to 285 tons.Conclusion. For the period of 1986-2003, the average annual catch of common carp and silver crucian carp was 94 tons each and 79 tons of silver carp; the total share of these three species in catches was 85%. Over the past 9 years (2009-2017), the total share of these fish in the catches has decreased to 66%. The average annual catch of common carp and silver carps was almost halved, while the catch of less valuable silver crucian carp increased and reached 103 tons.

TECHNOLOGY FOR WASHED FISH MINCE OF THE OBJECTS OF AVAILABLE FISHERY IN THE VOLGA-CASPIAN BASIN

Portion of freshwater species able to fishing beyond the TAC limits increases recently in the total volume of fishery in the Volga-Caspian basin. These species regarded as «other freshwater fish» are presented mainly by silver crucian carp Carassius gibelio and red eye Scardinius erythrophthalmus. These low-valuable species could be used for manufacturing of minced fish and various food products on this base. Technological properties of the raw fish and samples of unwashed, washed, and double-washed mince of these species are examined, both before and during storage. The technology of double-washing in water with 1 % food supplement Omfresh Plus (salt, dextrose, maltodextrin, mononatrium glutamate, and spice extract of lemon, cumin or rosemary) is developed in the innovation research laboratory of Food Biotechnology and Biologically Active Substances at Astrakhan State Technical University. For testing, two pilot batches of the minced red eye and silver crucian carp were manufactured by Astrakhan Fisheries Ltd. The output of edible mince after double-washing was 41.4 % for red eye and 41.0 % for silver crucian carp. Organoleptic, physical and chemical properties of the washed mince complied well with the requirements of GOST (state standard) R 55505-2013 «Frozen edible fish mince. Specifications». According to the standard, they are: water content 79.0–82.0 %, sodium chloride concentration 0.17–0.35 %, water retaining capacity > 50 %. After 7 months of cold storage at the temperature below –18 о C, the nitrogen ratio (volatile basic nitrogen relative to formally titrated nitrogen, VBN/FTN) in the minced fish exceeded 8 % that indicated a decrease of its quality, so the recommended storage time was adopted as 6 months. Effective viscosity of the minced fish changed insignificantly during the storage: from 2386.4 to 2443.2 Pa.s for red eye and from 1669.6 to 1775.2 Pa.s for crucian carp that meant that the samples have a stable consistency and are quite suitable for manufacturing of various molded food products. Recipes of molded dry-jerked sticks and boiled-smoked sausages are developed. These products were manufactured from the washed fish mince stored 6 months. According to their organoleptic, physical and chemical parameters, they corresponded to the standard requirements. So, the technology of washed mince of silver crucian carp and red eye is successfully tested in industrial conditions and can be recommended to fish-processing enterprises of the Volga-Caspian basin for rational usage of prospective objects of fishery in order to increase the release of food fish protein products.

PHENETIC RESEARCH OF PAIRED FINS OF A SILVER CRUCIAN

In the course of the study, data on phenetic patterns of the genotype in the paired fins of bone fishes were obtained for the first time. When analyzing a sample of silver crucian carp in the skeleton of the thoracic and pelvic fins, about 10 phenetic manifestations of the genotype were found. Of these, 7 are phenos in the pectoral fins and 3 in the ventrals. The findings also indicate possible genetic differences between the sexes.