BIOLOGICAL RESOURCES
Quantitative samples of fish, crabs and shrimps from the Razdolnaya estuary are analyzed. The area surveyed in May-September of 1990–2014 includes the internal estuary of this largest river of southern Primorye and its external estuary — the top of the Amur Bay with the depth < 13 m. In total, 478 samples were collected: 244 in the external estuary by trawl and 234 in the internal estuary by fry seine. Distribution density and biomass are calculated using the «areal» method with certain coefficients of catchability (1.0 for fry seine). The upper freshwater layer (salinity 0–5 ‰) was observed in the lower stream of the river till sandy bar, the brackish-water cline was traced at the river bottom from the mouth to the distance 10–15 km upstream. The seawater with salinity > 30 ‰ did not penetrate over sand bar to the river. Species diversity of fish and decapods was presented by 108 taxa (fishes — 88, decapods — 20) belonged to 43 families, among them 84 species were caught in the Amur Bay and 41 species in the Razdolnaya, but no more than 67 species were caught in the Amur Bay only and 24 species — in the Razdolnaya only, other 17 species were found in both external and internal estuaries (Acanthogobius flavimanus, Acanthogobius lactipes, Crangon septemspinosa, Crangon spp., Eriocheir japonica, Hypomesus nipponensis, Giporhamphus sajori, Konosirus punctatus, Liopsetta pinnifasciata, Oncorhynchus masou masou, Palaemon sp., Pholis nebulosa, Planiliza haematocheila, Pugettia quadridens, Salangichthys microdon, Syngnathus schlegeli and Tribolodon spp.). Total biomass was higher (9.1 g/m2 ) in the external estuary than in the internal estuary (6.7 g/m2 ) with the mean value 9.0 g/m2 . It was almost uniform over the internal estuary with only slight increasing on the distance about 5 km from the mouth. Simpson index of dominance increases from external to internal estuary but decreases in the river in the order: 0.127 at Peschany Peninsula — 0.168 in the northwestern Amur Bay — from 0.193 to 0.252 in the internal estuary — 0.164 in the river. Six clusters with similar species composition are defined, they change in direction from the sea to the river in the following order of the dominant species: L. pinnifasciata in the sea — prawns gen. Palaemon at the bar (upper part of the external estuary) — P. haematocheila at the river mouth (lower part of the internal estuary) — P. haematocheila and E. japonica in the main part of the internal estuary — Acanthorhodeus chankaensis and Gobio macrocephalus (with the highest biomass up to 22 g/m2 ) in the minor adjoining river stream — G. macrocephalus in the upper part of the internal estuary.
ENVIRONMENTS OF FISHERIES RESOURCES
Seasonal changes of chlorophyll a profiles are traced over the Amur Bay (Peter the Great Bay, Japan Sea) in May-October, 2017 by means of oceanographic sonde-profiler equipped with fluorometer. Two principally different types of the vertical profiles are revealed, which were formed by different mechanisms of productivity: i) Chl a concentration had the maximum at the sea surface and decreased with the depth in the internal part of the bay occupied by the estuarine waters, and ii) Chl a concentration had the maximum below the seasonal pycnocline in the external part of the bay connected with the open sea. The highest Chl a concentration was observed in July-August for the estuarine type because of summer monsoon flood on the rivers, but in September for the marine type because of the coastal upwelling induced by monsoon winds change. Comparing these results with estimations of Chl a concentration made with the satellite data, insufficient correspondence is concluded for the external part of the bay, outside the estuarine zone, because the satellite data don’t reflect well the chlorophyll a in the subsurface layer and its seasonal variations. Thus, underestimation of real productivity and feeding ability of marine areas is available with the satellite data on chlorophyll a.
TECHNOLOGY FOR PROCESSING OF AQUATIC ORGANISMS,
Complete utilization of all wastes of fish processing becomes actual in modern conditions of depletion of the fish raw materials because of the commercial catch decreasing in the Volga-Caspian Basin. Abilities of fish oil extraction from fins of catfish are considered. Several technologies of the oil extraction from this waste are tested: thermal, carbamide-thermal, combined carbamide-thermal, and hydromechanical. Organoleptic parameters of the raw materials and produced fatty products are determined in accordance with the state standard № 7631-2008. Water, protein, fat, and mineral substances content in the raw material and physical and chemical properties of the produced fish oil are measured by standard methods given in the state standard № 7636-85, using the thin-layer chromatography. The fat content in the raw material is evaluated as 33.8 %. The fish oil output from the fat-containing raw materials is determined. The carbamide-thermal method is defined as the optimal one for oil extraction from fins of catfish. At the first stage, the raw material is heated to 70 о C during 60 minutes, then it is mixed with 1.5 % of carbamide in 30 % solution and the liquid and dense fractions of the mixture are separated under 3000 rpm in 30 minutes; at the second stage, the dense fraction is heated to 70°C, mixed with 20 % of water, and the mixture is heated to 75 о C during 60 min, then the liquid and dense fractions of the mixture are separated again; finally, the liquid fractions from both stages of treatment are subjected to sedimentation during 10 minutes under ambient temperature and the semi-finished fatty products are separated by 15 min. centrifuging at 4000 rpm. Phospholipids, monoglycerides, sterols, hydrocarbons, sterol esters, and the main fractions of triglycerides and carotenoids are presented in the fish oil produced with this technology, so it could be used in veterinary. This method for fish oil extraction from the fins of catfish is applied to the enterprises Parshikov and Fabrika Vesna and showed its efficiency in industrial conditions.
ISSN 2658-5510 (Online)