Vitaliy Victorovich Barabanov’s research while affiliated with All-Russian Research Institute Fisheries and Oceanography and other places

The article presents an analysis of the boundaries of the Volga pre-estuarine forbidden space in retrospect and in the present period. The dynamics of the area of the Volga pre-estuary forbidden space is shown, which over the last century has decreased by more than 10 times. Most of the water area of the Volga pre-estuary forbidden space is currently located on land. Reason: drop in the level of the Caspian Sea and a decrease in the volume of Volga runoff. Using the example of a separate northwestern section of the delta and delta front of the river The Volga River clearly shows how the coastline of the Caspian Sea and, accordingly, the protective zone of the Volga pre-estuary forbidden space have changed. Taking into account the current water and fishery situation, the dynamics of the fall in the level of the Caspian Sea, proposals were made to update the northern boundary of the space, draw the coastline along the mark of 28.7 m BS and expand the protected areas.

The aim of the paper is an expert assessment of the quantitative, qualitative and species composition of IUU-fishing and their dynamics for 2017-2021. Analysis and synthesis of materials of ichthyologic examinations received from law enforcement agencies in the Volga-Caspian branch of “VNIRO” (“CaspNIRKh”). For the first time, an assessment of IUU fishing of sturgeon in the Caspian Sea for 2017-2021 was carried out. Quantitative and qualitative assessments of IUU-fishing, its species composition and their dynamics for 2017-2021 were obtained. The results of this study canbe used in predictive models of the dynamics of sturgeon stocks and in the analysis of the situation with the protection of these fish species in the Caspian Sea.

The silver bream Blicca bjoerkna and the small-sized common bream Abramis brama are characterized by external similarity, which contributes to manipulations with the substitution of one species (common bream) by another (silver bream) when taking into account the volume of industrial fishing in the Astrakhan region. This is due to the fact that in the period of spring fishing season during common bream spawning migration, the share of non-commercial common bream in commercial catches increases (to 20–30 %), the catch of which is limited in accordance with the Fishing Rules. In order not to exceed the allowable volume of by-catch of non-large common bream, fish producers register en masse catches of small-sized bream as a catch of silver bream, which causes significant damage to common bream fish stocks through oversampling of first-time maturing individuals of the population. In recent years, the share of non-commercial common bream recorded as a silver bream in May alone is 13–28% of its official catch during this period. In order to reduce the catch of first spawning common bream producers of non-commercial length on the water bodies of the Astrakhan region in the period from April 21 to May 20, it is recommended to introduce a ban on industrial fishing of silver bream.

The purpose of this work was to establish the informative value of methods of structural analysis of biological fluids in determining the prospects of using atherina (Atherina boyeri caspia (Risso, 1810)) as a source of dietary protein in aquaculture. For the first time, solid-phase structures of atherina muscle homogenates were studied. It is known that the solid phase of biological fluids formed under conditions of wedge-shaped dehydration is a visualization of biochemical processes occurring in an organism or organ. The study of the morphological picture of a dried drop (facies) makes it possible to establish associative links between the features of the structuring of the studied liquid and its composition, as well as to determine the nature of the impact of environmental factors on a living system. The results of the study made it possible to establish the main type of homogenate facies and its morphological parameters, which indicate the consistency of biochemical processes and the presence of high-grade protein in the muscle tissue of the Caspian atherina, caught both in the spring and autumn seasons. The size and weight parameters of fish, the content of water-soluble protein in muscle tissue are characterized. For the first time, a comparative analysis of the level of water-soluble protein and solid-phase structures of muscle homogenates of Caspian atherina caught in different seasons in the coastal waters of Dagestan was carried out. Atherina is a food component for many fish living in the Caspian Sea. It was determined that in October, the content of muscle water-soluble protein in atherina tended to increase relative to March. During the feeding period, the accumulated part of the protein components turns into lipid components, which accumulate intensively, therefore, there are no significant seasonal differences in the content of water-soluble protein. It has been established that the biochemical processes occurring in muscle tissues are reflected in the solid-phase structures of biological fluids formed under conditions of wedge-shaped dehydration. The obtained results of the trend towards an increase in water-soluble muscle proteins in the body and an increase in the population in recent years indicate the importance of the use of Caspian atherina in the quality of live feed at fish farms.

Based on research materials from 2003–2022, a review of the dynamics of stocks of aquatic biological resources for an unregulated section of the Volga River below the Volga hydroelectric dam within the Astrakhan region was carried out. The reasons, mainly of anthropogenic nature, causing changes in stocks are shown. The multidirectional nature of changes in the state of populations of aquatic biological resources depending on the sensitivity of species to environmental factors and their consumer value is demonstrated. The steps aimed at improving the situation are proposed.

The article highlights physiological and biochemical parameters of atherina (Atherina boyeri caspia Risso, 1810) in the Middle Caspian Sea at various stages of the annual cycle. The state of the fish organism was studied in the period from February to October 2022, which characterized the pre-spawning, spawning and feeding periods. The size-weight and age parameters of atherina were determined. The concentration of the main reserve substances of the fish body - total lipids and water-soluble protein – was analyzed in the muscles of the atherina. In the pre-spawning period and at the beginning of spawning of females, the level of morphological changes in the gonads was studied. There were no found significant differences in the content of total lipids and water-soluble protein in the muscles of males and females. Patterns of changes in the amount of muscle water-soluble proteins and total lipids were recorded in the entire sample of the Caspian atherina during the pre-spawning period and at the beginning of spawning. This is typical for portioned spawning fish, in which the energy expenditure of the body is directed to the formation, maturation of gonads, the removal of sexual products and the maturation of the next portions during the spawning period. In September-October, that is, already at the stage of feeding, a multidirectional character in lipid and protein metabolism was noted in the body of atherina. According to the results of histological examination, the beginning of spawning in atherina was noted in April. Mature oocytes with resorption at an average level of 30-31% were recorded in the ovaries of portioned spawning atherina in February-April, which characterized the adaptive mechanisms of the organism in the conditions of this habitat. In September, there was a significantly positive (p < 0.05) statistical correlation between the concentration of total muscle lipids and the mass of fish (r = +0.47), which characterized a positive energy balance in the body, so necessary for the next stages of life.

The article considers the original results of observations and analysis of the catches of atherina (Atherina boyeri caspia (Eichwald)) by months by stationary nets in the Terek-Caspian fishery subarea (Republic of Dagestan). The size-weight and age indicators of the spawning stocks of atherina have been characterized. For the first time in recent years the conditions for atherina spawning in the western part of the Middle and Northern Caspian are described. All biostatistical indicators of atherina obtained in the recent years (2016–2021) are listed: average linear weight parameters, average fatness coefficient according to Fulton (0.944) indicate a high fattening of fish. Size and weight composition of females and males, age-related fluctuations in length and weight, comparative analysis of atherina concentrations, characteristics of atherina reproduction in the conditions of the Northern and Middle Caspian, fecundity of different age groups, quantitative distribution of roe, larvae and fry of atherina, as well as dynamics of the age composition from catches prove a satisfactory state of stocks of this fish species. Comparative analyses of autumn concentrations of atherina in the Middle Caspian in 1958–1963 and in 2018–2021 are presented, as well as spp/h of trawling, age-related fluctuations in the length and weight in the autumn period (2016–2021). It has been found that atherina in the Caspian Sea is the main object of by-catch when fishing for kilka with stationary seines (in average 56.3 tons per year); it plays an important role as a food component for many fish species (sea herring, sturgeon) and mammals (Caspian seal) living in the waters of the Caspian Sea. Prospective volumes of processing atherina for fishmeal are also considered for the first time. On the scale of the Caspian Sea, with intensive kilka fishing by stationary seines as by-catch, it is possible to catch atherina in the amount of 150–200 tons. Despite the small volumes, they would significantly cover the deficit in the fish feed. Due to the increasing population of atherina in the natural conditions it is required to actively involve atherina in the fishing processes of the organizations in order to maximize the development of the commercial stock.

The aim of the paper is a qualitative assessment of the stock of long - clawed crayfish on the basis of the indicator approach. Methods used: indicator approach of qualitative stock assessment, methods of descriptive statistics, regression analysis. Novelty: a qualitative assessment of the stocks of long - clawed crayfish in the Astrakhan region by the indicator approach has not been previously carried out. Result: Qualitative assessments of the state of the stock of long- clawed crayfish in the Astrakhan region in 2016-2020 were obtained. The results of the assessments showed that in 2016, 2019 and 2020 its stock in the Astrakhan region was in an uncertain state (an integral assessment showed no dynamics in the state of the stock for the worse or better), and in 2017 and 2018 - in the alarming state (the integral assessment showed a negative trend in the state of the stock). The final integral assessment made it possible to formulate recommendations for the further exploitation of the stock of this species of hydrobiont. Practical significance : this study represents the application of the indicator approach in the biological sub -stantiation of the assessment of the total allowable catch of long - clawed crayfish in the Astrakhan region.