Vol 21, No 2 (2020)
ОБЗОРЫ
131-155
Abstract
Information on age, size-weight structure, fecundity and sex ratio of four species of Pacific Salmon reproduced in Magadan region is presented. Changes in the structure of biological indicators for the first two decades (2001-2019) of the 21st century in the main populations of pink salmon, chum salmon, coho salmon and sockeye salmon are shown. The presence of wedge variability of dimensional-weight characteristics in pink salmon and coho salmon in latitude direction has been established. The pink salmon of an odd row of generations is characterized by a larger size-weight indicators. There has been an increase in average age in chum salmon populations compared to the early 2000s. A perennial prevalence of individuals with two freshwater years of life has been established in coho salmon populations. During anadromous migration, the size-weight indices of coho salmon decrease. Sockeye salmon is represented by limnophilic and rheophilic forms. Resident dwarf males and females are noted in limnophilic nerka populations.
ПРОМЫСЕЛ ГИДРОБИОНТОВ
218-234
Abstract
The paper describes current state of the northern shrimp stock assessment in the Barents Sea, as well as challenges in estimating total fishable biomass, carrying capacity and maximum sustainable yield. A comparative analysis of the results was carried out under various adjustments of the production model, including those used at the Joint NAFO/ICES Pandalus Assessment Working Group (NIPAG). The absolute stock assessment, as well as TAC assessment, as a derivative of the stock and its growth rate, in whole, depend not on the input data, but on our expert considerations about carrying capacity. This could be explained, primarily, by insignificant fishery impact on the stock against substantial interannual variation of the stock due to natural reasons. Besides, significant spatial variability of the area with numerous commercial aggregations complicates the stock modeling as a single population within stock-fisheries system. At the same time, it is possible to use trends methods instead of the analytical model without serious harm to scientific advice. In this case, the stock status could be assessed in the context of management requirements to ensure long-term sustainable exploitation, and the advice is provided based on a precautionary approach and maximum sustainable yield framework.
АКВАКУЛЬТУРА И ИСКУССТВЕННОЕ ВОСПРОИЗВОДСТВО
188-202
Abstract
The work presents the results of studies to determine the optimal weight and stocking density of juvenile pikeperch during transfer from pond to industrial growing conditions. It is shown that larvae with an average weight of 116 mg are better adapted to transfer from ponds to pools for artificial feed than juveniles weighing 627 mg. In both cases, pikeperch fingerlings reached the weight of 1 g in 25-31 days, but pikeperch juveniles with a lower weight had higher survival rates (up to 69% vs. 20-40%), growth (average daily increase of 7,3-8,4% vs. 2,6%) and stocking density (up to 12,0 individuals per liter vs. 3,2 individuals per liter). The decrease of stocking density to 2,3 individuals per liter and its increase to 12,0 individuals per liter determined a faster growth of juveniles in the pools in the first weeks of rearing than at a stocking density of 8,6 individuals per liter, which indirectly indicates an earlier adaptation of juveniles to new conditions and the transition to an artificial diet. The survival rate of pikeperch was also higher with a reduced (2,3 individuals per liter) and increased (12,0 individuals per liter) growing density - 69 and 45%, respectively, against 37% with the stocking density of 8,6 individuals per liter. The results of pikeperch rearing at the stocking density of 12,0 individuals per liter were characterized by the highest fish productivity - 6 g/l, which is 31- 67% more than in other versions of the experiment. The use of live feed (Artemia Nauplius) allowed to improve the adaptive properties of pond juveniles during their transfer to industrial conditions and increase their survival rate to 37%, against 23% compared to a one-time transfer of pikeperch to mono diets from artificial feed (with the same stocking density of 8,6 individuals per liter). The physiological analysis of pikeperch fingerlings grown in a combined (pond and industrial) way indicates the similarity of morphophysiological, biochemical and hematological parameters with pond juveniles, which indicates both the usefulness of the fish itself and the growing conditions for the needs of pike perch juveniles, including feed and feeding regimes.
203-217
Abstract
Based on a model describing changes in the number of fish generations during the life cycle, stocks and commercial returns received from young Amur sturgeon are calculated. The efficiency of its factory reproduction in comparison with sturgeon of the Volga - Caspian basin is estimated. The influence of spawning frequency and fishing mortality on the stocks formed from young fish and the resulting catches is studied.
ДИНАМИКА ЧИСЛЕННОСТИ
235-249
Abstract
A cohort population dynamics may be represented as a hidden Bayesian model with abundances as hidden states and catches as observations. Using these models, one can evaluate posterior densities and calculate such point-wise characteristics as means, medians, variances and so on. With rare exceptions (as linear Gaussian models), the recurrence equations met by the posterior densities have no analytic solutions. We describe several particle (Monte Carlo) methods that may be used for the density approximations and evaluations of their statistical quantities for nonlinear non-Gaussian models as well. The Fishmetica package was extended with functions for generating samples and masses for time series filtering, prediction, and smoothing. Evaluations in Julia were made for a test dataset with assumed Gaussian distributions of residuals and different numbers of particles. Numerical results were compared with known analytic ones.
METHODOLOGICAL ASPECTS OF FISHERY RESEARCH
250-262
Abstract
The article discusses new opportunities for obtaining and analyzing fisheries information related to the global implementation of positioning systems for vessels including those fishing for aquatic biological resources. Information on content of data transmitted in automatic identification system mode as well as on available Internet resources hosting such information is provided. Examples of use of vessel positioning data for research purposes and for the operational support of fisheries are presented.
BIOLOGY OF COMMERCIAL HYDROBIONTS
169-180
Abstract
The results of many years of fisheries studies in reservoirs Kursk region provides information about the characteristics of hydrologic-hydrochemical regime, the structure of planktonic and benthic communities and modern composition of the fish fauna of Zheleznogorsk, Stary Oskol and Kurchatov reservoirs. The long-term dynamics of net catches and catches of small fry is shown. A change in the structure of net catches was found depending on the mesh step of the applied nets. The fish part of the community of this group of reservoirs is quite stable and is represented mainly by eurybiont species of the limnophilic ecological group. An assessment of the negative impact of tilapia on the ichthyocene of the Kurchatov reservoir is given.
181-187
Abstract
The specific structure, number and growth of fingerlings of fishes during the summer period 2012, 2014 and in a foreshore of the Meshinsky gulf of the Kuibyshev reservoir depending on hydro-meteorological conditions is examined 2017. It is established that total number of types during the summer period in a foreshore equaled 20. Among them fingerlings of a kilka in 2012 and bleak in 2014 and 2017 were the dominating types, i.e. it were a la portionspawning species. The greatest value of size of an index of a specific variety of Shannon is noted in 2017 with a high number thresh also rather low value of an indicator of abundant. Productivity thresh fishes was defined by features of the mode of level and water temperature. Growth of fingerlings of fishes these years was defined by duration of the vegetative period at the bream and an bleak, and at a kilka length and body weight of fingerlings depended on number in the fish crop of its individuals from the first and second spawning.
ИСТОРИЯ РЫБОХОЗЯЙСТВЕННОЙ НАУКИ
156-168
Abstract
River-basin Yenisei white salmon research history is given for more than 100 year period, information about the herd structure, age and growth, puberty and fertility, nutrition, fishing, attempts of artificial reproduction. Notice that amplitudious anthropogenic influence significantly changed the ecotope of this species, fish stock and population size decreased noticeably by the beginning of the NNI century. River Yenisei inconnu population conservation activities chronology is given. Results presented about River-basin Yenisei inconnu fishrearing development, among others the possible juveniles release volumes.
ISSN 0234-2774 (Print)
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