RECOMMENDATIONS OF MAXIMUM PERMISSIBLE VOLUMES OF RELEASE OF AQUATIC BIOLOGICAL RESOURCES: REGULATORY REGULATION AND PRACTICAL IMPLEMENTATION

The addition of natural reproduction of hydrobionts by the fish farming to provide a fishery resources and preserve the biological diversity of water ecosystems. Fish farming based on scientific recommendations in Russia according to federal legislation. The need to develop scientific recommendations has been related to the fact conditions of each water body determine the number of fish juveniles that can be provided with conditions for their growth. Currently, the term "maximum permissible volumes of release" (PDOV) used in regulatory documents governing the development of recommendations for fish farming. At the same time, the definition of this term is not given in the legislation, which implies its interpretation. The lack of explicit wording of the term makes it possible to use a variety of approaches and methods in the preparation of recommendations. Аs expected, the use of different methods gives different results. There is debate about the eligibility of applying different approaches when discussing the results, since each expert has a different view on the problem of determining the maximum permissible number for release. This situation indicates the need to approve unified methodological approaches to assessing the maximum permissible number of fish juveniles to release. It is necessary to supplement governing document with provisions in which, based on the availability and quality of available information on the reproduction conditions and the feed base of juvenile fish, existing methodological approaches to determining the maximum permissible number for release, various levels of information support can be distinguished to substantiate the maximum permissible number of fish juveniles.

Monitoring the Milwaukee Harbor breakwater : an Engineering With Nature® (EWN®) demonstration project

The US Army Corps of Engineers (USACE) maintains breakwaters in Milwaukee Harbor. USACE’s Engineering With Nature® (EWN®) breakwater demonstration project created rocky aquatic habitat with cobbles (10–20 cm) covering boulders (6–8 metric tons) along a 152 m section. A prolific population of Hemimysis anomala, an introduced Pontocaspian mysid and important food source for local pelagic fishes, was significantly (p < .05) more abundant on cobbles versus boulders. Food-habits data of alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) provided evidence that H. anomala were a common prey item. Night surveys and gill netting confirmed O. mordax preferred foraging on the cobbles (p < .05) and consumed more H. anomala than at the reference site (p < .05). H. anomala comprised a significant portion of the diets of young-of-the-year (YOY) yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris) caught on the breakwater. The natural features’ construction on the breakwater increased the available habitat for this benthopelagic macroinvertebrate and created a novel ecosystem benefiting forage fish and a nursery habitat benefiting nearshore game fish juveniles. These data will encourage the application of EWN concepts during structural repairs at other built navigation infrastructure.

EVALUATING CONDITIONS AND EFFICIENCY OF AQUATIC BIOLOGICAL RESOURCES REPRODUCTION IN LAKE TSATSA UNDER ANTHROPOGENIC LOAD ON LAKE ECOSYSTEM

The paper presents for the first time the results of long-term observations of the conditions and efficiency of the natural reproduction of aquatic biological resources in Lake Tsatsa in-cluded in the Sarpinsky lakes system. In a comparative aspect, the data from studying the commercial fish natural reproduction during 2016-2019 are presented (according to the juvenile fish yield). There has been considered the species composition, as well as the changes of juvenile abundance on the spawning grounds of Lake Tsatsa under different hydraulicity of spring floods during the observed period. The species composition of the main commercial fish juveniles is represented by 10 species. The most stable natural reproduction (high productivity of juveniles) was observed in roach, rudd and perch. Over the entire observation period, the number of roach juveniles dominated by 1.23-3.87 thousand sp./ha. The abundance of pike perch, pike, silver bream and tench has also remained stable for four years, but with the lower quantitative characteristics. The analysis of data on the productivity of juveniles showed that the water regime had the most significant effect on the natural reproduction of carp in Lake Tsatsa. The efficiency of its natural reproduction increases significantly in a high-water year (by 6-32 times) compared with dry years. The influence of hydrological and temperature regimes on the efficiency of natural reproduction of commercial fish has been shown. The terms of spawning of the most abundant commercial fish species are given. The main factors of the anthropogenic impact affecting the ecosystem of Lake Tsatsa and reducing the abundance of the aquatic biological resources reserves due to their natural reproduction have been determined. The data obtained in the course of the research will help solving the problem of amending and supplementing the fishing rules, since there were no terms (periods) in the rules for placing a ban on catching aquatic biological resources for this reservoir

Estimation of natural reproduction efficiency of semi-anadromous and river fish species in inland water bodies of the Republic of Dagestan, Russia

Aim. Estimation of the natural reproduction efficiency and patterns of formation of fish stocks.Material and Methods. Collection of material was carried out in 2010-2019 in inland water bodies in Dagestan and its shallow Caspian Sea coastal zone. Estimation of the number of juveniles in rivers and canals was carried out using ichthyoplankton cone seines. Fry seines were used to count juveniles of fish in water bodies and in the coastal area. 470 samples of juveniles were collected and 5640 juveniles were analysed. The collection and processing of materials were carried out according to generally accepted methods.Results. The main environmental factors determining the productivity of fish juveniles in the study area in the long-term have been identified. During the observation period, juvenile fish of 15 species were recorded in spawning grounds of inland water bodies. Roach, bream, carp, crucian carp, rudd and vimba bream dominate. In terms of numbers, roach juveniles predominate: their relative proportion being 31.02% with an increase from 27.1% in 2010 to 35.4% in 2018.The second place was occupied by bream juveniles, whose average relative proportion was 12.1%. The third place was occupied by carp juveniles with an average proportion of 9%. Juvenile zander, catfish, pike and kutum are relatively low in abundance from 2 to 4%. The yield of juvenile fish in 2010-2019 decreased 1.7 times compared to 1990-1995.Conclusion. It was established that a decrease in the number of juvenile fishes occurs under the influence of unfavorable environmental factors: decrease in sea level; reduction in spawning areas; the shallowing and silting of migration routes due to the lack of a stable water supply. Measures are proposed to improve the living conditions of aquatic biological resources, aimed at increasing the efficiency of their natural reproduction.

To history of ichthiofaunistic research of Karkinitsky Gulf of the Black sea

The article is focused on the history of studing the fishfauna of Karkinitsky Gulf of the Black Sea in the XX–XXI centuries. There have been singled out three stages in studying fishfauna of the region: since the late 50’s of the XIX century up to the early 20th century. (K. F. Kessler); at the turn of the 20th century (expeditions of S. A. Zernov, later – researches of L. V. Arnoldi, V. A. Vodyanitsky, K. A. Vinogradov, etc.) up to the 60s of the 20th century; since 2008 to the present day (A. R. Boltachev, E. P. Karpova). Data on the fishfauna of Karkinitsky Gulf during a half-century period has been found insufficient: since late 50s of the 20th century up to the beginning of the 21st century. There has been shown the importance of Karkinitsky Gulf as a habitat for the rare protected fish species and the feeding area of valuable fish juveniles. The influence of anthropogenic factors over the past 50 years has been proved to cause qualitative changes in the composition of the fishfauna of Karkinitsky Gulf: degradation of the seagrass biocenosis in shallow bays caused by siltation due to the discharge of fresh water from the fields and rice paddies, and the replacement of native ichthyofauna by freshwater species. The importance of systematic studies in this area is emphasized to assess the status of the fishfauna of Karkinitsky Gulf

NEGATIVE ANTHROPOGENIC INFLUENCE OF COOLING SYSTEMS OF POWER PLANTS AND WAYS OF ITS OVERCOMING

The issues of the impact of the cooling systems of ship power plants on the fish resources of the seas and continental reservoirs are considered. Widespread open cooling systems consume intake water. The filters used are not capable of trapping plankton and fish juveniles. As a result, when passing through the system, they die almost completely. Consequently food chains are destroyed and the fish resources of the seas are reduced. Numerical estimates of the damage are given. It is shown that the problem can be solved by introducing closed cooling systems. The necessary methods for increasing the heat sink of systems have been developed. As a result, it becomes possible to significantly reduce the weight and dimensions of the systems, which contributes to their implementation in practice.

Color quality and antioxidant activity evaluation of clown loach juvenile, Chromobotia macracanthus Bleeker 1852 by addition of astaxanthin in diet

Botia or clown loach is the one of fishes was originated from Indonesia and as an ornamental fish commodity in the global market. Clown loach both nature and cultured have some problems when reared in aquaria that is the decrease of color quality. An innovation technology to improve color quality through diet formulates is needed. The aims of this research were to increase the color quality using astaxanthin in diet and to find out the role of astaxanthin as antioxidant in clown loach. The study consists of four treatments of astaxanthin dosages in the diet with isoprotein and isoenergy, namely 0, 50, 100 and 150 mg kg-1 with four replications. The fish juveniles with size of 3.44±0.51 cm and 0.56±0.02 g of weight with density of one fish per littre were used. The test diet was given three times a day during 60 days. The results showed that there were no significant differences antioxidant activity such as superoxide dismutase enzymes and malondialdehyde. However, there was a significant effect (P<0.05) to color quality of the chroma and total carotenoid, whereas no significantly different in lightness. The addition of astaxanthin was effective to improve the color quality of clown loach juvenile. Thus, 100 mg kg-1 of astaxanthin in diet is an optimal dose for clown loach juvenile.

FEEDING PECULIARITIES OF FISH JUVENILES DURING HIGH WATER LEVEL IN KARYMAI STREAM IN SUMMER 2018

The results of study on the food composition of juvenile fish during an anomalous flood in Karymai stream in summer 2018 are presented. The problem of the occurrence of an abnormally low supply of juveniles of most salmonids and the use of the maximum number of components for species survival under such conditions are discussed. Possible directions of the formation of interspecific food relations in fresh waters are considered.