Determination of effective standards for the introduction of fodder additive Aquatan in the diet of rainbow trut with a biological assessment of the influence on fisheries

In connection with the global tendency to prohibit the use of antibiotics in animal husbandry, the prospect of using in ichthyopathological practice preparations from plant materials, which are mostly non-toxic, rarely cause side effects, have an antibacterial effect against a wide range of pathogens of bacterial diseases, opens up. One of these preparations is the feed additive Aquatan (Farmatan Aqua) based on ellagitannins from sweet chestnut wood manufactured by Tanin Sevnica (Slovenia). The aim of this work was to study the effect of different dosages of Aquatan on the survival rate, the rate of mass accumulation and the growth rate of rainbow trout reared in the industrial conditions of the cage farm on the waste warm waters of the nuclear power plant and to assess the production and economic efficiency of the application. The tests were carried out for 34 days in February-March 2021 on the basis of an aquaculture cage farm of LLC “Fish Federation”, located in the water area of the waste canal of warm waste water of the Leningrad nuclear power plant (LNPP) in the area of the LNPP-2 industrial zone in the city of Sosnovy Bor, Leningrad Region. The object of the study is rainbow trout yearlings brought from different fish farms. A total of 247,131 specimens were planted, with an average weight of 156.5–235.7 g and a total weight of 43 950.67 kg. The main hydrochemical indicators of water at the enterprise for the trial period met the water quality requirements for growing salmon fish OST 15.372-87. The feeding was carried out with the production compound feed for salmonids of the firm Alltech® Coppens Supreme-22. In experimental cages, fish were fed with compound feed with the addition of the preparation Aquatan at various concentrations (1, 2, and 3 g/kg of feed); in the control, feed without additive was used. As a result of the experiment, a positive effect of the Aquatan additive in dosages of 2–3 g / 1 kg of feed on growth, mass accumulation, survival and feed costs was established, while when adding 1 g / 1 kg of feed, such an effect was not recorded.

Using binders for feed producing needed for aquaculture

The article is dedicated to binders, which are used as components of aquaculture feeds. It includes generalization results of modern scientific-applied stuff, mostly obtained by foreign researches, since this kind of information presented at domestic specialized journals in extremely small volume. An information about functional purpose for main feed components — protein- and oil-containing, antioxidants and some others — was presented. Binders impaction on aquatic feed attraction and it’s nutritional value was shown, general functional purposes for binding agents also explained. A small analytical description for Russian binder market presented, a modern classification for binders also was shown as well as main segments in feed market where these binders can be used. Differences in rheological characteristics of various binders and it’s interaction mechanism with feed components within granules are described. Significant differences between Russian and foreign methodologies, used for researching of structurally-mechanical characteristics of feed pellets, are indicated and needs in domestic and foreign analytical techniques harmonization was justified. This article includes results of foreign investigations, dedicated of binders applied using (such as starches, obtained from various raw sources, carrageenan, CMC, pectin, agar, gelatin and so on) while pelleted and extruded feeds production was summarized. Crayfishes, shrimps, sea urchins and fishes (gibel carp, olive flounder) were used for researching and were fed by feeds with these binders. The best kinds of binders and it’s most effective concentrations for feeds, used for various species was defined, impaction on fish farming efficiency also was studied for some of these binders. Needs for further researching works with binders for using in feed production industry was justified. English version of the article is available at URL: https://panor.ru/articles/use-of-binding-substances-in-the-production-of-mixed-feeds-for-aquaculture/74633.html

The growth intra-group variability of perch Perca fluviatilis L., 1758 (Percidae) from Vyacheslavsky Reservoir

The dates on back calculation of perch growth from Vyacheslavsky (Astana) reservoir located in the Akmola oblast of the Republic of Kazakhstan are presented. We studied 2 samples, separated by a time interval approximately equal to duration of one generation. The growth rates of perch in this water body are slower in comparison with previously studied populations. The calculated length of perch have changed little for four years. Sexual and generational variability of growth is not observed. There is a fairly high level of correlation between calculated parameters of body length in adjacent generations, which indicates the stability or insignificant variability of the habitat conditions of perch in the reservoir. It can also show of the immutability of the main influencing factors and their vectors of impact. Taking into account the fact that these factors are a negative, the growth rates of perch in reservoir show a tendency to decrease. Von Bertalanffy’s growth equation performed better in the 2015 sample. This was reflected in the coefficient of Poly-Munro growth efficiency and calculated (theoretical) weight growth. The decrease in the “quality” of population biological parameters indicates beginning of degradation within the group, possibly. But, now observed differences are still at an unreliable level and are characterized only as tendencies. Based on the logical analysis, the main reason for decline in growth rate was termination of commercial fishing, which upset the existing balance in the perch population and caused the so-called “neglect of fishing”.

Peculiarities of the course of bacterial diseases of rainbow trut in industrial farms of North-West Russia

Currently, in the Leningrad Region and the Republic of Karelia, trout farming is carried out mainly in cage farms, and in recent years, small closed water supply units (RAS) are gaining popularity and are actively used. In the first years of operation, outbreaks of serious infectious diseases occurring in the form of bacterial hemorrhagic septicemia, as well as toxicosis, were observed in such installations. In cage farms, a joint course of bacterial and parasitic diseases is possible. In the course of the work, 11 cage farms in the Leningrad Region and the Republic of Karelia were surveyed, as well as 4 RAS in the Gatchinsky and Luga Districts of the Leningrad Region. The manifestation of aeromonas bacterial and infection and trienophorosis in the cage farm was associated with the growing conditions — high water temperatures, lack of feeding, and the presence of a formed focus of invasion in the water source. In the spring-summer and summer-autumn periods in cage farms, the manifestation of myxobacteriosis caused by Flavobacterium psychrichila is possible. In summer, the danger is a bacterial infection proceeding as a bacterial hemorrhagic septicemia (pathogens — Yersenia ruckeri and Flexibacter columnaris). In autumn, outbreaks of pseudomonosis are possible in cage farms. The causative agent is Pseudomonas fluorescens. However, it is also possible to find Pseudomonas putida, which is more characteristic of cyprinids. In the RAS, the death of fish was caused by mixed infections. The causative agents are Yersenia ruckeri and Carnobacterium piscicola; bacteria of the genera Flavobacterium and Aeromonas. Such a complex of aeromonads with flavobacteria is characterized by increased aggressiveness and can cause a serious septic infection. Timely measures taken, including the normalization of housing and feeding conditions, as well as therapeutic and prophylactic measures, made it possible to suppress the development of infections, toxicosis and improve the condition of fish on these farms.

Overview of retrospective and modern data on arrival fodder organisms in lake Balkhash

The article analyzes the acclimatization work carried out, the current state of the food supply and the feasibility of introducing new food items. Lake Balkhash, in the first years of commercial development, was characterized by extreme poverty of the food base, especially the bottom fauna. During the period of planned acclimatization work, 1958–1965, 10 species of valuable food items were introduced into the reservoir. Many species, as expected, settled in the western part of the lake, where they not only expanded the species composition of bentonts, but also increased the feeding capacity of the reservoir — from 1.3 to 20 times. However, with an increase in salinity from west to east, the composition of benthos became poorer and its biomass decreased due to the gradual loss of mysids, corophiids, polychaetes and monodacnae from its composition. At the present stage, the biomass of zoobenthos in the eastern part of Lake Balkhash is 20–40 times lower than the indicators of the western part. To increase feed in Eastern Balkhash in 2012–2014. Experimental work was carried out on the survival in the Balkhash water of euryhaline invertebrates from the Aral Sea — polychaetes and bivalve molluscs. Based on the positive result, a biological justification was developed for the acclimatization of these invertebrates in the lake. Balkhash, but due to lack of funding, the work itself was not carried out. Within the framework of the above program, it is necessary to continue work on the introduction of brackish-water benthic organisms from the Aral Sea, as well as to ensure the feeding needs of juvenile fish throughout the growing season, there is a proposal for the introduction of Calanipeda aquae-dulcis Kritsch into the reservoir. Research on the issues raised in the article is funded by the Ministry of Ecology, Geology and Natural Resources of the Republic of Kazakhstan (Grant No. BR10264205,).

In vivo male african catfish sperm obtaining and evaluation for artificial reproduction

African catfish is a valuable unpretentious object of breeding. It is successfully grown in re-circulating aquaculture systems in mild climate areas. However, artificial reproduction of the African catfish has problems with the collecting of high-quality sperm for fertilization of eggs. Abdominal massage does not give results even after appropriate hormonal stimulation: sperm is released in a small volume, often with an admixture of urine and blood. At the same time, most spermatozoa are motionless. This is due to the morphological features of the gonad structure: the seminal tubules are of the percoid type, in which there are seminal vesicles that prevent sperm release. When breeding catfish, the method of slaughtering males is mainly used, followed by the extraction of gonads, their grinding and straining through gauze or a sieve. Therefore, an urgent task is to develop methods for in vivo male African catfish high-quality sperm collecting. This report shows the technique of gonadectomy and surgery techniques for extracting one or both gonads. General anesthesia was performed by immersing the fish in a solution of clove oil. The optimal dose of clove oil for anesthesia was determined as 0.10–0.20 ml/l. The surgical area was treated with an antiseptic solution. The skin was dissected and separated from abdominal muscles. After acutorsion of testicular vessels, the gonad was excised entirely, since with partial resection, the remaining part of the parenchyma oozes, causing inflammation of the abdominal cavity and impaired healing of the surgical wound. Intermittent octal sutures were applied separately to the peritoneum with abdominal muscles and skin to create additional anastomoses and prevent complications.

Application of probiotics in trout farms in North-West Russia

In recent years, various probiotic and immunomodulating drugs have been actively used in aquaculture. The group of probiotics includes preparations of the Vetom series, created on the basis of the spore-forming bacteria Bacillus subtilus and Bacillus licheniformis. Recently, a large positive experience has been accumulated in the use of Vetom 1.1 in fish farming. The drug is actively used in trout cage farms in Karelia and the Leningrad region. Vetom 1.1 was administered orally with food at a dosage of 50–75 mg/kg ichthyomass per day for 10 days. An improvement in the epizootic state of fish was observed: regeneration of the affected fins and branchial epithelium, normalization of the blood state. Biocomplex Multibacterin (previously in research — Multibacterin OMEGA-10) is a functional food based on lactobacillus (Lactobacillus acidophilus). The drug has a high antagonistic activity against microorganisms — pathogens of bacterial etiology, stimulates the synthesis of immunoglobulins, improves metabolic processes in the body of animals, and stimulates regeneration processes. Multibacterin is recommended for introduction into trout feed in case of toxicosis, bacterial and fungal infection at a dosage of 0.1 ml/kg of ichthyomass for 10 days. The study of the effect of the Multibacterin biocomplex on the state of rainbow trout of different age groups, reared under different conditions, was carried out. With the introduction of the probiotic Multibacterin into the feed, a decrease in the death of fish was noted to 9.5% versus 20% in the control. An improvement in the state of the branchial epithelium was revealed, and the development of the regenerative process on the affected branchial lobes was noted. These preparations help to maintain the immunity of fish and can be recommended for use in aquaculture.

Some aspects of fishery development of sturgeon hybrids in Russia. Part 2

With the development of commercial sturgeon breeding, creating hybrid forms of sturgeon fish in order to obtain a larger volume of gourmet marketable products is of increasing interest to fish farmers. The choice of objects for creating hybrid forms for commercial cultivation depends on the conditions and biotechnologies of intensive fish culture. One of the widely used technologies that can several times reduce the time for growing objects and receive viable juveniles and marketable products year-round is the technology using recirculating aquaculture system (RAS). With this cultivation technique, the advantage is given to species with high adaptive capabilities and growth intensity. The most popular objects for hybridization and creation of hybrid forms are beluga, sterlet, Siberian and Russian sturgeon, etc. Beluga is the largest representative of the sturgeon family. It reaches commodity weight (3–5 kg) against the background of natural temperatures within 2–3 years. The Sterlet is a pure freshwater form. It is an excellent object for cross-breeding with other sturgeon species, in particular with beluga to obtain a bester hybrid. The Siberian sturgeon grows most intensively at a temperature of 15–25°C, however, the growth persists at lower temperatures (1–10°C). The Russian sturgeon in artificial conditions reaches a marketable weight of 1.5–3.0 kg in the second-third years of cultivation. In order to facilitate the orientation of fish farms, fish farmers engaged in the production of commercial products, the article discusses the creation of hybrid forms of sturgeon fish in domestic and foreign aquaculture, provides their brief fish-breeding and biological characteristics when grown in fish farms of various types. Knowledge of the fish-breeding and biological characteristics of sturgeon fish species hybrids when grown in specific conditions will make it possible to successfully introduce them into the practice of commercial cultivation. English version of the article is available at URL: https://panor.ru/articles/some-aspects-of-fishery-development-of-sturgeon-hybrids-in-russia-part-2/74467.html

Changes in morphological and physiological parameters of adult marsh frogs at different phases of their feeding and breeding technology

The article discusses the possibility of keeping a marsh frog in a farm on the territory of central Russia to obtain delicious meat. For this, at different stages of keeping and after spawning, body weight and length, as well as hematological parameters, were studied. During the study, marsh frogs were kept in different conditions, depending on the season of the year, and fed on different foods. During the summer and early autumn, when kept in a summer enclosure in the air temperature range from 15 to 23 °C, when fed with natural food (live invertebrates) and fed with cultivated cockroaches and flour beetle, a positive increase and an increase in weight was observed. Hematological indices were slightly below the conditional norm, but the number of segmented neutrophils and eosinophils in frogs in the aviary turned out to be quite high, since the natural food they consumed could activate antiparasitic immunity. When the frogs were kept in an aquarium at an air temperature of 22 °C and fed only with cultivated food, the distribution of weight gain and plumb weight was approximately equal. After hibernation at 4 °C, the frogs lost a lot of weight and were placed in a special spawning pool. After hormonal stimulation of frogs with a mixture of drugs “chorionic gonadotropin” and “surfagon”, successful spawning was observed with 100% fertilization of eggs, while the plumb line was small and more uniform. A low number of red blood cells and a low hemoglobin were found in the blood. The total number of neutrophils in frogs kept in the pool decreased, and the number of monocytes increased by 3 times, exceeding the conditional norm by half, which may indicate a monocytic-macrophage reaction necessary for the resorption of remnants of reproductive products. There was also a rapid development of a conditioned reflex in frogs to feeding on a floating feeder, which is an important link in the mechanization of frog farms.

Prospects for the development of aquaculture in the southern regions of Russia

The article presents an analysis of the prospects for the development of aquaculture in the southern regions of Russia. It is shown that the volume of aquaculture in the southern regions of the country in 2020 amounted to more than 78.6 thousand tons, which is 24% of the all-Russian. The Southern Federal District is one of the three leaders in the production of aquaculture products, its volume amounted to 81.4 thousand tons in 2019 and 70.2 thousand tons in 2020. About 90.6% of aquaculture products were received in the Rostov and Astrakhan regions, Krasnodar Krai. The volume of commercial production in the Republic of Crimea has increased significantly (by 23%). Pasture aquaculture, pond and industrial fish farming, recreational aquaculture, and mariculture are promising areas in the federal District. There is a great variety of growing objects, these are both traditional species for the region and the country — carp, herbivorous, sturgeon, and pike, common and channel catfish, walleye, perch, pilengas, paddlefish, buffalo. In addition, shellfish farms are actively developing on the coast of Crimea. The prospects of interaction between fundamental, branch, university science and enterprises of the real sector of the economy are shown. In order to achieve sustainable development of the country’s aquaculture, it is necessary to strengthen state support measures, especially for small businesses and fish farming. At the same time, support should be provided not only at the state, but also at the regional level.