Marking fin spine of juvenile sturgeon (acipenseriformes: acipenseridae) using oxytetracycline and the comparing of growth performance

ABSTRACT This study aimed to describe and validate the formation of the rings in the spine of the pectoral fin and to determine the coherence of the OTC mark with the rings of three species of Caspian Sea sturgeon, the Persian sturgeon (Acipenser persicus), the Starry sturgeon (Acipenser stellatus) and Ship sturgeon (Acipenser nudiventris). Validation was achieved by comparing the total radius of the fin spine of fish of known age after one and two years of growth with the measured radius of the first and second rings in the zone. There was no overlap between the measured radius for the first year and the increase for the second. The Ship sturgeon showed the largest width of the second ring followed by the Persian sturgeon and Stellate sturgeon. The results indicate that the highest growth parameter belongs to the juvenile Ship sturgeon. This research showed that chemically marking the fin spines of juvenile Acipenseridae leads to unbiased estimates and contributes to the knowledge of the population dynamics of these species. The study found that the combination of the dial ring of the pectoral fin spine with growth validated the age estimation in juvenile sturgeon Ship, Persian, and Starry sturgeon.

Dietary magnesium requirement on dietary minerals and physiological function of juvenile hybrid sturgeon (Acipenser schrenckii♀ × Acipenser baerii♂)

Sturgeons are an economically important freshwater aquacultural fish in China and elsewhere. Research was conducted to study the magnesium requirement of juvenile hybrid sturgeon (Acipenser schrenckii♀ × Acipenser baerii♂) based on mineral composition, proximate chemical analysis, antioxidant enzyme levels, and growth metrics. Different levels of magnesium supplements (43.2, 157.3, 326.5, 549.6, 743.9, 938.4, and 1118.2 mg kg−1) were fed to juvenile sturgeon for 8 weeks. Five hundred twenty-five juvenile hybrid sturgeons (an average initial body weight of 7.65 g) were randomly divided into 7 groups with 3 replicates each (25 fish per replicate, tanks of 100×50×50 cm, dissolved oxygen ≥ 5.0 mg L−1, 12 light:12 dark) and fed 4 times per day with the experimental diets containing 40.78% crude protein and 10.03% crude fat. The body tissues and blood of fish were then sampled and analyzed. Growth performance was not significantly different between treatments (P>0.05). The optimal dietary magnesium requirement for hybrid sturgeon was estimated to be 355.16, 573.6, or 584.6 mg kg−1 dietary magnesium based on whole-body Mg retention, the whole-body or vertebrae magnesium content versus dietary magnesium levels. The whole-body calcium to phosphorus ratio of the 43.2 and 326.5 mg kg−1 groups was significantly higher than that of the 938.4 mg kg−1 group (P< 0.05). A dietary magnesium concentration of 350–700 mg kg−1 improved the antioxidant capacity by decreasing the serum malondialdehyde and enhancing serum superoxide dismutase, glutathione peroxidase, and catalase activities.

Testing of experimental feed for young Australian red-clawed crayfish that meets its nutritional needs

One of the relatively promising types of world aquaculture is the Australian redclawed crayfish, which is one of the relatively promising objects in warm-water aquaculture. Compared to other farmed crustaceans (shrimps, crabs), Australian crayfish is characterized by a high growth rate and unpretentiousness to the conditions of aging. In the process of cultivation of red-clawed crayfish, industrial granulated feeds developed for other types of hydrobionts (shrimps, fish) are currently used. In the presence of biotechnological standards for growing juveniles and commercial products of red-clawed crayfish, the question remains open about the lack of production of balanced specialized feeds for them. The purpose of this work was to test an experimental feed developed according to its own recipe for young Australian red-clawed crayfish. The main stages of the technology of preparation of the above feed are described. The experimental feed was compared with production dry feed according to the main parameters (qualitative composition, nutritional value, consumer characteristics). Taking into account the nutritional needs of crayfish in the main nutrients (protein, fat, fiber), three types of food were selected: for loricarium catfish, for juvenile sturgeon and experimental. In accordance with them, three variants of the experiment were laid down, where the conditions of maintenance (planting density, temperature and light modes, feeding frequency) were identical, except for differences in the type of feed. During the experiment, the main differences in the size and weight parameters of groups of juvenile Australian crayfish cultured using these feeds were revealed. The necessary conditions for keeping crustaceans in the laboratory and the scheme of their control are described.

Study of the osmotic regulation processing in the juvenile Persian sturgeon, Acipenser persicus. Borodin, 1897 in transfer directly to the Caspian seawater

The aim of this study was to transfer directly juvenile Acipenser persicus from freshwater to the Caspian Seawater (CSW). The fish in different age and size (weight (W) & length (L)) groups (I: 35days, W: 2.75±0.15g & L: 7.93±0.47cm; II: 50days, W: 3.15±0.12g & L: 8.31±0.28cm; III: 65days, W: 4.33±0.12g & L: 9.39±0.29cm; n=90 for each group) and in two different saline water (FW: <0.5‰ and CSW: 12.5‰) were investigated. The fish were transferred directly from FW to CSW. After 168 hours, blood samples were taken from the fish. The results showed that the survival in all groups in CSW was from 56% up to 76% and increased with increasing age and weight of fish. Some hematological parameters and levels of cortisol, osmolarity and ion concentration (Na+, K+, Ca+2 and Mg+2) in the plasma were determined. The functional levels of the mechanism of osmotic and ionic homeostasis were similar in all groups (P>0.05) but differed in experimental media (P<0.05). Significant differences were observed between the levels of plasma ion concentrations in different media (P<0.05). Plasma Na+, K+ and Ca+2 concentrations were higher than those of FW media, but lower than in Brackish water media (P<0.05). Plasma Mg+2 concentrations were lower than those of FW and Brackish water media (P<0.05). The Hct, Hb, MCV, MCH and plasma osmolarity decreased and MCHC and plasma cortisol levels increased with increasing salinity (P<0.05). But the number of WBC and RBC did not change (P<0.05) and reached a stable state. Therefore, it is possible to release juvenile sturgeon directly from FW to CSW with increasing weight and age.

The use of coniferous phyto-additives in the diet of sturgeons

The researches have been conducted on the study of coniferous phyto-additives as part of the compound feed for sturgeons. In this feed additive there is a biologically active component, consisting of the sum of the extractives of the woody green of the Scotch pine. Based on the studies, it can be concluded that the coniferous-energy feed additive has a beneficial effect on the intestinal microflora of juvenile sturgeon. The mass of fish at the end of rearing increased in the second group by 13.6 % (р < 0.001). The fatness ratio increased by 4.1%. Significantly increased the survival rate of fish in the experimental group: by 5.6 %. As a result of the use of phyto-additives, there was an increase in the level of profitability by 11.7 %.

MORPHOLOGICAL AND PHYSIOLOGICAL CHARACTERISTICS OF JUVENILE STURGEON REARED IN HATCHERIES OF THE ASTRAKHAN REGION

The article focuses on the study of changeability of morphological and physiological characteristics of 850 specimens of beluga ( Huso huso ) and sturgeon ( Acipenser gueldenstaedtii ) juveniles obtained at the Ikryaninskiy and Bertyulskiy sturgeon hatcheries in the Astrakhan region. There was determined weight of the body, heart, liver and spleen, as well as the relative mass of these organs - cardiosomatic, hepatosomatic indices and index of a spleen. Sturgeon juveniles were studied within 47-127 days, beluga juveniles within 40-116 days. Certain tendency was noted: cardiosomatic index decreased with aging in both sturgeon and beluga, i.e. the relative weight of the heart in ontogenesis changes inversely to the body weight, which corresponds to literature data. Comparison of the dynamics of the liver relative weight in sturgeon and beluga juveniles showed that it coincides at two segments: maximum raise to 50-60ths day from the birth and a gradual decrease in older juveniles. The value of spleen index in juveniles of both types rose with aging. It was found in the course of the study that the size of internal organs could change, getting smaller under unfavorable factors, in particular, when juveniles suffer from the lack of feeds. In such circumstances the dynamics of developing main internal organs drastically slows down, which reflects on physiological adequacy (quality) of juveniles. Thus, morphological and physiological indicators characterizing the degree of the vitals development can be used not only for characterizing species differences of the investigated group of fish at all stages of ontogenesis, but as important factor for assessing conditions of Russian sturgeons juvenile breeding and the degree of morphological and physiological maturity of the juveniles before releasing into the natural water body.

Dispersal and survival of stocked juvenile hatchery-reared Atlantic sturgeon (Acipenser oxyrinchus)

The post-stocking dispersal of juvenile Atlantic sturgeon (Acipenser oxyrinchus Mitchill) in the Wis3oka River (southern Poland) was investigated using biotelemetry. Thirty-five hatchery-reared juvenile A. oxyrinchus were tagged with radio or acoustic transmitters and tracked using mobile surveys and fixed receivers. Daily movement patterns were similar in 2009 and 2010. The sturgeon migrated with a mean speed of 1.42 km h-1 in 2009 and of 2.06 km h-1 in 2010. Migration rate was not regarded as being dependent on juvenile sturgeon size. The confirmed survival of individuals from the two field seasons differed slightly over the course of this study. Short-term survival of A. oxyrinchus was 86.7 and 90% in 2009 and 2010, respectively.