An experience of obtaining mature eggs of the Siberian sturgeon (Acipenser baerii (Brandt, 1869)) in non-traditional period

Purpose. To investigate the peculiarities of obtaining ovulated eggs of the Siberian sturgeon in hatchery conditions in non-traditional (winter) period and determine major features of brood fish used for the experiments. Methodology. The material for the study were age-10+ Siberian sturgeon females with body weights of 6.20-8.24 kg grown in conditions of floating cages in a water body with natural temperature regime of the forest-steppe zone of Ukraine. The experiments were conducted with a regulated water temperature regime in the third decade of January with the use of natural gonadotropic drugs for the stimulation of egg maturation in fish. Brood fish were prepared for the experiment in the recirculating aquaculture system. Measurement of fisheries parameters and study of physicochemical factors of the aquatic medium were performed according to generally accepted methods. Experiment results were assessed statistically using standard software. Findings. With water temperature of 14-15оС, depending on the dosage of the gonadotropic drug, different efficiencies of gonad maturation in experimental groups of fish were detected. More than 85% of females matured after dosing of gonadotropic drugs 3.5 and 4.5 mg / kg. In the version with a minimum dose of gonadotropic substance 2.5 mg / kg responded positively to hormonal stimulation 57% of females. The average weight of eggs obtained in some groups of brood fish was 819.5-1079.0 g. Average working fecundity and relative working fecundity in experimental groups of the Siberian sturgeon females varied within 47.95-52.64 thousand eggs and 6.93-7.17 thousand eggs/kg of fish body weight, respectively. The duration of maturation after the second (resolving) administration of the gonadotropic drug until the moment of the occurrence of the ovulation process varied mainly within 15-20 hours. Originality. The peculiarities of obtaining mature eggs of the Siberian sturgeon with the use of methods of industrial reproduction of sturgeons, which are new for the aquaculture of Ukraine, were studied. Practical value. The study results are of interest for the development of modern methods of sturgeon aquaculture in conditions of fish farms of industrial type. Key words: brood Siberian sturgeon, industrial aquaculture, non-traditional technologies, eggs, ovulation, fisheries parameters.

Biochemical and hematological parameters of the roach Rutilus rutilus heckelii (Nordmann, 1840) from the Sea of Azov stock in the spring season of 2020–2021

This work presents the results of the investigation of the physiological state of the roach Rutilus rutilus heckelii breeders from the Sea of Azov stock during the spawning period. It has been established that, in the spring season of 2020 and 2021, the content of proteins and lipids in fish tissues, as well as hematological parameters in all investigated roach specimens from different water bodies were consistent with the average long-term values. The content of proteins in the muscles and liver of roach does not differ by sex. A higher protein content in the gonads of females is characteristic of the pre-spawning period due to the process of gonad maturation. The high content of lipids in the gonads of males apparently results from the lower energy consumption for maturation of the gonads and spawning. The average concentration of sodium and potassium ions decreased in comparison with the values obtained in 2020, while the concentration of chloride anions increased. It has been concluded that the physiological state of all investigated roach specimens was normal.

A Comparison of Reproductive Performances in Young and Old Females: A Case Study on the Atlantic Bluefin Tuna in the Mediterranean Sea

In the Mediterranean Sea, a demographic substructure of the Atlantic bluefin tuna Thunnus thynnus has emerged over the last decade, with old and young individuals exhibiting different horizontal movements and spatial–temporal patterns of gonad maturation. In the present study, histology and molecular reproductive markers were integrated with the gonad-specific mir-202 gene expression and ovarian localization to provide a comprehensive picture of the reproductive performances in young and old females and investigate the role played by the mir-202 during gonadal maturation. During the reproductive period, old females (>100 kg; 194.6 ± 33.9 cm straight fork length; 11.3 ± 2.7 years old) were found to have greater reproductive performances than younger females (<80 kg; 139.3 ± 18.8 cm straight fork length; 8.4 ± 1.1 years old) according to gene expression results, suggesting a prolonged spawning season, earlier arrival on spawning grounds and/or better condition in older females. The mir-202-5p showed no global changes; it was abundantly expressed in granulosa cells and faintly present in the ooplasm. On the other hand, the mir-202-3p expression profile reflected levels of oocyte maturation molecular markers (star, lhr) and both histological and molecular (casp3) levels of follicular atresia. Overall, old females exhibited greater reproductive performances than younger females, likely reflecting different reproductive dynamics linked to the physical condition, habitat usage and migratory behaviour. These results highlight the importance of preserving large and old females in the context of fishery management. Finally, the mir-202 appears to be a good candidate to regulate the reproductive output of this species in an autocrine/paracrine manner through either stage- or age-dependent processes.

Effects of GnRH and Anti-Dopamine on Gonad Maturation of Osteochilus melanopleurus (Bleeker, 1852)

The Osteochilus melanopleurus (Bleeker, 1852) is one of the endogenous fish in the Siak River waters of Riau province which has high economic value. However, the fulfillment of needs still depends on the catch in nature. Efforts to overcome these problems are the availability of mature gonads. Broadly to accelerate the maturation of gonads through hormone induction until the fish are ready to be spawned to produce fish fry continuously. The purpose of this study was to analyze the effect of gonadotropin and anti-dopamine hormone induction with the trademark “Oodev” on the final gonad maturity (TKG) of the prospective broodstock of O. melanopleurus. The research was conducted from April to August 2021 in the fish rearing column and the experimental pond, Faculty of Fisheries and Marine Science. The research method was a Completely Randomized Design with 4 treatment levels and 3 replications, while the treatments were P0 (without Oodev injection), P1 (Oodev dose 0.5 mL/kg), P2 (0.7 mL/kg), and P3 (0,9 mL/kg). Measured responses: percentage of broodstock that reached TKG and egg diameter. The results of the research that have been carried out, the measurement of the diameter of the eggs produced showed that the use of the Oodev hormone at a dose of 0.7 mL/kg body weight of O.melanopleurus given every week for twelve weeks was able to stimulate the development of the gonads of O.melanopleurus. Ovaprim injection of 0.7 mL/kg body weight produced 89,566 eggs with a latency of 4 hours. oodev injection dose of 0.7 ml/kg BW or P2 treatment has succeeded in achieving a TKG of 82%.

The dynamics of the liver weight and liver indices in the course of gonad maturation of gadid species on Eastern Kamchatka

Longterm data on the liver weight, hepatosomatic (HSI) and gonadosomatic (GSI) indices of walleye pollock, Pacific cod and saffron cod are analyzed on Eastern Kamchatka in seasonal aspect and in the course of gonad maturation. Individual values of the indices extensively vary and depend on the fish body length, season and stage of gonad maturity. The dynamics of the HSI is agree to the dynamics of the GSI during the year and depending on gonad maturity. The maximum values of the HSI are typical for walleye pollock and Pacific cod individuals with the gonads of the III stage of maturity. The maximum values of the index in saffron cod are found in mature individuals with immature gonads. The minimum values are demonstrated by the fish with the gonads at the stage of final spawning or of post-spawning recovery. During the annual reproduction cycle males and females of walleye pollock and cod realize different scenarios of spending and accumulating liver fat. Whereas the maximum HSI is observed in the fish with the gonads at the III maturity stage, the minimum values in males are typical for individuals with smelting gonads, and in females – on finishing the spawn. That can be connected to possible feeding for the individual. Liver weight and liver index can increase in males just shortly after finishing spawning, in females that is found only at the stage of post-spawning recovery.

Caractéristiques morphologique et histologique des gonades de Pseudotolithus elongatus (Bowdich, 1825) de la lagune Ebrié en Côte d’Ivoire

Pseudotolithus elongatus est un poisson régulièrement rencontré dans les débarquements de la pêche artisanale et commerciale pratiquée en lagune Ebrié. Cependant, en Côte d’Ivoire aucune étude n’a encore été menée sur cette espèce bien qu’elle ait une valeur commerciale élevée et qu’elle soit beaucoup prisée par la population. Du fait de l'intérêt commercial que présente P. elongatus, l'étude de sa reproduction est nécessaire si l'on souhaite assurer la pérennité de l’espèce et satisfaire le consommateur. L’étude de la morphologie et de l’histologie des gonades a été basée sur la taille, la forme, la coloration la présence ou l’absence d’ovocytes mûrs, le diamètre des ovocytes et l’observation histologique. Les résultats obtenus ont révélé six stades de maturation des gonades avec une gamétogenèse continue observée chez cette espèce. L’ensemble de ces informations contribueront à pérenniser l’espèce par une gestion rationnelle du stock. English title: Morphological and histological characteristics of the gonads of pseudotolithus elongatus (Bowdich, 1825), from Ebrié lagoon, Côte d’Ivoire Pseudotolithus elongatus is a fish regularly met in the landings of the artisanal and commercial fishing on Ebrie lagoon. However, in Ivory Coast no study has been conducted on this species although it has a high commercial value and it is very appreciated by the people. Because of the commercial interest of P. elongatus studying its reproduction is necessary if one wishes to improve operations in order to ensure the sustainability of the species and satisfy the consumer. The studies of gonads morphology and histology of Pseudotolithus elongatus was based on the size, shape, staining of the gonads, the presence or absence of ripe oocytes, the diameter of the oocytes and the histological observation. The results obtained indicate six stages of gonad maturation with continuous gametogenesis observed in this species. All of this information will contribute to perpetuate this species through rational management of the stock.

Early warming stress on rainbow trout juveniles impairs male reproduction but contrastingly elicits intergenerational thermotolerance

The exposure of adult fish to warm or high temperatures is known to impair reproduction, yet the long-term reproductive impacts for treatments at early life are not well clarified. This study aimed to evaluate the effects of warm temperature (WT) during juvenile stage on gonad maturation, gamete quality, and offspring thermotolerance in rainbow trout. While the comparison of basic reproductive parameters in WT females did not reveal any kind of impairment, many WT males showed an atrophied, undeveloped gonad, or a smaller testis with lower milt volume; sperm quality parameters in WT males and deformity rates in the respective progeny were also highly affected. However, despite of such negative effects, many of the remaining progeny presented better rates of survival and growth when exposed to the same conditions as those of parental fish (WT), suggesting that thermal stress in parr stage males elicited intergenerational thermotolerance after a single generation. The present results support that prolonged warming stress during early life stages can adversely affect key reproductive aspects, but contrastingly increase offspring performance at upper thermal ranges. These findings have implications on the capacity of fish to adapt and to cope with global warming.

Development of industrial scale reproduction in male sturgeons using Volga sterlet population as an example

The article describes special aspects of reproduction system development in male sturgeons using Volga sterlet population as an example (Acipenser ruthenus Linnaeus, 1758) within industrial enterprise of the Konakovskiy coarse fishery branch of the FSBSI Russian Federation Research Institute Of Fishery and Oceanography (VNIRO). The study results showed that gonad maturation stage I–II is completed at the age of 2 years if the total thermal constant is at least 11 thousand degree-days. Cytological sex differentiation occurs in the formed gland and begins at the age of three years if the thermal constant is more than 15 thousand degree-days. The onset of cytological differentiation can be determined by spermatogenesis waves characterised by intensive development of the male gonad III–VI maturity stages. Semelparity is typical for sturgeons, thus, the wave of spermatogenesis is seasonal, which indicates their limited participation in the spawning season at fish farms with natural water temperature. The knowledge of reproductive system development aspects in male sturgeons as illustrated by Volga sterlet population in the setting of industrial enterprise allows improving the practice of spermatogenesis process management at industrial farms ensuring the production of reproductive products of high fish-breeding quality at the time required for the enterprise. Considering the thermal constants made up by sterlet (males) spawners, it is possible to synchronise fish breeding processes (cycles) when receiving reproductive products from female sterlet and ensure repeated production of reproductive products from the same males in the settings of farms with controlled water temperature (throughout a calendar year). English version of the article is available at URL: https://panor.ru/articles/process-of-development-of-the-reproductive-system-in-male-sturgeon-in-industrial-conditions-on-the-example-of-the-sterlet-of-the-volga-population/68305.html