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Made available in DSpace on 2021-06-25T12:18:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The present study aimed to evaluate two different methods of artificial reproduction induction, and characterize the embryonic development ofSalminus hilarii. Different than observed for other tropical fish species, artificial reproduction induction followed by hand-stripping of gametes was considered unfeasible forS.hilarii, as no gamete fertilization was observed. However, females that were induced and spawned naturally presented a fertilization rate of 65.64 +/- 0.54%. With a mean temperature of 26.20 +/- 0.90oC it was possible to clearly distinguish a large perivitelline space at 14 min after fertilization (AF) and at 49 min AF more than 50% of the embryos presented two blastomeres, and these cleavages occurred until 1 h 54 min AF. The gastrula phase was characterized at 3 h 56 min AF, and blastopore closure was observed at 8 h 31 min AF. At 9 h 1 min, organogenesis started, with a clear distinction of the yolk mass, embryonic axis, cephalic and caudal regions; at 11 h 51 min AF the embryos already had advanced segmentation and a free tail. Total hatching occurred at 21 h 17 min and after opening the mouth, which occurred at 33 h 9 min, the larvae ofS.hilariipresented a strong and characteristic cannibalism. This information can be considered fundamental to improvingS.hilariiproduction in captivity and for collaboration with a conservation programme in the upper Tiete river basin. Univ Mogi das Cruzes, Nucleo Integrad Biotecnoi, Av Dr Candido Xavier de Almeida Souza 200, BR-08780911 Mogi Das Cruzes, SP, Brazil Univ Estadual Paulista Julio de Mesquita Filho CA, Ctr Aquicultura, Via Acesso Prof Paulo Donato Castaane S-N, BR-14884900 Jaboticabal, SP, Brazil Univ Sao Paulo, Inst Biociencias, Dept Fisiol, Rua Matao,Trav 14,321, BR-05508090 Sao Paulo, SP, Brazil Univ Sao Paulo, Ctr Biol Marinha, Rodovia Manoel Hipolito do Rego,Km 131,5, BR-11612109 Sao Sebastiao, SP, Brazil Univ Estadual Paulista Julio de Mesquita Filho CA, Ctr Aquicultura, Via Acesso Prof Paulo Donato Castaane S-N, BR-14884900 Jaboticabal, SP, Brazil FAPESP: FAPESP 2001/10483-1 FAPESP: 2008/57687-0 FAPESP: 2014/16320-7 FAPESP: 2017/06765-0 CNPq: CNPq 134451/2005-8

С целью повышения эффективности искусственного воспроизводства популяций ценных видов рыб разработаны новые методы управления их размножением, выживаемостью и ростом, которые представлены в виде изобретений. Для управления размножением производителей разработаны методы стимуляции и задержки полового созревания производителей осетровых и костистых рыб. Для стимуляции полового созревания были разработаны препараты изолированной передней и изолированной задней долей гипофиза. Их внедрение в осетроводстве позволило повысить степень их рыбоводного использования в среднем на 15% и достичь экономии гипофиза до 40%. Для задержки полового созревания производителей разработан метод их промышленного резервирования в среде критической солёности 4–8‰, причём как в морской воде, так и в растворах поваренной соли. Производственными испытаниями доказана возможность сохранения рыбоводного качества производителей и получения доброкачественного потомства в этой среде при верхних нерестовых температурах в течение производственно необходимых сроков. С целью заводского воспроизводства природных популяций промысловых рыб разработан метод управления их размножением триадой адекватных экологических факторов ‒ «критической» солёностью, температурой и освещённостью при видоспецифических пороговых воздействиях. На этой основе разработан полносистемный метод воспроизводства популяций ценных видов промысловых рыб (севрюги и Балтийского лосося), охватывающий все этапы заводской биотехники. Новый метод осуществляется путём массовой морской заготовки производителей, получения потомства в морских садках и, после заводского речного выращивания молоди до готовности к миграции, конечного доращивания в морских садках крупной жизнестойкой молоди. Для промышленного внедрения всей предложенной биотехники и круглогодичной аквакультуры разработаны системы водоснабжения рыбоводных заводов и рыбоводных хозяйств на основе внесезонного подземного гидрокондиционирования среды выращивания и на природно-промышленных принципах инженерной экологии. In order to increase the efficiency of artificial reproduction of populations of valuable fish species new methods for managing their reproduction, survival and growth have been developed, which are presented in the form of inventions. To control the reproduction of producers methods have been developed to stimulate and delay puberty of sturgeon and bony fish producers. To stimulate puberty preparations for the isolated anterior and isolated posterior lobes of the pituitary gland have been developed. Their introduction in sturgeon breeding made it possible to increase the degree of their fish farming use by an average of 15% and to achieve a pituitary gland economy of up to 40%. To delay the puberty of producers, a method for their industrial reservation in an environment of critical salinity of 4–8‰ has been developed both in sea water and in solutions of sodium chloride. Production tests have proven the possibility of preserving the fish-breeding quality of producers and obtaining benign offspring in this environment at the upper spawning temperatures during the production required periods of time. With the aim of factory reproduction of natural populations of commercial fish a method has been developed to control their reproduction by a triad of adequate ecological factors – “critical” salinity, temperature and illumination under species-specific threshold effects. On this basis a full-system method of reproducing populations of valuable species of commercial fish (stellate sturgeon and Baltic salmon) has been developed covering all stages of factory biotechnology. The new method is carried out by mass marine harvesting of producers obtaining offspring in sea pens and after the factory river rearing of hatchling until ready for migration the final rearing of large viable juveniles in sea pens. For the industrial introduction of all the proposed biotechnics and year-round aquaculture, water supply systems for fish breeding plants and fish farms were developed on the basis of off-season underground hydroconditioning of the growing environment and on the natural and industrial principles of engineering ecology.

Although ruffe (Gymnocephalus cernua) are widely distributed in Eurasia, in some regions (i.e., North America) ruffe are considered an invasive species. There have been no reports on artificial reproduction of this species. A study, therefore, was conducted to evaluate reproduction of ruffe with results of specimens captured from their natural habitat and cultured (F1 generation) specimens being compared. Spawning specimens from both stocks were treated with hormonal preparations: carp pituitary homogenate (CPH), Ovopel, Ovaprim and human chorionic gonadotropin (hCG) and results were analyzed by comparing response to the specimens of control groups. Spermiation outcomes and sperm motility of the captured and cultured ruffe were similar and with all hormonal treatments, there was a slightly greater sperm motility (55.6 %–57.1 %) in comparison to specimens of control groups (46.7 %–47.1 %). For captured specimens, there was no asynchronous development of oocytes, whereas in cultured specimens 32 % of females had asynchronous development of oocytes. The ovulation rate in specimens of all treated groups was 100 %, whereas specimens in the control groups did not reproductively mature and have ovulations. The latency time from time of hormonal treatments to initiation of reproductive functions depended on the spawning agent used and oocyte maturation stage and there was the shortest latency after using CPH and the longest with hCG treatment. The embryo survival and hatching rates varied with use of different hormonal preparations to induce reproduction: greatest hatching rates with hCG treatment (86.4 %–88.9 %), followed by Ovaprim (78.2 %–80.2 %) and least hatching rate with Ovopel and CPH treatments (66.0 %–67.1 % and 64.0 %–66.0 %, respectively).

Fertilization is one of the most important procedures in artificial reproduction and it directly affects the reproduction outcome. When there is optimization of fertilization, there can be a positive effect on subsequent reproductive processes and economic aspects of aquaculture. This study was conducted to determine time for which oocytes and sperm of barbel Barbus barbus retain fertilization capacity following placement in freshwater. Furthermore, the amount of ovarian fluid, excreted by fish during spawning with eggs (OFI; %) was determined, along with the chemical composition and effects on fertilization were determined. Gametes, ovarian fluid, and seminal plasma from barbel spawning specimens of the F4 generation were used to conduct the study. Ovarian fluid accounted for 14%–68% of contents of the mass released at spawning and post-spawning composition differed depending on whether hormonal treatments were utilized for control of reproduction. There was an association (R2 = 0.982; P = 0.000) between the pH of ovarian fluid and the barbel embryo survival rate. There was the greatest survival rate (>60 %) when the pH range of 7.9–8.4 and there was a lesser embryo viability when pH values were lesser or greater than values within this range (P

An alarming number of large mammalian species with low reproduction rates is threatened with extinction. As basic knowledge of reproductive physiology is currently lacking in many species, increasing the understanding of reproductive physiology is imperative and includes the development of novel artificial reproduction technologies. Despite the relatively comprehensive knowledge on molecular mechanisms underlying reproduction in livestock species such as cattle, pregnancy failures are likewise far from understood. Contrary to other wildlife species, the European roe deer (Capreolus capreolus) displays a remarkably high pregnancy rate. In parts, cattle and roe deer exhibit comparable features of preimplantation embryo development. Therefore, understanding the high fertility rate in the roe deer holds a great potential for cross-species knowledge gain. As the only known species among the artiodactylae, the roe deer displays a long period of embryonic diapause. The preimplantation blastocyst reaches a diameter of 1 mm only at around 4 months compared to around 13 days post estrus in cattle. The expanded blastocyst survives in a uterine microenvironment that contains a unique set of yet unidentified factors that allow embryonic stem cells to proliferate at low pace without impairing their developmental potential. Upon reactivation, intimate embryo-maternal communication comparable to those reported in cattle is thought to occur. In this review, current knowledge, parallels and differences of reproductive physiology in cattle and roe deer are reviewed. The roe deer is proposed as a unique model species to (1) enhance our knowledge of fertility processes, (2) define factors that support embryo survival for an extended period, (3) advance knowledge on embryonic stem cells, and (4) unravel potential implications for the development of novel strategies for artificial reproductive technologies.

Optimization of artificial reproduction, by increasing the survival rate of embryos and hatching rate, is of major importance for reducing genetic diversity, especially in fish captured from their natural habitat that subsequently spawn in hatcheries. The artificial reproduction of ide, Leuciscus idus (L.) was conducted in controlled conditions. The spawning agents included: different doses of human chorionic gonadotropin (hCG) that was compared with common carp pituitary homogenate (CPH), Ovopel – a commercial agent for induction of spawning that contains mammalian gonadotropin releasing hormone analogue (mGnRHa) with dopamine antagonists (DA): metoclopramide (MET) and Ovaprim – a commercial agent containing salmon gonadotropin releasing hormone analogue (sGnRHa) and a dopamine antagonists (DA): domperidone (DOM). There were no ovulations in females from control groups. There were no differences between the ovulation rates (90 %) or embryo survival (> 92 %) and hatching rates (> 91 %) when there was administration of hCG doses between 500 and 1000 IU/kg. When there was comparison of different spawning agents, the ovulation rate was 100 % for all treated groups. There were the shortest and longest latency times to the time of ovulation after administration of CPH (26 h) and hCG (79 h), respectively. The greatest embryo survival (> 93 %) and hatching (> 91 %) rates occurred as a result of hCG administration with these values being slightly greater than when there was treatment with Ovaprim. The association between latency time and hatching rate indicated that when there was a slower final oocyte maturation (FOM) there were greater hatching rates.

Surrogacy techniques allow for the birth of children who are then raised by parents who may have no genetic or biological connection with them at all. Italian legislation on medically assisted procreation bans such practices, under national criminal codes, and yet the intended parents’ ability to legally register children born abroad via surrogacy has not been affected by such legislation. Italian jurisprudence has acknowledged the parental status of same-sex couples, following the same path outlined by the European Court of Human Rights. The paper’s author elaborates on court decision n. 145/2018, from the Naples Court of Appeals, which has stated that surrogacy children may be connected to their intended parents merely by virtue of “mental” elements, based on affection, harmony and listening enjoyed by the child within the family setting. The author is critical of that view, in light of conflicting research findings on children growing up in same-sex families. In that regard, the author argues that even though homosexual couples may well turn out to be good parents, families made up of fathers and mothers still constitute the best scenario for the children, from a social perspective. It is however necessary for lawmakers to step in and better regulate an utterly sensitive area of law, one that might engender adverse repercussions on the children’s well-being, in terms of growth and psychological development, following their becoming part of homosexual families. (www.actabiomedica.it)

European eel Anguilla anguilla is among the highly valued species for aquaculture. Since its peculiar biology, it is not yet possible to complete the whole life cycle in artificial conditions and its supply depends entirely on wild catches. In the last 50 years this species has suffered a population reduction of 99 % mainly due to overfishing. In a conservation perspective, it is of fundamental importance to improve the aquaculture production of European eel, to avoid the extinction of this species and preserve its residual genetic variability, allowing at the same time the fulfilling of costumers request without increasing its harvesting pressure.In this study we aimed to deepen the knowledge about the mechanisms at the basis of reproduction of the European eel in semi-natural conditions, through direct observation of spawning behaviour and through the paternity assignment using microsatellite markers. The systematic and prolonged observation of the reproductive behaviour of European eel and the contextual parentage analyses we carried out for the very first time in this species on 39 adults and 432 F1 randomly collected. We contributed to unravel the sexual behaviour of this species in the most common artificial reproduction conditions (polyandry), and define the precise courtship sequence until the release of gametes, and the male-male hierarchy in courtship. We characterized for the first time three main types of male: dominant (the first who starts the courtship, and the one with the majority of F1 assigned), subordinate (which starts the courtship only in a second time and with a minor percentage of F1 ascribed) and ineffective (which sometime appears totally disinterested to courtship and has few F1 or none).The evidences here produced represent an important attempt for developing good reproduction practices of the critically endangered European eel, providing a good starting point for its future aquaculture production. Keywords: Anguilla anguilla, Aquaculture, Artificial breeding, Kinship analysis, Parentage assignment

Simple Summary This paper describes a technique of pneumatic stripping of whitefish (Coregonus lavaretus) eggs with the use of oxygen, nitrogen, and air. This study demonstrates that pneumatic stripping allows the collection of high-quality whitefish eggs. Moreover, we found that gas flow rates should not exceed 0.5 L∙min−1 to minimize post-spawning mortality in whitefish. The eggs obtained by pneumatic stripping using oxygen, nitrogen, or air had high hatching rates. We assumed that air stripping is a promising approach for improvement of the whitefish stripping procedure. Abstract We describe the technique of pneumatic stripping of whitefish (Coregonus lavaretus) eggs with the use of oxygen, nitrogen, and air. Eggs obtained via the traditional method (by pressing the abdominal surfaces) served as a control group. It was established that the gas flow rate during pneumatic stripping should not exceed 0.5 L∙min−1, since higher air flow resulted in increased post-spawning mortality. The pneumatic stripping method of egg collection was no faster than hand stripping; however, the time required per female was more consistent. It was found that the pH of the ovarian fluid obtained during hand and pneumatic stripping was not related to the success rate of fertilization. Pneumatic stripping resulted in a higher quality of collected eggs and a higher and more consistent hatching rate as compared with the hand-stripped samples, regardless of the gas used. The results presented here lead us to recommend the pneumatic method for obtaining eggs from whitefish, since it is a simple, reproducible method and improves the reproductive performance and developmental success of the fish eggs.

The study was conducted to evaluate reciprocal hybridizations in the African catfishes Clarias gariepinus and Clarias jaensis using artificial reproduction under controlled hatchery conditions. The results revealed that the highest fertilization (82.77%) and hatching (67.77%) rates were achieved in the hybrid cross female C. jaensis × male C. gariepinus (Fcj × Mcg). Deformed larvae rates ranged from 9.01 to 16.33%; the hybrid Fcj × Mcg recorded the lowest rate. Survival rates in the larval stage were higher than 80% whatever crossing considered. However, it was higher in the hybrid Fcj × Mcg unlike its homologous female C. gariepinus × male C. jaensis (Fcg × Mcj) which recorded the lowest value (81.70%). In the fry stages D32, survival rates were low than 65%. They were higher and comparable in parental cross Fcg × Mcg (57%) and hybrid cross Fcj × Mcg (61.67%). The lowest survival rate (41.16%) was recorded in parental cross Fcj × Mcj. The hybrid cross Fcj × Mcg expressed the highest growth performances close to those of parental cross Fcg × Mcg, unlike parental cross Fcj × Mcj. Size heterogeneity was greater in hybrids. In all crosses, the condition factor K was low (0.58 to 0.85%), the length-weight relationship was significant with determination coefficient R2 greater than 0.9. The growth was of the negative allometric type (with b less than 3). Positive heterosis has been recorded for both survival and growth at all stages of development. It was concluded that C. jaensis × C. gariepinus hybridizations are indeed possible and would contribute to improve Clarias fry production in captivity. However, the pure strains of Clariidae remain endangered in the natural environment.

The burbot (Lota L.) is one of the most promising freshwater new fish species for cold-water aquaculture. Due to the lack of availability of wild spawners, it is imperative to breed cultured spawners. In the present study, artificial reproduction of a cultured stock of burbot was carried out and then compared with wild fish reproduction results. Patterns of burbot final oocyte maturation were developed and they were compared during artificial reproduction of wild and cultured burbot. For the first time, a model of final oocyte maturation (FOM) was formulated in a hormonally stimulated female burbot. The relationship between the oocyte maturity stage is straightforward and, at a water temperature of 2 °C, progress by the next stage was observed in two-day intervals. This model was tested on a group of wild and cultured fish (generation F1) originating from the Vistula Lagoon (Northern Poland). In both cases, the very high utility of the proposed model in the artificial reproduction of burbot was confirmed. The fertilization was very high. In wild and cultured forms was similar and was over 95% (95.4 ± 0.3 and 95.3 ± 0.3 as mean ± SD for wild and cultured, respectively). The differences in the survival to eyed-egg-stage (92.2 ± 0.8 and 91.9 ± 0.7 for wild and cultured, respectively) and hatchability of eggs (91.1 ± 0.9 and 90.9 ± 0.8 for wild and cultured, respectively) were statistically insignificant. In summary, a cultured stock of burbot spawners can be successfully used for the stable production of the stocking material of this species.

Worldwide, there is a dramatic decline in freshwater eel populations (Anguilla spp.), resulting in an urgent need to improve eel management and artificial reproduction protocols. Unfortunately, eels in captivity do not reproduce spontaneously as they remain in a (pre)-pubertal state resulting from a strong neural blockage. Eel propagation is possible to some extent by applying extensive, expensive, unnatural hormonal treatments. However, the success rates are still far too low to support a sustainable farming industry, due to low gamete quality and low survival rates of larvae. Artificial reproduction of eels has been pursued for almost 80 years, and maturation protocols have changed little. In order to improve current protocols it is clear that a different approach towards stimulating sexual maturation is required. In many fish species, changes in external environmental cues, such as photoperiod and temperature, are crucial to induce gonadal recrudescence and development. Still, the natural triggers involved in the gametogenesis of eels are poorly understood. The time-keeping hormone melatonin is a well-known transmitter of external cues, and influences various physiological processes, including reproduction. In eels, we hypothesize that melatonin is an important key player in the regulation of sexual maturation. Thus far, its mode of action is still an area which needs to be explored. In this review, we provide an overview of the current knowledge of studied natural cues possibly affecting reproductive function and the plausible role of melatonin in the regulation of puberty in eels.

The objective of this study was to describe a standard universally accepted artificial culture protocol for zebrafish. Also, developmental stages of embryogenesis were also described. Because Zebrafish are considered as a model organism and are widely used in biomedical research to study human genes and human diseases. Despite this, the artificial reproduction of zebrafish is poorly described, and there is not any standard universally accepted artificial culture protocol. To satisfy the scientist working in the biomedical area, a standard culture method of zebrafish under controlled laboratory conditions must be developed. The present study was conducted at the Aquaria Research unit of Marine Sciences and Technology Faculty of Iskenderun Technical University, Iskenderun Turkey, from March 2018 to October 2018. Spawn traps and gravels are not used for spawning of broodstock. Female and male broodstock were selected from our previously cultured stock, based on their swollen abdomens. Mean body lengths for female and male were 3.34±0.40, 2.97±0.3 cm and the mean weights were 0.38±0.14, 0.25±0.27 g, respectively. First eggs were squeezed from the ovaries then milt was taken from the testes onto the eggs. Fertilisation was done artificially by the dry method. The eggs hatch within 4-5 days at 28±1°C. The mean diameter of eggs and fecundity were measured using a micrometre attached to a microscope. During the experimental studies, the water quality parameters were also maintained at optimum. In the present study, temperature and pH were maintained at 28±1°C, and 7.28 respectively and which were the best for reproduction of zebrafish. Fecundity differed widely between individuals, and the number of eggs ranged from 7 to 110. The average diameter of the eggs ranged from 405± 0,001 to 570 ± 0,001 µm. Mainly seven developmental stages of embryogenesis were described; the zygote, cleavage, blastula, gastrula, segmentation, pharyngula and hatching stages. The results of the present study suggest that with the right artificial culture conditions and proper manual stripping, the required number of eggs and embryos for biomedical research can be easily obtained.

Patagonian blenny (E. maclovinus) is a marine species recently placed in captivity and which are potentially farmable. Understanding and improving its sperm capacity to withstand short-term storage conditions is a key element of initiating an artificial propagation program for this species. The aim of this study is to evaluate the ultrastructure and quality of E. maclovinus sperm during refrigerated storage. To address this objective, scanning electron microscopy (SEM), cytofluorimetric analysis (membrane integrity; reactive oxygen species generation; mitochondrial membrane potential) and cell respiration/mitochondrial-function analysis (ATP content; oxygen consumption) could be useful for optimizing or improving management for artificial reproduction of this species. Severe damage of plasma membranes was observed by SEM at day 7 and 14 of in vitro storage. Analyses of sperm quality were conducted during the 14-day cold storage period when sperm were in diluted (with Cortland solution) and undiluted conditions. When there were diluted conditions, there was greater preservation of motile capacity (from day-7; P 0.05), membrane integrity (from day-7; P 0.05), mitochondrial membrane potential (from day-10; P 0.05) and ATP stores (from day-3; P 0.05). Oxygen consumption indicators were 18.6% ±14.7% greater in the undiluted samples from day-3, and 32.1%±2.1% of the total spermatozoa had ample amounts of superoxide anion in both undiluted and diluted semen on day-0. The use of Cortland solution extended the viability of sperm when there were longer storage times. Factors that have a greater effect on the quality of semen during storage are reactive oxygen species generation and ATP depletion. In conclusion, Patagonian blenny spermatozoa can be stored at 4 °C between 7 and 10 days using Cortland solution.

The elimination of egg stickiness is required for effective artificial reproduction of northern pike, but until now, available methods have required at least 40 min. Sodium hypochlorite was tested under laboratory conditions, and exposure to aqueous concentrations of 0.025-0.05% for 40 s effectively eliminated stickiness without adverse effects. Fertilization and hatching rates in laboratory trials were similar to those observed in eggs treated with traditional methods using clay or milk for 40 or 60 min, respectively, as well as those without treatment. Testing using conventional hatchery incubation techniques did not reveal differences in fertilization rates, while the number of hatched larva was significantly higher in eggs treated with sodium hypochlorite vs. clay. Eggs treated with sodium hypochlorite retained transparency, which facilitated monitoring of embryo development.

Purpose. To determine main the technological parameters of artificial reproduction of sterlet (Аcipenser ruthenus) and Siberian sturgeon (Acipenser baerii) with a combined use of industrial aquaculture methods. Methodology. The material for the study were brood sterlet and Siberian sturgeon reared in cage conditions in a water body with natural temperature regime of the forest-steppe of Ukraine. The experiments were performed at a regulated water temperature regime at different periods of the spring (March-May) with the use of natural gonad-stimulating hormones for the stimulation of the maturation of sexual products in fish. During the process of the preparation of brood fish for fish breeding works, a recirculating water supply facility was used. The determination of technological parameters and study of physical-chemical factors of the environment were performed according to generally accepted methods. Findings . At a water temperature of 14-16оС, high efficiency of gonad maturation was observed in sterlet and Siberian sturgeon females with mean weight of 2.8 and 11.6 kg, respectively. The mean weight of eggs obtained from the brood fish was 0.45 kg in sterlet and 1.48 kg in Siberian sturgeon. The mean working fecundity was 43.29 thousand eggs in sterlet and 83.75 thousand eggs in Siberian sturgeon at a relative working fecundity of 15.44 and 7.49 thousand eggs/kg of fish body weight, respectively. During the process of egg incubation, development of fish embryos at the gastrulation stage was on average 87.17% in sterlet and 84.50% in Siberian sturgeon. The output of free embryos of both species from the quantity of embryos on the stage 15 of embryonal development was close to 83-84%. Originality . Peculiarities of the production of embryos from brood sterlet and Siberian sturgeon with a combined use of different methods of industrial aquaculture in the conditions of a sturgeon farm of the forest-steppe physical-geographical zone of Ukraine have been studied. Practical value . The results of the study are of interest for the devolvement of modern methods of sturgeon aquaculture in the conditions of an industrial type farm.

In this research we evaluated simple aspects of the sperm biology of Genypterus blacodes, in particular assessing the effects of pH (6, 7, 8 and 9), temperature (4, 8 and 16 °C) and osmolalities 100% sea water (1010 mOsm/kg, Control), 75% sea water (774 mOsm/kg, T1), 50% sea water (488 mOsm/kg, T2) and distilled water (0 mOsm/kg, T3)) on the motility of Genypterus blacodes intratesticular spermatozoa.In addition, we determined the fertilization rate. Our results show that G. blacodes spermatozoa have a sperm density of 5.35 ± 0.16 × 109 spermatozoa/mL. Sperm motility is initiated on contact with a hyperosmotic swimming medium under normal conditions (1010 mOsm/kg, pH 8 and 8 °C). The longest motility duration (432.48 ± 8.89 s) was recorded at 4 °C. The maximum percentage of motile cells was recorded at 8 °C (65.66 ± 4.95) at osmolality 1010 mOsm/kg, whereas an optimum was observed at pH 8. The fertility rate was 73.9 ± 17%. This is the first report on sperm motility of G. blacodes spermatozoa. In conclusion, the results of this study permit a baseline to be established for further research and protocols for artificial reproduction of this species to be developed and optimized. In addition, the information gathered in this research will be useful for developing the biotechnology of Genypterus blacodes. Keywords: Genypterus blacodes, Sperm motility, Osmolality, pH, Temperature

Prochilodus lineatus is a South American fish of great economic and social importance that is impacted by high fishing pressure. Restocking programmes have tried to be effective in recovering natural populations; however, genetic and reproductive methodologies are necessary to make feasible the survival of released fingerlings. The genetic variability of P. lineatus subjected to semi-natural and artificial reproduction was evaluated. Caudal fin samples from 25 breeders subjected to an artificial reproduction were collected at different sex ratios (1♂:1♀ and 2♂:1♀), and 138 fingerlings originated from these spawning. Similarly, samples were collected from 10 breeders (1♂:1♀) subjected to a semi-natural reproduction, and 70 fingerlings were generated from this spawning. Ten microsatellite loci were evaluated, producing 142 alleles. High interpopulation variability for broodstock and fingerlings was observed in both reproductive systems. A deficit of heterozygotes through the inbreeding coefficient (Fis) was obtained. Moreover, a deviation in the Hardy–Weinberg equilibrium of the fingerlings in both systems was detected. Fst values indicated a moderate genetic differentiation in 1:1 artificial reproduction system and low differentiation in 2:1 artificial and 1:1 seminatural reproduction system. Despite the high genetic variability, genetics analyses in the next generations of fingerlings will be necessary considering the likelihood of a decrease in genetic variability.

Under present conditions of depletion of natural resources and introduction of a moratorium for commercial sturgeon fishing there is a need to take urgent and radical steps in order to conserve the Caspian populations of these valuable species. Natural and artificial reproduction efficiency shall be improved in order to restore sturgeon population level in the Volga-Caspian basin. The analysis of the current state of natural sturgeon reproduction in the Volga river unregulated part has shown that due to a variety of reasons its efficiency has been minimized. The role and importance of artificial reproduction is increasing, yet in the last years its efficiency has been negated because of increasing deficiency of sturgeon sires in natural populations. Timely composition of productive stocks in the fish ponds of 6 Astrakhan region sturgeon breeding hatcheries allows to provide artificial reproduction fish-breeding operations with high quality spawns and milters within the conditions of their population’s decline in the natural habitats. The data on the quantity and the biomass of the sturgeon productive stocks at the Astrakhan sturgeon hatcheries prove that the prospects for developing artificial reproduction are possible only due to using stocks available at the hatcheries.

Embryonic development of lower vertebrates can be influenced by many factors, especially when outside of the mother's body and under the influence of variable abiotic and biotic factors. In this study, the effects of fertilization of post-ovulatory aged (overmature) oocytes of ide Leuciscus idus on the risk of developing anomalies in ide larvae were assessed under controlled conditions. There was a negative effect of delayed fertilization of post-ovulatory aged (overmature) oocytes in the ovary on the quality of offspring, which caused reduced survival 3 days post-fertilization and at the hatching stage (68.3 vs. 81.2% and 47.2 vs. 79.7% for the overmature and mature groups, respectively). It also increased the occurrence of numerous developmental defects (19.3 vs. 0.8% for the overmature and mature groups, respectively), including the development of Siamese twins. This is the first reported case of the occurrence of Siamese twins in ide. The ide Siamese twins look like hen eggs with 2 heads and are different from 'typical' Siamese twins in fish.

Understanding the effects of environmental factors on sperm motility characteristics can increase artificial reproduction efficiency in species that do not spawn naturally in captivity, such as Megaleporinus obtusidens. This study evaluated the effects of the osmolality (25, 85, 145, 205, 265, and 325 mOsm kg−1) and composition of activating solutions (NaCl, KCl, or fructose) on the percentage of motile sperm, and the swimming velocity and path straightness of M. obtusidens spermatozoa. The concentrations of major ions in the seminal fluid were also assessed and Na+ (74.46 mmol L−1), K+ (37.24 mmol L−1), and Cl− (114.29 mmol L−1) were the most abundant. When the activating solution was hypertonic (325 mOsm kg−1) compared to the seminal fluid (293 mOsm kg−1), sperm motility was completely inhibited. A wide range of osmolalities that initiated sperm motility were identified for all three solutions. Both, the percentage of motile sperm and the motility duration were reduced (P 50%) up to 40 s after activation and the motile phase lasted for >50 s, regardless of the activating solution composition. Over the postactivation time, the curvilinear velocity and straightness were similar (P > .05) for fructose and NaCl solutions, whereas KCl solutions induced a higher (P

In this study the comparison of spontaneous and hormone-induced reproduction of burbot under controlled conditions was made. During the first two years of the study, burbot spawned spontaneously and artificially after hormonal treatment. The application of sGnRHa resulted in a 100% ovulation rate within 4 to 5 days. Over the 20 days of the experiment, in both years, 65% of females (13 from 20) spawned spontaneously. The biological quality of eggs, expressed as a percentage of live embryos (58.6–60.3%), was generally lower than in only hormone-induced spawned groups (84.2–89.2%). The embryo survival in groups spawned spontaneously decreased in time during the spawning season. Hormonal stimulation of non-ovulated females caused 43–57% of ovulation but with low embryo survival rates (34.2–44.2%). In the third year of the study, 55% of females ovulated spontaneously during the first 10 days of the experiment. Stimulation of non-ovulated females resulted in final oocyte maturation and ovulation in 78% of females. The embryo survival rate was higher (63.2%) than in fish stimulated hormonally after 20 days of spontaneous spawning (but not after 10 days). The application of hormonal treatment in burbot reproduction under controlled conditions shortened latency time, synchronized final oocyte maturation and resulted in high embryo survival rate.

In this study, 12 samples of chum salmon from the southern and central parts of Primorye were studied with ten microsatellite loci. All studied localities of chum salmon of Primorye formed three main genetically different groups: (1) the Narva–Barabashevka–Ryazanovka cluster of southern Primorye, (2) Kievka River, and (3) Avvakumovka River. The revealed genetic heterogeneity of chum salmon showed clear population structure in accordance with the geographical location of the samples. The study suggests that, for the purposes of artificial reproduction of chum salmon, it is desirable to perform egg planting with regard to the described population structure of chum salmon of Primorye.

Within the research of efficiency of Atlantic salmon the artificial reproduction, feeding rate, distribution and growth of farm-raised one-year-old Atlantic salmon have been examined. The fish has been released into nursery areas with different hydrological characteristics located in the Rivers Kola, Umba, Srednyaya and Akkim in the Murmansk region. The observations have being conducted for 1–5 months since the moment of fish release. In natural habitat, juveniles rapidly distribute downstream and upstream regardless of water temperature, depth and current velocity. In all examined nursery areas adapting one-year-old juveniles prefer to stay at weak current sites close to the shore, hiding in the gravel. In all the cases farmed parr shows high feed rate, but qualitative composition of their food differs significantly from food composition of wild juveniles. Revealed peculiarities of adapting parr's distribution and qualitative food composition indicate the impact of long-term rearing at hatcheries on fish behavior. Growth rate of one-year-old juveniles is arcwise connected with fraction composition of gravel and the level of bottom fouling: the bigger bottom rocks are and the thicker the fouling is, the more intensive fish growth is. The revealed correlations have been described with equations of linear regression. Connections between juvenile growth and water temperature, current velocity and depth of the area have not been detected. The research outcomes could provide a basis for scientific advice for planning release sites and number of released one-year-old Atlantic salmon by hatcheries in the Murmansk region.