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Conditions of salmon reproduction in 2016–2020 are considered for seven Sakhalin fish hatcheries: Lesnoy, Taranaysky, Buyuklovsky, Firsovka, Lazovoy, Lublino, Okhotsky, with evaluation of water temperature, dissolved oxygen content, and qualitative and quantitative parameters of sanitary-indicative and conditionally pathogenic microflora in the water entered the hatcheries at the stages of eggs and larvae incubation and rearing of juveniles. Indirect indicators as morbidity and mortality of fish were used for the conditions assessment, as well. At all examined hatcheries, the water met requirements for water bodies suitable for fisheries by microbiological indicators. The water temperature and dissolved oxygen content provided rather favorable conditions for the salmon reproduction at all stages of the breeding cycle that was proven by normative values of fish mortality and absence of diseases. However, ranges of temperature and oxygen content at certain stages of chum and pink salmon breeding were wider than the optimal ones described in technological documents and scientific literature.

The aim of this study was to analyze the survival and growth of intergeneric (Acispenser ruthenus × Huso huso L.) sterbel hybrids obtained by fertilizing sterlet eggs with cryopreserved beluga semen. The rate of embryonic development did not differ between sterbel hybrids (experimental groups) and sterlets (control groups), and the hatching period was identical in all groups. The survival rate of hybrid larvae was higher in the experimental groups than in the control groups. Body weight and body length measurements revealed that sterbel hybrids grew at a faster rate than the control group sterlets. The hybrid origin of sterbels produced with the use of cryopreserved beluga semen was confirmed in a genetic analysis based on species-specific DNA fragments. To the best of the authors' knowledge, this is the first study to analyze the growth of sterbel hybrids derived from cryopreserved semen. The research findings indicate that this type of intergeneric hybridization delivers satisfactory results and can be applied in sturgeon aquaculture. [ABSTRACT FROM AUTHOR]

Conger eel (Conger myriaster) is an economically important species in China. Due to the complex life history of the conger eel, achieving artificial reproduction has remained elusive. This study aimed to explore the effect of water stimulation on hormonal regulation during the artificial reproduction of conger eel. The experiment was divided into four groups: A1 (no hormone injection, still water), A2 (no hormone injection, flowing water), B1 (hormone injection, still water), and B2 (hormone injection, flowing water). The flowing water group maintained a flow velocity of 0.4 ± 0.05 m/s for 12 h daily throughout the 60-day period. Steroid hormone levels in the serum and ovaries of conger eels were analyzed using UPLC-MS/MS and ELISA on the 30th and 60th days of the experiment. The relative expression levels of follicle-stimulating hormone (FSHβ) and luteinizing hormone (LHβ) in the pituitary were determined by quantitative PCR. The results showed a significantly lower gonadosomatic index (GSI) in B2 compared to B1 (p < 0.05) on the 30th day. FSH was found to act only in the early stages of ovarian development, with water stimulation significantly enhancing FSH synthesis (p < 0.05), while FSHβ gene was not expressed after hormone injection. Conversely, LH was highly expressed in late ovarian development, with flowing water stimulation significantly promoting LH synthesis (p < 0.05). Serum cortisol (COR) levels were significantly higher in the flowing water group than in the still water group (p < 0.05). Furthermore, estradiol (E2) content of B2 was significantly lower than that of B1 on the 30th and 60th day. Overall, flowing water stimulation enhanced the synthesis of FSH in early ovarian development and LH in late ovarian development, while reducing E2 accumulation in the ovaries. In this study, the effect of flowing water stimulation on hormone regulation during the artificial reproduction of conger eel was initially investigated to provide a theoretical basis for optimizing artificial reproduction techniques. [ABSTRACT FROM AUTHOR]

Carl Djerassi’s ‘An Immaculate Misconception: Sex in an Age of Mechanical Reproduction’ belongs to the science-in-theatre genre. The play revolves around the incidents in a reproductive biology laboratory and investigates the ethical implications of intracytoplasmic sperm injection, a pathbreaking scientific innovation in the field of assisted reproductive technology. In selecting key scientific themes as the subject matter of his literary works, Djerassi attempts to disseminate scientific ideas to a non-scientific audience. This is a significant step towards narrowing the gap of mutual incomprehension between scientists and non-scientists. [ABSTRACT FROM AUTHOR]

Introduction: The successful cryopreservation of common carp sperm is crucial for its application in aquaculture and selective breeding programs. This study investigates the efficacy of cryopreserving sperm in large containers (5 mL) with a low dilution rate (1:1) in three different cryoprotective media and thawing in different conditions. Methods: The developed method utilizes a low-ionic (hypotonic) cryoprotective medium, freezing with a controlled cooling rate, and high-temperature sperm thawing (60°C). The investigation employs a detailed spermatozoon motility assessment. Results: Post-thaw motility of 32.3% ± 14% and initial curvilinear velocity of 89 ± 20 mm/s across 30 males were observed. Principal component analysis of sperm kinematic characteristics revealed distinct populations of sperm cells exhibiting varying responses to cryopreservation. The developed method achieved successful fertilization comparable to that of the non-frozen control group using sperm from a single cryotube (2.5 mL, approximately 50 * 109 spermatozoa) to fertilize 200 g of eggs (1:120,000 egg:spz). Discussion: This novel approach demonstrates an effective cryopreservation protocol for common carp sperm in large-volume cryo-containers in combination with low-ionic cryomedia and high thawing temperature, providing methods well-suited for fisheries practices and selective breeding programs. Future studies of the biological properties of different sperm subpopulations in post-thaw sperm samples can contribute to a deeper understanding of sperm biology, improve cryopreservation techniques, and enhance the success rates of assisted reproductive technologies. [ABSTRACT FROM AUTHOR]

Abstract. Tench is one of the most valuable species in freshwater aquaculture. However, slow growth rate does not allow obtaining marketable products of this species on a significant scale, since it is currently used mainly as an additional object of aquaculture. The study on artificial reproduction consisted of two experiments and, respectively, was conducted during 2021 and 2022 in the incubation workshop of the Karpatskyi Vodohrai Fish Farm, located in the city of Pustomyty, Lviv Oblast. The objects of the study were mature age-4–7 brood tench and the sexual products obtained from them. In the first series of experiments, 2 females and 10 males were used in each experiment; in the second experiment, 5 females and 15 males, respectively. Common carp pituitary gland and a Hungarian synthetic analogue Ovopel were used as a hormonal stimulator during the spawning campaign in the first year of the study, while Prissian carp pituitary gland and Ovopel were used in the following year. The average individual body weight of females used in the study ranged 1.4 to 1.8 kg. At the same time, females produced more than 200 g of eggs that varied from 12.1% to 14.9% of the female’s body weight. In both experiments where the synthetic analogue was used as a stimulating drug, this value was higher by 2.8% and 2.1%, respectively. On average, 1 g contained 365.8 eggs, ranging 330–395 eggs. Accordingly, the industrial fecundity in the first experiment was in the range of 60.0–89.4 thousand eggs, with the average value 81.7 thousand eggs in Test I and 66.5 thousand eggs in Test II. In the second experiment, the variation range was 55.4–117.3 thousand eggs, with the average of 79.5 thousand eggs in Test I and 75.0 thousand eggs in Test II. On average, 48.6 thousand eggs were produced per 1 kg of the female's body weight in the first experiment and 51.6 thousand eggs in the second. The average weight of the males used in the experiments ranged from 728.0 g to 1,008.0 g. At the same time, the average ejaculate volume was 0.59 mm3 in the first experiment and 0.78 mm3 in the second. According to this parameter, the superiority of the males stimulated with the synthetic hormone was 11.1% in the first experiment and 7.4% in the second. The males stimulated with the common carp hormone had 3.8% higher rate of duration of active movement, while the males stimulated with the pituitary gland of the Prussian carp were, on the contrary, inferior by 12.2%. Fertilization rates in both experiments were higher in the experiments where the broodstocks were stimulated with the naturally occurring hormone. The superiority was 1.5% in the first experiment and 3.3%in the second. However, according to the survival rate, larvae obtained from the females stimulated with the artificial hormone had 10.9% higher rate in the first year of study and 2.3% lower in the second year. Therefore, the research results confirm the perspective of using preparations of natural and synthetic origin for the artificial reproduction of tench and contribute to obtaining viable fish seeds that can be used in the future to obtain marketable products or to release fish to natural water bodies so as to support natural populations for commercial, sport or recreational fishing.

Purpose. The main goal of the thematic review was the analysis and generalization of literary sources on the peculiarities of its biology, technological aspects of artificial reproduction and growing of vyrezub (Rutilus frisii frisii Nordman, 1840) for the restoration of its natural population in water bodies of Ukraine. To evaluate the perspectives of artificial reproduction and growing of vyrezub in aquaculture of Ukraine. Findings. As a result of human impact on river networks of Ukraine, the abundance of vyrezub significantly decreased, it has become a rare and at the same time an endangered species. According to retrospective data, vyrezub previously belonged to the widespread commercial species of the Dnipro and Southern Bug rivers. The biological features of this species have been analyzed, the observance of which can allow obtaining viable fish seeds in aquaculture conditions. The adaptive possibilities of vyrezub to artificial conditions of reproduction have been reviewed. Historical information on the reproduction of this species over the last century has been analyzed. On the territory of Ukraine, first attempts to artificially reproduce vyrezub were carried out by specialists of Ukrcherrybvod. According to the results of studies of Ukrainian scientists, several stages of artificial reproduction of vyrezub have been identified, namely: taking spawners from natural water bodies, obtaining eggs and sperm, incubation of eggs in incubation devices, obtaining 6 g fish seeds, release of viable juveniles into natural water bodies. However, the works on artificial reproduction of vyrezub were not successful, which was the reason for their complete cessation. In particular, this species is promising for growing in polyculture, as it does not create intense trophic competition with most objects of freshwater aquaculture, and as a result of the consumption of mollusks will reduce the likelihood of the spread of some invasive fish diseases. Practical value. The review of information sources on various aspects of the use of vyrezub in aquaculture will contribute to the development of a system of separate links of the technology of its cultivation for the needs of rearing in the conditions of aquaculture enterprises and stocking of internal water bodies with viable juveniles.

Recent loss of rhinoceros subspecies has renewed interest in using more advanced assisted reproductive technologies (ART) in rhinoceroses and elephants. Currently, only semen collection, semen preservation and artificial insemination (AI) have been used repeatedly with success in these species. Although ovum pick-up (OPU) and intra-cytoplasmic sperm injection (ICSI) have been reported recently in rhinoceroses, the techniques are not yet optimised. In contrast, multiple ART applications are routinely used in the horse. Since elephants and rhinoceroses share some reproductive features with equids, we postulate that procedures such as OPU, ICSI, in vitro fertilisation (IVF) and embryo transfer (ET), which are well established in the horse, may represent a basis to develop protocols for endangered pachyderms. In this review, we summarise current knowledge on reproductive physiology relevant to ART. We discuss the current state of ART in all three families and the requirements for the successful implementation of OPU, ICSI, IVF and ET in these species.

IntroductionThe successful cryopreservation of common carp sperm is crucial for its application in aquaculture and selective breeding programs. This study investigates the efficacy of cryopreserving sperm in large containers (5 mL) with a low dilution rate (1:1) in three different cryoprotective media and thawing in different conditions.MethodsThe developed method utilizes a low-ionic (hypotonic) cryoprotective medium, freezing with a controlled cooling rate, and high-temperature sperm thawing (60°C). The investigation employs a detailed spermatozoon motility assessment.ResultsPost-thaw motility of 32.3% ± 14% and initial curvilinear velocity of 89 ± 20 μm/s across 30 males were observed. Principal component analysis of sperm kinematic characteristics revealed distinct populations of sperm cells exhibiting varying responses to cryopreservation. The developed method achieved successful fertilization comparable to that of the non-frozen control group using sperm from a single cryotube (2.5 mL, approximately 50 * 109 spermatozoa) to fertilize 200 g of eggs (1:120,000 egg:spz).DiscussionThis novel approach demonstrates an effective cryopreservation protocol for common carp sperm in large-volume cryo-containers in combination with low-ionic cryomedia and high thawing temperature, providing methods well-suited for fisheries practices and selective breeding programs. Future studies of the biological properties of different sperm subpopulations in post-thaw sperm samples can contribute to a deeper understanding of sperm biology, improve cryopreservation techniques, and enhance the success rates of assisted reproductive technologies.

This study assessed the effectiveness of triploidy in tambaqui (Colossoma macropomum) and compared the fertilization, survival, growth performance, and hematological parameters of diploid and triploid fish. After artificial reproduction, freshly fertilized eggs were subjected to cold, heat or double thermal shock or were not exposed to the thermal shock (control group). Double thermal shock presented fertilization rate significantly lower than other treatments. Larvae submitted to cold thermal shock had a higher weight than the control and heat thermal shock treatments. The final weight of juveniles exposed to cold thermal shock was significantly higher than the other treatments with triploid induction. There was no significant difference for survival and hematological variables. The cold thermal shock produced more triploid individuals (33.33%) than the heat and double thermal shock (both 11.11%). The cold thermal shock was the most effective technique for obtaining triploid fish and it contributed to increasing the weight of tambaqui larvae. [ABSTRACT FROM AUTHOR]

Feeding features of juvenile muksun Coregonus muksun (Pallas, 1814) when growing in cages installed on the channel of the Lower Ob are considered. It was found that, along with artificial food, juveniles feed on zoobenthos and zooplankton organisms that enter cages during drifting, and consumption was noted from the first to the last days of rearing. The bulk of the food bolus was artificial food, 88.3–94.3%; aquatic invertebrates accounted for 1.3–5.7% of the weight of the food bolus where Chironomid larvae dominated. There were no statistically significant differences in the intake of invertebrates by young muksun before and after feeding (p = 0.442) at average values of 0.005 and 0.006 g, respectively. The ability of the transition of juveniles from artificial to natural food base at all stages of development was noted, which is an indicator of successful adaptation to environmental conditions during cage rearing in the channels of the Ob River. [ABSTRACT FROM AUTHOR]

The European eel, Anguilla anguilla (Linnaeus, 1758), is a species of high conservation and commercial value. Also, with a high aquacultural value, it was one of the most farmed species in Europe before its decline. Conservation measures for this species are currently being implemented, some of which are the release of adults to allow them to migrate to spawning grounds and artificial reproduction to minimise the impact of overfishing. Much progress has been made regarding the closing of the life cycle, but several problems remain to be solved, such as the weaning and growth of larvae. In this regard, the study of local populations and the identification of the best spawners could be a good way forward as it would help to identify spawners with high reproductive potential and good offspring quality. In this study, we compared the reproductive performance of female eels from migratory areas of the Northern Adriatic Sea at different maturation stages (10 pre-migrant stage; 10 migrant stage), treating both groups with the same hormonal protocol (weekly carp pituitary extract, injection of 17α,20β-Dihydroxy-4-pregnen-3-one at complete oocyte maturation). The research showed that eels at the beginning of metamorphosis (SI III), i.e., eels not yet ready to undertake migration, achieve reproductive performance equal to that of eels ready for migration (SI IV). Their performance was on par in both qualitative and quantitative terms. The optimal results in hatching (with values of 65.8 ± 3.2% for pre-migrant and 68.2 ± 4.1% for migrant) and survival rates (with value of 25.7 ± 5.4% pre-migrants; 27.2 ± 3.7% migrants), as well as the results about the time to reach full gonadal maturation, may have positive implications when considering release and restocking measures. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the survival and growth of intergeneric (Acispenser ruthenus × Huso huso L.) sterbel hybrids obtained by fertilizing sterlet eggs with cryopreserved beluga semen. The rate of embryonic development did not differ between sterbel hybrids (experimental groups) and sterlets (control groups), and the hatching period was identical in all groups. The survival rate of hybrid larvae was higher in the experimental groups than in the control groups. Body weight and body length measurements revealed that sterbel hybrids grew at a faster rate than the control group sterlets. The hybrid origin of sterbels produced with the use of cryopreserved beluga semen was confirmed in a genetic analysis based on species-specific DNA fragments. To the best of the authors’ knowledge, this is the first study to analyze the growth of sterbel hybrids derived from cryopreserved semen. The research findings indicate that this type of intergeneric hybridization delivers satisfactory results and can be applied in sturgeon aquaculture.

Copyright of Revista Veterinaria is the property of Universidad Nacional del Nordeste and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Southern black drum (Pogonias courbina) is a species distributed along the western Atlantic Ocean, and it is the largest Sciaenidae observed in the coast of Rio Grande do Sul state, Brazil. However, it is listed as a vulnerable species at The IUCN Red List of Threatened Species™, and their fishing is prohibited. The objective of this study was to determine the sperm characteristics of P. courbina. Sperm samples of five young males (two-year-old fish) were collected through abdominal pressure. The sperm kinetics parameters were sperm motility (MOT) 10.7 ± 5.6%, curvilinear velocity (VCL) 120.07 ± 16.16 mm s ± 1, average path velocity (VAP) 75.64 ± 23.78 mm s ± 1, straight-line velocity (VSL) 62.49 ± 15.83 mm s ± 1, straightness (STR) 83.9 ± 5.3%, wobble (WOB) 61.9 ± 12.7%, beat cross frequency (BCF) 42.981 ± 4.627 Hz and progression (PRG) 1,805.4 ± 564.5 µm. The proportion of normal spermatozoa was 35.6 ± 6.1%. About the abnormalities observed, 22.7% occurred in the tail (short tail = 0.6 ± 0.5%, distally curled tail = 2.4 ± 1.6%, strongly curled tail = 1.9 ± 1.3%, broken tail = 7.9 ± 5.1%, folded tail = 5.5 ± 0.8%, loose tail = 4.4 ± 1.9%); 14.2% occurred in the head (degenerate head = 4.2 ± 1.6%, microcephaly = 1.8 ± 2.5%, loose head = 8.2 ± 2.1%) and 27.5% of the spermatozoa showed cytoplasmatic gouts (proximal gout = 20.0 ± 8.4%, distal gout = 7.5 ± 2.8%). Besides that, a correlation analysis was performed between sperm morphology and kinetics parameters, and the spermatozoa were measured for the morphometric parameters. There was a positive correlation between BCF and normal spermatozoa (r = 0.9269). A negative correlation occurred between BCF and loose head (r = -0.9047); WOB and strongly curled tail (r = -0.8911); and PROG and strongly curled tail (r = -0.9191). The morphometric measures found for the head were length of 2.50 ± 0.21 µm and width of 2.12 ± 0.22 µm, and for the tail it was length of 37.97 ± 2.01 µm. It was possible to verify that the animals have sperm characteristics that indicate reproductive aptitude, but an abnormal behavior on sperm activation and high presence of the cytoplasmic gout abnormality indicates that the animals are not fully mature in their first reproductive season. This work contributes to a better understanding of the P. courbina spermatic parameters, what can be allies to recovery this species population in nature and promote its production in fish farms. [ABSTRACT FROM AUTHOR]

Aim. The aim of the study is to analyze the current state of artificial reproduction of the Caspian sturgeon and to identify the problems of reducing efficiency and ways to solve them.Discussion. The current critical state of the Caspian sturgeon, which accounts for up to 90% of the world's related resources, is of concern to the entire community, due to the threat of extinction of these relic individuals on the planet. This can be prevented by increasing the efficiency of reproduction. However, natural reproduction is practically reduced to zero, so the real and only possible solution is artificial reproduction. This analytical review presents five tasks, the successful solution of which will improve the current state of artificial reproduction in the Volga‐Caspian basin. The main task is the provision of fish breeding processes with producers, which, in the absence of fish of natural generation, are derived from brood stocks. Of particular concern is the threatened state of the Caspian beluga and stellate sturgeon. It is necessary to increase the release of their juveniles, for which financial stimulation of this activity is necessary. It is necessary to move more actively to the release of juveniles of an enlarged (7‐10 g) size and their export to feeding places in the waters of the Northern Caspian, which will contribute to an increase in fishing return.Conclusion. It is necessary to increase funding for research into the reproductive function of females and for artificial generation, as well as for the maintenance of production herds – a golden fund for restoring natural reserves. The attention of all the Caspian states should be drawn to the intensification of activities for the artificial reproduction of these unique fish species in the Caspian basin.

Artificial reproduction of pacific salmon in the Russian Far East, as a rule, is carried out with gross violations of scientific recommendations. Perhaps, that’s why positive and negative effects of the salmon farming largely neutralize each other. The following paradox is noted for the Far-Eastern basin: the salmon catches decrease in the areas where fish farming is active but increase in the areas where the salmon reproduction is almost completely provided by natural spawning grounds. Fishery, conservation of natural populations, and artificial reproduction of fish juveniles are still separate and disconnected spheres in Russia, largely due to general state of the national salmon economy.

Copyright of Veterinarska Stanica is the property of Croatian Veterinary Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simple Summary: In recent years, Kazakhstan has entered a period of rapid economic development, which will definitely lead to an increase in the anthropogenic pressure on natural resources. Subsequently, adequate measures must be taken to reduce the anthropogenic impact on natural resources, including the ichthyofauna. Therefore, the barbel was included in the Red Book of the Republic of Kazakhstan in 2008. Stocks of commercial fish valuable in the past such as barbels in the Aral–Syrdarya basin are now catastrophically reduced as a result of the anthropogenic impact on the ichthyofauna and natural environment of the Aral Sea region. Currently, the only way to restore the number of barbels is artificial reproduction, in order to preserve biodiversity and restore stocks of this valuable species in the natural environment and aquaculture. The current status of the barbels inhabiting the Kazakhstan section of the Syrdarya River needs special study, as has been noted since the second half of the 20th century. Stocks of commercial fish valuable in the past as barbels in the Aral–Syrdarya basin are now catastrophically reduced as a result of anthropogenic impact on the ichthyofauna and natural environment of the Aral Sea region. The study of the condition; abundance and distribution range is necessary to determine measures for their restoration in natural habitats and their breeding in fish farms. Research on the biotechnology of barbel breeding with subsequent acclimatization and reacclimatization of these fish species will not only improve the composition of the ichthyofauna of the Aral–Syrdarya basin, but also preserve the genetic potential of natural populations. At present, the only way to restore the population of the Aral barbel is stocking hatchery reared juveniles in natural environments. Under the current situation, a way forward is seen in the creation of domesticated replacement-broodstocks of barbels. As a result of the influence of anthropogenic factors, the populations of this species have come to almost complete degradation and depletion and require the development and adoption of urgent measures for their conservation and restoration through reintroduction, which is a priority and urgent task for the fisheries of the republic. [ABSTRACT FROM AUTHOR]

Tench is one of the most valuable species in freshwater aquaculture. However, slow growth rate does not allow obtaining marketable products of this species on a significant scale, since it is currently used mainly as an additional object of aquaculture. The study on artificial reproduction consisted of two experiments and, respectively, was conducted during 2021 and 2022 in the incubation workshop of the Karpatskyi Vodohrai Fish Farm, located in the city of Pustomyty, Lviv Oblast. The objects of the study were mature age-4-7 brood tench and the sexual products obtained from them. In the first series of experiments, 2 females and 10 males were used in each experiment; in the second experiment, 5 females and 15 males, respectively. Common carp pituitary gland and a Hungarian synthetic analogue Ovopel were used as a hormonal stimulator during the spawning campaign in the first year of the study, while Prissian carp pituitary gland and Ovopel were used in the following year. The average individual body weight of females used in the study ranged 1.4 to 1.8 kg. At the same time, females produced more than 200 g of eggs that varied from 12.1% to 14.9% of the female's body weight. In both experiments where the synthetic analogue was used as a stimulating drug, this value was higher by 2.8% and 2.1%, respectively. On average, 1 g contained 365.8 eggs, ranging 330-395 eggs. Accordingly, the industrial fecundity in the first experiment was in the range of 60.0-89.4 thousand eggs, with the average value 81.7 thousand eggs in Test I and 66.5 thousand eggs in Test II. In the second experiment, the variation range was 55.4-117.3 thousand eggs, with the average of 79.5 thousand eggs in Test I and 75.0 thousand eggs in Test II. On average, 48.6 thousand eggs were produced per 1 kg of the female's body weight in the first experiment and 51.6 thousand eggs in the second. The average weight of the males used in the experiments ranged from 728.0 g to 1,008.0 g. At the same time, the average ejaculate volume was 0.59 mm³ in the first experiment and 0.78 mm³ in the second. According to this parameter, the superiority of the males stimulated with the synthetic hormone was 11.1% in the first experiment and 7.4% in the second. The males stimulated with the common carp hormone had 3.8% higher rate of duration of active movement, while the males stimulated with the pituitary gland of the Prussian carp were, on the contrary, inferior by 12.2%. Fertilization rates in both experiments were higher in the experiments where the broodstocks were stimulated with the naturally occurring hormone. The superiority was 1.5% in the first experiment and 3.3%in the second. However, according to the survival rate, larvae obtained from the females stimulated with the artificial hormone had 10.9% higher rate in the first year of study and 2.3% lower in the second year. Therefore, the research results confirm the perspective of using preparations of natural and synthetic origin for the artificial reproduction of tench and contribute to obtaining viable fish seeds that can be used in the future to obtain marketable products or to release fish to natural water bodies so as to support natural populations for commercial, sport or recreational fishing. [ABSTRACT FROM AUTHOR]

Sichuan taimen (Hucho bleekeri), a critically endangered species, is listed as a first-class protected species in China. The natural population has been missing from most of its known distribution areas for many years but was rediscovered in the Taibai River in 2012, providing an important resource for the conservation stocking of the Sichuan taimen. In this study, 43 wild adult Sichuan taimen collected from the Taibai River were determined for gamete maturity for artificial reproduction using ultrasonography. The echogenicity of the gonads before and after hormonal induction was described to determine broodstock identification, injection dose of hormones, and spawning time. Four batches of artificial breeding were successfully achieved in 2013, 2014, and 2016. Broodstock (19 females and 16 males) spawned with average fertilization and hatching rates reaching 80.2% and 61.0%, respectively. This study demonstrates that ultrasonic imaging is a convenient and efficient method to track the state of gonads of mature Sichuan taimen during artificial reproduction, which will assist in broodstock cultivation, and further large-scale proliferation and effective resource restoration of the Sichuan taimen. [ABSTRACT FROM AUTHOR]

Simple Summary: Sturgeon (Acipenseridae) fish are a valuable fish in aquaculture not only because of the taste of their meat, but also because of the caviar obtained from the production process. Sturgeon species differ from teleosts in the main stages of the life cycle, in particular embryonic development. Therefore, research regarding the controlled reproduction and egg incubation are key during breeding and hybridization programs of sturgeon species. Moreover, sturgeon hybrids are characterized by high values of performance, breeding, and reproductive parameters, and their rearing is often more economically efficient than the rearing of purebred species Therefore in this study we analyzed selected stages of embryonic development in Siberian sturgeon (Acipenser baerii) and hybrids of Siberian sturgeon and Russian sturgeon (Acipenser baerii × Acipenser gueldenstaedtii). The embryo survival rate was higher in group B hybrids i.e., ♀ [Siberian sturgeon × Russian sturgeon] × ♂ Siberian sturgeon than in the control group (Siberian sturgeon), whereas group A hybrids i.e., ♀ [Siberian sturgeon × Russian sturgeon] × ♂ Siberian sturgeon were characterized by lower survival rates than the group C embryos (control). These results suggest that the survival of hybrid embryos could be determined by individual traits, such as gamete (eggs and sperm) quality and genetic factors. The aim of this study was to describe the selected stages of embryonic development in Siberian sturgeon (Acipenser baerii) and hybrids of Siberian sturgeons and Russian sturgeons (Acipenser baerii × Acipenser gueldenstaedtii). For this purpose, embryos representing nine distinct developmental stages (stage 1—2.0 hpf, stage 2—5.5 hpf, stage 3—13.0 hpf, stage 4—20.0 hpf, stage 5—24.0 hpf, stage 6—26.0 hpf, stage 7—35.0 hpf, stage 8—55.0 hpf, and, stage 9—160.0 hpf; hpf—hours postfertilization) were sampled from each group (group A, group B, and group C) during incubation. Stages of embryogenesis were identified based on a 30-point scale of embryonic development in sturgeons. A total of 13 developmental stages were identified, including early cleavage, blastula formation, early and late gastrulation, onset of neurulation, beginning of organogenesis, and prelarvae. During gastrulation, the survival of hybrid embryos was highest in group B (93.8%) and lowest in group A (86.7%). Embryonic deformation was not observed during experimental incubation. The archived data relating to the embryonic development of Siberian sturgeon × Russian sturgeon hybrids could be applied to identify the individual stages of embryogenesis in hybrid sturgeons during egg incubation. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate variations in sperm parameters of wild Mugil cephalus (known as flathead grey mullet)during its natural spawning season in 2015, in addition to the conventional indices, gonadosomatic and hepato-somatic indices (GSI and HSI) and condition factor (K) in male and female Mugil cephalus from July 2014 to December 2015. Sperm motility was assessed by a Computer-Assisted Sperm Analysis (CASA) measuring Curvilinear Velocity (VCL), Straight Line Velocity (VSL), Average Path Velocity (VAP) and Linearity (LIN). Based on GSI, the results demonstrated that M. cephalus spawns in autumn with its peak in November. Variations in K and HSI were clearly associated with reproduction activity. Sperm quality parameters varied significantly during the spawning season. Sperm volume decreased significantly from 0.41 ± 0.33 mL on November 7 to 0.26 ± 0.22 mL on December 2, while spermatozoa concentration increased significantly from 0.35 ± 1 × 109 mL−1 to 26.48 ± 42.5 × 109 mL−1. The highest VCL (27.26 ± 1.05 μm s−1), VSL (13.40 ± 1.03 μm s−1), VAP (17.91 ± 1.08 μm s−1) and LIN (36.64 ± 1.69%) values were observed in November. The current finding provided valuable information on M. cephalus reproduction in Algerian coastal environment, particularly by revealing optimal periods for further artificial reproduction, especially concerning sperm cryopreservation. [ABSTRACT FROM AUTHOR]

Effectiveness of the salmon juveniles feeding was examined during six cycles of fish breeding for pink salmon Oncorhynhus gorbuscha, chum salmon O. keta, cherry salmon O. masou, and coho salmon O. kisutsh at 12 fish hatcheries belonged to the Sakhalin branch of FBSI Glavrybvod with using of different starter feeds produced by Aller Aqua (Denmark) and Aquatech (Russia). All hatcheries worked in the coldwater regime of rearing. Both feeds were rather effective for all species that was evidenced by low feeding coefficients, usually 0.6–0.8. Anyway, average value of the feeding coefficient was lower for the starter feed Aquatech at all factories. Beyond a high quality of this feed, its availability in two variants of flotation was important, as the slowly sinking and floating forms. The floating food was found to be more suitable for the growing juvenile pink salmon at all farms. On the other hand, both starter feeds were suitable for chum salmon, their priority for this species depended on fish farm and obviously was determined by combination of many factors, such as temperature conditions, configuration of canals and ponds, their hydrodynamics, feed dispensers, etc.

The European eel, Anguilla anguilla (Linnaeus, 1758), is a species of high conservation and commercial value. Also, with a high aquacultural value, it was one of the most farmed species in Europe before its decline. Conservation measures for this species are currently being implemented, some of which are the release of adults to allow them to migrate to spawning grounds and artificial reproduction to minimise the impact of overfishing. Much progress has been made regarding the closing of the life cycle, but several problems remain to be solved, such as the weaning and growth of larvae. In this regard, the study of local populations and the identification of the best spawners could be a good way forward as it would help to identify spawners with high reproductive potential and good offspring quality. In this study, we compared the reproductive performance of female eels from migratory areas of the Northern Adriatic Sea at different maturation stages (10 pre-migrant stage; 10 migrant stage), treating both groups with the same hormonal protocol (weekly carp pituitary extract, injection of 17α,20β-Dihydroxy-4-pregnen-3-one at complete oocyte maturation). The research showed that eels at the beginning of metamorphosis (SI III), i.e., eels not yet ready to undertake migration, achieve reproductive performance equal to that of eels ready for migration (SI IV). Their performance was on par in both qualitative and quantitative terms. The optimal results in hatching (with values of 65.8 ± 3.2% for pre-migrant and 68.2 ± 4.1% for migrant) and survival rates (with value of 25.7 ± 5.4% pre-migrants; 27.2 ± 3.7% migrants), as well as the results about the time to reach full gonadal maturation, may have positive implications when considering release and restocking measures.

The study of embryonic development in fish and how water temperature affects the life stage in this group is of pivotal importance to support works that aim at the conservation, management, and recovery of endangered or high economic valuable species. It allows a better evaluation of the species and the identification of morphophysiological changes related to the environmental factor in question. In addition, hybridization emerges as a biotechnological tool that may be applied as a technique for the creation of sterile animals that can be used as recipients for the germ cell transplantation approach, thus contributing to the conservation of different fish species. Based on this, we artificially reproduced two Amazonian fish species, Astyanax bimaculatus, and Moenkhausia oligolepis, and the resulting offspring of each species had their embryonic development followed at room temperature (25 °C) and at high temperature (30 °C). In addition, we performed interspecific crossbreeding between the species, and the offspring were also incubated and observed under the above conditions. The results showed that the high temperature accelerates the embryonic development of both, the offspring from A. bimaculatus and from hybridization. However, no larvae survived. Regarding M. oligolepis, the embryos did not develop, dying at 4:40 post-fertilization. For the hybridization, only the crossbreeding between females of A. bimaculatus and males of M. oligolepis resulted in normal larvae. They presented their own morphological characteristics, showing no total or partial characteristics from the parents, besides presenting atrophied and sterile gonads. Heat waters were proven to compromise the embryonic development of both Amazonian species. On the other side, the hybridization between those two Amazonian species has shown to be a tool with great potential for sterilization and the development of individuals suitable for use as surrogate breeders aiming for the ecological maintenance of various fish species.

In this study, the inseminated sperm method (sperm injection into the ovarian lobe in externally fertilised fish species) combined with hormonal induction was conducted as a novel method to produce hybrid catfish by induced/tank spawning. In the treated group, four Clarias gariepinus ♀ were inseminated equally with Heterobranchus longifilis sperm in the ovaries at a dosage of 1 mL/fish and then introduced into four spawning cages together with four C. gariepinus ♂. Ovulation was induced by extracted carp pituitary (CPE) hormonal administration (♀; 5 mg CPE/BW kg). The hybridization rate was determined on the basis of morphological markers to distinguish between pure African catfish and hybrid in juvenile stage. A control experiment was also designed to determine this and to explore possible interactions between the two genotypes. In the control group, in vitro fertilisation (IVF) was used to produce pure progeny of C. gariepinus and the hybrid progeny between C. gariepinus ♀ × H. longifilis ♂. Exogenously fed larvae from each treatment were raised and compared after 28 days in four replications; the mixed group contained 50 C. gariepinus and 50 hybrids from IVF grown together, while every 100 larvae from each cage spawning pair were grown separately. The hybridisation rate determined based on morphological traits was 98.11 ± 1.59 (mean ± S.D.) for 28-day-old reared offspring. There were no significant differences (P > 0.05) in survival rate (%) between C. gariepinus (45.79 ± 6.82 %) and the hybrid (54.21 ± 6.82 %) in the control treatment; therefore, neither genotype had a negative effect on the other during the rearing period. From this result, we supposed that the hybridisation rate was also over 95 % at the moment of fertilisation. This approach could be an alternative method for producing hybrid catfish or other fish species without in vitro fertilisation.

Simple Summary: The artificial reproduction of endangered Sturgeon in the transboundary Caspian basin has been performed by five states (Russia, Iran, Kazakhstan, Azerbaijan, Turkmenistan). The Russian Federation is the Sturgeon breeding leader with the largest number of Sturgeon Hatcheries—eight, which produce and release up to 61 million Sturgeon juveniles into the natural habitat. This technology was systematized and published in the Caspian states national and international scientific press and FAO. However, this guide does not sufficiently reflect the presence of Sturgeon anomalies in early ontogenesis, identified in the second half of the 20th century. The change in Sturgeon breeding paradigm from wild producers to brood stock spawners provides the incentive and basis for detailed study of Sturgeon anomalies. All previously known Sturgeon anomalies are divided into nine classes. Assessment of Sturgeon anomalies as predictors of their survival in the natural habitat will allow the evaluation of the Sturgeon stock status in the Caspian Sea. Purpose: Review the experience, principles and parameters of the sturgeon assessment quality by anomalies in early ontogeny. Results: Maintaining the number of sturgeon fish in the transboundary Caspian Sea is provided by five states (Russia, Iran, Azerbaijan, Turkmenistan, Kazakhstan) at 16 Sturgeon hatcheries, where their artificial reproduction is carried out. FAO recognizes Russia's leadership in creating the basic technology for the sturgeon artificial reproduction, but the other four Caspian states also make a significant contribution to its modern optimizations. There is almost a century of tradition behind the technological development of artificial reproduction in sturgeons. During the artificial reproduction of sturgeons, anomalies in the structure and functions may occur, such as deformities, defects in organs and tissues, edema, hematomas, etc. The sturgeon anomalies classification is based on structural and functional principles. Identification of anomalies is carried out on the basis of a previously created classification, divided into nine large classes. Identification of sturgeon anomalies during the period of their artificial reproduction makes it possible to clarify the real value of replenishment of their stock. Methods: Analysis of professional scientific literature and practical guides. Conclusions: The presence and number of Sturgeon anomalies make it possible to determine their death percentage to calculate the real number of replenishment of the Caspian Sturgeon stock. [ABSTRACT FROM AUTHOR]

Ex situ conservation comprises some of the oldest and best-known conservation methods and it has been applied for different fish stocks. This study describes attempts undertaken to preserve the long-migrating River Vistula (Poland) brown trout by a sea-ranching programme in the River Dalälven (Sweden). This focal strain was threatened in its native river and a major reason for selecting the River Dalälven was that its river mouth faces north as does that of the River Vistula. In the Swedish river, the Vistula trout in the 1970s and early 1980s returned early in the autumn and were generally large-sized (compared to the native strain of the River Dalälven). Over the study period (1978–2012), the size of returning adult fish declined, the return date becoming later in the year, and the number of spawners also declined. The reasons for these changes were probably caused by several interacting factors: (1) the most likely being high mortality of early returning fish which were held for longest in captivity before being used in the artificial spawning process; (2) the fact that the hatchery process was adapted to the Dalälven strain and not the Vistula one; (3) that the Vistula fish were marked by removing both pelvic fins (possible reducing subsequent survival); and (4) low genetic variation (as a result of few returning individuals). Thus, for several reasons, this ex situ conservation attempt for Vistula trout in Sweden is thought to have failed. [ABSTRACT FROM AUTHOR]

Many economically important fish have a long sexual maturation cycle, with the first sexual maturation time exceeding four years, which poses a long-term challenge for the cultivation of excellent varieties of these fish. Gonadal development and reproductive timing of fish are closely related to changes in environmental temperature. This study used the common carp as an economic fish model and set up three aquaculture modes for a one-month old common carp population: constant temperature test group (CTTG), normal temperature control group (NTCG), and variable temperature control group (VTCG). A long-term (approximately 11 months), temperature-controlled aquaculture experiment was conducted. The results of growth traits and gonadal development tests showed that at 10 months, the body length and weight of the CTTG were significantly higher than those of the other two groups. At seven months, the gonadosomatic index (GSI) value of CTTG was also significantly higher than that of the other two groups; At 10 months, the serum estradiol (E2) concentration of CTTG was significantly higher than that of the other two groups, while the testosterone (T) levels of VTCG and CTTG were significantly higher than those of NTCG, and only the 11-ketotestosterone (11-KT) concentration of VTCG was significantly higher than that of the other two groups. Simultaneously, qPCR analysis of sex hormone regulatory genes revealed that the expression of Cyp19a1a in CTTG ovaries was significantly higher than that in NTCG and VTCG ovaries, whereas the expression of Cyp11b and Hsd11b2 in VTCG ovaries was significantly higher than that in NTCG and CTTG ovaries. At 12 months, artificial reproduction revealed that only fish from the CTTG (66.67%) successfully laid eggs and fertilized normally. The results indicate that long-term constant temperature cultivation at 28 °C starting from the juvenile stage is not only beneficial for the body growth of common carp, but also promotes their gonadal development. This may be due to the conversion of T into E2 by Cyp19a1a in the common carp, ultimately facilitating the functional development of gonadal tissue under hypothalamus-pituitary-gonadal (HPG) axis regulation, normal egg laying, and fertilization. This study reduced the normal first sexual maturation time of common carp by at least 50% and provides a reference for the rapid cultivation of excellent varieties of other economically important fishes. [Display omitted] • Common carp has a high yield and is an ideal model for the Cyprinidae family. • Constant temperature aquaculture promote the gonadal development of common carp. • This method reduced the sexual maturation time of common carp by at least 50%. • This method can be directly used for rapid cultivation of excellent varieties. [ABSTRACT FROM AUTHOR]

Controlled indoor reproduction of European eel is commonly recognized as a prospective tool to prevent extinction of this fish species. There is a little information about diversity of bacterial microflora of European eel during long maturation under controlled but changing thermal and salinity conditions. Characteristics of the composition of the bacterial microflora inhabiting the body surface of fish kept firstly in fresh and then in salt water, may help enhance the survival of spawners and spawning efficiency. Knowledge about the presence of potentially pathogenic bacterial species and their antibiotic resistance is particularly important. Methods: This study analyzed the bacterial microflora of two types of necrotic changes on the skin of eel females during artificial maturation under fresh and saltwater conditions. Results: A total of two hundred and forty bacterial strains were isolated from necrotic dermal changes on fish in freshwater and saltwater conditions. Both the bacterial number and biodiversity were greater in freshwater than in saltwater. Psychrophilic bacterial strains in freshwater were twice as abundant as in saltwater, especially among isolates which were cultured from the mucus or from ulcerative changes around the chip injection point (up to 1010 cfu/mL). 16 S ribosomal RNA gene sequencing of isolates from the freshwater conditions revealed the presence of twenty genera of bacteria, including: Pseudomonas sp., Comamonas sp., Escherichia sp., Aeromonas sp., Citrobacter sp., Burkholderia sp., Pantoea sp., Enterobacter sp., Yersinia sp., Edwardsiella sp., Serratia sp., Bordetella sp., Morganella sp. and Chromobacterium sp. In saltwater conditions, five genera of bacteria were found dominantly: Pseudomonas sp., Aeromonas sp., Yersinia sp., Vibrio sp., Edwardsiella sp. In freshwater conditions, the bacteria were mostly resistant or resistant to all tested antimicrobial drugs. Conclusions: Changes in bacterial microflora during controlled indoor reproduction of European eel predispose fish to bacterial infection especially during the first freshwater step of female maturation. New, alternative to antibiotic therapy, methods should be adopted to prevent infections and enhance spawning efficiency.

• New insights into egg quality and larval vitality of eel have been obtained. • Recombinant gonadotropins have been used to mature female eels and produce larvae. • Progesterone can be applied instead of DHP for ovulation induction. • A deformity determination key is introduced to characterize larval abnormalities. • Findings will contribute to improving the production of robust larvae. To date, the eel industry still depends on wild-caught juveniles that are grown to marketable size. There is an urgent need to close the eel life cycle in captivity to make aquaculture independent of the natural population. With this artificial reproduction protocol, yolk-sac larvae can be produced but egg quality may be impaired. Low survival rates and high deformity rates are frequently observed during the first week after hatching. Over the past four years, we have conducted studies with the aim to optimize the artificial reproduction protocol, thereby focussing on increasing egg and larval quality. Weekly carp or salmon pituitary extract (PE) treatment was successfully replaced with recombinant gonadotropins (rGTHs) to mature female eels and produce larvae. 17α,20β-dihydroxy-4-pregnen-3-one (DHP) was replaced with upstream precursor progesterone (P) to induce the endogenous production of DHP by the female eel. DHP and P were found equally potent in inducing oocyte maturation and ovulation. The effects of antibiotics on larval survival and the occurrence of deformities were investigated. Antibiotic treatment increased survival and decreased the occurrence of deformities indicating bacterial infection as an important cause. A deformity determination key for young eel larvae has been developed that provides a framework of reference for larval deformities which will be instrumental with gaining insights on the reasons behind each larval deformity. These improvements of the artificial reproduction protocol and hatchery practices will contribute to the production of robust eel larvae that survive, grow and metamorphose into juveniles that will later be able to reproduce in captivity. [ABSTRACT FROM AUTHOR]

Artificial reproduction is a bottleneck to produce stocking material for many species of freshwater fish. One of these species is the asp, Leuciscus aspius. Research in the field of artificial reproduction of this species is very scarce and often incomplete. There are no breeding protocols specifying optimal environmental conditions and hormonal stimulation for many species of rheophilic cyprinids, including asp. Since the number of natural asp populations is constantly decreasing, it is important to support natural stocks by restocking with high quality stocking material. For this reason, optimized protocols are needed to breed this species under controlled conditions to produce stocking material with high biodiversity and good health. Such an approach will make it possible to maintain the population of natural asp at a constant level. The aim of this study was to develop the protocol of asp artificial reproduction using optimized thermal conditions and appropriate hormonal stimulation. In experiment I, the influence of constant temperature (10.0, 12.0 and 14.0 °C) on the effectiveness of artificial reproduction of asp. In experiment II, the effectiveness of asp reproduction was checked after the application of spawning agents: Ovopel, Ovaprim or a combination of these two agents The obtained results indicate that for the final maturation of oocytes (FOM) and artificial reproduction of asp in controlled conditions, water temperatures of 10–12 °C are the most useful. Under these thermal conditions, the highest percentages of female's ovulation and embryo survival, as well as the percentage of hatching, were obtained. Hormone injections are necessary to perform final oocyte maturation (FOM) in female asp in captivity. All spawning agents used were especially useful for artificial reproduction of asp, however, the best values of the studied indices, such as ovulation rate and embryo survival, were obtained after the application of Ovaprim or the combination of Ovopel and Ovaprim in water temperature at a range of 10–12 °C. It was found that the pH of ovarian fluid may be a preliminary indicator of the biological quality of eggs in asps. The optimal pH value is 8.0–8.4. At pH below 7.4, no viable embryos were observed. • The optimum temperature range for the final gametes maturation of gametes in asp is 10–12 °C. • The shortest latency time with the lowest biological quality of eggs was recorded at 14°C. • All tested combinations of spawning agents were successful in the reproduction of wild asp. • pH of ovarian fluid can be used as a primary indicator of asp eggs quality. [ABSTRACT FROM AUTHOR]

Sichuan taimen (Hucho bleekeri), a critically endangered species, is listed as a first-class protected species in China. The natural population has been missing from most of its known distribution areas for many years but was rediscovered in the Taibai River in 2012, providing an important resource for the conservation stocking of the Sichuan taimen. In this study, 43 wild adult Sichuan taimen collected from the Taibai River were determined for gamete maturity for artificial reproduction using ultrasonography. The echogenicity of the gonads before and after hormonal induction was described to determine broodstock identification, injection dose of hormones, and spawning time. Four batches of artificial breeding were successfully achieved in 2013, 2014, and 2016. Broodstock (19 females and 16 males) spawned with average fertilization and hatching rates reaching 80.2% and 61.0%, respectively. This study demonstrates that ultrasonic imaging is a convenient and efficient method to track the state of gonads of mature Sichuan taimen during artificial reproduction, which will assist in broodstock cultivation, and further large-scale proliferation and effective resource restoration of the Sichuan taimen.

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Among the important techniques of the scientific revolution that occurred in the field of medicine and neighborhoods, we find artificial reproduction and it is multiple: IVF, IVF, and surrogate mother, and it has emerged as one of the solutions to get rid of a deep problem that has been troubling mankind; that is, sterility, it was a long-awaited hope but in return she carried With it is a set of variables that have puzzled mankind, and it has raised the fear of man, and it threatens his dignity and morals, and with this threat the question of ethics has emerged in the form of a new moral thought. [ABSTRACT FROM AUTHOR]

One of the most important stages of domestication in each species is to maintain the animal in a rearing condition up to reaching to maturity and reproduction. Therefore, this study was performed with the aim of reproducing the pikeperch (Sander lucioperca) grown in a captivity condition. For this purpose, two groups of fish including control group (without hormone injection) and hormone induction group (HCG injection at 200 IU/kg) were considered and each group consisted of two replicates and 5 fish in each tank. The results showed that the fish spawned after 74 to 90 hours, but the difference between the two groups in this regard was not significant. The latency time was determined in case of degree-hour in non-injected breeders to 1396.9 ± 157.2 and in injected breeders to 1261.5 ± 34.2 degree-hours (P = 0.356). The response rate of fish in non-injected breeders was 87.5 ± 17.7% and in injected breeders was 75 ± 0.0% (P = 0.423). The quality of nests did not show any significant difference between the two groups. Fertilization rate was 87.3 ± 3.5% in non-injected fish and 82.7 ± 5.4% in injected fish (P = 0.412). According to the obtained results, it can be concluded that due to the complete adaptation of farmed fish to the captive rearing condition, it can be possible to propagate pikeperch without hormonal induction while the desired temperature and suitable spawning ground are available. [ABSTRACT FROM AUTHOR]

Information on the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has amplified quickly since its spread; however, many issues remain unclear. SARS-CoV-2 is mainly transmitted through respiratory secretions. However, the potential for SARS-CoV-2 sexual transmission by semen is worthy of study. The cell-receptors of SARS-CoV-2, the angiotensin-converting enzyme-2 receptors, are highly expressed in human testis and may enable this virus to cause testicular tissue damage with bad effect on male fertility. SARS-CoV-2 presentation ranges from asymptomatic carriage to acute respiratory distress and fatal pneumonia, and elderly persons with underlying comorbidities usually suffer from a severe clinical picture. Asymptomatic individuals can spread the virus through their respiratory secretions and possibly through sexual transmission. SARS-CoV-2 can persist viable if cryopreserved in semen samples in sperm cryobankes. As far as I know, there is a gap in knowledge about SARS-CoV-2 transmission through semen, indicating the need for further research. This review attempts to understand the SARS-CoV-2 sexual transmission by semen. One recent study confirmed the theoretical risk of SARS-CoV-2 transmission by semen, but few studies negate this theory. Given that, an increasing number of asymptomatic and reactivated SARS-CoV-2 cases are being reported, attention to semen safety and SARS-CoV-2 transmission should be considered particularly in high-risk areas, to ensure the safety of male gametes for artificial reproduction and the general public. Avoiding cryopreservation of male gametes, condom use or even abstinence might be of paramount importance for these persons.

All available data on sakhalin sturgeon Acipenser mikadoi are summarized. Its historical and modern habitats are described and their significant reduction is noted. Now the species is abundant in the Russian part of its range only — in the Tumnin River, where it is represented in commercial catches by two clearly different groups: large-sized juveniles (FL 43–68 cm) and mature fish (FL 135–169 cm). Juveniles of sakhalin sturgeon migrate during their first years, as their osmoregulatory system forms, to the lower reaches of Tumnin, to the internal estuary, and then to the Datta Bay, the Tatar Strait and the Japan Sea. When returned to the Tumnin, the spawners of sakhalin sturgeon have the length 135–169 cm (n = 29) and weight 15–36 kg. Sex ratio among the caught mature fish is 13.0 : 4 or 3.2 : 1 for females : males, on average. Fecundity of the sturgeon females sampled for artificial reproduction varied from 44.8 to 150.0 thousand eggs, on average 87.3 ± 12.1 . 103 eggs. In total, 17 mature spawners of A.mikadoi were caught in the Tumnin River in 2006–2019 for artificial reproduction (♀ = 13, ♂ = 4), 13 individuals were injected, among them 4/5 of females and 2/3 of males gave high-quality sex products. Producers of this species were distinguished by high survival during manipulations of fish breeding (100 %). Their progeny had low survival, both embryos during incubation and juveniles during rearing; the survival rate for the stage from eggs laid for incubation to juveniles with weight 3.4–7.0 g was 1.85 %. The low survival was supposedly reasoned by combination of unfavorable environmental factors and fish-breeding manipulations. Totally 11,214 juveniles of sakhalin sturgeon with weight from 3.4 to 7.0 g were released into the natural habitat (Tumnin river) in 2007, 2008, 2015, 2017, and 2019. At Anyui sturgeon fish hatchery, the broodstock of sakhalin sturgeon with 274 individuals of 5 ages is created and operated successfully. The male sturgeons in the hatchery mature at the age of 8 years. Here, 11 males of the 2007–2008 year-classes participated in the spawning in 2015–2019. Re-maturation of males was not recorded yet. For the broodstock formation in other fish hatcheries, 200 juveniles of sakhalin sturgeon were transferred to them. To preserve the species, a set of measures is proposed to strengthen its protection and to enhance its artificial reproduction, including the fry releasing into the rivers of the mainland coast, Sakhalin Island, and Japan.

The present study aimed at evaluating the effects of different thermal regimes and synthetic hormones on sperm quality as well two (low vs. high) salmon gonadoliberin (sGnRHa) dosages on egg quality in indoor-reared pikeperch. Two groups of females were formed receiving either 5 µg kg−1 or 50 µg kg−1 of sGnRHa. Likewise, four groups of males were formed that were hormonally treated at either 5 °C or 9 °C, and each temperature receiving either 25 µg kg−1 of sGnRHa or 10 µg kg−1 recombinant human chorionic gonadotropin (hCGrec). Each group consisted of five specimens. Low dosage of sGnRHa showed lower survival of embryos (17.4 ± 29.1% vs. 50.3 ± 7.3%), while there were no differences in sperm quality parameters among the male groups. Overall, best male performance was seen in the group injected with sGnRHa at 9 °C, having the greatest values for all but one of the evaluated parameters. A higher dosage of 50 µg kg−1 can be supported as optimal for a stable thermal regime in pikeperch artificial reproduction, while the differences in the physiological state of breeders under the different thermal regimes should be of interest in future studies. No differences in assessed sperm quality parameters indicate that males are tolerant to thermal manipulations while synthetic form of gonadotropin is applicable for pikeperch propagation and should be evaluated in a more comprehensive study.

With the continuous improvement of artificial reproduction technology, in vitro fertilization (IVF) or embryo transfer technology has developed rapidly. At the same time, the proportion of crimes related to surrogacy is also increasing. Surrogacy has different problems in judicial practice, laws and regulations, and theory. Specifically, it can be subdivided into: due to the lack of surrogacy regulation in current laws and regulations, there are related problems centered on surrogacy behavior. On the one hand, it often encounters bottlenecks due to the lack of legal support in judicial practice; On the other hand, at the theoretical level, because surrogacy involves the exclusive rights of life, such as physical rights and reproductive rights, this practical issue is controversial and has mixed opinions, which leads to the fault phenomenon in the application of this issue at the judicial level. Based on this situation, this paper starts from the practical level, enumerates the typical cases involving criminal acts in the process of surrogacy, and regulates them with the existing criminal law norms. Secondly, refine the characteristics and elements of surrogacy behavior in the above-mentioned practical level, think about this phenomenon, and redefine the concept of surrogacy based on the current social environment. Finally, on the basis of the above concept of surrogacy, return to the level of criminal law, take the dichotomy of surrogacy regulation as the guidance, and take the surrogacy institution as the main body of crime. It jointly explores the way to solve the black industrial chain of surrogacy. [ABSTRACT FROM AUTHOR]

Abstract Wild fish domestication can be considered a strategic approach to endangered species conservation, supporting studies and reducing economic and environmental costs. Three of the most important strategies in the domestication processes of fish are the adaptation of wild fish to captivity, the reproduction of the adapted fish and the production and maintenance of the young individuals. That being said, the present study is divided in three experiments: the 1st aimed to adapt wild Pseudopimelodus mangurus to captivity environment using different feeding approaches and a prophylactic strategie; the 2nd aimed to reproduce the adapted individuals from the 1st experiment; and the 3rd aimed to train the P. mangurus juveniles to accept commercial diets. The 1st and 2nd experiments were successful at the maintenance and artificial reproduction of P. mangurus kept in tanks between the reproductive seasons. The results suggest that the reproductive performance of animals kept in captivity (initial relative fertility-IRF = 609.25 ± 36.6 eggs/g) was similar (p > 0,05) to the performance found in wild individuals (IRF = 679.21 ± 45.66 eggs/g). Feed training of P. mangurus juveniles (3rd experiment) was also conducted, evaluating three feeding treatments with different concentrations of bovine heart and ration. At the end of the experiment, the treatment containing half bovine heart and half commercial feeding resulted in the highest values of weight gain (0.10 ± 0.16 g), specific growth rate (0.37 ± 0.11 mm), length (47.78 ± 2.35 mm) and growth (2.15 ± 2.27 mm), suggesting reasonable acceptability to artificial diets in the cultivation of this species. As conclusion, the present study contributes with the development of techniques for the domestication of fresh water fish species with commercial value or andangered of extinction, showing the domestication and reproduction of wild P. mangurus in captivity. However, more studies have to be conducted in order to improve the acceptance of artificial feeding by juveniles and to increase their survival rate.

Brycon hilarii is a neotropical fish whose population in rivers is being threatened by overfishing, construction of hydroelectric dams, transposition of riverbeds, and pollution. Fundamental knowledge of the reproductive characteristics of this species is necessary to enable its breeding in captivity, for aquaculture as well as for biological conservation. The aim of this study was to investigate and describe the sperm parameters, their correlations, and relevant factors, and how these issues can affect sperm quality in B. hilarii. Sperm was collected after hormonal induction using carp pituitary homogenate. Spermatozoa concentration, total length, motility, and percentage of normal cells were measured to be 2.85 × 109 cells mL−1, 40.28 µm, 68.1%, and 51.6%, respectively. Tail abnormalities were most frequent; however, head abnormalities were closely related to practically all sperm kinetic parameters. Present results suggest that these abnormalities affect motility and movement kinetics, and modifying the pattern of sperm cell movement, sinuosity of movement and vigor. The potential application of this study in aquaculture management of B. hilarii is crucial for the artificial reproduction of fish and represents a significant contribution to the knowledge of its reproductive biology, facilitating the reproduction of the species.

The aim of this study was to describe the selected stages of embryonic development in Siberian sturgeon (Acipenser baerii) and hybrids of Siberian sturgeons and Russian sturgeons (Acipenser baerii × Acipenser gueldenstaedtii). For this purpose, embryos representing nine distinct developmental stages (stage 1—2.0 hpf, stage 2—5.5 hpf, stage 3—13.0 hpf, stage 4—20.0 hpf, stage 5—24.0 hpf, stage 6—26.0 hpf, stage 7—35.0 hpf, stage 8—55.0 hpf, and, stage 9—160.0 hpf; hpf—hours postfertilization) were sampled from each group (group A, group B, and group C) during incubation. Stages of embryogenesis were identified based on a 30-point scale of embryonic development in sturgeons. A total of 13 developmental stages were identified, including early cleavage, blastula formation, early and late gastrulation, onset of neurulation, beginning of organogenesis, and prelarvae. During gastrulation, the survival of hybrid embryos was highest in group B (93.8%) and lowest in group A (86.7%). Embryonic deformation was not observed during experimental incubation. The archived data relating to the embryonic development of Siberian sturgeon × Russian sturgeon hybrids could be applied to identify the individual stages of embryogenesis in hybrid sturgeons during egg incubation.

Orestias ascotanensis Parenti is a critically endangered endemic species of the Chilean high Andean systems, found only in the springs of the Ascotán saltpan. Considering the importance of reproduction and early life history stages in population persistence in fishes, understanding these is essential for successful conservation efforts. We studied the larval development of O. ascotanensis under controlled temperature and photoperiod conditions. A total of 50 O. ascotanensis specimens were captured during 2014 and 2015 and moved to the laboratory to be kept under controlled conditions and diet. Females were subjected to hormone therapy using Ovaprim® to induce oviposition, which was followed by artificial fertilization under dry conditions. Water temperature was maintained at 20 °C (± 1 °C), conductivity values oscillated in the interval of 2800–3600 µS/cm3, and the photoperiod was established as 16:8 (light hours:dark hours). The larvae hatched within 14 to 18 days. Three larval stages were established: (i) flexion larva with yolk sac, (ii) flexion larva, and (iii) post-flexion larva. The newly hatched larvae were highly prepared for the free-living stage and they absorbed the yolk sac in 5–7 days. The intense pigmentation of O. ascotanensis eggs and larvae and the high degree of development at hatching may represent adaptations to extreme conditions, such as high levels of solar radiation and significant changes in daytime temperatures. A range of anthropogenic activities have caused the contraction and degradation of the habitat of O. ascotanensis, producing serious concern regarding the conservation status of the species. [ABSTRACT FROM AUTHOR]

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Reproductive obstacles have led scientists to develop novel techniques/technologies for artificial reproduction. We aimed to investigate the possibility of propagating zebrafish females using sperm ovarian lavage with and without presence of male stimulus. This experiment consisted of several treatments: traditional spawning approaches with females and wild-type males (AB♀ × AB♂); no males present with non-manipulated females (AB♀); no males present with females inseminated with NaCl into ovarian lobes [AB♀(inj.NaCl)]; no males present with females inseminated with sperm from transgenic males into ovarian lobes [AB♀(inj.Tg♂)]; non-manipulated females kept separately from wild-type males (AB♀|AB♂); females kept separately from wild-type males and inseminated with NaCl into ovarian lobes [AB♀(inj.NaCl)|AB♂]; and females kept separately from wild-type males and inseminated with sperm from transgenic males into ovarian lobes [AB♀(inj.Tg♂)|AB♂]. There were no released eggs in both negative control treatments (AB♀ and AB♀|AB♂). Egg production increased (ranged from 0 to 28.5 eggs/female) when females were injected in the presence [AB♀ (inj.NaCl) |AB♂] or absence of male stimulus [AB♀ (inj.NaCl) and (AB♀(inj.Tg♂)]. A further increase in egg production [relative to AB♀, AB♀ (inj.NaCl), and AB♀|AB♂] was detected when females were inseminated with pooled sperm from transgenic males in the presence of male stimulus [AB♀(inj.Tg♂)|AB♂; ranged from 2.5 to 55 eggs/female] or when using traditional spawning approaches (AB♀ × AB♂; ranged from 25 to 131 eggs/female). Females inseminated with sperm produced embryos, although no differences were detected when females were inseminated with pooled sperm from transgenic males in presence (11.8 ± 16.3%) or absence (average = 12.6 ± 9.2%) of male stimulus. Traditional spawning approaches produced the most eggs (81.2 ± 42.3 per female) and highest fertilization rate (81.3 ± 10.4). • Sperm injected in wild zebrafish ovaries before spawning. • Injected females released eggs without males or without direct presence of males. • Sperm fertilized eggs, which were released from body cavity by spontanous ovulation. • Method provides a proof of principle for successful spawning without males in ovulipar species. [ABSTRACT FROM AUTHOR]

This study aimed to find the optimal strategy for the application of salmon gonadotropin-releasing hormone analogue (sGnRHa) in outdoor-cultured pikeperch males in an exceptionally early term in early November. According to the histological examination, on the day of hormonal treatment, pikeperch testes were in the late stadium of spermatogenesis, with 78.7% of germ cells attributed to sperm cells. Five experimental groups were established varying on hormonal preparations and water temperature: (1) sGnRHa (25 μg kg−1) was applied to fish at pre-warming at water temperature of 11 °C (GnRH-LOW); (2) sGnRHa (25 μg kg−1) was applied to fish post-warming at water temperature of 15 °C (GnRH-HIGH); (3) priming group (5 μg kg−1 at 11 °C +25 μg kg−1 at 15 °C); (4) reference group – fish were injected with human chorionic gonadotropin; (5) control group - fish were injected with saline solution. Sperm was obtained from all fish in hormonally treated groups, whereas the fish treated with saline did not spermiate. The greatest values of the straight-line velocity (VSL), the curvilinear velocity (VCL), and the angular path velocity (VAP) of sperm cells, as well as the amounts of Mg2+, K+, and Na+ in the sperm seminal plasma, were obtained in GnRH-HIGH, whereas the GnRH-LOW group yielded the greatest sperm volume. Among the ions in seminal plasma, K+ and Na+ dominated and showed a relationship with sperm kinematic parameters. According to the obtained data, sGnRHa can be considered as an appropriate hormonal preparation to induce spermiation at an early preseason. Either before or after warming, sGnRHa application can yield sperm of proper quantity and quality as early as 5 months before the natural spawning season. A comprehensive study is recommended to evaluate the full period of sperm availability in outdoor-reared males, followed by direct evaluation of the fertilizing capacity.