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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]

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]

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]

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]

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]

Sperm metabolism consists of a sophisticated network of biochemical reactions and varies between species, resulting in different metabolic strategies for ATP production to maintain sperm functionality. ATP can be produced through glycolysis or in the mitochondria by oxidative phosphorylation (OXPHOS). Since OXPHOS is the predominant metabolic pathway in horses spermatozoa, various assessments of mitochondrial activity are used to evaluate fertility, utilizing techniques such as fluorescent probes analysed via microscopy or flow cytometry, and polarographic electrode assays to measure current flow in response to an applied voltage. Though, these methods are limited by low throughput, as they assess mitochondrial activity at a single time point under a specific treatment condition. This study explores, for the first time, the application of the Agilent Seahorse XFp Technology to evaluate metabolism in stallion spermatozoa. This method enables real-time measurement of cellular metabolism across multiple samples or experimental conditions simultaneously. Ejaculates from eight different stallions were collected, and pools were prepared from three of them. Sperm viability and mitochondrial activity were evaluated by fluorescence microscopy, sperm motility by a computer-assisted sperm analysis system, and sperm metabolism was analysed via the Seahorse XFp analyser. Results confirmed a preference for OXPHOS over glycolysis in ATP production in stallion sperm, with mitochondria contributing significantly to total ATP generation. The Seahorse XFp Technology proved effective in evaluating equine sperm bioenergetics, offering insights into metabolic pathways critical for sperm function. In conclusion, this technology grants a new method for high-throughput analysis of sperm metabolism and quality, which could be applied to future reproductive studies in male equine fertility. • Equine spermatozoa present preference for OXPHOS over glycolysis in ATP production. • The Seahorse XFp Technology is effective in evaluating equine sperm bioenergetics. • Seahorse XFp may aid in analysing sperm metabolism in assisted reproductive techniques. [ABSTRACT FROM AUTHOR]

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]

• 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]

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]

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]

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]

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]

During the 1970s and 2010, the population of Anguilla anguilla declined significantly, and the species is now classified as a critically endangered species by the International Union for Conservation of Nature (IUCN). Considering its social, economic, and ecological importance, it is necessary to understand the biological mechanism that controls population dynamics, in particular the passage from the resident phase to the migratory phase. During this phase of their life cycle, the environment plays a key role in the maturation of the spawners which will eventually undertake a long spawning migration to the Sargasso Sea. An assessment of the morphological characteristics of eels during their silvering process and reproductive activity was conducted by collecting 1513 female eels from seven lagoons in the North Adriatic Sea. Morphometric analyses show that eels classified as pre-migratory according to the Silver Index are histologically (65% of eels with oocytes in the most advanced stage of development) and morphologically ready to migrate. Accordingly, pre-migrant eels treated with hormone induction performed similarly to migrant eels. They mated and spawned spontaneously in the tank with a percentage of 81.0%, and 88.2% of them produced viable eggs. The results showed how the North Adriatic lagoons could present favourable conditions that permit the fast development of females with high reproductive potential. This data can be used to develop successful strategies to conserve and manage eel populations. • New achievements on knowledge in European eel biology and ecology. • Reproductive activity of pre-migrant eels is in line with migrant eels. • North Adriatic lagoons present favourable growth conditions. [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 SARSCoV- 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. [ABSTRACT FROM AUTHOR]

The present study aimed to characterize the embryogenesis and larval development of matrinchã (Brycon orthotaenia), through the analysis of egg and larval morphology. Fertilized eggs had a mean diameter of 1.17 mm, with yolk occupying most of the egg (1.06 mm). Embryogenesis lasted for 15 hr at an average temperature of 27°C. At hatching, yolk‐sac larvae measured 3.67 mm in mean standard length (SL). Pre‐flexion, flexion and post‐flexion larva had 5.01, 8.24 and 11.88 mm mean SL, respectively, with significant increases observed particularly in head length, head height, and eye diameter. The yolk persisted in the yolk‐sac and pre‐flexion stages (5.96 mm SL). The mouth opening could first be observed 13 hr after hatching, and cannibalism was observed 29 hr after hatching in pre‐flexion larvae after absorption of the yolk sac; in such cases, the larvae had already developed teeth and a complete digestive tract. For an endangered species such as matrinchã, early life history studies are important because they provide researchers with a better understanding of critical stages of development and thus enhance captive management by rearing and restocking of the species. [ABSTRACT FROM AUTHOR]

Aquaculture of red swamp crayfish, Procambarus clarkii (Girard, 1852), has developed rapidly worldwide in recent years with promising prospects. However, limited knowledge about temperature effects on reproductive performance and embryonic development has hindered the development of crayfish aquaculture. The two present studies were conducted to identify optimal water temperatures (17 °C, 21 °C, 25 °C, 29 °C and 33 °C) for reproductive performance (experiment 1) and embryonic development (experiment 2) of P. clarkii. Totally, there were 12 replicates, with 480 adults and embryos from 60 ovigerous crayfish selected for experiment 1 and 2, respectively. In the first experiment, the survival of adult crayfish was not significantly affected by the temperatures tested. However, significantly higher feeding rates, spawning rates, and fecundity were obtained at 21 °C and 25 °C when compared to those at 29 °C and 33 °C. Polynomial models and loess regression fitted to the experimental data showed that highest spawning rates and fecundity occurred at 21 °C while shortest duration from mating to spawning was found at 33 °C. In the second experiment, we found that optimal embryonic development was at 25 °C with shorter hatching time and no abnormalities observed. However, while embryos showed abnormalities and subsequently died at 29 °C and 33 °C. We further built a temperature-dependent developmental model for P. clarkii embryos: D (developmental time, days) = 3,140,837(T- 2.03)−3.76. Based on these results, the temperature range 21 °C – 25 °C was recommended for adult crayfish reproduction and 25 °C was recommended for embryonic development. This study indicates that manipulating water temperature is an effective alternative to current artificial reproduction techniques (e.g. eyestalk ablation and injection hormones) to induce spawning and embryonic development and thus provides mass production of juvenile P. clarkii for aquaculture. • 21 °C – 25 °C was recommended for crayfish reproduction and 25 °C was recommended for embryonic development. • Embryos showed abnormalities and subsequently died at higher temperatures (29 °C and 33 °C). • The temperature-dependent developmental model allows predicting juveniles recruitment in aquaculture. • Manipulating water temperature is an effective alternative to traditional artificial reproduction techniques to induce spawning and embryonic development. [ABSTRACT FROM AUTHOR]

Although several papers were dealing with intensively reared broodstocks, most of the published artificial reproduction protocols were applied in wild pikeperch breeders. Therefore, we aimed to evaluate the effects of ovulation induction agents, namely human chorionic gonadotropin (hCG) and salmon gonadotropin–releasing hormone analogue (sGnRHa) on the reproductive performance in pre-seasonal artificial propagation of cultured pikeperch. Breeders were harvested from an outdoor in-pond circulation system in mid-September and transferred to indoor facility in late January, conditioned and injected with either 50 μg kg−1 of sGnRHa or 500 IU kg−1 of hCG, with six females in each hormonal group. Stripped eggs from each female were sampled for chemical composition analysis, fertilised with the milt of two males, incubated and obtained larvae were further reared. No significant differences were noticed between the treatments in any of the analysed parameters of embryo survival nor larviculture performance. Rather high differences in intragroup variation were seen between the treatments, expressed in several-fold higher coefficients of variation in embryo survival in experimental and commercial conditions in the hCG group. Eggs obtained from females treated with hCG had a significantly higher lipid content (31.1% ± 2.0%) compared to sGnRHa-treated females (27.4% ± 1.8%). Fatty acid profiles of the eggs revealed differences in total n − 6 and linoleic acid 18:2n − 6 content while n − 3/n − 6 was significantly lower in the hCG group. Gonadoliberins reduced the variability in the spawning outcome. It appears that hormones can modify the eggs' fat content during the pre-season artificial reproduction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The Zingel asper or apron is one of Europe's most threatened freshwater fish (classified as critically endangered by the International Union for Conservation of Nature, IUCN). It is also listed in appendices II and IV of the European Habitats Directive (1992) and in appendices II and III of the Berne Convention (1979). The geographical distribution of this percid, endemic to the Rhône basin, is extremely limited, making it particularly vulnerable. Since 2005, the Besançon Natural History Museum has been involved in conservation programmes (LIFE Apron II and a national action plan) to improve the knowledge on its ex situ reproduction, the aim being to produce individuals with which to conduct experimental studies (toxicity tests, design of fish passes, etc.), carry out public presentations (aquariums, nature reserves, etc.) and implement pilot reintroduction schemes, without having to systematically take samples from the natural environment. Innovative devices were designed in the Besançon Citadelle Aquarium to enable replication of complete reproduction cycles in artificial conditions. Control of thermal and zootechnical parameters associated with the development of “artificial spawning grounds" have allowed us to understand the different phases involved in reproducing and maintaining this species in captivity. We were able to observe numerous behaviours, which have never been seen in natural environments, in particular during spawning and early life stage development phases. Several experiments were conducted to study how hatching rates varied according to the duration of the winter cold period, known as “vernalization", applied to broodstock. Hatching rates in the order of 80% were obtained with broodstock subjected to a cold period of 120 days at 5°C, from the beginning of November to the end of February. In contrast, hatching rates dropped rapidly for groups of broodstock subjected to vernalization periods of less than 90 days, and with a cold period of only 30 days, the eggs deteriorated before hatching. A precise annual thermal cycle has therefore been identified, corresponding to the different life phases of Z. asper in captivity. A particular focus of our work was on breeding of fry to ensure that they achieve survival rates in the order of 80% during the first month, and 90% the following month. The results of these experiments have supported other studies and more than 26,000 juveniles have been released into the Drôme River. Regular genetic monitoring of this reintroduced population has allowed us to ensure that they are reproducing naturally. Z. asper born in captivity are also widely used in initiatives to raise public awareness (exhibitions, etc.). To date, the Z. asper breeding programme in the Besançon Natural History Museum is the only one of its kind for this percid, but the high sensitivity of broodstock to the intensity and duration of the vernalization period should raise concerns about the sustainability of its populations in the face of climate change. [ABSTRACT FROM AUTHOR]

Abstract: Controlled reproduction is a requirement for developing effective mollusc cultivation for commercial or restoration purposes. In this study, a protocol for spawning induction using noninvasive methods in limpets was developed, using the common Mediterranean species, Patella caerulea Linnaeus, 1758. Six nonlethal spawning induction treatments were tested: three chemical (two concentrations of H2O2 and KCl) and three physical (bubbling, warm and cold thermal shock). All treatments, except thermal shocks, induced the spawning of fertile gametes. Bubbling resulted the best treatment in providing spawning response, being the easiest and least invasive method tested. After eggs fertilization, larval development was followed until metamorphosis, testing fed and unfed conditions. Settlement took place after 7 days. The developed protocol represents a benchmark for further application to other limpets, for aquaculture or repopulation. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to test the use of hormonal preparations, which are commonly used in the artificial reproduction of various fish species, on Perca fluviatilis in order to develop and optimize an artificial reproductive technology under controlled conditions. The hormonal preparations used in the experiment were carp hypophysis and Nerestin 6A, and the biological material consisted of 20 females and 6 males. The females were divided into two lots: (L1) carp hypophysis (4 mg / kg female body weight) and (L2) Nerestin 5A (0.25 ml / kg females body weight). Hormonal stimulation was done by intraperitoneal syringe administration for the carp hypophysis and intramuscular injection for Nerestin 5A, both in two divided doses as follows: 20% of the total dose in the first injection and 80% in the second. Males did not require hormonal stimulation. The average body weight of females was 399.1 ± 9.66 g (L1) and 425.10 ± 25.77 (L2). The average latency time between the first injection and the ovulation time was 121.43 ± 10.87 hours in L1 and 84.71 ± 6.12 hours in the case of L2. The mean value of the relative fecundity index was 209±66.5 x103 eggs/kg in L1 and 273.1±34.5 x103 eggs/kg in L2. The mean value of the absolute fecundity index was 87.2±23.4 x103 eggs/female in L1 and 109±11.1 x103 eggs/female in L2. The fertility rate had average values of 87.80 ± 2.63 for group L1 and 91.14 ± 2.87 for L2. The survival of females during the experiment was 80% in the L1 group, 90% in the L2 group and 100% in the males. The hatching rate averaged 36% in the first group (L1) and 52% in the second group (L2). Significant statistical differences between the two groups were recorded for the amount of harvested eggs and latency time, these indicators being higher for the L2 group, while insignificant differences were recorded for the other indicators. The results have shown that artificial reproduction is possible under controlled conditions and can be used to develop aquaculture of the species. [ABSTRACT FROM AUTHOR]

Interreligious relations between Christianity and Islam are rapidly changing on both theoretical as well as practical fields. The paper is dealing with bioethical issue of artificial reproduction as it is discussed in the world of Islam. The paper is focused on the methodological approaches to bioethical issues in a context of Sharia law in general. In particular it deals with cultural aspects of decision making process. The interpretation and understanding the process is presented in the Christian way of discernment. [ABSTRACT FROM AUTHOR]

The in vitro fertilisation method is widespread in fish aquaculture. In general, calculated doses of different hormones are injected intramuscularly or intraperitoneally, by using a syringe and needle, to induce ovulation and spermiation. We tested a novel approach to delivering sperm and hormone together to eggs, in African catfish, and concluded that sperm plus carp pituitary extract injection into the ovary lobes (through the oviduct) leads to successful ovulation and recovery of developing embryos in all of the experimental conditions applied. These results indicate that injected spermatozoa with suspended carp pituitary are stored in the ovary lobes for up to 10 h without loss of biological activity and that the ovulated eggs could be fertilised by the injected sperm, after being released from the body cavity. In addition, the seminal fluid was an appropriate delivery vehicle for the ovulation inducing hormone (i.e. carp pituitary) via ovarian lavage. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Motility of spermatozoa in most freshwater teleost species is suppressed by the osmolality of the seminal plasma in the testes, sperm ducts and initiated by a decrease of osmolality upon spawning in fresh water. We hypothesized that, similarly to internally fertilising fish species, spermatozoa of freshly stripped sperm, when injected directly into the ovary through the oviduct, will remain inactivated and maintain its fertilisation capacity for extended periods. Fertilisation is expected to occur after ovulated oocytes with spermatozoa on their surfaces are released into the water. To test this hypothesis, experiments were carried out on carp ( Cyprinus carpio ) as a model fish. Stripped and pooled sperm samples were injected by catheter into the ovarian cavity through the oviduct 2 h and 12 h before expected spawning. To prevent any loss of gametes the genital area of treated females were stitched by a standard protocol used in large-scale hatchery systems. At ovulation, eggs were stripped and fertilised with salt-carbamide solution. All sperm-injected females produced some fertilised eggs that developed normally while fertilisation rates varied considerably (24.2–81.2%). This proof of principle experiment demonstrates the potential for routine use as alternative to in vitro fertilisation for the propagation of fish species. [ABSTRACT FROM AUTHOR]

This study aimed to set up a method for the long-term management of Adriatic sturgeon, through the analysis of sex steroids and the genetic profiling of individuals in order to maximize the already reduced genetic variability of this species. Ten A. naccarii adults (nine of captive origin, one captured in the Ticino river and then moved into captivity) and eight subadults located in a semi-natural land-locked pond in Abbiategrasso (Milan, Italy) were analysed. Plasma testosterone differed significantly in the eight analysed subadults allowing their differentiation into two groups: the first group with an average testosterone concentration of 5.42 ± 1.31 ng/ml (probably female) and the second group with an average of 423.14 ± 75.97 ng/ml (probably male), as subsequently confirmed by artificial stripping. The plasma testosterone level was also significantly different between adult males and females (371.37 ± 43.58 vs. 95.34 ± 51.10 ng/ml), while the E2 levels showed no significant differences. Animals were genotyped on the basis of 10 microsatellite loci and their parental relationships were defined: four adults, two females and two males, generated the eight subadults. On the basis of pedigree analyses and genetic distances, 15 unrelated couples were identified for the future breeding seasons. Finally, the adult female captured in the Ticino River showed an interesting genetic profile, widely different from all of the other 17 specimens analysed, and represents a valuable source of genetic diversity. [ABSTRACT FROM AUTHOR]

Use of carp pituitary extract (CPE) as a hormone inducer for Leporinus obtusidens is cost-prohibitive; moreover, CPE contains unknown concentrations of gonadotropins. We evaluated the efficacy of gonadorelin as a substitute by analyzing its effect on sperm characteristics of L. obtusidens and cost-effectiveness (20, 40, 60, 80, and 100 μg kg −1 ). Untreated and CPE-treated (4 mg kg −1 ) fish were used as negative and positive controls, respectively. Following a single intramuscular dose of hormones, semen was collected at 200°-h. At doses from 60 μg kg −1 , all fish produced higher milt volume ( P < 0.05) than the negative control (0.2–0.8 mL kg −1 ), equal ( P > 0.05) to the positive control (3.52 ± 0.97 mL kg −1 ). Gonadorelin did not affect sperm concentration ( P > 0.05). The percentage of morphologically normal spermatozoa was >64% in all treatments. The number of spermatozoa with intact membrane (70%–85%) was equal ( P > 0.05) to that in the controls. Relative to the negative control, gonadorelin did not affect the motility rate ( P > 0.05). Curvilinear velocity was equal ( P > 0.05) to that in both controls. The sperm swimming path was linear (0.9) 10 s after activation and was not ( P > 0.05) dose-dependent. Considering the response rate of gonadorelin-induced fish and the similarity of semen quality compared to controls, the lowest effective dose to produce a higher volume of semen in L. obtusidens is 60 μg kg −1 , and the cost to induce 1 kg of L. obtusidens is 14.0% lower than that with CPE. [ABSTRACT FROM AUTHOR]

Ovulation in the European eel can be induced by injection of DHP (17α,20β-dihydroxy-4-pregnen-3-one). The timing of injection is based on the developmental stage of the oocytes. The oocyte stage is determined by invasive biopsy or through external indicators of the oocyte hydration response: body weight index (BWI) and body girth index (BGI). However, in European eel, BWI and BGI are inaccurate indicators because the individual hydration response is highly variable. The aim of this study was to identify indicators of oocyte maturation non-invasively by applying ultrasonography. Ultrasound parameters that were determined were the body wall thickness; diameter of the cloaca opening; grey scale median (GSM) of the ovary, and diameters (vertical and horizontal) and surface area of ovary, liver and swim bladder. Data of farmed and wild eels were combined for correlation analyses and principal component analyses (PCA). Ovary and liver parameters were not correlated with the average oocyte stage. Body wall thickness was negatively correlated to the average oocyte stage but variability was high. The swim bladder vertical diameter (Sbv) was negatively correlated with the average oocyte stage and with the oocyte diameter. Swim bladder area (Sba) was also negatively correlated to the average oocyte stage but less accurate. Results showed that during the final stages of oocyte maturation, the swim bladder becomes smaller. This is most probably due to the pressure that is caused by the increasing ovaries as a result of the oocyte hydration response. Females with an average oocyte stage between 4.5 and 7.0 and an average oocyte diameter higher than 800 μm, had Sbv values decreasing from 4.3 to 2.4 mm and Sba values from 52 down to 11 mm 2 . The correlation between Sbv and oocyte stage is more strict than for BWI or BGI which makes Sbv not only a parameter that can be determined non-invasively but also one that is more accurate in indicating the oocyte developmental stage. Therefore, ultrasonography, and in particular the ultrasound imaging of the swim bladder, represents a useful tool to assist with the timing of spawning as induced by injection of DHP. [ABSTRACT FROM AUTHOR]

The age of fish can affect reproductive performance in relation to the gamete quality and productivity which might be expected to be changed in older individuals. The consideration can be important in artificial propagation in relation to the selection of broodstock. We determined the age-related changes in male and female reproductive characteristics of the bighead carp Hypophthalmichthys nobilis and then we examined the effects of age on the male and female reproductive fitness in terms of fertilization, hatching, and larvae survival rate. A total of eight 3-4-year-old males and eight 4-5-year-old females were crossed using a factorial breeding design. Fertilization, hatching, and larvae survival rates were counted. We found no significant difference between 3 and 4 year olds in the sperm motility traits, density, and spermatocrit, but significant differences ( p < 0.05) were observed in the ionic composition (mainly Na, K, Ca, Mg), acid phosphatase, and glucose level. The quantitative characteristics between two age groups (4 and 5-year-olds) of the females showed significant differences ( p < 0.05) in total weight of stripped egg, ovarian weight, and relative fecundity, while no significant differences were found in egg size, absolute fecundity, and gonadosomatic index (GSI). In fertilization trials, we found that male age strongly influences fertilization ( p < 0.05), embryonic development ( p < 0.05), and larval survivability ( p < 0.001), while significant female effects, as well as male and female interactions ( p < 0.001 for all) were only observed for 7 days post-hatching larval survivability. One-way ANOVA showed significant differences among the fertilization (F = 3.797, p = 0.05), hatching (F = 4.802, p = 0.03), and larvae survival rate (F = 32.94, p = 0.001). Our results suggest that crosses between 4-year-old males and 5-year-old females of bighead carp achieved the best reproductive output. [ABSTRACT FROM AUTHOR]

This study focused on the reproduction effectiveness of 10 breeding strains of common carp (Polish strains 2, 3, 6; Hungarian strains 0, W, 7; Lithuanian strain B; French strain F; Israeli strain D and Yugoslavian strain J) after stimulation of ovulation with carp pituitary homogenate or Ovopel. The percentage of females with recorded ovulation became higher after Ovopel treatment in as many as eight breeding strains (2, 3, 6, 0, W, B, F, D). The interaction between the spawning agent and the breeding strain was statistically significant ( P ≤ 0.05) for the mass of spawn and non-significant for traits determining the quality of eggs. Among the 10 breeding strains, in 4 (3, 7, B, J) the least-squares means ( LSM) for the weight of egg (g) were higher for fish stimulated with Ovopel. Among the strains tested, in seven (3, W, F, J, 2, 7, B), the LSM for the percentage of living embryos after 36 h incubation were higher for fish treated with Ovopel. The evaluation of reproduction effects based on the values of such parameters as the percentage of ovulating females, weight of eggs (g) and the percentage of live embryos (36 h) showed that after Ovopel treatment the poorer effects were obtained only for strains 6, 0 and D. [ABSTRACT FROM AUTHOR]

Naked carp (Gymnocypris przewalskii) is the only fish species commercially harvested in Qinghai Lake, which is the largest inland saltwater lake in China. Multiple ecological stresses such as long-term overfishing, drying-up of riverine inflows, and decreases in spawning habitat caused the naked carp population to decrease from 320,000 tons before the 1950s to only 3000 tons by the early 2000s. We used matrix projection population modeling to quantitatively simulate the dynamics of the naked carp population from the 1950s to the 2020s. Five versions of the matrix model were developed from the field and laboratory information that represented different population states (high but declining, low abundance, very low abundance, initial recovery, pristine). Equilibrium analysis was applied to density-independent versions of the matrices and population growth rate, age composition, and elasticities were compared among versions. Stochastic, density-dependent version of the most recent decade (recovering) version was used to simulate the time-dependent responses to a range of levels of artificial reproduction (addition of age-1 from hatchery) and of the pristine version to simulate combinations of fishing rate and minimum age of harvest. Results showed the major role of overfishing in the population decline and that the population growth rate was most sensitive to the survival of juveniles and the spawning success of early-age adults. Dynamic simulations showed a rapid population response to artificial reproduction when population abundance was low and that if artificial reproduction continues at its current level, then population biomass would reach 75% of its pristine biomass after 50 years. Simulations with the pristine version identified sustainable fishing levels and the importance of protecting the first few ages of maturity. Overall, modeling results showed that artificial reproduction under conditions of no fishing is an effective approach to restoring the naked carp population. Further effectiveness should consider maximizing survival in the months just after release and maintaining genetic and phenotypic diversity. More information on density-dependent growth, survival, and reproduction, as well as on the genetic diversity and growth and migratory behavior (phenotypic variation) of released and native-spawned fish, would help inform management and conservation strategies and practices going forward. [Display omitted] • Matrix population model was applied to naked carp to predict management effects. • Results identified the importance of juvenile survival and early-age reproduction. • Recovering the naked carp population is feasible through artificial reproduction. • Once the population is recovered, sustainable harvest is possible. [ABSTRACT FROM AUTHOR]

African weakly electric mormyrid fish show a high diversity of their electric organ discharge (EOD) both across and within genera. Thanks to a recently developed technique of artificial reproduction in mormyrid fish, we were able to perform hybridizations between different genera and within one genus ( Campylomormyrus ). The hybrids of intergenus hybridizations exhibited different degrees of reduced survival related to the phylogenetic distance of the parent species: hybrids of the crosses between C. rhynchophorus and its sister genus Gnathonemus survived and developed normally. Hybrids between C. rhynchophorus and a Mormyrus species (a more basal clade compared to Campylomormyrus s) survived up to 42 days and developed many malformations, e.g., at the level of the unpaired fins. Hybrids between C. numenius and Hippopotamyrus pictus (a derived clade, only distantly related to Campylomormyrus ) only survived for two days during embryological development. Eight different hybrid combinations among five Campylomormyrus species ( C. tamandua , C. compressirostris , C. tshokwe , C. rhynchophorus , C. numenius ) were performed. The aim of the hybridizations was to combine species with (1) either caudal or rostral position of the main stalk innervating the electrocytes in the electric organ and (2) short, median or long duration of their EOD. The hybrids, though they are still juveniles, show very interesting features concerning electrocyte geometry as well as EOD form and duration: the caudal position of the stalk is prevailing over the rostral position, and the penetration of the stalk is dominant over the non-penetrating feature (in the Campylomormyrus hybrids); in the hybrid between C. rhynchophorus and Gnathonemus petersii it is the opposite. When crossing species with long and short EODs, it is always the long duration EOD that is expressed in the hybrids. The F1-Hybrids of the cross C. tamandua × C. compressirostris are fertile: viable F2-fish could be obtained with artificial reproduction. [ABSTRACT FROM AUTHOR]

This study aimed to compare the fertility of eggs between artificially matured female silver eels that spawned spontaneously and those that were spawned by manual stripping. The effects of the two methods of spawning on ovulation and fertilization rate were also investigated. For this purpose, 18 wild female European eels captured in Bonello lagoon (North Adriatic Sea) were carp pituitary extract-injected to undergo sexual maturation and ovulation; a final injection of 17,20β-dihydroxy-4-pregnen-3-one ( DHP) was administered when at least 30% of the oocytes were fully transparent. After the DHP-injection, nine eels were transferred to a new closed recirculating aquaculture system, where they were housed with spermiating males (sex ratio 4/1) to allow spontaneous spawning ( SPT-group); the remaining nine eels were transferred to a 250 L tank and ovulation was checked at four-hourly intervals by manual stripping ( STR-group). The number of eggs per female in the SPT-group was significantly greater than that in the STR-group. Furthermore, fertilization rates in the SPT-group were notably higher than those observed in the STR-group. Significantly, the best performances were obtained among eels in which at least 50% of oocytes were fully transparent at the time DHP was administered. We conclude that the fertility of eggs from spontaneously spawning eels is superior to that of eggs acquired by strip-spawning and artificial fertilization. [ABSTRACT FROM AUTHOR]

Standardization of fertilization protocols is crucial for improving reproductive techniques for externally fertilizing fish in captive breeding. Therefore, the objectives of this study were to determine the effects of preincubation of eggs and activation medium on the percentage of eyed embryos for ide ( Leuciscus idus ). Pooled eggs from five females were preincubated in three different activating media for 0, 30, 60, 90, and 120 seconds and then fertilized by pooled sperm from five males. At the eyed-egg stage, the percentage of viable embryos was later calculated. Results showed that preincubation time was significant for the freshwater activation medium (P < 0.001), such that the percentage of eyed embryos declined across the preincubation time gradient. Additionally, there was an effect on the percentage of eyed embryos when eggs were incubated with Woynarovich solution (P < 0.001), such that a decline was detected at 90 seconds, whereas no effect was detected for the saline water medium. Activating medium had a significant effect on the percentage of eyed embryos for each preincubation time (P < 0.05). More precisely, freshwater produced the lowest percentage of eyed embryos at all preincubation times (ranged from 1.9% at 120 seconds to 43.6% at 0 seconds), whereas saline water and Woynarovich solution produced the highest percentage of eyed embryos at 0 seconds and 30 seconds before incubation. Woynarovich solution produced the highest percentage of eyed embryos at 60 seconds (65.26%), whereas saline water produced the highest percentage at 90 seconds (68.37%). No difference was detected between saline water and Woynarovich solution at 120 seconds. Examination of sperm traits showed no impact of activating medium on computer assisted sperm analysis parameters. Together, these results suggest that saline water or Woynarovich solution improve fertilization rate in ide during IVF; thus, these media are useful for standardizing fertilization protocols and controlled reproduction for this species. [ABSTRACT FROM AUTHOR]

Reducing egg stickiness is a crucial step in artificial culture of sturgeon eggs, with commonly used methods being time consuming or interfering with hatching. Sodium hypochlorite (SH) at varying concentrations and exposure times was tested on sterlet Acipenser ruthenus eggs, with 0.03% SH for 40 s effectively eliminating stickiness without impairment to eggs, embryo development, or hatching when compared with other de-adhesion methods (clay; NaCl, urea, and tannic acid). Field tests using sterlet, Siberian sturgeon Acipenser baerii , and Russian sturgeon Acipenser gueldenstaedtii showed similar numbers of larvae hatched using SH and clay. Immunohistochemistry revealed a protein carbonyl group only on the surface of eggs treated with SH, evidence of oxidation as the mode of action and indicating that oxidation did not affect inner egg layers or cytoplasm. Treatment with SH is a rapid, simple, and inexpensive method for de-adhesion of sturgeon eggs. Statement of relevance Sturgeons represent a valuable group of fish in aquaculture, especially for caviar, but also for meat production. This study describes a novel approach to sturgeon egg de-adhesion involving oxidation of egg surface. The method requires little time, is low cost, and disinfects and softens the egg surface, which facilitates hatching. [ABSTRACT FROM AUTHOR]

The aim of the current paper was to establish and to optimize the doses of Nerestin 5A hormonal synthesis mixture utilised for hormonal bio-stimulation of females belonging to Polyodon spathula breed, function of water temperature. The current research were carried out on three females' batches, of same age (13 years) and reared in the same environmental conditions in an aquaculture farm from Iaşi County. From all females from reproduction batch were gathered roes using biopsy method and was calculated polarization coefficient of their nucleolus. In this way were chosen 3 individuals from each batch, all of them having polarization coefficient between 0.05-0.07. Experiment started when water temperature reached the value of 13°C, when were injected the females from first batch, after that at 15°C second batch and at 17°C for the third one. Injecting was realised in two rounds: first 20% from dose and second, after 12 hours, 80%. The utilised doses were of 0.12, 0.2 and 0.3 ml/kg female body. Maturation percent was of 100% at all those three females' batches differing, function of water temperature, time for maturation. So, at the same administrated dose with the increasing of water temperature is observed a decreasing of maturation time. Roes' quantity which was gathered was between 73-79 g/kg female body. [ABSTRACT FROM AUTHOR]

The number of wild animal species is gradually decreasing due to poaching, hunting and habitat loss. While several endangered animal species have been successfully preserved at the zoo, assisted reproductive technology (ART) must be applied to restore wild animals. In the case of critically endangered animals, somatic cell cloning is considered the most appropriate method of ART. Somatic cell cloning can be beneficial for the reproduction of endangered species with limited female populations. However, gene and cell banks, and understanding of reproductive physiology and optimization of ART for wild animals are urgently required for further activation of artificial reproduction of endangered species, which enlarges its application and maintains biodiversity. Care should also be taken to consider ethical and legal issues associated with somatic cell cloning for conservation of endangered animals. [ABSTRACT FROM AUTHOR]

Standardization of fertilization protocols for sterlet Acipenser ruthenus is crucial for improving reproductive techniques and for conservation purposes. Our objectives were to determine the number of sperm (tested 430,000:1, 43,000:1, 4300:1, 430:1 sperm to egg) required to fertilize eggs and explore how pre-incubation of eggs in freshwater for 0 min, 0.5 min, 1 min, and 10 min interacts with different sperm ratios. Fertilization success ranged from 29.7% at 430:1 to 84.2% at 430,000:1. Pre-incubation time had no effect on fertilization success at 430,000:1 and 43,000:1 sperm to egg ratios, while it was significant at the 4300:1 and 430:1 ratios. The use of adequate experimental suboptimal sperm to egg ratio revealed a positive effect of pre-incubation time, such that at the 430:1 ratio, 0.5 min pre-incubation increased the fertilization rate than 10 min. At 0 min pre-incubation the proportion of fertilized eggs increased at the 430,000:1 ratio, while at 1 min fertilization increased at the 4300:1 ratio. At the 10 min pre-incubation time, fertilization increased at the 43,000:1 ratio. Moreover, at the 0.5 min pre-incubation time, the 43,000:1 ratio increased the fertilization rate than the 430:1 ratio. Generally, for 430:1 ratio, the fertilization rate is lower than in control. Transmission electron microscopy showed that pre-incubation of eggs in water for <10 min does not trigger a cortical reaction or the formation of a perivitelline space. Results suggest that with a low sperm to egg ratio 0.5 to 1 min pre-incubation of eggs in freshwater prior to fertilization can enhance fertilization rate of sterlet. [ABSTRACT FROM AUTHOR]

The aim of this qualitative study was to explore how recipients viewed payment of sperm donors. The study was conducted in Belgium, where, as in many countries, sperm donors receive recompense for their time and expenses. Face-to-face semi-structured interviews were conducted with 34 heterosexual and lesbian couples who, at the time of data collection, had at least one donor-conceived child aged 7–10 years or who were undergoing donor conception treatment. Although participants commonly described the issue of financial compensation as something that did not really concern them, all supported the idea that some level of payment was acceptable or even necessary. The participants also identified several ways in which donor payment offered advantages to their own position as (future) parents. Although the idea is commonly rehearsed that sperm donation is a gift and that monetary transaction for conception is demeaning, the participants of this study did not generally share this view. To them, a small financial return served as a symbolic acknowledgement of the donor's contribution and helped secure the type of relationship they expected from their donor. There was clearly concern, however, over high payments and the risk of attracting the wrong kind of donor. [ABSTRACT FROM AUTHOR]

The aim of this article was to analyse the process of pikeperch, Sander lucioperca, egg swelling and to apply tannic acid to eliminate egg stickiness at different moments of the swelling process on artificially obtained eggs. The first experiment involved observation of egg swelling process and the second determined the effect of temperature (12, 14 and 16°C) on the egg swelling rate. The third experiment involved elimination of egg stickiness in a tannin solution (0.75 g L−1) where eggs were submerged in a solution for 0.5, 1, 2 and 5 min - 5, 10, 15, 20, 25 and 30 min following gamete activation. The results indicate that the pikeperch egg swelling process lasts 30 min. It was found that the temperature did not affect the process duration. The results of the third experiment showed that the effectiveness of tannic acid application in egg stickiness elimination increases with time. The best result was obtained in groups of eggs submerged for 1 and 2 min (86.5% and 80.5% of larvae were obtained respectively) 30 min following the gamete activation. The results presented in this study for the first time indicate the possibility of highly effective procedure of egg stickiness elimination with tannic acid in pikeperch aquaculture. [ABSTRACT FROM AUTHOR]

This paper describes a study in which different types of the reproduction of wild vimba bream (Vimba vimba) under controlled conditions were compared. Reproduction was performed by using three methods: spontaneous (natural spawning- NS groups): without hormones but with nests, semi-artificial (S groups) with hormones and nests, and artificial (A groups) with hormones and manual stripping of gametes. In groups S and A, different types of hormonal stimulation were tested: common carp pituitary homogenate (CPH), human chorionic gonadotropin (hCG), and commercial pellets containing mammalian GnRHa and dopamine antagonist-metoclopramide (Ovopel). The number of spawning fish, i.e., spermiating males and ovulating females, were compared depending on the type of breeding and the stimulant used. The lowest number of finally matured fish: spermiating males (67 %) and ovulating females (0 %) were noted in the spontaneously reproduced group. The best method of reproducing wild vimba bream under controlled conditions was the semi-artificial approach with hormonal stimulation and spawning nests, where ovulation rates in hormonally treated groups were between 43 % and 71 %, vs 26–57 % in artificial spawning groups. No ovulation observe in control groups in S and A types of reproduction. The highest embryo survival to the eyed-egg-stage was noted in group A-hCG (average 88.2). A higher value of spawning effectiveness (Se) with the use of the same hormones was obtained for groups S (0.374–0.574) than for groups A (0.252–0.493). In both cases, the highest Se was recorded for Ovopel stimulated fish and the lowest in hCG stimulated groups. • Environmental stimulation alone does not induce final gamete maturation in vimba bream. • Artificial reproduction does not fully succeed in the reproduction of vimba bream. • The best results were obtained using the semi-artificial reproduction method. [ABSTRACT FROM AUTHOR]

The purpose of this essay is to show how, on a wide variety of issues, Rabbi Moshe Feinstein broke new ground with the established Orthodox rabbinic consensus and blazed a new trail in Jewish medical ethics. Rabbi Feinstein took power away from the rabbis and let patients decide their treatment, he opened the door for a Jewish approach to palliative care, he supported the use of new technologies to aid in reproduction, he endorsed altruistic living organ donation and recognized brain death (thus laying the groundwork for Orthodox Jewish acceptance of heart transplantation), he downplayed the value of social worth in triage decisions, and was a fierce defender of the rights of the fetus. I develop broader theological principles from Rabbi Feinstein's ethical positions and compare them to those of his Jewish and Christian contemporaries. [ABSTRACT FROM AUTHOR]