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Paralichthys adspersus is a native species from the Pacific coast of South America that is of great economic importance for Peruvian aquaculture. Even though establishing sustainable farming depends on avoiding irreversible damage to the population gene pool due to processes such as inbreeding, studies focusing on genetically characterizing farmed stocks are yet to be documented. By using ten microsatellite loci on captive and wild individuals of P. adspersus, we successfully characterized the only commercial broodstock of this species in Peru by means of determining the genetic diversity and inferring relatedness. Although most microsatellite loci showed deviations from Hardy-Weinberg equilibrium, the genetic diversity levels in the commercial broodstock were considered healthy compared to those obtained for a wild population, with an average number of alleles of 17.40, an effective number of alleles of 9.14, and an observed and expected heterozygosity of 0.49 and 0.87. No significant differences between the broodstock and the wild population in terms of genetic diversity were observed. The fixation index and analysis of molecular variance also indicated a low rate of differentiation between both populations. In relatedness estimation, the analysis based on five method-of-moment estimators and a maximum-likelihood estimator showed the category “unrelated” as being the most probable relationship among the individuals within the commercial broodstock. Our findings reveal the conservation of genetic diversity in this population and outline potential breeding strategies that hatchery managers could use to minimize the loss of genetic diversity and long-term inbreeding. This could help establish proper genetic management in captive populations of P. adspersus and should apply to other captive stocks where pedigree information is lacking.

The release of captive‐bred plants and animals has increased worldwide to augment declining species. However, insufficient attention has been given to understanding how neutral and adaptive genetic variation are partitioned within and among proximal natural populations, and the patterns and drivers of gene flow over small spatial scales, which can be important for restoration success. A seascape genomics approach was used to investigate population structure, local adaptation, and the extent to which environmental gradients influence genetic variation among natural and restored populations of Chesapeake Bay eastern oysters Crassostrea virginica. We also investigated the impact of hatchery practices on neutral genetic diversity of restored reefs and quantified the broader genetic impacts of large‐scale hatchery‐based bivalve restoration. Restored reefs showed similar levels of diversity as natural reefs, and striking relationships were found between planting frequency and broodstock numbers and genetic diversity metrics (effective population size and relatedness), suggesting that hatchery practices can have a major impact on diversity. Despite long‐term restoration activities, haphazard historical translocations, and high dispersal potential of larvae that could homogenize allele frequencies among populations, moderate neutral population genetic structure was uncovered. Moreover, environmental factors, namely salinity, pH, and temperature, play a major role in the distribution of neutral and adaptive genetic variation. For marine invertebrates in heterogeneous seascapes, collecting broodstock from large populations experiencing similar environments to candidate sites may provide the most appropriate sources for restoration and ensure population resilience in the face of rapid environmental change. This is one of a few studies to demonstrate empirically that hatchery practices have a major impact on the retention of genetic diversity. Overall, these results contribute to the growing body of evidence for fine‐scale genetic structure and local adaptation in broadcast‐spawning marine species and provide novel information for the management of an important fisheries resource.

The effect of dietary β-glucan on seminal plasma composition, sperm characteristics, expression of aquaporins, and antioxidative defence genes of golden mahseer was evaluated. For that, four experimental diets containing 0 (control), 0.5, 1, and 1.5% β-glucan were fed to male golden mahseer brooders for 130 days. Feeding of 0.5% β-glucan was found to improve sperm characteristics, viz. sperm count, motility, viability, and morphology with no effect on gonadosomatic index and seminal plasma energy resources. The marked down-regulation in the transcript abundance of testicular aqp3a noticed in 1.5% β-glucan fed brooders corresponds to their poor sperm quality. Further, the mRNA expression of genes encoding antioxidant enzymes, namely gst and sod1, was lowest in 0.5% β-glucan fed brooders. In contrast, control and higher β-glucan (1 and 1.5%) groups displayed relatively higher expression levels of testicular gst and sod1. On the other hand, the higher seminal plasma total antioxidant capacity observed in 0.5 and 1% β-glucan fed brooders indicated increased scavenging ability of reactive oxygen species. Overall, supplementation of 0.5% β-glucan improved sperm quality and antioxidative potential, but the higher inclusion (1.5%) negatively affected sperm characteristics. Collectively, dietary β-glucan (0.5%) can be a practical approach to developing quality broodstock of golden mahseer.

Taman Kili-Kili Beach is designated as an Essential Ecosystem Area (KEE). 188/39/KPTS/013/2020. According to the Supervisory Community Group (Pokmaswas), in 2011-2020, there was an increase in broodstock as many as 52 turtles, and the eggs saved as many as 3323 eggs. However, since 2013 Pokmaswas data shows a decrease in the population of hawksbill and green turtles in turtle conservation areas, which is thought to be caused by climate change, global warming, and animals. This study aims to analyze environmental baselines, turtle populations, and the value of turtle ecotourism (ecological, economic values) and develop strategies to support turtle conservation at Taman Kili-Kili Beach Trenggalek Regency. The results of the adjustment of nesting habitats and turtle ecotourism, calculation of the Habitat Conformity Index (IKH) of turtle nesting, IKH = 77.77%, which belongs to the category (S1) is very suitable to be used as a conservation area and turtle nesting habitat. While the results of the calculation of the Turtle Ecotourism Conformity Index (IKW), IKW = 84.93%, which is included in the (S1) category, which is very suitable for use a turtle tourism area. The strategy for developing turtle ecotourism is in quadrant II, meaning that it utilizes the strengths possessed in the turtle conservation area by minimizing the threats that it will experience.

Oreochromis is the most important tropical freshwater fish genus for aquaculture purposes, with various introduction and translocation events having played an integral part of its management. Some Oreochromis species such as the Nile tilapia, O. niloticus, are thought to be superior for aquacultural purposes when compared to other species. Hence, understanding the admixed nature of the species within a native system is of key importance for the development of future broodstock. Using a combination of mitochondrial (COI) and nuclear (microsatellites) DNA, we tested for the presence of O. niloticus and O. leucostictus hybrids within the Lake Edward-George system. The present study revealed that, despite their natural overlapping ranges, hybridization between O. niloticus and O. leucostictus appears to be rare within the Lake Edward-George system, suggesting that the native populations of these two species may serve as suitable broodstock to develop future aquaculture strains. Moreover, our study provides the first COI sequences for O. leucostictus from its native range and adds to the growing database of O. niloticus sequences.

Highlight Research The reproductive characteristics of L. hoevenii were examined The potentially smallest maturity sizes of female and male L. hoevenii were 350 g and 180 g, respectively The fecundity of a 1,000 g L. hoevenii can be more than 100,000 eggs L. hoevenii was determined as a multiple spawner Abstract Sultan fish ( Leptobarbus hoevenii ) is a high value freshwater fish, cultured in some Southeast Asian countries, including Malaysia and Thailand. However, information on its reproductive characteristics is very scarce. This study examined the gonadosomatic index (GSI), fecundity, egg diameter, and determined whether L. hoevenii is a single- or multiple-spawner. Twenty male and female pond-farmed L. hoevenii broodstock were obtained to measure their total length (TL), body weight (BW) and gonad weight to calculate the GSI. Ten females were randomly sampled from the 20 to determine their fecundity. A total of 1,500 eggs were sampled from each female. The egg diameter was measured then its frequency distribution was analyzed to detect the number of egg class group, and to determine whether L. hoevenii is a single- or multiple spawner. The female L. hoevenii examined were 32.2-47.1 cm and 350-1,200 g, while the males were 30.7-45.8 cm and 180-970 g in TL and BW, respectively. All female specimens contained gonads. The potentially smallest mature samples were recorded at 350 g (female) and 180 g (male). GSI for the female and male L. hoevenii were 1.81-12.28 % and 1.03-5.09 %, respectively. The fecundity was 35,467 -128,067 eggs, while the highest fecundity was observed in a 1,000 g fish. The observed egg diameter ranged from 500 to 1,855 μm. Two to five groups of egg class were detected, indicating that L. hoevenii is a multiple spawner.

Hormonal sex - reversal is widely recognized as having significant advantage over both manual sexing and hybridization. The present study carried out in the aquaculture center of Kankan aimed at producing monosex male fry of Oreochromis niloticus in order to increase the yield of this species. During this study, 95 Oreochromis niloticus broodstock including 21 males and 74 females were paired (spawned) in a spawning tank of 135 m2 surface for 15 days. The respective mean weights of the spawners were 448.6 ±157.7 g for males and 406.7±115.9 g for females. Hormonal treatment was performed on 900 larvae with an average initial weight of 0.028 g from the 10th post fertilization to the 38th day in a tank of one (1) m3. The larvae were fed with 1 kg of imported "Raanan Premium Fish" powdered feed titrated with 40% protein, mixed in a hormonal solution containing 17-α-methyltestosterone and 90% ethanol with respective doses of 100 mg and 500 ml. At the end of hormonal treatment, 578 fry with a final average weight of 4.5 g were conducted in a pre-pregnancy tank with a surface area of 50 m2 for 30 days and yielded at the end of pre-pregnancy 501 fry with a final average weight of 13 g, a daily growth rate of 0.22 g, a specific growth rate of 1.7%, a survival rate of 64% and a mortality rate of 36%. After sex identification (sexing), the rates of hormonal treatment were 83.33% and 16.66% for males and females, respectively. In conclusion, the popularization of the results of this study could be considered as an alternative for a production of monosex male population in Oreochromis niloticus that will feed the networks of local producers to improve the production of the species throughout the country. Keywords: Oreochromis niloticus, hormone, sex, larvae and tank.

This study analyzed the potential of harvesting eggs and fry at different time intervals for improved seed production of Nile tilapia. Broodstock were put in 3x1m2 hapas at a sex ratio of 3 females: 1male. Eggs and fry were harvested at intervals of 8 days, 10 days, 12 days and 14 days respectively. The results showed a direct positive relationship between the harvesting frequencies and total seed production, where Broodfish in the 14 days treatment produced the highest total seed output (13979 ± 314) followed by 12 days (10167 ± 248), 10 days (6645 ± 135) and 8 days (4509 ± 112) respectively. The 8 days harvesting frequency consistently recorded zero swim up fry throughout the study while the 10 days treatment yielded the highest egg counts of 4272 ± 127. The specific growth rates and condition factors of females did not significantly differ among all the treatments.

International audience; Chub mackerel Scomber japonicus and blue mackerel S. australasicus have become important aquaculture target species in Japan. For an efficient and stable aquaculture production of mackerels, it is desirable to work with a female-biased broodstock and thus to be able to manage precisely their sex ratio. As these two mackerel species do not have any external sexual dimorphism, direct biopsy of the gonads or measurement of sex hormone plasma levels is used in research to determine their phenotypic sex. However, these methods are associated with handling stress that results in gonadal atresia. Besides, it is difficult to identify sex using these methods in immature individuals. Therefore, genetic sexing would be desirable in these species to overcome these problems. In this study, we developed molecular sex identification tools for both chub and blue mackerels using sex-specific single-nucleotide variations (SNVs) identified by pool-sequencing (pool-seq) analyses. Genomic DNA was isolated from 30 males and females, in each species, and sequenced as pooled samples. Results of these pool-seq analyses identified a clear XX/XY male heterogametic sex-determination system in blue mackerel and a ZZ/ZW female heterogametic system in chub mackerel. Using this pool-seq information, we designed primer sets for genetic sex identification in both species. Results demonstrated that these primer sets are robust and accurate in assessing the genotypic sex of both blue and chub mackerels (accuracy > 99.5% in the chub, and > 94.5% in the blue mackerel) in various geographical samples of different ages. This method can now be applied for the efficient management of sex ratios in both mackerel aquaculture populations and wild-caught animals for fisheries management.

In Cameroon, wild strains of Clarias gariepinus (Burchell, 1822) are often used for artificial reproduction in hatchery facilities, but there is insufficient information on their reproductive capacity and progeny performance. The reproductive capacity of two strains of C. gariepinus from the Mezam and Mungo Rivers and the performance of their F1 larvae obtained following hybridization were assessed. Reproduction was carried out with four crosses as follows: Mezam (♂) x Mezam (♀) (T1), Mezam (♂) x Mungo (♀) (T2), Mungo (♂) x Mezam (♀) (T3) and Mungo (♂) x Mungo (♀) (T4). Thereafter, three days old larvae obtained following reproduction were subjected to a 30 day experimental trial with standard feeds. The performance of larvae obtained from T4 was not assessed since larvae obtained were too few for the experiment. Although the broodstock of the different strains did not differ significantly in size, Mezam stock had significantly (p = 0.00) bigger eggs when compared to Mungo stock. Fecundity of 52480 was recorded for Mezam stock compared to 32985 for Mungo stock. Fertilization and hatchability rates differed significantly (p < 0.05) among the crosses, with the highest (82.28 and 81.31%, respectively) in T1, followed by T3 (65.96 and 61.28%, respectively), and the least (38.61 and 2.81%, respectively) in T4. The best larval survival was recorded in T1 (37.17%) and the least in T2 (15.67%), meanwhile T3 recorded best growth after 30 days. In terms of fertilization and hatchability, T1 was more suitable for artificial reproduction, but T3 is more encouraged for aquaculture based on its reproductive capacity and larval performance.

The adaptive capacity of marine calcifiers to ocean acidification (OA) is a topic of great interest to evolutionary biologists and ecologists. Previous studies have provided evidence to suggest that larval resilience to high pCO2 seawater for these species is a trait with a genetic basis and variability in natural populations. To date, however, it remains unclear how the selective effects of OA occur within the context of complex genetic interactions underpinning larval development in many of the most vulnerable taxa. Here we evaluated phenotypic and genetic changes during larval development of Pacific oysters (Crassostrea gigas) reared in ambient (~400 µatm) and high (~1600 µatm) pCO2 conditions, both in domesticated and naturalized “wild” oysters from the Pacific Northwest, USA. Using pooled DNA samples, we determined changes in allele frequencies across larval development, from early “D‐stage” larvae to metamorphosed juveniles (spat), in both groups and environments. Domesticated larvae had ~26% fewer loci with changing allele frequencies across developmental stages and

Kisspeptin, upstream of the hypothalamic-pituitary-gonadal axis, play an essential role in the reproductive process. In the present study, the effect of different types of kisspeptin, including goldfish (Carassius auratus) kiss1 kisspeptin (Kiss1), human kisspeptin (Hkiss) and their combination (Kiss1+H) on the reproductive-related genes (kiss1, Kissr and Cyp19) of adult female goldfish was investigated in comparison with Ovaprim (a synthetic GnRH hormone). Kiss1 and Hkiss were synthesized using a solid-phase synthesis approach. Peptides were injected at a dose of 100 μg/kg body weight. The brain and ovarian tissues of samples were separated for histological studies 24 hr post-injection. The expression of the kiss1, Kissr and Cyp19 genes was measured by RT-PCR. The results showed a significant increase in expression of the reproductive-related genes. Histological analysis revealed higher number of mature oocytes in kisspeptin treated groups compare to other ones. In conclusion, Hkiss and Kiss1+H are the most effective peptides in oocyte maturation and expression of reproductive-related genes. In addition, it seems that kisspeptins in other domestic animals can be used to stimulate the hypothalamus-pituitary-gonadal axis.

Thirty-three broodstock of common carp (Cyprinus carpio) obtained from Panyam Fish Farm, plateau state Nigeria was used to evaluate the percentage hatchability of carp through induced natural spawning in outdoor Hapa net system, and induced breeding by stripping in indoor concrete Ponds. Spawning and fertilization was natural for experimental group 1. Ovaprim hormone was used to induce broodstock in experimental group 2 and 3, but unlike experimental group 3, experimental group 2 was not stripped manually, as the induced female broodstock shed her eggs naturally. At the end of the experiment, the mean number of eggs in one gram was found to be (733.33±3.53a) in treatment 3, as compared to that of experimental group 2 (702.00±3.21b) and experimental group 1 (709.33±4.91b), with a significant difference at (P

The study was carried out for six (6) weeks at the Department of Fisheries Teaching and Research farm, Modibbo Adama University, Yola, to compare the reproductive performance of Clarias gariepinus using synthetic (ovaprim) and natural (C. gariepinus pituitary extract) hormones . At the end of the feeding trial, the fecundity, percentage fertilization, hatchability, and survival rates of the hatchlings were estimated using standard procedure. The hatchlings were further raised for six weeks and the increase in weight was determined. The results showed that female broodstock injected with C. gariepinus pituitary extract (CgPE) had a higher fecundity (124,000) while the female injected with Ovaprim had 65,000 eggs. The weight of the testes significantly differed (p

The present study provides the complete report on the embryonic and larval development of pink ear emperor, Lethrinus lentjan (Lacepede, 1802). Eggs were obtained from captive-reared broodstock of pink ear emperors from 1-year of age maintained in a 10-tonne recirculating aquaculture system (RAS). The brood fishes spawned throughout the year without hormonal induction. Fertilized eggs (692.65 ± 6.67 μm) were pelagic, transparent, non-adhesive and with a single oil globule measuring 146.63 ± 3.51 μm. Description of the different phases of embryogenesis, namely the zygote, cleavage, blastula, gastrula, segmentation of the fish is provided. Additionally, the developments during larval development period after hatching, which extends till the completion of yolk-sac absorption (pre-larvae) and the end of metamorphosis (post-larval) are also included in the present study. The embryonic development was completed within 14 h 40 min after fertilization. The newly hatched larvae had an average body length of 1.39 ± 0.08 mm, with a yolk sac measuring 787.67 ± 42.65 μm. The mouth opening was observed at 2 days post-hatch (dph). The yolk sac was completely absorbed by 2 dph, and the preflexion stage began, and it continued till 14 dph. Notochord flexion began by 15 dph and extended to 20 dph. The appearance of the typical adult colouration and scale formation started by 22 dph and by 35 dph the larvae reached the juvenile stage. The data on the embryonic and larval development will help to standardize the larval rearing techniques for the species.

The present research was conducted to investigate the effects of fish oil (FO) substitutions with corn oil (CO) on the gonad development of female Tor tambroides broodstocks, a high value freshwater fish. Three isonitrogenous (450 g kg−1 crude protein) and isolipidic (105 g kg−1 crude lipid) were formulated to contain FO and CO at a ratio of 1:0, 1:1 and 0:1, respectively, and fed to female fish (n = 10 fish × 3 replicate × 3 treatment; average weight = 910.0 ± 130.0 g) for five months. At the end of the feeding trial, there were no significant differences (p > .05) on the gonadosomatic index (GSI), hepatosomatic index, 17β-oestradiol (E2) concentration and muscle fatty acids (FA) composition. However, fish fed with diet containing FO to CO at a ratio of 1:1 demonstrated higher percentage of GSI, E2 concentration (ng ml−1) and the presence of vitellogenic oocytes in the histological data compared to the other two feeding diets. The FA composition also highlighted that T. tambroides broodstocks can elongate polyunsaturated FA to highly unsaturated FA. Based on these preliminary results, it shows that T. tambroides prefer diets with supplementation of both n3 and n6 oil source. However, more studies need to be done to strengthen this conclusion.

Describe the embryonic development of Paralabrax humeralis (Peruvian rock seabass) and the present morphology of its eggs and yolk-sac larvae using the eggs spawned by P. humeralis broodstock in captivity. The spawning occurred naturally and spontaneously in early November 2018. The egg is pelagic and round, with a diameter of 0.98 ± 0.02 mm, an oil globule, and a diameter of 0.2 ± 0.02 mm. Embryonic development started with meroblastic cleavage, reaching the first cleavage stage at 0.4 h post-fertilization (HPF), and reached 64 cells at 2.2 HPF. Blastula period, 128 cells to 30% epiboly, end at 11.3 HPF. Gastrula period, 50% epiboly to 90% epiboly, end at 19.6 HPF. In the organogenesis period, forming Kupffer’s vesicle appeared at 22.5 HPF, the separation of the caudal fin from the yolk at 30.3 HPF, and the hatching of the first larvae at 47.9 HPF. Water temperature was kept at 17.2 ± 0.2°C. The yolk-sac larvae measured 2.22 ± 0.1 mm with a pigmentation pattern of pinpoint melanophores, all along with the embryo and xanthophores in the cephalic region, trunk, and caudal region, as well as in the oil globule. The larva takes feeds from three days post-hatch-out.

The present study was conducted to create a new strategy for increasing the transport efficiency of brood-stock Nile tilapia (Oreochromis niloticus) using clove and mint oils for 3.5 h. The fish study was exposed to conditions simulating those normally used in transporting. This study was performed in a fish research center of the Arish University. The average initial weight of the broodstock was 117.07 ± 09.07g (± standard error). The broodstock was randomly distributed into 10 clear plastic aquaria (30 liters capacity) with a stocking density of one brood-stock/3.75 liter of water. The present study examined two concentrations of clove oil as a deep anesthetic for 5 min and two concentrations of mint oil as a sedative. It included five treatments in duplicate, namely, the control group, G1: clove and mint oil at 100 and 20 µL/L, respectively; G2: 100 and 10 µL/L of clove and mint oil, respectively; G3: 50 and 20 µL/L of clove and mint oil, respectively; and G4: 50 and 10 µL/L of clove and mint oil, respectively. Blood samples were taken from all groups before transporting from a random sample and after transport. Results confirmed that G1 had the best parameters of water quality and blood indicators with the highest survival rate followed by G2. Moreover, using clove and mint oil improved the transport efficiency and survival rate after 24 h of fish transporting compared to that of the control group.

Mutiara catfish is one of the most important catfish strains developed in Indonesia. However, the growth stability of cultured non-transgenic Mutiara catfish fluctuates. This problem can be solved by developing transgenic Mutiara catfish (containing the African catfish growth hormone gene, CgGH) to improve the stability of fish growth. Controlled handling of eggs is carried out to reproduce this superior fish in each generation. The egg handling in a controlled system was performed to reproduce this superior fish in each generation. The G3 transgenic Mutiara catfish eggs production was carried out with three different broodstock pairs (pairs A, B and C). The results of observations of the rate of embryogenesis and hatching of the G3 eggs showed that eggs from pair A were faster than B and C. Transgenic catfish eggs hatch 1-1.5 hours faster than non-transgenic fish eggs at room temperature.

For preventing transmission of pathogens from broodstock fish to offspring, the non-hardened eggs are routinely disinfected with iodophore solution immediately after fertilization. In the present study, 25–50 mg l-1 Chloramine T® (active substance: tosylchloramide), 10–50 μl l-1 Wofasteril® (active substances: acetylhydroperoxide, hydrogen peroxide, and acetic acid) and 10–50 μl l-1 of a 30% hydrogen peroxide solution were tested for disinfection of non-hardened brown trout, Salmo trutta, eggs in comparison to 10 ml l-1 of an iodophore solution (Betaisodona®). Five different egg batches were used and the effect of disinfection on the percentage of eyed stage embryos (32 days post fertilization [dpf] at 9° C) and swim-up larvae (42 dpf), on bacteria, and fungus load (in 3 and 32 dpf embryos using different culture broths and qPCR), and on lipid peroxidation and protein carbonylation (in 3 dpf embryos) was investigated. A 20-min treatment of non-hardened eggs with the 4 biocides in abovementioned concentrations had no negative effect on the percentage of eyed stage embryos (92–100% of the control) and normal shaped swim-up larvae (90–100% of the control). All tested treatments including Betaisodona caused oxidative stress to 3 dpf embryos, as they significantly increased the levels of protein carbonyls for 2- to 3-fold in comparison to non-disinfected controls. Thiobarbituric acid-reactive substances did not increase after 10 ml l-1 Betaisodona and 10 μl l-1 hydrogen peroxide treatment, but increased by 1.5- to 3-fold after all other treatments. All tested biocides significantly and persistently decreased the load with bacteria in comparison to non-disinfected controls for 25–99% depending on the disinfection treatment and bacteria species. 50 mg l-1 Chloramine T, 50 μl l-1 hydrogen peroxide solution, and 50 μl l-1 Wofasteril had up to 80% higher disinfection efficiency than 10 ml l-1 Betaisodona for specific species of bacteria. The oomycete Saprolegnia parasitica and the total bacteria load were persistently decreased neither with Chloramine T, Wofasteril, and hydrogen peroxide nor with Betaisodona. It is concluded that hydrogen peroxide, Wofasteril, and Chloramine T are at least similar efficient for disinfection of non-hardened eggs as iodophor solution. They are more economical as the effective concentrations are much lower.

The stock enhancement programs for black sea bream Acanthopagrus schlegelii have been conducted in China for a few years. However, little information has been reported concerning the effectiveness and genetic effect of black sea bream stock enhancement. In order to detect the contribution of released individuals in Zhujiang River Estuary (ZRE) and Daya Bay (DB), six microsatellite markers were used to identify the hatchery-released individuals. In addition, this pedigree of hatchery populations (broodfish and hatchery-released offspring) was traced to detect the number of effective parents (Ne), the inbreeding coefficient and the decrease of genetic variability in the reproduction. The pedigree reconstruction showed that at least 69 (out of 93) broodfish had offspring. The estimated Ne was 54.8, consequently the inbreeding coefficient was 0.91%. The genetic diversity of hatchery-released offspring was lower than that in that of broodfish (heterozygosity alleles, 0.727–0.774), some alleles (number of alleles, 61–69) and genetic variance were lost during reproduction. It was observed that wild samples had higher levels of genetic diversity compared with hatchery populations as well as recaptured samples in releasing area. A total of 128 hatchery-released black sea bream were identified among 487 recaptured samples in ZRE, while a total of 15 samples were identified among 96 samples in DB. In summary, there was a high survival of released fish. Nevertheless, the results provided evidence to consider a loss of genetic variation in hatchery-released stock and a negative genetic effect of the stock enhancement.

White spot syndrome virus (WSSV) is a virulent disease that disrupts shrimp farm operations throughout the world. While the United States has had only limited outbreaks of WSSV within the past several decades, it is important to ensure that this disease does not infect wild penaeid shrimp populations. In Texas, there is a potential for WSSV to spread to wild penaeid populations in the Gulf of Mexico via infected imported nonnative bait shrimp, imported broodstock, or wild crustacean hosts. Due to these potential threats, the Texas Parks and Wildlife Coastal Fisheries Division monitored WSSV in wild brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus from seven major bay systems along the Texas coast during 2019. While no positive samples were detected from the collected shrimp, a power analysis illustrated a potential for low-level WSSV prevalence within Texas shrimp populations that would not be detectable by this monitoring survey. Overall, WSSV does not appear to be a major threat in the Texas region of the Gulf of Mexico, but continual observation and monitoring of wild penaeid shrimp is necessary to protect this resource from future WSSV outbreaks.

An experiment was performed to observe the potentiality of synthetic hormone analogue in artificial propagation i.e., the embryonic and larval development of Heteropneustes fossilis. Broodfish were injected with S-GnRHa according to the following concentration: 1, 2.5 and 5 ml kg-1 of body weight (BW) to females and 0.5, 1.125 and 2.5 ml kg-1 BW to males, in treatment groups T1, T2 and T3, respectively each with three replicates. The fishes were ovulated at about 10-11 hours after the hormone injection. Result showed the highest fertilization (83.11±1.36) and hatching rate (89.56±1.04) in T2, whereas ovulation rate was 100% in all treatment groups. First cleavage was observed in 30 minutes of post-fertilization. Embryonic developmental period sequentially for 2-cell, 4-cell, 8-cell, 16-cell, 32-cell, 64-cell, Morula, Blastula, Gastrula, somatic formation, yolk-plug, twisting movement and pre-hatching were 00:30, 00:45, 01:10, 01:30, 02:00, 02:30, 03:00, 04:00, 06:40, 09:00-18:00, 19:00, 20:00-21:00 and 22:00 hours, respectively. Hatching occurred after 23:00 hours of fertilization. Finally, the current result suggested that S-GnRHa might be an effective synthetic hormone in artificial propagation of H. fossilis.

Hybridization is an effective method for the genetic improvement of farmed species. In this study, three broodstock populations (Changjiang, CJ, Dongting, DT, and Dianshan, DS) of oriental river prawn, Macrobrachium nipponense were used, and DS was used as the female broodstock. Through three-line hybridization, two hybrid populations were finally obtained. The F3 generation of the broodstock population and the F1 generation of the hybrid population were cultured indoors for 3 months. Through morphological analysis (cluster analysis, discriminant analysis and path analysis) it was found that the hybrid population and the broodstock had some differences, but not enough to reach the subspecies level, and the dominant traits exhibited differentiation and reorganization. This study identified SNP genetic markers, carried out systematic evolution analysis and genetic diversity analysis and found that the nucleotide diversity π and heterozygosity Het of the hybrid population were higher than those of the broodstock. Among broodstocks, the differentiation index (Fst ) of SCD and SDC was smallest (0.055). This research provides some valuable reference for genetic breeding.

The pejerrey, is a species introduced to Lake Titicaca from the continental waters of Argentina. The study was carried out at the Titicaca Trout Fishing Company, located in front of the city of Pomata, Puno Region, at an altitude of 3882 msnm. The objective of this study was to evaluate the growth of Odontesthes bonariensis from two batches (A and B) grown in Titicaca, Peru, in floating cages developed in 2018 and 2019. Silverside juveniles of 77.9 mm in length were used. average 120 days old, sowing a total of 8500 individuals (batch A = 5300 and batch B = 3200), from artificial spawning of broodstock confined in floating cages. After 360 days in batch A, a maximum total length of 230.0 ± 2.10 mm was achieved, total weight 80.0 ± 1.73 g, the feed conversion was found at 1.7 ± 1.39. In batch B, a maximum total length of 231.7 mm ± 2.70 was obtained, total weight 83.07 ± 1.67 g and the feed conversion factor was found at 1.3 ± 0.67. The feed used was commercial trout feed. It is concluded that the trials of silverside growth in floating cages in Lake Titicaca (Peru), presented encouraging results, showing that the fish tolerates the type of culture and could become an alternative for the development of aquaculture in the region.

Parentage-based tagging (PBT) is a nonlethal, genetic tagging method that has been successfully applied in hatchery-supplemented populations to manage hatchery brood stock and monitor hatchery harvest and straying rates. We show that PBT can also improve the accuracy of escapement estimates by significantly reducing the number of hatchery-origin fish falsely classified as natural-origin. Unlike conventional abundance estimates, which use physical marks and tags to distinguish hatchery individuals from their wild counterparts, PBT identifies origin independent of physical form. We applied PBT to populations of Chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss), which are classified as Threatened under the Endangered Species Act and subject to extensive hatchery supplementation efforts. For spawn years 2014–2018, 16 511 adipose-intact Chinook salmon and 21 953 adipose-intact steelhead were sampled, and PBT identified 19.6% of returning Chinook salmon and 8.3% of steelhead were of hatchery-origin, despite having no physical or mechanical marks. The 90% confidence intervals for escapement estimates of natural-origin Chinook salmon and steelhead made with and without corrections using PBT were nonoverlapping for nine of ten comparisons, indicating that failing to account for unmarked, untagged hatchery-origin fish would result in a significant overestimation of natural abundance.

Anthropogenic activities may facilitate undesirable hybridization and genomic introgression between fish species. Walleye (Sander vitreus) and sauger (Sander canadensis) are economically valuable freshwater species that can spontaneously hybridize in areas of sympatry. Levels of genomic introgression between walleye and sauger may be increased by modifications to waterbodies (e.g., reservoir development) and inadvertent propagation of hybrids in stocking programs. We used genotyping by sequencing (GBS) to examine 217 fish from two large reservoirs with mixed populations of walleye and sauger in Saskatchewan, Canada (Lake Diefenbaker, Tobin Lake). Analyses with 20,038 (r90) and 478 (r100) single nucleotide polymorphisms clearly resolved walleye and sauger, and classified hybrids with high confidence. F1, F2, and multigeneration hybrids were detected in Lake Diefenbaker, indicating potentially high levels of genomic introgression. In contrast, only F1 hybrids were detected in Tobin Lake. Field classification of fish was unreliable; 7% of fish were misidentified based on broad species categories. Important for activities such as brood stock selection, 12 of 173 (7%) fish field identified as pure walleye, and one of 24 (4%) identified as pure sauger were actually hybrids. In addition, two of 15 (13%) field‐identified hybrids were actually pure walleye or sauger. We conclude that hybridization and introgression are occurring in Saskatchewan reservoirs and that caution is warranted when using these populations in stocking programs. GBS offers a powerful and flexible tool for examining hybridization without preidentification of informative loci, eliminating some of the key challenges associated with other marker types.

In recent decades, mortality caused by ostreid herpesvirus (OsHV-1) and a variant (OsHV-1 μvar) has severely impacted the production of Pacific oyster, Crassostrea gigas, chronologically in France, New Zealand (NZ) and Australia (Jenkins et al., 2013; Keeling et al., 2014; Segarra et al., 2010). This study was conceived based on observations made in several commercial hatcheries and research institutes in these countries where vertical transmission of OsHV-1 μvar has been absent or extremely rare. We have collated data from the production of Pacific oysters across these countries to assess the risk associated with breeding oysters from broodstock grown in OsHV-1 μvar-infected waters. The aim is to provide a reference point for regulatory authorities to use when developing or updating biosecurity management policy associated with the hatchery production of Pacific oysters.

This study characterised selected peripheral blood (PB) haematological parameters, liver, serum and muscle metabolic features in three- and five-year old male and female giant kokopu (Galaxias argenteus) broodstock reared indoor at 16°C. Sex and age did not affect PB total cell count, and haematocrit values. However, higher erythrocytes in five-year old fish, elevated thrombocyte and lymphocyte counts in three-year old fish indicate age-specific cellular regulation. Higher thrombocyte counts in female fish suggest sex-specific regulation. At a metabolic level, liver abundance for long chain saturated fatty acids were higher in males, while females had elevated levels of polyunsaturated fatty acids. Essential and non-essential amino acids in liver and serum were also elevated in females compared to males. These findings suggest differential allocation of fatty acids and amino acids to reflect requirements for gonadal, development and provisioning. Similarly, age significantly resulted in higher liver and serum abundances of some non-essential amino acids in three-year olds compared to five-year old fish, suggesting higher metabolism in younger fish. Overall, results enhance our understanding of sex- and age-based differences in fish haematology, muscle, liver, and serum metabolite profiles in healthy G. argenteus. Future studies should carefully consider potential age- and sex-specific differences in metabolic responses. This article is protected by copyright. All rights reserved.

Despite the utility of blood analyte evaluation as a diagnostic tool to assist in monitoring the health of marine fishes, baseline data are often lacking for many commercially important finfish species. The objective of this study was to compare hematology and plasma chemistry data for adult wild-caught Almaco Jack Seriola rivoliana at time of capture and again following a period of acclimation to a recirculating aquaculture system and hyposalinity treatment. A total of 30 clinically healthy adult fish were caught via hook and line in the eastern Gulf of Mexico, approximately 120 mi offshore from Madeira Beach, Florida. Blood was collected from a subset of these fish (n = 13) immediately after capture and again at 16 weeks postcapture from another subset (n = 12) following a 45-d antiparasitic hyposalinity treatment. A 19% increase in fish body weight was observed during the study period (16 weeks) and no overt health issues or mortality were noted. Compared to fish that were sampled immediately following capture, several significant differences (P < 0.05) were observed. Absolute white blood cells were lower in captive held fish, suggesting biological variation, antigenic stimulation in wild fish, and/or immunosuppression associated with stress in captive held fish. Lower sodium, chloride, and calculated osmolality indicate osmoregulatory adjustments following the hyposalinity treatment by 16 weeks postcapture. Other observed plasma biochemical differences presumptively reflect dietary and/or environmental changes, or physiological variation following acclimation to captive culture conditions. This study reports baseline blood analyte data of wild-caught Almaco Jack and documents hematological and plasma biochemical responses to their new environment as captive broodstock. Baseline hematological and plasma biochemistry data obtained during this study are the first reported for this species.

The aquaculture industry is growing and includes the farming and breeding of more than 580 aquatic species worldwide. The rainbow trout (Oncorhynchus mykiss, Walbaum 1792) is the most commonly bred trout species in Hungary. As broodfish form the basis of most fish farms, investigation into tumours occurring in trout, although under-researched, has proven to be a valuable and necessary field of study. During our investigation, we examined a broodstock of 3- to 6-year-old rainbow trouts (800) affected with idiopathic intestinal tumours (3%) which had consequentially led to ileus (40%). While performing necropsy, initial pathological observations showed intussusceptions. Tumours were discovered upon opening the body cavity, as well as metastasis forming in the livers and in the vessels of the gills. Histopathological and immunohistochemical tests allowed us to identify the neoplasms. The primary adenocarcinoma was found to have been developed within the intestines of the fish. The tumour tissue broke through the basal membrane and infiltrated the propria, protruding asymmetrically into the lumen of the mid-intestines, causing it to narrow significantly. This subsequently led to passage disorders, invagination of the intestinal segment and finally the emaciation of the fish. Histopathological and immunohistochemical inspection of the tumour cells displayed a high mitotic index, confirming malignancy.

Penaeus monodon is the primary shrimp species farmed in Australia. Based on an extensive survey of the literature and industry information, we identified and compiled 318 different parameters related to shrimp aquaculture enterprises and production. Using these as input parameters, we performed detailed bioeconomic modelling for evaluating the economic viability of intensive culture scenarios and identified the major drivers of business profitability under Australian conditions. Three business types (hatchery, grow-out and combined hatchery + grow-out) were evaluated by simulating varying numbers of female broodstock and ponds in operation based on annual, six-monthly, quarterly and monthly stocking events per year over a 10-year period. Net present value was the main economic variable for comparison. The hatchery business was most profitable in scenario with 250 females being spawned monthly or 500 females at least quarterly, that is, >2000 females spawned per year. Feed, acquisition of broodstock and fixed labour were major costs for hatchery scenarios. For a grow-out business, all scenarios were profitable even at the smallest scale modelled (50 ponds stocked annually). Feed, power and purchase of post-larvae were major costs for grow-out business. The combined business was the most profitable for a large enterprise and required at least 100 ponds stocked over the year. The three major costs in the combined business were feed, power and labour. Sensitivity analyses showed feed cost and survival parameters were critical for profitability.

Giant prawns (Macrobrachium rosenbergii) need enough nutrients for the reproductive process. One way to give feed which contains high enough protein. Complete nutritional content, especially protein, can be found in natural food. The type of natural feed used for main feeds including squid, sea worms, trash fish. Complete nutrient content can affect the rate of gonadal development and fecundity. (Squid, sea worms, trash fish) on the level of gonadal maturity and density of broodstock parents (Macrobrachium rosenbergii). This research was conducted by a completely randomized design (CRD) trial design. This study used 4 replications of different types of feeding. The types of feed given are squid, sea worms, trash fish, and pellets at a dose of 5% from biomass/day. The parameters of observation include observation of the level of gonad resistance, fundamentality of broodstock parent, and measurement of water quality (temperature, pH, and dissolved oxygen). The results showed that the administration of different types of feed (sea worms, trash fish) had a very significant effect on the level of maturity and had a significant effect on the probability of prawns (M. rosenbergii). After analysis of variance, the results of F Calculations are greater than F Table 0.05 and F Table 0.01. The smallest significant difference test (LSD) was obtained in P1 (Squid feed) with the Gonad maturity rate ± 5- 6 days as much as 83 % parent and fecundity average results of 28,846 ± 4,925.3 thousand / 45 g.

This present study was conducted to determine fry production in different male-female sex ratios of Oreochromis niloticusbroodstock in order to improve fry production, which handicapped the development of fish farming in northern Senegal. A total of 180 broodfish (47 males and 133 females) were stocked at a density of 2 fish /m2and was replicated three times for each sex ratio of 1:2, 1:3and 1:4 (male : female). Mean body weight ranges from 136.47±2.13 and 107.27±2.14 g for female and male O. niloticusbroodstock, respectively. The experiment was conducted for 90 days and the broods were fed on commercial diet containing 32% crude protein.Fish were held in 9 rectangular tanks of 30 m3 each (10 × 3 × 1) and half-filled. The results showed that number of fry produced at different sex ratios were significantly different, with sex ratio of 1:2 producing a highest number of fry (279.67) per female, followed by the 1:3and 1:4 treatment recorded the lowest.Broodstock sex ratios also did not affect female survival rates and all treatments had 100% survival rates. Temperature, dissolved oxygen and pH values obtained were suitable for good water quality and normal tilapia reproduction.In conclusion, the results of the present study recommend to stock Oreochromis niloticus brooders when stocked at a density of 2 fish /m2 at a sex ratio of 1 male : 2 female in order to obtain the highest fry production.

SummaryOur study aimed to establish the response ofSalminus franciscanusto hypophysation and describe the main morphological events of its embryonic process. Wild fish were captured in São Francisco River and selected broodstock (females: 66.4 ± 11.1 cm and 4.04 ± 2.32 kg; males: 58.3 ± 10.2 cm and 3.62 ± 1.12 kg) were kept at 26.1 ± 0.6°C for induction of final maturation/gamete release via the hypophysation technique. In females, two doses (0.8 and 5.6 mg/kg body weight) of crude pituitary extract of common carp (Cyprinus carpio) were administered with a 14 h interval. For males, a single dose (2.7 mg/kg body weight) of crude pituitary extract was applied at the same time as the females’ second dose. Oocytes and sperm were manually stripped 8 h after a females’ second hormonal dose. Fertilization was carried out using the dry method. Eggs were kept in funnel-type 60 L incubators at 24.3 ± 0.3°C and were analyzed and photographed every 10 min. After hormonal induction, 60% of females and 100% of males reacted positively and no broodstock mortality was recorded. The females released an average of 385.2 ± 78.4 g of oocytes and the fertilization rate observed was 50.4 ± 12.3%. The blastopore closure occurred at 7.5 h, somite formation at 12 h and hatching at 20 h post-fertilization. In general, the results of this study improve the understanding of the reproductive biology of dourado and confirm its potential for fish farming in the neotropical region.

The proximal composition, amino acids and fatty acid profile were determined in whole body of wild and captive southern hake (Merluccius australis) in order to evaluate the differences in nutrients content due to the nutritional quality of the feed consumed during broodstock conditioning of this species. Body composition of southern hake did not show significant differences in dry matter, protein or ash content between both studied groups. Conversely, lipid content was significantly higher in the whole body of captive fish compared to the wild fish. In addition, the concentration of linoleic, docosahexaenoic and eicosapentaenoic acids, showed significantly higher level in captive hake than the wild hake. Amino acids concentrations did not vary between fish, except threonine and taurine. Threonine concentration was higher in wild hake whereas taurine concentration was higher in captive hake. The results of this comparative study provide a better understanding of the effects of supplemented feed currently used to acclimate and maintain in captivity southern hake broodstock.

Despite several studies on fish hormone therapy, finding new candidates may provide more reproductive efficiency in artificial propagation. Kisspeptins, being upstream of the hypothalamic-pituitary-gonadal axis, appear to play a key role in the reproduction process. In the present study, the effect of different variants of kisspeptide, including goldfish (Carassius auratus) kiss1 kisspeptin (Kiss1), human kisspeptin (Hkiss), and their combination (Kiss1 + H), on the reproductive indices of goldfish broodstock in comparison to Ovaprim (a typical synthetic Gnrh hormone) was investigated. Peptides (Kiss1 and Hkiss) were synthesized using a solid-phase synthesis approach. Kiss1 and Hkiss were injected at a dose of 100 μg kg-1 body weight, blood samples were taken 6 h after injection and sex hormones (E2, Dhp, and 11-Kt), gonadotropins (Lh and Fsh), cortisol and reproductive indices (fecundity, fertilization and hatching percentage) were measured. The results showed a significant increase of plasma sex hormones and gonadotropins in fish treated with kisspeptins. In addition, the cortisol and lipoprotein lipase in Kiss1, Hkiss and Kiss1 + H were remarkably increased compared to Ovaprim. In conclusion, kisspeptins could be a more suitable candidate than Ovaprim for accelerating and synchronizing oocyte maturation in the fisheries industry.

One hundred and five (105) accessions of cassava collected in the South West and Littoral Cameroon regions were evaluated on a morphological and epidemiological basis. The objective was to study the phenotypic diversity of accessions and its structure based on variables selected among the cassava (Manihot esculentaCrantz) descriptors. Descriptive analysis showed significant phenotypic differences for the traits. Principal component analysis confirmed this important morphological variability. The hierarchical ascending classification made it possible to structure the accessions into 6 and 4 groups. In Ekona, group I consists of accessions with high incidence (IN = 54.03 ± 20.41), group II contains high height (H = 2.01 ± 0.41m), group IV consists of accessions with high severity (SE = 40.44 ± 11.68), petiole length (LP = 39.66 ± 0.03), lobe length (LL = 19.00 ± 0.2 cm) and lobe number (NL = 7.66 ± 0.2).In Njombe, group I consists of accessions with a high incidence (IN = 59.31 ± 20.38), lobe length (LL = 18.08 ± 1.00 cm) and considerable lobe number (NL = 7.44 ± 0.2). These groups offer a wide range of broodstock choices for the creation of improved cassava varieties with interesting potential and adapted to these agro-ecological zones.

The results of a comparative analysis of the efficiency of the artificial reproduction of Atlantic salmon (Salmo salar) individuals released to the Kola River at ages of 3 years (1980–2002) and 1 year (2003–2017) are given. After the fish hatcheries began to release artificially reared anadromous salmon individuals at the age of 1 year, their qualitative parameters did not significantly change. The value of the commercial return became somewhat lower for the released yearlings than for the 3-year-old individuals; however, it remained satisfactorily high. It is recommended to reduce the release volume to avoid the overpopulation of juveniles; it is also suggested to evenly distribute them over the nursery grounds that are most suitable for their adaptation and select spawners for broodstock according to the historically established subpopulation structure.

Eyed salmonid eggs can be subjected to large temperature swings during development, particularly when shipped in ice-filled containers from broodstock facilities to production hatcheries. This study examined the effect of thermal tempering on the survival of brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss eyed eggs to hatch. Eyed eggs at 1°C were either directly placed in 11°C water or allowed to thermally temper from 1°C to 11°C gradually over an hour. In addition, each of the tempering treatments occurred either with or without a 10-minute iodophor disinfection treatment. Tempering had no significant effect on survival-to-hatch in either species (85% - 97%). However, survival was significantly lower in rainbow trout eggs subjected to iodine disinfection (73% - 75%) compared to non-disinfected eggs (91% - 97%), likely because of the close proximity to hatch. The results of this study indicate that slowly raising the temperature (thermal tempering) of brown trout and rainbow trout eyed eggs is unnecessary. Additionally, iodine disinfection of eyed salmonid eggs in close proximity to hatching should be avoided.

Rastrineobola argetea (fishmeal) was compared to roasted soybean meal as protein ingredients for brood stock African cat fish (Clarias gariepinus) in March 2019 on Geossy farm, Uganda. The fish were observed for growth and reproductive indices. Brood stocks of average weight 327 g were fed on different feeds for a month. Feed A contained soybeans as the sole main protein source. Feed B contained fishmeal as the sole protein source. Feed C was the control (usual farm feeds). Growth indices of B were significantly higher than of A (p = 0.0001, P < 0.05). It is implausible to substitute fishmeal 100% by soybean meal even with heat treatment to remove ant nutritional factors. Fish meal has essential amino acids and fatty acids that are not in soybeans, soybeans can best be used in combination with fishmeal but the most economical ratios need more research. The reproductive indices had no significant differences for feed A, B and control. Replacing fish meal with soybeans had no significant effect on the reproductive indices. Fish meal increases the growth indices and the gonadal weight of Clarias gariepinus, soybean meal is good during brood stock management because it increases fecundity although lighter eggs are observed.

Rainbow trout (Onchorhynchus mykiss) is one of the most important freshwater aquaculture fish in Iran. It is necessary to develop available molecular marker such as SNPs, which represent a useful tool in detecting adaptive signals in populations and also parentage assignment for O. mykiss. Genetic architecture of broodstock populations is important for breeding programs, as it enables decisions on broodstock screening and genomic selection. In this study, 52 novel single nucleotide polymorphism (SNP) markers for O. mykiss were discovered and validated based on transcriptome sequencing, by means of paired-end sequencing in an Illumina HiSeq 2500 platform. The SNPs were identified through liver transcriptome sequencing from fifteen samples. The observed and expected heterozygosities ranged from 0.177 to 1.000 and 0.239 to 0.638, respectively. The minimum allele frequency (MAF) ranged from 0.166 to 0.489. Among these SNP loci, twenty-two loci showed significant departures from the Hardy–Weinberg equilibrium after Bonferroni correction (p