Spawning Performance Research Articles

Effects of thyroxin and luteinizing hormone releasing hormone on reproductive physiology of Rohu (Labeo rohita): Insights into spawning performance, oocyte maturation, steroidogenesis, and follicular development genes

As the global aquaculture industry grows, attention is increasingly turning towards assisted reproductive technologies. In this study, we examined the impact of D-Ala6, Pro9-Net-mGnRH (LHRHa: 0.4 mL/kg) and two doses (1 and 10 μg/kg fish) of thyroxin (T4) administered through a single injection on oocyte maturation, spawning performance, sex steroid hormone levels, as well as the expression of genes related to steroidogenesis and follicle development (ZP2, Cyp19a1a and SF-1) in Rohu (Labeo rohita). The study found that untreated female Rohu did not spawn, while those treated with LHRHa and thyroxin ovulated and spawned across a hormonal gradient. The highest spawning success was observed with a thyroxin dosage of 10 µg/kg (no significant change with a dose of 1 μg/kg), and female latency period decreased with increasing dosage. Additionally, females treated with thyroxin exhibited significantly higher fecundity than other experimental groups. Treatment with LHRHa and two doses of thyroxin significantly increased the gonadal somatic index compared to the control and sham groups. Hormonal treatment also led to increased fertilization success, hatching rate, and larval survival. At 12 h post-injection, females treated with thyroxin exhibited a significant decline in estradiol levels and expression of Zp2, Cyp19a1a, and SF-1 compared to other experimental groups. Levels of DHP significantly increased across the hormonal gradient. Histological analyses supported a steroidogenic shift, where oocyte maturation was accelerated by hormone administration, particularly with both doses of thyroxin. In conclusion, the findings suggest that thyroxin is a recommended treatment for assisted reproduction of Rohu due to its ability to induce spawning, increase fecundity and improve larval survival.

Effects of Synthetic Hormones on Fertilization, Fecundity, Hatching and Gonado-Somatic Index of Giant Snakehead (Channa Marulius) in Captivity

The effects of a crude protein (40% CP) diet on the spawning performance of giant Snakehead (Channa marulius) broodstock were assessed in this study through a three-week feeding trial. Mature C. marulius brood stock (N = 36) was taken from the brooders pond and stocked into nine small experimental breeding ponds, each measuring 4mx2mx1.5m (LxWxD). Following acclimatization, all male and female C. marulius broodstock with an average weight of 1.5–2.5 kg BW and a length of 70 cm were removed from the small breeding ponds. The current study's objective was to induce breeding in C. marulius by injecting synthetic hormones intramuscularly and monitoring fertilization, fecundity, hatching, and gonado-somatic index. Using a completely randomized design (CRD), nine fishponds were split into three treatments (T1, T2, and T3) during the study period, each with three replicates. In addition to evaluating the effects of artificially applied hormones, Conceptal® (T1), Suprefact® (T2), and Ovaprim® (T3), this study aimed to comprehend the reproductive biology of C. marulius. The hormones were injected into the test fish at the following proportion (0.3ml, 0.4ml and 0.5ml to male and 0.8ml, 0.9ml and 1.0ml to female’s ml/kg body weight) and then released into the earthen ponds for large scale production of seed. Two-way analysis of variance (ANOVA) was used. The results showed no successful spawning on Conceptal®. The gonado-somatic index (GSI) estimates for the study period showed that Suprefact had the highest average GSI values for both males and females (3.32±1.62% and 1.67±0.18%, respectively), followed by Ovaprim (1.13±0.56 and 1.22±0.68, respectively). Absolute fecundity was also estimated. The result showed that fish stimulated with suprefact (T2) obtained the highest average fecundity (3079.3±100.7%), fertilization rate (96.33±1.20%), hatching rate (94.67±2.40%), and survival rate (95.75±1.51%), then in ovaprim fecundity rate (1669.3±836.5%), fertilization rate (58.00±29.02), hatching rate (61.27±30.65), survival rate (64.67±32.34%), respectively. In conclusion, the use of Suprefact® and Ovaprim® can optimise the results of C. marulius breeding induction in small experimental breeding ponds, ensuring higher-quality eggs and a greater number of normal larvae.

Effect of pituitary gland from spent and unspent female brood fish on the spawning performance of African catfish (<i>Clarias gariepinus</i>)

Pitutary gland produces, accumulates and stores gonadotropic hormone which plays active role in ovulation as intermediary between central nervous system and gonads. However, information on the efficacy of pituitary gland from newly spent Clarias gariepinus for inducing ovulation is yet established. The effect of pituitary gland from spent and unspent female fish on the induced breeding performance of Clarias gariepinus was tested. The experiment was set up in a completely randomized design (CRD). Nine (9) brood stock distributed into three treatments were used for the experiment (Treatment 1 was injected with 0.5ml synthetic hormone (Ovulin), Treatment 2 was injected with pituitary from already spent female fish and Treatment 3 was injected with pituitary from unspent fish) and each treatment was replicated three times. The result showed that Treatment 2 had the highest mean values for fecundity rate (122.92%) and was not significantly different from the other treatments. It also has higher value for fertilization rate (60.67%) and high stripping percentage but lower (P < 0.05) hatching rate (13.619) when compared with Treatment 1 which had the highest value for hatching rate (22.79%) followed by Treatment 2 (19.739%) with statistical similarity (P > 0.05). The present research demonstrated that C. gariepinus can successfully be induced to ovulate with pituitary from spent female fish, ensuring maximum use of brood fish and production of high-quality eggs and normal hatchlings.

Reproductive performance of the fluted clams (Tridacna squamosa) through different serotonin hormone doses for spawning induction

Exploring the reproductive performance one of the giant clam species being cultured in Indonesia. The fluted clams (Tridacna squamosa) are a keystone species for Indonesia’s marineculture and restocking program, categorized as a protected commodities by Convention on International Trade in Endangered Species (CITES) due to anthropogenic pressure on wild population. To assess and improve their reproductive performance, induction of different serotonin was applied consisting of control (0 mM), T1 (1.1 mM), T2 (1.4 mM), and T3 (1.7 mM). New significant insights emerge, results indicate response’s time of pre-spawning T1 and T2 were approximately 45 s, while T3 was 60 s, respectively T2 is highest spawning success at 91.67%, contrasting with 50% by T3, also spawning latency varied, with the quickest gamete release (3 min) by T2, on the contrary T3 (4 min). Observed eggs released at approximately 24 min (T2), 84 min (T1) with an egg diameter of 128.72±1.56 μm yet absent in T3. Polynomial regression of fecundity from differential dosing approach attained an R² = 0.3885, highlights an optimal 1.36 mM dosage for maximizing spawning performance, indicating T2 as an adequate dose with moderate egg abnormalities 8.7% and. FR, HR, and SR ranged from to 70-80% respectively.

Evolution of sex ratio and egg production of gilthead seabream (Sparus aurata) over the course of five reproductive seasons

Spawning performance -relative fecundity and fertilization success- was studied in two hatchery-reared broodstocks of gilthead seabream (Sparus aurata) held under relatively constant well-water temperature (18–20 °C) and simulated natural photoperiod, for five consecutive spawning seasons, between 3 and 7 years of age. The spawning season lasted between 4 and 6 months each year, and the total number of eggs produced annually ranged between 1 480 000 and 3 100 000 eggs/kg female body weight, being the highest during the first and second spawning season. No difference was observed in monthly relative fecundity between years -although high variation existed within years, whereas fertilization success was the highest during the second and third reproductive season, and dropped significantly during the last year of the study. The male percentage of the broodstocks was 35% during the first spawning season of the females, and thereafter it decreased further and remained stable at around 15%–20% for the second and third spawning season. Substitution of older females with smaller males to readjust male percentage to 50% in the fourth spawning season, was followed by sex change of larger males to females and a drop of the male percentage to 18% in the following spawning season. The present study demonstrated the long spawning season of gilthead seabream -especially under constant water temperature, the high fecundity and fertilization success, and the stabilization of male percentage to ∼20% after the first spawning season or when a broodstock is modified to increase male percentage. These results are useful to the aquaculture industry, demonstrating that there is no need to add males to gilthead seabream broodstocks over the years, as the sex ratio is stabilized and egg production and fertilization success remain high with a relatively low male:female sex ratio.

Individual spawning performance and mating pair combinations in captive grouper aggregations

Individual spawning performance and mating pair combinations in captive grouper aggregations

Maturation and spawning performance of hormonally-induced precocious female barramundi (Lates calcarifer) and implications of their use in selective breeding

Breeding programs for barramundi (Lates calcarifer) are impeded by the lack of control over the sexual development of broodstock. As a protandrous hermaphrodite, barramundi initially sexually mature as male at 2–3 years (2–4 kg body weight; BW), before changing sex to female at 4–6 years (>6–8 kg BW). Recently, precocious female barramundi have been generated using a single intramuscular estrogen implant, providing the potential to speed up the sex change process and implement same-age mating of male and female broodfish. However, the functional maturation of hormonally-induced precocious females and their ability to spawn and produce viable progeny remains untested.Male barramundi (~2.2 kg BW, 57.8 cm total length; TL) were hormonally induced to sex change using an estrogen implant. The precocious female barramundi were cannulated at 6 (T1), 8 (T2), 10 (T3), 11.5 (T4) and 13 (T5) months after sex change, with oocytes measured and staged to determine reproductive condition. At T3, four females (~4.2 kg BW, 67.8 cm TL) with oocytes >350 μm in size were transferred to a spawning tank along with four males to assess their spawning performances. Mass spawning events were induced at T3, T4 and T5, and eggs released on the first and second spawning nights were collected to determine rates of fertilization, hatching and larval survival at 24 and 48 h post-hatch.At each cannulation event (T1 - T5), several precocious females were confirmed to have mature oocytes and were considered ready for induced spawning. Conversely, in some individuals, only immature oocytes were during each cannulation event. The four precocious females induced to spawn generated large numbers of eggs, with 7.7 million (T3), 10.9 million (T4) and 9.1 million (T5) eggs obtained across the two nights of each mass spawning event. Fertilization of oocytes was not observed at T3 and was likely due to male inactivity. Spawning performance improved considerably for T4 and T5 spawns, with the highest fertilization rate (64%) and hatching rate (72%) observed during T5 - Night 1. Furthermore, larval survival at 24 and 48 h after hatching was 99% and 94%, respectively. Total larval production across both nights of the T5 spawn exceeded 3 million individuals. Spawning performances of precocious females were comparable to routine commercial stocks of large females (8–15 kg), and confirmed that precociously induced female barramundi can produce the quantity of seedstock required in existing selective breeding programs. Further research examining the factors involved in promoting oocyte growth and maturation is needed to enhance the rate at which mature precocious females are available for spawning.

Induced Breeding of Fresh Water Menoda Catfish (Hemibagrus Menoda) Using Ovupin Hormone

An experiment on induced breeding of menoda catfish, Hemibagrus menoda was conducted during the period from May 2017 to July 2018 by using commercial Ovupin hormone (GnRHa, Gonadotropin Releasing Hormone Analogues) to attain its optimum dose. The study consists of three treatments, each with three replications. The objective of the experiment was to find out the effective dose for induced breeding. The breeding parameters were determined in terms of ovulation, fertilization, hatching, and survival rate. A total of 36 males and 18 females lived brood fish were kept in the ratio of 2♂:1♀ for breeding purpose. The commercial Ovupin hormone were injected at the doses of 4 (T1), 6 (T2), 7 (T3) mL Ovupin·kg-1body weight for female and 1.5(T1), 2 (T2), 3(T3) mL Ovupin·kg-1 body weight for male in a triplicate replication. In this study, it was found that treatment T2 demonstrated the best spawning performance for both male and female and were statistically significant (p<0.05). The investigation indicated that the dose of Ovupin hormone 6mL Ovupin·kg-1body weight for female and 2 mL Ovupin·kg-1 body weight for male determines the highest spawning performance of menoda catfish which should be recommended for high quality eggs and larvae. J. Biodivers. Conserv. Bioresour. Manag. 2020, 6(2): 11-18

Lack of negative effects of fasting of gilthead seabream (Sparus aurata) breeders during the spawning period on maternal and egg nutrient composition, fertilization success, and early embryo/larval development.

The effect of fasting on spawning performance, maternal, and egg nutrient composition, and on embryo/larval development was monitored in gilthead seabream (Sparus aurata). Two broodstocks were fasted during two consecutive years, for a period of 43 and 54days within the spawning season, in a preliminary (year 1, 5-year-old breeders) and the main study (year 2, 6-year-old breeders), respectively. Mean daily fecundity showed a declining trend during fasting in the main study only, while fertilization success was high in both years and it was not affected by fasting, as was hatching and 5-day larval survival. There was a loss of 23.5% of maternal body mass due to fasting, and a reduction in gonadosomatic and hepatosomatic indexes, as well as crude protein in maternal muscle and gonads, but not in the liver. After fasting, muscle Σω-6 PUFA and C18:3ω-3 were reduced while C20:4ω-6, 20:5ω-3/20:4ω-6, and C22:6ω-3/20:4ω-6 increased; in the liver, significant reductions were observed in C16:0, C18:3 ω-3, 20:5ω-3/C22:6ω-3 and increases in C18:0, C20:5ω-3, Σω-6 PUFA, and 20:5ω-3/20:4ω-6; in gonads, C15:0, ΣMUFA, 20:5ω-3/C22:6ω-3, 20:5ω-3/20:4ω-6 were increased, while C18:1ω-9 and C20:5ω-3 decreased. Contrary to maternal tissues, the energy density and proximate composition of the eggs did not change due to fasting. The study suggests that fasting of gilthead seabream breeders for 6-8weeks during the spawning period does not affect spawning performance, egg proximate composition, or embryo and early larval development since maternal nutrient reserves are mobilized to maintain optimal egg nutrient composition.

SPAWNING OF BLACK GHOST KNIFEFISH, Apteronotus albifrons WITH DIFFERENT SEX RATIOS

Black ghost knifefish, Apteronotus albifrons, is a South America-introduced ornamental fish species that has been widely cultivated in Indonesia. Some farmers breed this fish with different sex ratios, but the optimum sex ratio remains unclear. This study aimed to evaluate the spawning behavior and reproductive performance of black ghost knifefish with different sex ratios. The treatments in this study were arranged in a completely randomized design consisting of different sex ratios between males and females, namely: A (one male : three females), B (two males : three females), and C (three males : three females). Each treatment was done in triplicate. The broodstock were maintained in an aquarium (80 cm x 40 cm x 40 cm) and fed with bloodworm twice a day. The water was changed every day as much as 60% of the total volume. During the experiment, the parameters of spawning behavior, number of fish spawning, number of eggs, fertilization rate, hatching rate, and daily spawning frequencies were observed. The observation was done for seven days. The study results showed that black ghost knifefish spawned at night (11 pm - 2 am). The mating and spawning occurred between one male and one female. Competition between males was observed in the treatments indicated by aggressive movements of a male toward the others, such as sudden approaching, chasing, and driving away the others. Fish in treatment-B spawned consistently from day-1 to day-5. Fish in treatment-A spawned from day-2 to day-4, while fish in treatment-C spawned only on day-7. The reproductive performance parameters showed no significant difference in all treatments except the hatching rate parameter of treatment-B. The study concludes that better reproductive performance of black ghost knifefish, A. albifrons can be achieved with a spawning ratio of two males and three females. Further research on individual and mass spawning methods with the best spawning ratio of the fish is required.

STUDY OF PITUITARY GLAND EXTRACT UTILIZATION FROM STRIPED CATFISH WASTE FOR REPRODUCTION PERFORMANCE IMPROVEMENT OF NORTH AFRICAN CATFISH (Clarias gariepinus)

One of the problems in North African Catfish (Clarias gariepinus) breeding is the inability to spawn spontaneously due to a specific spawning season. This happens due to reproductive dysfunction resulting in a slow development of gonads in catfish broodstock. This research aimed to study the effect of injection of pituitary gland extract from Striped Catfish head waste on the spawning performance of North Africans Catfish. This study used a completely randomized design (CRD) with 4 treatments and 3 replications. The treatments were A (pituitary gland 0 mg/kg broodstock), B (pituitary gland 200 mg/kg broodstock), C (pituitary gland 300 mg/kg broodstock), and D (pituitary gland 400 mg/kg broodstock). The spawning process was performed with a ratio of 1:1 between male and female broodstock. The pituitary gland was injected into the head of female catfish at 07:30 pm and at 04:00 am. The research parameters observed were relative fecundity, fertilization rate (FR), hatching rate (HR), and survival rate (SR). The results showed that injection of the pituitary gland from Striped Catfish head waste could increase spawning performance with relative fecundity reaching of 31,357±12,265 eggs/ kg of female broodstock, FR 65±4%, HR 74±14%, and SR 81±10%. Therefore, hypophysation by utilizing Striped Catfish head waste is effectively increases the spawning performance of North African Catfish (Clarias gariepinus) seen from the high values of relative fecundity, FR, HR, and SR of larvae in treatment B (200 mg/kg broodstock).

Ova Fatty Acids Composition and Spawning Performances of Silver Carp, Hypophthalmichthys molitrix (Morocco)

The present study is performed in order to determine the relationship between fatty acid (FA) profile of silver carp (Hypophthalmichthys molitrix) eggs and fertilization success, embryos viability and larval production. Mature unfertilized ova were collected during the reproductive season from 23 mature and healthy females, reared in Deroua fish farm (Morocco). Total lipids were extracted from ova sample and subjected to trans-esterification then the resulting fatty acids methyl esters were analyzed by gas chromatography tandem mass spectrometry (GC/MS/MS). The results showed that silver carp ova are dominated on total FA by docosahexaenoic acid (DHA) (21.21%) followed by oleic acid (21.07%), palmitic acid (17.71%) and eicosapentaenoic acid (EPA) (10.25%). During the breeding season, polyunsaturateds (PUFAs), monounsaturateds (MUFAs) and saturated fatty acids (SFA) didn’t show any significant difference. Moreover, within the PUFAs, the n-3 series were more abundant than the n-6 series, the total mean was 31.57 ± 1.01% and 5.33 ± 0.32%, respectively. No correlation was between fatty acids and the fertilization success. Maternal weight has effect on the levels of oleic acid (C18:1), arachidonic acid (C20:4) and docosahexaenoic acid (C22:6) in the egg whereas levels of palmetoleic acid (C16:1), eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6) are related to female age.

Comparison of visual and molecular taxonomic methods to identify ichthyoplankton in the North Sea

AbstractThe North Sea is an important spawning and nursery ground for many demersal and pelagic fishes whose spawning areas are largely overlapping in time and space. This makes ichthyoplankton visual identification from the various species particularly challenging. Despite historically intensive research in the area, detailed information on spawning sites and times for many taxa, are incomplete. To update and detail the mapping of fish spawning performance and distribution in the central and northern regions of the North Sea, the performance of a visual method and a molecular taxonomic approach used for taxonomic classification of ichthyoplankton was evaluated. Samples of fish eggs and larvae were collected regularly and in parallel at different latitudinal locations from the central to the northern North Sea, including a sample with 78 larvae used for direct comparison between both methods. A total of 5332 individuals were inspected and 36 different species were identified. The visual processing identified 89% of the collected larvae to species level, however, for the eggs the taxonomic resolution was lower with only 5% identified to species level. In comparison to visual identification, molecular barcoding gave higher precision of identification for larvae and especially for the eggs. For the larvae, 98% were assigned to species level, and for the eggs 94% were assigned to species level. We find that molecular barcoding is more effective and precise in taxonomic identification of both eggs and larvae to species level. However, visual identification is still needed to provide information on the developmental stages.

Annually twice induced spawnings provide multiple benefits: Experimental evidence from an Indian major carp ( Catla catla , Hamilton 1822)

Multiple spawnings are special reproductive tactics that many fish evolved to obtain different types of direct and/or indirect spawning benefits. This has led to two pertinent questions: (a) what types of benefit does a commercially important fish provide during multiple induced spawnings annually? and (b) is there any trade-off between traits during these spawnings? To address these questions, the present study was carried out with two separate experiments during two spawning events of an Indian major carp (Catla catla) to assess: (a) male's spawning performances and (b) female's spawning performances. The male's spawning data revealed that they produced significantly higher amount of milt and hatchlings during the first spawning, while they significantly reduced hatchling deformation rate, enhanced offspring survival rate and enlarged offspring body size during the second spawning. The female's spawning information unveiled no significant differences in total egg weight, hatching rate and hatchling deformation rate between the first and second spawning. However, females had significantly higher offspring survival rate during the first spawning and enhanced offspring body size during the second spawning. Interestingly, the analysis of trait associations revealed that males allocated energy with a trade-off between milt weight and offspring survival rate, whereas females showed a trade-off between hatching rate and offspring survival rate. Thus, the study provides some important information for carp breeders and associated stakeholders to know which spawning season is preferable for the higher production of eggs, milt and good quality larvae.

Evaluation of cGnRH IIa for induction spawning of two ornamental Synodontis species

Efficacy, reliability, and safety are of principal concern for spawning aids used in reproduction protocols for aquaculture species. Ovaprim®, a salmon gonadotropin releasing hormone analog (sGnRH IIIa, D-Arg6-Pro9-Net, 20 μg/mL) and a dopamine antagonist (Domperidone, 10 mg/mL), is currently the preferred choice for induction spawning of ornamental fishes. However, this preparation may be unreliable or completely ineffective in some cases. cGnRH IIa (D-Arg6, Pro9-NHet) has garnered recent interest as an alternative GnRH subtype which offers increased biological activity, reliability, and may ultimately help to increase on farm productivity and expand the diversity of species able to be cultured. The objective of this study was to evaluate the efficacy of cGnRH IIa and Ovaprim® on various quantitative and qualitative measures of spawning performance in Synodontis nigriventris and Synodontis eupterus.Four hormone doses were evaluated (50, 100, 200 μg/kg cGnRH IIa; 10 μg/kg sGnRH IIIa), each of which also contained an equal concentration of a dopamine antagonist (5 mg/kg domperidone). Fish were palpated to check for ovulation at 16, 20, and 24 h post injection. Upon successful ovulation, eggs were manually stripped, weighed, and fertilized. A subsample was photographed under a dissecting microscope for subsequent determination of fertilization success and egg diameter. Hatching success for individual spawns was calculated from subsamples of fertilized eggs stocked into hatching containers.Results indicated similar ovulation success among the four hormone treatments at the 16, 20, and 24 h time periods. Total fecundity, fertilization, embryo diameter, hatching success, larval notochord length, and larval mortality did not vary significantly among treatments. These results suggest that cGnRH IIa exhibits comparable spawning performance to the industry standard Ovaprim®, for induced spawning of S. nigriventris and S. eupterus.

Spawning performance and egg quality of wild-caught and first generation southern flounder Paralichthys lethostigma broodstock induced with piscine and mammalian GnRH analogs

Spawning performance and egg quality were compared in wild-caught and F1 generation southern flounder broodstock following induction with mammalian mLHRHa or piscine sGnRHa at different doses. Forty F1 and 33 wild vitellogenic females (mean oocyte diameter ≥ 0.385 mm) were implanted with an 80% cholesterol-20% cellulose pellet at doses (μg/kg bw) of 0 (control), 5 (low), 25 (mid) and 50 (high) mLHRHa, or with similar doses of sGnRHa. Ovulated females (N = 5–8 per treatment) were strip-spawned and eggs were fertilized in vitro with sperm from two males. Egg quality was categorized according to fertilization and hatching success: 75–100% (high), 50–75% (medium-high), 25–50% (medium-low), and 0–25% (low). Egg production (number of eggs/kg female bw × 103) was highest at the low dose of mLHRHa in F1 females (146.4) and sGnRHa in wild females (128) and was lowest at the intermediate dose sGnRHa in F1 females (61.9) and the high dose sGnRHa in wild females (40.6). Number of fertilized eggs produced per kg bw (× 103) was highest at the low dose mLHRHa in F1 females (113.5) and sGnRHa in wild females (95.4) and lowest at the high dose sGnRHa in F1 females (18.7) and sGnRHa in wild females (7.8). Number of yolksac larvae produced per kg bw (× 103) was highest at the low dose of mLHRHa in F1 females (74) and sGnRHa in wild females (73.5) and was lowest at the high dose of sGnRHa in F1 females (2.0) and in wild females (1.2). Number of larvae per kg bw (× 103) surviving to 96 h post-hatching was highest at the low dose mLHRHa in F1 females (67.5) and sGnRHa in wild females (66.5) and was lowest at the high dose sGnRHa in F1 (0.72) and sGnRHa in wild females (0.68). In F1 females, larval production was significantly greater (P < .01) at lower doses and greater (P < .01) for mLHRHa than for sGnRHa at all doses. For wild females, larval production was greater at lower doses of sGnRHa, with the inverse trend observed for mLHRHa (hormone dose × type interaction, P < .05). Taurine concentrations (nmol/mg dw) were higher (P < .05) in ovulated eggs of high quality (27.4) than in eggs of med-low (14.8) and low (17.5) quality, supporting an important role in broodstock nutrition and in early development. The results help standardize GnRHa therapies for spawning of wild and F1 southern flounder.

Design and performance of recirculating aquaculture system for marine finfish broodstock development

Tropical and subtropical climatic conditions in India present an ideal and unique opportunity for being the leader in tropical marine finfish aquaculture. However, the problem persist due to non-availability of marine finfish seed for the culture. In response to this problem, broodstock development of different tropical marine finfishes for seed production was started. The present study was undertaken to design a recirculating aquaculture system (RAS) and studying their performance in managing the various water quality required for the marine finfish broodstock development and breeding. The design of RAS, developed in the present study, included a broodstock tank, egg collection chamber, electrical pump, rapid sand filter, venturi type protein skimmer and biological filter. Two RAS were designed, one was stocked with a demersal fish species, orange spotted grouper (Epinephelus coioides) and the other was stocked with a pelagic fish species, Indian pompano (Trachinotus mookalee) at the rate 1 and 0.5 kg/m3 with a sex ratio of 1:1 and 1:2 (female: male) respectively. Various physio-chemical parameters, viz, total ammonia nitrogen (TAN), nitrite, nitrate, pH, alkalinity, temperature, free carbon dioxide (CO2) and dissolved oxygen (DO) of both tank water were analyzed to assess the performance of recirculating aquaculture system in maintaining the water quality. Gonadal development of the fishes was assessed and the spawning performance was recorded and finally, economic performance of the system was also evaluated. During the entire experimental period, mean monthly total ammonia nitrogen was less than 0.07 and 0.06 mg L−1 and mean monthly nitrite was less than 0.02 and 0.01 mg L−1 in orange spotted grouper and Indian pompano RAS tanks respectively. The pH (7.8–8.2), DO (>4 mg/L) and alkalinity (100–120 mg/L) were found to be in optimum range in both recirculating aquaculture systems. Carbon dioxide was found to be nil during the entire experimental period in both the systems. In fact these levels were comparable or less than that is reported as the permissible limits for broodstock development. Indian pompano and Orange spotted grouper matured and spawning was obtained with production of fertilized eggs round the year. Economic evaluation showed the price of 10,000 fertilized eggs of orange spotted grouper to be US $ 1.33. The design of RAS devised in the present study is efficient in controlling and maintaining optimum water quality for broodstock development of both demersal and pelagic finfishes. The fishes stocked in RAS attained final maturation and round the year spawning was obtained.

Embryonic development of diploid and triploid eggs ofClarias gariepinus(Burchell, 1822)

This study was conducted to evaluate the spawning performance and embryonic development of diploid and triploid eggs of the African Catfish, Clarias gariepinus. Triploidization was induced by heat ...

The Impact of Leechiosis on Semi-Artificial Spawning Performance and Hematological Parameters of Silver Carp (Hypophthalmichthys Molitrix) Brooders and Common Carp (Cyprinus carpio) Fingerlings with A Reference to Its Stress Response and Treatment

<div><!--block-->There was a decrease in artificial spawning performance of hatchery-reared cyprinid brooders in the spring of 2016 in an Egyptian hatchery. In this study, cyprinid brooders and fingerlings were clinically examined in situ, which showed that they were affected with leechiosis. Hemiclepsis marginata were identified as a causative agent of leechiosis. The prevalence of leechiosis was highest in silver carp (Hypophthalmichthys molitrix) brooders and common carp (Cyprinus carpio) fingerlings. The infested brooders and fingerlings showed red to white marks, severe hemorrhages, and dark contracted worms on their skin. The impact of leechiosis on semi-artificial spawning performance and hematological parameters of H. molitrix brooders was evaluated by determining the eggs weight, fertility, hatching percentage and the complete blood picture. Leechiosis had a significant impact on eggs weight, fertility, and hatching percentage. Microcytic hypochromic anemia, leukocytosis, lymphopenia, and heterophilia were recorded in the infested brooders. Regarding the association between leechiosis and stress response, the total antioxidant enzymes were found to be significantly decreased, whereas malondialdehyde levels were increased in the infested brooders compared with those in control samples. Under the experimental condition, leechiosis could be controlled among C. carpio fingerlings using trichlorfon, after which normal hematological parameters were recorded for the treated C. carpio fingerlings. Regarding the field conditions, trichlorfon could successfully control leechiosis in H. molitrix brooders and C. carpio fingerlings.</div>

The practice and effectiveness of ecological operation experiment on spawning of the four major Chinese carps by Three Gorges Reservoir

Eco-operation experiment by the Three Gorges Reservoir was carried out ten times to facilitate spawning of the four major Chinese carps in the lower reaches of Yangtze River, from 2011 to 2017. To get knowledge of fish spawning response to man-made flood process, and also assessing the positive effect of eco-operation on fish spawning, fish eggs were monitored daily by drift-net method, in a fixed profile in Shashi reach between mid-May to mid-July each year. Basing on the consecutive data and research for seven years, the practice and effectiveness of TGR eco-operation experiment on fish spawning were summarized and prospected. The main findings were as follows: eco-operation experiment usually operated in a suitable condition from late May to the end of June. Based on the hydrological monitoring data in Yichang station, the continuous days of rising limb varied from 3 days to 9 days, the mean diurnal increment of water level varied from 0.43 m to 1.30 m, and the water temperature varied from 20℃ to 24℃, except in 2013 that only below 18℃, during eco-operation period within seven years. According to the fish eggs monitoring data in Shashi reach, annual egg abundance of the four major Chinese carps ranged from 116 to 610 million, grass carps and silver carps were two dominant species with proportion of more than 80%. Egg abundance of the four carps produced in eco-operation period accounted for about 38% averagely of total amount in the whole monitoring period, with nine floods in total of thirty-three floods. Four indicators representing fish spawning performance, the time interval from water rising to spawn happening, duration time of spawning, extent of spawning grounds, and spawning scale, were calculated in each spawning event corresponding to each flood process. All indicators gave evidence that spawning performance of the four carps were better in eco-operation period, compared with other routine operation period. It was concluded the Three Gorges Reservoir eco-operation had done its work on boosting spawning of the four major Chinese carps, but further and foremost research should be developed on the following aspects, quantifying the eco-operation effect, optimizing the eco-operation index, and extending the eco-operation target to other important life history stage of fishes.