Relative Fecundity Research Articles

Aspects of Growth, Diet, and Reproduction of <i>Oreochromis niloticus</i> (Linnaeus, 1758) in a Hypertrophic Milieu, the Municipal Lake of Yaoundé, Cameroon

The Nile tilapia, <i>Oreochromis niloticus</i>, is a highly valued fish species in Africa for subsistence and commercial purposes. However, overfishing activities in non-supervised lakes or reservoirs threaten its availability. In the view of contributing to the database on the life history traits of this species in Cameroon and supporting its sustainable management, the present study investigated the growth patterns, food preferences, and reproductive aspects of <i>O. niloticus</i> in a hypertrophic milieu, the Yaoundé Municipal Lake, from May to October 2018. Fish specimens were sampled, measured, weighed, and sexed. The digestive tract of each specimen and the females’ gonads were collected. The intestines were measured, and the stomach contents were identified. The females’ reproductive aspects were determined. Overall, 101 specimens were collected and distributed among 48 (47.5%) males and 53 (52.5%) females, with a sex ratio of 1: 1.1. In this hypoxic (1.35 ± 0.4 mg/L) and highly conductive (210.5 ± 56.9 µS/cm) milieu, <i>O. niloticus</i> displayed a relatively good condition (<i>Kn</i> > 1) throughout the sampling period and negative allometric growth patterns for both sexes (<i>b </i>< 3; <i>p</i> < 0.001). Materials from plant origin were the preferred prey types, with an index of relative importance (IRI) of 78.20%; meanwhile, mud and materials from animal origin were secondary prey items (IRI: 13 ‒ 17%). The relative gut length (RGL) value above 3.0 and the foraging activity on detritus suggest that <i>O. niloticus</i> has an herbivorous or detritivorous dietary habit and is a bottom-feeder. Female length at first maturity (L<sub>50</sub>) was 17 cm. Their gonado-somatic index (GSI) showed sexual activity throughout the whole sampling period, with the peak spawning phase happening in August. The absolute fecundity of gravid females varied between 316 and 1816 oocytes (942 ± 430 oocytes), and the relative fecundity ranged from 1–5 oocytes/gram of body weight (3 ±1 oocytes/g). The results highlight the performance of the Nile tilapia in this ecosystem and provide information for its sustainable use and improvement of fish culture.

Reproductive biology of long-whiskered catfish (Mystus aor) relative to temperature and precipitation from the Kaptai Lake of Bangladesh.

Life-history information is necessary for effective conservation, aquaculture development and broodstock management of fishing populations, especially for fish with significant economic exploitation. Aiming to characterise the life-history traits in relation to the environmental parameters of the long-whiskered catfish, Mystus aor, a commercially important species from Kaptai Lake, Bangladesh, different life-history data were analysed. The monthly condition factor (K) ranged from 1.15 to 1.41, and the relative condition factor (Kn) ranged from 0.14 to 0.25. The estimated relative fecundity was 18474-55504 eggs/per fish, and the maximal oocyte diameter was found in May (0.83 ± 0.11μm). The lengths at first sexual maturity (Lm) for male and female M. aor were 49.5 cm and 54.1 cm, respectively. The GSI was peaked in May for both males and females, and histological analysis also revealed the presence of yolk granules and several mature spermatids in April and May in both sexes. Analysis of environmental data over 40 years in the Kaptai lake ecosystem indicate the significant increase in the precipitation rate in spawning month which is highly correlated with the spawning season. The findings of the current study will serve as a baseline for the conservation and broodstock management in the Kaptai Lake of Bangladesh.

Recent data of the biology of the twaite shad, Alosa fallax returning for spawning to the Szczecin Lagoon (southern Baltic Sea)

In 2022–2023 specimens of A. fallax are recorded for the first time in approximately 17 years in Szczecin Lagoon. We collected 11 specimens of juveniles, 9 premature and mature females, and 9 premature and mature males (20.3–40.7 cm of total length, aged from 1+ to 4+). The 2+ aged fish was slightly dominated (34.5% of the whole sample). Females in the Szczecin Lagoon were ready to spawn in the age of 3+ and 4+ years, while males partly in 2+, and in the age of 3+ and 4+. Fulton’s condition factor of this fish was 0.93±0.14 and Clark’s 0.78±0.14. Analysis of correlations between the total length and individual weight of fish revealed that the growth of A. fallax was allometric (b < 3.0). The range of gonadosomatic index (GSI) was 0.12–26.59%, while the mean of the absolute and relative fecundity was 58,756 eggs per female and 139,650 eggs per kilogram of body weight. The obtained results indicate the occurrence of an anadromous population of Alosa fallax in the studied water areas. However, there is still a need to obtain detailed information on the population status and the biology of A. fallax in these areas in order to designate special conservation areas (SACs) for their protection, especially taking into account spawning habitats.

Effect of Microplastic Exposure to the Reproductive Energy and Fecundity of Female Wami Tilapia (Oreochromis urolepis, Norman 1922) Fish

ABSTRACTThere is mounting evidence indicating that microplastics (MPs, < 5 mm) cause reproductive dysfunction in fish, yet information on the long‐term effects of MP exposure remains scarce. In this study, Wami tilapia fries were exposed to 38–45 µm polyethylene (PE) MPs for their first 2 months in treatment groups of control (0 PE MPs/mL), 1, 10, and 100 PE MPs/mL (with 60 individuals per group in triplicates), and subsequently maintained in a ratio of 3 females to 1 male for an additional 5 months. Reproductive proxies and parameters of female fish health were calculated, and models were developed according to the Akaike information criterion (AIC) and no significant differences in fecundity, relative fecundity, hepatosomatic index (HSI), weight, length, gonadosomatic index, and oocyte packing density were found between treatment groups (one‐Way ANOVA, p > 0.05). However, condition factors varied significantly between treatment groups (Kruskal–Wallis Test, p = 0.006), with the control group differing significantly from the groups exposed to 1 PE MPs/mL (p = 0.007), 10 PE MPs/mL (p = 0.03), and 100 PE MPs/mL (p = 0.001). Fecundity showed strong correlations with weight and length in all treatment groups except the group exposed to 10 PE MPs/mL (weight: r = 0.471, p = 0.346; length: r = 0.688, p = 0.131) and showed insignificant correlations with condition factors and HSI. Multiple regression models revealed that weight significantly contributed to fecundity in all treatment groups except the group exposed to 10 PE MPs/mL. Histopathological analysis indicated damage to livers and small intestines proportional to the dose of PE MPs. This study demonstrates that long‐term exposure of fish to MPs has no significant effect on fecundity but impairs fish health, which could potentially jeopardize the quality of fish eggs and recruitment.

Life history of Mexican species of the genus <i>Tlaloc</i> (Cyprinodontiformes, Profundulidae)

Fish of the genus Tlaloc are distributed from southern Mexico to Central America and are a distinctive example of the endemic fauna of the Mesoamerican highlands, which has been scarcely studied in Mexico. The present study provides basic life-history data for the species Tlaloc hildebrandi, T. candalarius, and T. labialis, which are native to the headwaters of the Grijalva-Usumacinta basin in southeastern Mexico. We collected 918 specimens to determine their Length-Weight Relationship (LWR), Relative Condition Factor (Kr), sex ratio, Gonadosomatic Index (GSI), fecundity, and size at first sexual maturity. Both sexes of all species had positive allometric growth, except for T. candalarius females (isometric). Mean Kr and sex ratio values differed significantly among species. Females’ GSI values differed significantly among species but were highest during the dry season in all three species. Absolute fecundity was positively correlated with standard length and weight. Sexual maturity was reached at different lengths among species. Based on these results, we suggest that all three species present an opportunistic life strategy, which is very common in fish of the order Cyprinodontiformes. These results represent a first contribution on the life-history of this group of fish and provide basic information that is fundamental to ensuring their conservation.

Effect of Starvation and Refeeding on Gamete Quality and Fertilization in Rainbow Trout (Oncorhynchus mykiss) Broodstock

In this study, the impact of starvation and refeeding on broodstocks was observed by examining quality parameters of gametes and fertilization. While the control group fish were fed every day, the male and female members of the group were fed one week apart and placed in starvation after a week of feeding. Weight gain in the control group was the highest. The feed conversion ratio was normal in all groups (0.9-1.3%). Relative fecundity was (935±62 eggs/kg) in control group females; it was found to be (1317±241 eggs/kg) in starving females and statistically different in the groups (p < .05). The egg diameter of the group receiving intermittent feeding for a week (3.36±0.2 mm) was found to be the lowest. All spermatological parameters were similar between groups, except for sperm volume. The most sperm count was seen in the group that received one-week intermittent feeding (46.9± 20 ml). The results of fertilization with the control female in the fertilization study based on male individuals showed similarity for the male individuals of the trial group, the highest fertilization rate was seen in fertilization using the control female and control male.

The Reproductive Biology of Auchenoglanis biscutatus and Protopterus annectens from Lower River Benue Wadata, Makurdi-Nigeria

Data on the reproductive biology of Auchenoglanis biscutatus and Protopterus annectens were collected between april 2019 to march 2020. Reproductive parameters including sex ratio was determined as number of males by number of females, gonadosomatic index as total gonad weight by body weight and expressed in percentage while fecundity was obtained via volumetric and gravimetric methods. There was a slight dominance of males over females of both species (1.1:1) with more immature individuals caught within the study period. Higher GSI, gonad length and gonad weight (0.87±0.06, 15.94±0.89 and 3.01±0.19) were recorded in Auchenoglanis biscutatus during dry season while GSI and gonad weight (4.06±0.62, 5.63±0.45) of Protopterus annectens and number of mature fishes (0.35) were higher during rainy season. The relative fecundity for Auchenoglanis biscutatus investigated had no significant difference in both seasons (7.99±0.94, 8.22±0.78) while the relative fecundity for Protopterus annectentens differed significantly among the wet and dry seasons (3.43±0.94, 0.48±0.22). The relative fecundity of Protopterus annectens (11.59±2.04) was higher than that of Auchenoglanis biscutatus (8.04±0.75).it was concluded that the study of the sex ratio indicates that males were higher than females.

Relationship between dominance hierarchy steepness and rank-relatedness of benefits in primates.

In animal social groups, the extent to which individuals consistently win agonistic interactions and their ability to monopolize resources represent 2 core aspects of their competitive regime. However, whether these two aspects are closely correlated within groups has rarely been studied. Here, we tested the hypothesis that hierarchy steepness, which is generally used to represent power differentials between group members, predicts the variation in the distribution of fitness-related benefits (i.e. fecundity, infant survival, mating success, and feeding success) in relation to individual dominance ranks. We tested this hypothesis in primate groups using comparative phylogenetic meta-analytical techniques. Specifically, we reviewed published and unpublished studies to extract data on individual dominance ranks, their access to fitness-related benefits, and hierarchy steepness. We collected and included in our analysis a total of 153 data points, representing 27 species (including 2 chimpanzee sub-species). From these, we used 4 common methods to measure individual dominance ranks and hierarchy steepness, i.e. D ij -based normalized David's scores, randomized Elo-ratings, and David's scores and Elo-ratings estimated in Bayesian frameworks. We found that hierarchy steepness had no effect on the strength of the relationship between dominance rank and access to fitness-related benefits. Our results suggest that hierarchy steepness does not reflect between-group variation in the extent to which individual dominance affects the acquisition of fitness-related benefits in primates. Although the ability to win agonistic encounters is essential, we speculate that other behavioral strategies adopted by individuals may play crucial roles in resource acquisition in animal competitive regimes.

Effect of stocking density on gonadal development, pigmentation and survival of Carassius carassius (Crucian carp) in a biofloc system

The present study was carried out to investigate the optimum stocking density for gonadal development, pigmentation, and survival of Carassius carassius stocked at varying stocking densities under a biofloc-based system. C. carassius (25 ± 0.15 g) were randomly distributed in sixteen tanks, each with 250 L water at the stocking densities viz. 1 kg/m3, 2 kg/m3, 3 kg/m3, 4 kg/m3 (10, 20, 30 and 40 fish/250 L). The carbon‑nitrogen ratio of 15:1 was maintained using wheat flour as a carbon source. The best gonad performance in terms of absolute fecundity (4449.98 ± 115.636), relative fecundity (114.67 ± 2.770), GSI (5.62 ± 0.018 and 2.93 ± 0.014 for females & males respectively), and advanced maturation stages (vitellogenic oocytes and seminiferous tubules with spermatozoa) was observed in the density treatment having 20 fish/250 L. The skin carotenoid content showed an increasing trend with maximum content (8.11 ± 0.018 μg/g)) recorded for the fish stocked at 20/250 L. The scales of the fish from the same treatment presented a higher concentration of yellow orange pigments giving an overall golden hue to the scales while as the density and dispersion of melanophores increased with an increase in stocking density giving an overall darker coloration to the fish, indicating a stressful condition at higher stocking density. The survival rate of fish showed no significant difference (p≥0.05) between the various density groups. The results of this experiment elucidate that Carassius carassius could be cultured with better gonad performance, increased carotenoid content, and high survival at a stocking density of 2 kg/m3 in a biofloc system.

Vitamin Solutions Effects on Reproduction of Broodstock, Growth Performance, and Survival Rate of Pangasius Catfish Fingerlings.

This study evaluates the effect of different diets supplemented with vitamin solutions on Pangasius catfish broodstock reproduction, growth performances, and the survival rates of fish larvae and fingerling. The growth and reproductive performances of breeders fed with different test diets showed significant differences among the six tested diets (p < 0.05). The highest final body weight (FBW), weight gain (WG), daily weight gain (DWG), specific growth rate (SGR) of broodstock, and survival rate of Pangasius fingerlings were found in Treatment 5, which contained 0.6% H-OVN mixed with 12.6% algal oil, and Treatment 3, which contained 0.6% vitamin premix H-OVN. The average gonadosomatic index (GSI), relative fecundity index (RFI), fertilized eggs, hatching rates of eggs, and survival rate of fingerlings was 9.1 ± 2.8 (6.7-12.8%), 133,224 ± 39,090 (104,267-199,512 eggs/kg), 77.9 ± 22.2 (62.2-93.6%), and 45.3 ± 17.4 (22.0-66.3%), respectively. The findings of this study showed that the diet containing 35% CP contents supplemented with 0.6% vitamin premix H-OVN mixed with algal oils showed the highest results in terms of growth, reproductive performance indices, and survival rates of Pangasius catfish fingerlings.

Overcoming dysfunctional gametogenesis in hatchery-produced greater amberjack, Seriola dumerili using recombinant gonadotropins, and spawning induction using gonadotropin releasing hormone agonist-loaded implants

Female greater amberjack, Seriola dumerili reared in tanks have been inconsistent in entering or completing vitellogenesis. As a result, established spawning induction protocols employing gonadotropin-releasing hormone agonist (GnRHa) fail to induce oocyte maturation, ovulation and spawning. Males also exhibit reproductive dysfunctions resulting in low sperm production of relatively low quality. To ameliorate these problems, homologous Seriola dumerili single-chain recombinant Follicle stimulating hormone (sdrFsh) and Luteinizing hormone (sdrLh) were produced and administered to adult 4.8-year-old hatchery-produced (F1 generation) greater amberjack held in tanks, in order to enhance gametogenesis and increase reproductive performance (fecundity and fertilization success) upon spawning induction with GnRHa. Beginning at the onset of gametogenesis (27 April 2022), injections of sdrFsh and sdrLh were given for 6 consecutive weeks (a total of 7 treatments) in different combinations in males and females, and increasing doses. All fish treated with sdrFsh/Lh underwent complete gametogenesis, with females having oocytes in post-vitellogenesis and males producing releasable sperm at the time planned for the GnRHa spawning induction (6 June 2022). Furthermore, five of the six females initiated oocyte maturation prior to the GnRHa treatment, and at least one female also spawned spontaneously earlier (week 4). All but one untreated Control females did not complete vitellogenesis and exhibited follicular apoptosis/atresia, making them ineligible for GnRHa-induced spawning. Untreated Control males completed spermatogenesis and produced releasable sperm, but of somewhat lower spermatozoa density and significantly lower motility percentage and velocity compared to sdrFsh/Lh-treated males. GnRHa-induced spawning of the sdrFsh/Lh-treated fish enhanced mean daily relative fecundity and fertilization success, with embryo and larval survival >50%. These results are encouraging, and we expect that further optimization of dosage and administration timing can provide a reliable protocol for enhancing gametogenesis and promoting maturation in dysfunctional greater amberjack broodstocks maintained in aquaculture indoor facilities.

Influence of spawning year and size on reproductive parameters in adult European sea bass (Dicentrarchus labrax)

The current study sought to investigate the impact of the spawning year (SY) and mature female brooder weights (FBW) on the reproductive performance of Dicentrarchus labrax. In three fiberglass circular tanks, a total of 60 mature female brooders of Dicentrarchus labrax were allocated into three equal weight classes; < 1500, > 1500–< 2000 and > 2000–< 2500 g, respectively. The findings showed that the SY and FBW considerably affected on the final egg biomass per each female (EW/F) and diameter of spawned eggs (ED). For the two studied years, the averages of absolute and relative fecundity values that were significantly (P < 0.001) influenced by the SY are 71,924.16 and 51,168.24, and 43.01 and 43.21. Also, absolute fecundity increased noticeably with the maximal FBW. The hatchability % was strongly affected by SY and FBW. The average number of produced larvae per fish increased significantly (P < 0.001) with SY and highest FBW. The findings implied that FBW in correlation to SY can predict the production of a higher number of progenies from mature sea bass female fish, from which to develop novel approaches for selecting brooders during the spawning season.

Don't count your eggs before they resorb: Early collection of ovarian follicles influences estimates of Lake Trout fecundity in Yellowstone Lake

AbstractObjectiveUnderstanding recruitment dynamics is necessary to predict population‐level responses to exploitation, management actions, or anthropogenic influences. Fecundity is commonly used as a metric of recruitment dynamics and can guide successful management of fisheries. However, an individual female's fecundity is not constant over time; females resorb ovarian follicles to regulate fecundity as they approach spawning. This suggests that sampling for fecundity too early may produce inaccurate estimates of relative fecundity. In Yellowstone National Park, suppression of invasive Lake Trout Salvelinus namaycush reduced the abundance of mature fish by 92% between 2012 and 2022. The continued efficacy of this suppression effort requires accurate assessments of reproductive potential of the population that remains.MethodsWe sought to determine whether the timing of ovarian follicle collection affected estimates of mean relative fecundity. We collected ovarian follicles from female Lake Trout, which are autumn spawners, between mid‐August and early October in 2021 and 2022. The number of ovarian follicles per sample was counted to obtain estimates of relative fecundity for each female.ResultWe observed a 13% decline in estimated mean relative fecundity between individuals that were sampled before mid‐September and those that were sampled after mid‐September.ConclusionOur data support strategic timing of fecundity sampling to best capture the true reproductive capability of a population, which is a key metric used in models that guide adaptive management of fishes.

Antimüllerian hormone levels are associated with time to pregnancy in a cohort study of 3,150 women

ObjectiveTo study the association between AMH and time to pregnancy. While it has been hypothesized that serum anti-Müllerian hormone (AMH) levels may indicate the chance of conception, findings have been mixed. Given that any association is expected to be modest, and it is possible that previous studies have been underpowered, we investigated this relationship in the largest prospective cohort to date. DesignProspective time-to-pregnancy cohort study. Subjects3,150 US women who had been trying to conceive for less than 3 months and had purchased a Modern Fertility Hormone Test. ExposureWe developed a discrete time-to-event model utilizing a binomial complementary log-log error structure within a generalized additive modeling framework, adjusting for confounding factors such as age, BMI, parity, smoking status, PCOS, and others. Sensitivity analyses were performed in women with regular menstrual cycles (21-35 days), who did not report using fertility treatments, using alternate AMH categories (<0.7, 0.7-8.5, >8.5 ng/mL), and AMH as a continuous measure. Main Outcome MeasuresPrimary outcomes included cumulative conception probability within 12 cycles and relative fecundability per menstrual cycle. Conception was defined by a self-reported positive pregnancy test. ResultsParticipants contributed 7.21 ± 5.32 cycles, with 1,325 (42.1%) achieving a pregnancy. Women with low AMH (<1ng/mL, n=427) had a lower chance of natural conception (Adjusted Hazard Ratio (adjHR 0.77, 95%CI 0.64, 0.94, p=0.009) compared to women with a normal AMH (1 - 5.5ng/mL). There was no difference between high (5.5+ ng/ml) and normal AMH categories (adjHR 1.11, 95% CI 0.94, 1.31, p=0.2). The inclusion of AMH improved the model (net reclassification index 0.10 [ 0.06 - 0.14); P<0.001). The instantaneous probability of conception was highest in cycle 4 across all AMH categories: the probability of natural conception was 11.2% (95% CI 9.0, 14.0) for low AMH, 14.3% (95% CI 12.3, 16.5) for normal AMH, and 15.7% (95%CI 12.9, 19.0) for high AMH. In the regular cycles sensitivity analysis (n=1,791), the low AMH group had a lower chance of conception (adjHR 0.77 95% CI 0.61, 0.97, p = 0.028) in the low AMH group compared to normal AMH, and similarly in the continuous model (adjHR 0.90; 95% CI 0.85-0.95, p<0.0001). ConclusionLow AMH levels (<1 ng/ml) are independently associated with a modest but significant reduction in the chance of conception.

Insights into ovarian maturation and reproductive traits of the deep-water penaeid shrimp Metapenaeopsis andamanensis (Wood-Mason in Wood-Mason and Alcock, 1891) from southwestern India

The present study delves into the reproductive characteristics of Metapenaeopsis andamanensis, a commercially significant deep-water shrimp collected from Sakthikulangara, off Kollam, India (8°56′60.78″ N/76°32′34.27″ E) during September 2019 to May 2022. Despite its economic importance, the reproductive traits of this species remain elusive. This research comprehensively examines macroscopic and microscopic features associated with gonadal maturity stages, including determination of size at first maturity (CL50), gonadosomatic index, and fecundity of M. andamanensis. Male-to-female sex ratio was noted as 1:1.03 using chi-square analysis. The smallest mature individuals were observed at 12 mm and 16 mm carapace length for males and females, respectively. Macroscopic observation categorized females into five groups based on gonadal coloration, while microscopic examination identified seven stages using histological characteristics. Notably, the absence of cortical crypts in the periphery of oocyte cytoplasm, a characteristic feature of the genus Metapenaeopsis, was observed in this species. Males were classified into two categories based on macroscopic and microscopic observation. The gonadosomatic index ranged from 4.25 to 10.13 for mature female individuals, exhibiting a significant increase until stage IV. Continuous spawning was observed, with a peak in May and November. The size at first maturity for females and males was determined as carapace length (CL) 23.05 mm and 17.53 mm, respectively. The average absolute fecundity was calculated as 53,889 with an average relative fecundity of 9934 oocytes. This investigation contributes valuable insights into the reproductive traits of the deep-water penaeid shrimp M. andamanensis, facilitating the development of effective management strategies for sustainable fisheries.

Comparative Study on the Effects of two Commercial Hormones on the Induced Breeding of Channa striata (Bloch, 1983) under Agro-climatic Conditions of Assam, North East India

Background: Striped snakehead (Channa striata) is an air breathing fish with immense popularity as food. Successful breeding operation of this fish requires proper broodstock management and development of mass seed production technique. As spawning efficiency vary with species traits, climatic conditions and inducing agents for spawning, therefore, an experiment on the efficacy of two commercial GnRH based synthetic hormones viz., Gonopro-FH and OVAFISH on the induced breeding of Channa striata in captivity was conducted under agro-climatic conditions of Assam. Methods: Three doses of Gonopro-FH and Ovafish i.e. 0.40 (T1), 0.60 (T2) and 0.80 (T3) ml/kg for female and 0.3, 0.45 and 0.60 ml/kg body weight for male were administered to evaluate the efficacy. Result: Breeding aspects such as relative fecundity, fertilization rate, hatching rate, latency period and incubation period were found better with the dose of 0.45 ml/kg for male and 0.6 ml/kg for female. A higher relative fecundity was achieved by Gonopro FH administration. The results of this study may be useful in induce breeding and seed production of Channa striata.

Egg Quality and Fecundity of Clarias gariepinus Broodstock Cultured at Different Water Depths in Indoor Concrete Tanks

Aims: To investigate the fecundity and egg quality of C. gariepinus broodstock raised at 0.50 m, 0.75 m and 1.0 m pond water depth. Study Design: Treatments were assigned using complete randomized design. Place and Duration of Study: Fish Farm Complex of the Akwa Ibom State University (AKSU), Nigeria. Methodology: Nine female broodstock of C. gariepinus averaging 2.51 – 2.53 kg and 64.30 – 67.24 cm were raised for six months at 0.50 m, 0.75 m and 1.0 m pond water depth; referred to as treatments A, B and C, respectively Experimental fish were fed 42% crude protein commercial feed. The fecundity, relative fecundity, gonadosomatic index (GSI), egg weight and size were assessed. Results: The results revealed that the egg quality significantly (P=.00) increased with the water depth of the broodstock culture tank. Egg weight and GSI values from treatment C (363.40±0.57 g and 14.40±0.01 %, respectively) were significantly (P = .007) higher than those of treatment A (267.30±0.06 g and 10.66± 0.06 %, respectively) but showed no significant difference with those of Treatment B (331.07±1.20; 13.09±0.04 %). The corresponding egg diameter (1.01±00; 1.08±0.03 and 1.21± 0.01g), fecundity and relative fecundity of broodstock also increased with pond water depth (P = .003): 182,120.0±503.67, 72.66±0.40 &gt; 185,618.3± 745.98, 73.37±0.18 &gt; 188, 967.1± 295.19, 74.89±0.18, respectively. Conclusion: The water depth of the broodstock maintenance pond enhances fecundity and egg quality; it is better at 1.0 m depth for successful fry production. Broodstock may be maintained at lower pond water depths for growth purposes; prior to breeding.

Application of ultrasonography in abalone gonadal evaluation

The precise assessment of the gonad status and gamete development level is an essential step in abalone breeding. However, traditional methods are damaging to the animals, causing the waste of a quality parent. Ultrasound imaging as a noninvasive technique is a candidate substitute. This study aimed to verify the application of ultrasonography to the assessment of abalone gonad condition. Pacific abalones (n = 20) were randomly selected for ultrasonography, another six abalones in different gonad maturation stages (mature, between mature and immature, and immature) were also subjected to the same detection and histological analysis. Abalones (n = 10) were induced to spawn, and the changes in the gonad index and the types of germ cells were determined before and after spawning. Thirty-six female abalones were selected and divided into a high-gonad index group (HGI) and a low-gonad index group (LGI) according to the gonad index determined by ultrasonography, and their reproductive performance was compared during the entire breeding process. There was no significant difference in gonad index or gonad relative average thickness (GRAT) obtained from ultrasonography and histological methods. The gonad index and GRAT measured by ultrasound images significantly decreased after spawning. After spawning, a minimal quantity of mature gametes remained in gonad tissue as reflected in histology images. In a reproductive trial, the HGI group showed comprehensive and overwhelming reproductive advantages compared to the LGI group in total fecundity, relative fecundity, fertilization rate, hatching rate, abnormality rate, and attachment rate. Ultrasonography was demonstrated to be useful as a noninvasive method to evaluate abalone gonad condition. The ultimate goal is to achieve tracing and monitoring the abalone reproductive cycle through the ultrasound technique.

Unraveling the spawning and reproductive patterns of tomato hind grouper, Cephalopholis sonnerati (Valenciennes, 1828) from south Kerala waters.

The objective of this study is to provide information on the reproductive biology of tomato hind grouper, Cephalopholis sonnerati (Valenciennes, 1828) for conservation and management purposes. Fish caught by artisanal fishermen from September 2019 to August 2021 were analysed. A total of 280 females, 31 males, and 4 transitional and 178 sex-undetermined fish were analysed. The female to male sex proportion was 9:1, and the fish reached a maximum total body length of 38.5 and 54.5 cm for females and males, respectively. The following microscopic stages were identified: immature, developing, ripe, running ripe/releasing, and spent in both males and females. Several asynchronous development patterns were observed in the studied gonads, including multiple oocyte stages and early and advanced stages of sexual transition. High gonadosomatic index (GSI) for both males and females was recorded in March, May, and November. Running ripe and releasing stages in females were identified in the months from March to June, which indicates the spawning season. The absolute and relative fecundity of the species ranged from 162,723 ± 207,267 and 239 ± 285, respectively. An exponential relationship was found between fecundity and total body length (TL), fecundity and total body weight (TW), and fecundity and gonad weight (GW).

Effect of prolonged photoperiod on growth, gonadal development, sex ratio, and skin coloration of red tilapia (O. mossambicus × O. urolepis hornorum)

Farming of red tilapia is one promising direction in aquaculture. The objective of this study was to investigate the impact of long-day photoperiod on the growth performance, reproductive parameters, maturity, sex ratio, β-carotene content, and skin coloration of red tilapia. Early life larvae were allocated into three treatment groups in triplicates: T1 = control group (12L:12D), T2 = long-day group (18L:6D), and T3 = continuous illumination group (24L:0D) for 90 days. By the end of the experiment, gonadosomatic index (GSI), relative fecundity, steroid hormones, maturity stages, sex ratio, and ovarian and testicular histology were examined; also, growth performance, survival rate, skin color, and total β-carotene content were measured. The results indicated that GSI% and serum testosterone (T) in T3 group significantly increased with greater amount of spermatozoa of male fish. Also, growth parameters and HSI% in female fish displayed significantly increased for T3 group. Females in group T2 showed significant elevation in GSI%, relative fecundity, and estradiol (E2) with higher number of mature stage. Continuous light group (T3) showed shifted male sex ratio, while female percentage was higher in T2 group. The total β-carotene content of T3 group showed significant elevation with less number of black spots. This study demonstrated that continuous light manipulation during red tilapia early life could stimulate the growth and enhance coloration by reducing black spots that significantly affects economic profitability. Long-day application was effective in female reproductive performance and maturity. This study also served as an important reference for red tilapia aquaculture.