Search

The present study on some biological aspects of the Mormyridae fishes, was conducted between May and August 2015 in the Upper Sanaga at Lekie Department (Monatele Town), Center Cameroon. For this purpose, 125 specimens collected by local fishermen were used. Fishes were identified and measured, and their feeding and reproductive parameters were obtained after dissection. The catch composition of 4 species (Campylomormyrus phantasticus, Mormyrops anguilloides, Mormyrus macrophtalamus, Mormyrus tapirus) of Mormyridae identified in the region was very low (17%–30%). The mean ± standard deviation of total weight and total length were 103.14 ± 37.83 g and 27.47 ± 4.84 cm, respectively. The minimum and maximum size (of 21.1 cm and 43 cm) were recorded from C. phantasticus and M. anguilloides, respectively. The mean ± standard deviation of the relative length and mass of the digestive tract were 0.35% ± 0.20% and 5.27% ± 23.20%, respectively confirming that Mormyridae fish species have a strict carnivorous diet and consume prey that are difficult to digest. The size frequency distribution of the Mormyridae fishes showed that the majority of the fish caught are small sizes in classes 23–26 cm and 26–29 cm in C. phantasticus, M. macrophthalamus and M. tapirus. M. anguilloides did not record small specimens, however, it recorded larger sized specimens (41–44 cm) compared to the rest. The sex ratio ranged from 1M: 1.14F (M. anguilloides) to 1M: 4F (M. tapirus), mean 1M: 2.04F has been generally in favour of females. The gonadosomatic index (GSI) was generally low in all species. However, it was higher in females of C. phantasticus and M. anguilloides compared to other species. The hepatosomatic index (HSI) was weakly correlated with the GSI in these species.

This study investigates the ovarian development, spawning patterns, maturity size and fecundity of the goby Glossogobius giuris–a commercial fish in the Vietnamese Mekong Delta–based on the data analysis of 659 individuals. Specimens were caught using trawl nets from four sites representing freshwater (Cai Rang, Can Tho) to salinized regions in the dry season (Long Phu, Soc Trang), and brackish water regions (Hoa Binh, Bac Lieu and Dam Doi, Ca Mau) over the 12 months of 2020. Histological analysis showed that it was a multi-spawner as different stages of oocytes appeared in mature ovaries. The fish could spawn throughout the year, with a peak in April at the freshwater region and in September at salinized and brackish areas as mature ovaries appeared monthly during the studied period and gonadosomatic index displayed the highest value in April and in September, respectively. This goby’s primary egg releasing time tended to be regulated by salinity changes over the four sampling sites. Likewise, size at first maturity of this species could be related to the salinity variation as this value was the longest in freshwater (6.14 ± 0.17) and the shortest in the salinization region (4.82 ± 0.66). Batch fecundity is measured at 5,118–100,003 eggs/female and related to fish length and weight (r2 > 0.76). Findings can be useful for the development of fish conservation strategies and artificial reproducing studies.

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.

This study reflects the biometric characters of the endangered species Nandus nandus (Hamilton, 1822) including sex ratio, length-length relationships (LLRs), and length-weight relationships (LWRs) utilizing the sum of 14 linear variables, various meristic measurements, reproductive biology, and condition factor from the Borni Baor, a large wetland ecosystem of southwestern Bangladesh. A total of 579 specimens of N. nandus have been periodically collected from the Borni Baor throughout the year (January–December, 2019) using different traditional fishing gears. Highly significant LLRs (r2 > 0.90) values indicate that length parameters are profoundly associated with one another. In the LWR formula (W = aLb), higher exponent b values (b > 3.0) were demonstrating a positive allometric growth with a high correlation coefficient (r2 > 0.94). Moreover, monthly gonadosomatic index and dobriyal index fluctuations suggest the primary breeding season of this fish is from March to July. Data revealed the breeding time was associated strongly with the rainfall and air temperature (p

In this study, we investigated which strategy Macrobrachium amazonicum populations use to survive in river and estuary environments. In each environment, abiotic factors were analyzed in situ, and ovigerous females and males of M. amazonicum specimens were captured. To determine ovarian maturity and morphotypes, gonads were removed and processed histologically, and the gonadosomatic index and condition factor (K) were determined. Ovigerous females were analyzed to determine the relationship between ovarian maturation and the embryonic phases of eggs in the brood pouch. Precipitation, turbidity and dissolved oxygen showed differences between the estuary and river. The population of ovigerous females showed that ovarian maturation was simultaneous with embryonic development. However, the freshwater prawn populations in the river were smaller and consisted of a greater number of ovigerous females with maturing and mature ovaries. In the estuary, ovigerous females with spawned and reorganized ovaries were observed more frequently. In males, the GC morphotype was absent in the river, where the TC morphotype predominated and showed similar reproductive conditions as the GC morphotype in the estuary. M. amazonicum has strategies for allocating energy for reproduction or growth in different environments. This description established the trade-off as a strategy used by M. amazonicum to maintain the population in adverse environments.

We evaluated the effects of feeding 6%, 12% or 18% crude glycerin, containing 80.5% glycerol, on testicular histomorphometry and markers of oxidative stress and on plasma testosterone concentrations in lambs. Body weight, testicular biometric measurements, gonadosomatic index and net weight of the testicles were higher for the treated groups (P 0.05) compared with a control group that did not receive dietary glycerin. The mean total length of seminiferous tubules was higher in the 6% group (P 0.05), while the mean total tubular and seminiferous epithelium volumes increased in all treated groups (P 0.05). The volume of Leydig cells increased in the 12% group, while their number per gram of testicle decreased (P 0.05). There was a decrease in mean nuclear diameter and mean volume of Leydig cells, and an increase in the mean number of these cells per gram of testicle, in the 18% group (P 0.05). Plasma testosterone concentrations were unaffected. There was desquamation of seminiferous epithelium and vacuolation of Sertoli cells in the treated groups. Variable degrees of spermatocyte necrosis and the presence of giant cells were seen in all groups and there was intense vacuolation of Sertoli cells in the 12% and 18% groups. Superoxide dismutase and catalase production increased most in the 12% and 18% groups (P 0.05), while glutathione production was higher in the 18% group (P 0.05). Mean nitric oxide concentration decreased in all treated groups (P 0.05), while malondialdehyde production was higher in the 18% group than in the control and 6% groups (P 0.05). We conclude that the inclusion of 6% glycerin in the diet of lambs results in changes in testicular morphology that have been previously associated with improved reproductive function, but without evidence of oxidative stress.

A fresh water pufferfish Tetraodon lineatus in Egypt has limited information available. A total of 350 specimens were collected monthly from the river Nile, Aswan (2019). Specimens were 13.5–38.5 cm in total length with an average of 22.16 ± 5.02 cm and a total weight of 61.7–1456 g with an average of 339.86 ± 248.85 g. The length-weight relationship showed negative allometric growth, and both absolute and relative conditions decreased after March towards September, represents the spawning period. The sex ratio of 1 male to 1.28 females showed the predomination of females (56.23%) over males (43.77%) over the year. Males dominated the first length classes of 14–19 cm. The gonadosomatic index (GSI) was elevated from April to August, with its highest peak in June, and the unimodal curve indicated spawning once per year. The hepatosomatic index showed an inverse trend against the increase of GSI. Length at maturity was 18.7 cm for males and 18.2 for females. The lifespan of the fish was determined by the counting the growth rings of vertebrae No 3 was five years for both sexes at mean lengths of 14.5, 21.2, 26.3, 31.2, and 34.2 cm for 1st, 2nd, 3rd, 4th, and 5th, years respectively. Age group III was the most abundant followed by age group II. Asymptotic length was 46.29 cm, condition was 0.242 year−1, and to was −0.609 year−1, growth performance was 2.71, and longevity was 11.78 years. Our results are among the first biology and population dynamics data on the freshwater pufferfish in Egypt, and they indicate a satisfactory growth rate and ability to live longer than their age at maturity. These data could be utilized as the basis for scientific studies of physiology and toxicology, and useful in further management.

Mortality of fish has long been recognized as the evident indication of pollution, nevertheless, the increasing low-level pollution may lead to a long-term decline and eventual extinction of fish stocks. This study investigates the impact of a point source pollution (El-Sail Drain) on the biological parameters of redbelly tilapia (Coptodon zillii) in the River Nile at Aswan, Egypt. The present results showed a significant variation of the physicochemical parameters and heavy metals of the River Nile waters in the vicinity of El-Sail Drain. On the other hand, metal concentrations in the gonads of C. zillii from the downstream of the pollution source were significantly higher than that of the unimpacted upstream area. The sex ratios of C. zillii varied in the two studied areas, where it was 1:1.38 in the unimpacted area and was 1:0.9 in the impacted area. While the GSI values of the impacted area were decreased significantly (p

The recruitment of primary growth (PG) oocytes to the secondary growth (SG) phase within the ovulatory cycle, i.e. time interval between two sequential ovulation/spawning events, has rarely been examined in detail in a quantitative manner for batch spawning fishes with indeterminate fecundity. In the present study we analyzed the ovarian dynamics of Macedonian shad, Alosa macedonica, an iteroparous batch spawning clupeid with indeterminate fecundity, with the main goal to define the timing of PG recruitment and relate it to the ovulatory cycle. The latter was classified into four different phases (pre-ovulatory, running, post-ovulatory, intermediate) through postovulatory follicles and presence/absence of hydrated oocytes. Various indices of ovarian dynamics, including the formation and mean diameter of the advanced oocyte batch, the ovarian developmental stage, the oocyte size modality and the gonadosomatic index, varied among the ovulatory phases, evidencing cyclicity. Relative fecundity of newly recruited SG oocytes was used as an index of PG recruitment intensity and was shown to follow a specific pattern within the ovulatory cycle; PG recruitment occurred in a stepwise manner and in parallel with ovulation of the advanced oocyte batch, and synchronization of these two processes kept the ovary in a state of dynamic equilibrium.

Summary The round goby (Neogobius melanostomus) is one of the most abundant non-native species in the Gulf of Gdansk that use various strategies to increase fecundity and achieve invasive success. Oocyte hydration appears to be a specific osmotic adaptation of round goby's gametes for successful fertilization and hatching. The aim of this study was to demonstrate details of oocyte final maturation and hydration during the spawning-capable phase in round goby and also compare various indices such as 17β-estradiol (E2), hepatosomatic index (HSI) and gonadosomatic index (GSI) among oocyte final maturation stages. E2 fluctuated according to the development of oocyte batches. HSI did not show significant differences throughout the oocyte maturation. GSI was an inaccurate estimator of oocyte maturation in round goby. This study, for the first time, shows that hydration does accompany oocyte final maturation in this species. These findings are important to the cognition of biology and the adaptive strategies of this invasive species to environmental factors and can be essential components of the protection and preservation of native living resources in the Gulf of Gdansk.

Muscle and liver tissues of Lophius vomerinus off the coast of Namibia were analysed to investigated the influence of MeHg on the biological parameters of L.vomerinus by (i) determining if the variability in total MeHg concentrations is influenced by length, maturity status and sex, and (ii) assessing if there is a relationship between biological indices (Condition factor (K), Gonadosomatic Index (GSI) Hepatosomatic Index (HSI)) and MeHg concentrations. Correlations between total MeHg concentrations and fish length, K and HSI were observed. A weak positive correlation was observed between total MeHg and GSI for combined sex. Total MeHg concentration in tissues of L. vomerinus is significantly dependent on the maturity stages (p 0.05). K was significantly inversely correlated with total MeHg in tissues of L. vomerinus. The evidence presented in this study suggests that MeHg in L. vomerinus tissues could be detrimental to both its physiology and population dynamics.

Eurycomanone (EN), a quassinoid present in E. longifolia plants acts as a testosterone booster in male animals. The present study was aimed to explore the role of EN in females using fish as model organism. Chitosan nano-conjugated EN nanoparticles were synthesised and tested for their role in reproductive response in female catfish. Three injections of the formulation were given for a period of 21 days and the mRNA expression profile of important genes as well as serum hormones involved in steroid hormone synthesis were evaluated. In gonads, the mRNA expression of genes was upregulated except CYP19a1 (aromatase), that significantly decreased in the treatment groups. The hormone genes, FSH-β and LH-β mRNA levels in brain were upregulated whereas CYP19a2 was sharply downregulated following treatments. The testosterone varied non-significantly while the estradiol-17β serum hormone was significantly diminished. The effect was sustained in chitosan conjugated treatments compared to EN alone. The Gonadosomatic index (GSI) varied non-significantly in different treatments and control. In treatment groups, histological analysis showed the ovarian follicles in the regressed phase. Analysis of the results of the undertaken research leads to conclusion that that EN may not be beneficial for female reproduction due to its obstructive role in estrogenic production.

Choosing an alternative species of mussel for the aquaculture industries, will be possible if it has equal or greater yield than the mussel cultivated. This study compares the growth of the chilean native mussel Mytilus chilensis with the non-native Mediterranean mussel Mytilus galloprovincialis and evaluate if environmental variables and cultivation depth affects mussels growth. Mussel were seeded in summer, with the same mean total weight and shell length for both species. At the end of the experiment, shell length (SL), condition index and gonadosomatic index were compared over month, depth and species. Highly significant differences were found in shell length between month and depth and between month and species (p

The bay scallop Argopecten irradians, a warm-water and hermaphroditic bivalve species, is native of the Atlantic coast of North America and was introduced for aquaculture to the Chinese coast in 1982 and, in turn, to the Korean coast in 1996. The present study analyzed the gross biochemical composition and stable isotope ratios of separated organs (i.e., the adductor muscle, digestive gland, gonad, mantle, and gill tissues) of the scallop over a culturing cycle (September 2015 to May 2016), to understand its energy-storage allocation strategy in association with reproductive success for survival in the new habitat. The condition index (CI) of the bay scallop increased slowly but steadily from the beginning of deployment in the grow-out area in September and peaked in the following month of March. The gonadosomatic index (GSI) increased rapidly in April and peaked in May, when the CI decreased drastically. The seasonal somatic growth, as defined by dry tissue weight, of whole tissues and individual organ tissues differed from each other. Most of the energy reserves were stored in the adductor muscle in the summer–fall period. The subsequent sudden decreases in proteins and carbohydrates in the adductor muscle suggested that these reserves were used as catabolic substrates during winter maintenance in the December–January period, and during spring spawning in the April–May period. The δ13C values of all the lipid-free organ tissues displayed seasonal fluctuations in parallel with those of phytoplankton. Seasonal fluctuations in gross weights of biochemical constituents as well as δ13C and δ15N values of individual organ tissues confirmed a mobilization of proteins from the digestive gland to the gonad, suggesting that gonadal growth is catabolized by recently assimilated food (i.e., phytoplankton). Overall, our results clearly indicate that, although the bay scallop in a newly introduced coast of Korea possessed slightly different energy-gain-allocation processes vs the native US populations, they might adapt to new environments and keep an intrinsic trait of fast growth and reproductive success through a slight modification of adaptive strategy for survival.

Cephalopod species have evolved highly flexible spawning strategies, but the extent to which spawning strategy adopted is inextricably linked to the ovarian development. To address the spawning strategy of common cuttlefish Sepia officinalis outside northwest Africa, an analysis of ovarian development and hypothesis on spawning pattern was undertaken for specimens (mantle length of 126–270 mm from stages II to IV) collected from commercial catches off Mauritania during summer months of July and August 2015. It was found that the mature/spawning female S. officinalis covered a wide range of body size, being 148–270 mm ML, and showed non-stop food intake. The gonadosomatic index (GSI) increased steadily with maturity from 2.13% to 13.22%, being higher mean value of 8.65 ± 1.69% at mature/spawning stage. Potential fecundity (PF) increased with female size from 1306 to 3376 oocytes (mean 2327 ± 554.47). The oocytes were developing asynchronously as evidenced by the dominant small oocytes throughout sexual maturation and a bimodal size-frequency distribution of yolk oocytes for animals at maturing and mature/spawning stages. The mature oocytes in ovaries of mature/spawning individuals consistently accounted for less than 1% PF. There were about 770–1966 viable eggs that would be released during the spawning season. These evidences indicate that S. officinalis off Mauritania undergo the asynchronous ovarian development, and adopt a complementary spawning strategy falling somewhere along a continuum between intermittent and multiple spawning to adapt to the nutrient-rich Mauritanian upwelling system.

Determination of the stage of sexual maturation of an individual fish is commonly assessed using either microscopic or macroscopic staging. Microscopic staging examines either the internal cellular structure (histology) or the external appearance of the whole-oocyte (whole mount). Macroscopic staging is the visual evaluation of the external gonad development according to a standardised reference scale. Histology is the most widely used microscopic method and highly accurate but expensive and time consuming because it requires specialised equipment. Macroscopic staging is cheaper and faster but is associated with higher degree of error and bias. This study describe a methodological approach to assessing maturity stages of individual fish that is both inexpensive, rapid and more accurate than macroscopic staging. We have named it the gonometric method because it is based on direct measurements of the gonodasomatic index (GSI), which expresses gonad weight as a proportion of total or somatic weight. Immature, mature-active, and mature-inactive fish were classified using a logistic multinomial model giving a threshold value of GSI named here as GSIcut-off. The gonometric method was applied to four fish species that had different reproductive strategies, including demersal and pelagic species. For all four species the gonometric method estimated the maturity ogives with comparable precision to microscopic methods (p > 0.05). Across species, GSIcut-off values correlate with growth parameter of the von Bertalanffy growth function and length at 50% maturity, suggesting that the scaling of the GSIcut-off value is underpinned by fundamental allometric principles. Further testing of the gonometric method is required, but our results suggest that it has considerable potential for providing a faster and more accurate alternative to maturity staging without the need for extensive training requirements to ensure consistency across individual observers.

Antidepressant drugs have been detected in municipal wastewater effluents (MWWEs) at ng/L to low μg/L concentrations. We exposed fathead minnow (Pimephales promelas) over a full lifecycle to a mixture of five antidepressants at concentrations similar to a MWWE (1× AntiD Mix); venlafaxine at 2400 ng/L, citalopram at 240 ng/L, fluoxetine at 90 ng/L, sertraline at 20 ng/L, and bupropion at 90 ng/L, and 10× these concentrations (i.e. 10× AntiD Mix). Mean measured concentrations of venlafaxine, citalopram, fluoxetine, sertraline, and bupropion were 2300, 160, 110, 7 ng/L, and below detection limits, respectively, for the 1× AntiD Mix, and 33,000, 2900, 1000, 210, and 100 ng/L, respectively for the 10× AntiD Mix. During the life-cycle exposure, no significant changes were observed in survival of fathead minnows. When male fish from the exposed treatments reached maturity, their weights were increased compared to control males. There were no significant differences in condition factor, gonadosomatic index, or liver-somatic index in the exposed fish. Exposed fathead minnows produced similar numbers of eggs as control fish, and there were no changes in nest-defense behaviours of male minnows. Egg quality, % fertilization, and % hatching in F1 fry were unaffected by exposure to the antidepressants. Eggs hatched 0.5 d earlier, deformities in fry were 50% lower, and there were transient decreases in length of F1 larvae at 8 days post-hatch in offspring from the treatment with the 10× AntiD Mix. Overall, exposure to the antidepressant mixture at environmentally relevant concentrations (i.e. 1× AntiD Mix) caused no adverse effects in fathead minnows. Exposure to the 10× AntiD Mix increased the weight of adult male minnows and caused subtle effects in F1 offspring. This study is the first to assess sublethal effects in fish exposed to mixtures of antidepressants over a full lifecycle. Capsule No effects were observed in fathead minnow exposed for a lifecycle to antidepressant mixtures at environmentally-relevant concentrations.

The study was undertaken to explore the molecular mechanism of eurycomanone, a major compound of Eurycoma longifolia plant in increasing the reproductive processes in the male fish model. Chitosan-nanoconjugated eurycomanone nanoparticles with a significant particle size [130 nm (CED1); 144.1 nm (CED2)] and stable zeta potentials (+49.1 mV and +30 mV) were synthesized and evaluated against naked eurycomanone (ED1 and ED2). In present study, short-term and long-term experiments were conducted to evaluate the effect of nano-formulation on expression of endocrine-related genes, circulating hormone concentrations (Follicle stimulating hormone, FSH; luteinizing hormone, LH; progesterone, testosterone and 17-β estradiol) and reproductive capacity of male Clarias magur. In short-term experiment, the sampling of tissues was done on hourly basis after injection of eurycomanone either alone or with chitosan and long-term experiment was carried for 21 days and in this the injection was repeated after 7 days and 14 days. Treatments CED1 and CED2 showed controlled and sustained surge of the transcript level of selected genes (except aromatase) and serum hormones (except 17β-estradiol) compared to ED1 and ED2 groups. The transcript levels of aromatase and serum 17β-estradiol hormone showed the declining trend in the chitosan conjugated groups. The gonadosomatic index (GSI), reproductive capacity, intracellular calcium and selenium and cellular structure of testes were improved in CED1 and CED2 groups compared to other treatments. Furthermore, the effect of chitosan conjugated eurycomanone was evaluated in primary testicular cells and an increase in the mRNA expression level of endocrine-related genes was detected. This is the first report of the use of chitosan conjugated eurycomanone and present study elucidates the molecular mechanism of eurycomanone in increasing the reproductive output in animals.

Future scenarios of fish stocks and the impacts of climate variability and change on fisheries are critical to anticipate and minimize potential economic losses in this sector. In this study, we assessed the impact of recent sea warming and future climate change on anchovy in the Bay of Biscay, where sea surface temperature has increased in the last three decades. We analyzed the historical evolution of the anchovy spawning and built species distribution models that are projected under the RCP8.5 climate change scenario. The historical analysis of anchovy spawning showed that spawning peak advanced at a rate of 5.5 days/decade from 1987 to 2015, and the gonadosomatic index (as proxy of spawning activity) generally increased, which might be associated to changes in phytoplankton abundance. In addition, the spawning area expanded and contracted depending on the total egg production. In the future, the overall anchovy egg abundance in the Bay of Biscay is expected to increase between 1.05 and 2.66-fold under the RCP8.5 climate change scenario by the mid and end-of-the-21st-century, respectively. Projected environmental changes are expected to induce an expansion of the spawning area (7.8% and 16.4% for mid- and end-of-the-century) and higher egg densities.

Ovary is an important edible component of female crabs in many countries, and ovarian fullness (maturity) had become an important quality indicator used for crab marketing. Adult females Portunus trituberculatus are typically divided into four grades (Grade I - Ⅳ) based on ovarian fullness in the carapace during the marketing. This study investigated the chemical composition and nutritional quality of market size female P. trituberculatus. The gonadosomatic index (GSI), hepatosomatic index (HSI) and total edible yield (TEY) showed a stepwise increase from Grade Ⅰ to Ⅳ (P

In Seriola species, exposure to a long photoperiod regime is known to induce ovarian development. This study examined photoperiodic effects on pituitary gene expression and plasma levels of follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh) in previtellogenic greater amberjack (Seriola dumerili). The fish were exposed to short (8L:16D) or long (18L:6D) photoperiod. The water temperature was maintained at 22 °C. Compared with the short-photoperiod group, plasma Fsh levels were higher on days 10 and 30 in the long-photoperiod group, but plasma Lh levels did not significantly differ. On day 30, pituitary Fsh- and Lh-β subunit gene expressions were also higher in the long-photoperiod group than the short-photoperiod group, whereas α-subunit gene expressions were higher on days 20 and 30. Throughout the experiment, average gonadosomatic index and plasma E2 levels did not significantly differ between the two groups. This study clearly demonstrated that a long photoperiod induced Fsh release in the previtellogenic fish followed by upregulation of pituitary Fsh and Lh subunit gene expressions. An increase in plasma Fsh levels may be a key factor that mediates the photoperiodic effect on the initiation of ovarian development.

Food availability can become a factor driving the reproductive activity of tropical fish, particularly when primary production within their habitats fluctuates with tropical monsoons. The present study examined the involvement of insulin-like growth factors (IGF) in controlling the reproduction of the sapphire devil Chrysiptera cyanea, a reef-associated damselfish that is capable of manipulating its reproductive activity based on food availability. We cloned and characterized the cDNAs of igf1 and igf2 and determined their transcript levels in relation to seasonal and food-manipulated reproduction. The partial cDNAs of sapphire devil igf1 and igf2 had open reading frames (ORFs) composed of 600 bp (155 amino acid residue) and 636 bp (211 aa), respectively. Phylogenetic analyses revealed that IGF1 and IGF2 of the sapphire devil were clustered into those of teleosts. The gonadosomatic index increased from March to June. Vitellogenic oocytes and ovulatory follicles were observed in ovaries from May to June, which suggests that the spawning season lasts for at least 2 months. The hepatosomatic index, but not the condition factor, increased in March and June. The transcript levels of igf1 in the brain, but not in the liver, increased in April, June (vitellogenesis) and July (post vitellogenesis). Ovarian activity during the spawning season was maintained by high food supply (HH) for 30 days, although it was suppressed in the food-restriction treatment (LL) and restored in the re-feeding treatment (LH). The transcript levels of igfs in the brain, but not in the liver, in LH were lower than those in HH and LL. Moreover, immersing fish in seawater containing estradiol-17β suppressed transcript levels of igfs in the liver, but not in the brain. We conclude that reproductive activity during the spawning season is influenced by nutritive conditions and that crosstalk exists between the reproductive and growth network in the neural and peripheral tissues, thus controlling the reproductive activity of this species.

Aromatase inhibitors (AIs) block the conversion of testosterone to 17β-estradiol and thereby increase the serum testosterone levels. The present work was aimed for development and characterization of nanoconjugated AIs for studying the effect on the gonadal development in Clarias magur. Two AIs such as Fadrozole and Letrozole were used in this study and conjugated with chitosan nanoparticles. The size and zeta potential of the blank chitosan nanoparticles was 47.6 nm and 29 mV, respectively. The size of chitosan conjugated Letrozole (LZC) was 108.9 nm with a zeta potential of 18.9 mV while chitosan conjugated Fadrozole (FZC) showed the size of 150.5 nm with a zeta potential of 25.6 mV. Entrapment efficiency of LZC and FZC were 86.6% and 84.3%, respectively. The FTIR analysis confirmed the conjugation between chitosan and AIs. Fish receiving an intramuscular injection of LZC showed a higher level of serum testosterone than FZC injected fishes. On the other hand, a lower level of 17β-estradiol was observed in LZC treated fish. These results indicate the higher efficiency of letrozole over fadrozole. The oral delivery of Letrozole alone and conjugated with chitosan nanoparticles was carried out through feed (100 mg/kg of feed) to fingerlings. The LZC treated group showed advancement in the testicular development which was evident in serum hormonal analysis, histological examination of gonads and Gonadosomatic Index (GSI). Thus, the nano-formulation developed in the present study may be useful for improving the reproductive output in fish.

The objective of this research was to determine if growth performance of yellow perch (Perca flavescens) could be enhanced through nutritional programming when fed soybean meal-based (SBM) diets as their first feed. It was hypothesized that juvenile yellow perch could be nutritionally programmed by being fed SBM-based diets as their first formulated feed, and that this would result in improved growth performance when reintroduced to this diet later in life. It is assumed that nutritionally programmed fish transitioned back to fish meal (FM)-based diets during gametogenesis would eliminate reproductive effects from the SBM-based diets, such as reduced fecundity, egg quality or fertilization rate. The experimental design was carried out over four phases. In Phase 1, juvenile yellow perch were divided into four dietary treatments: 1) FM control, 2) wheat gluten meal (WG) and 3) and 4) two soybean meal (SBM-A/SBM-B) varieties, all fed to fish in triplicate. Plant proteins replaced 75% of the fish meal protein in the diet formulations, and diets were fed to juveniles for 2 months. In Phase 2, fish were combined in a “common garden” design, and all fed the FM diet for 9 months. In Phase 3, all fish were transitioned to the SBM-A diet for 7 months. Mean individual weights of fish and survival were measured at the beginning and end of each phase. Growth performance was calculated as weight gain (%) and specific growth rate (SGR, %/day. In Phase 4, fish were fed the FM diet over winter (6 months) when gametogenesis occurs and somatic growth was minimal. When females were ready to ovulate, they were manually stripped of eggs and fertilized with pond-raised males. Mean egg weight, total number of eggs, fecundity, gonadosomatic index (GSI), and fertilization rate were all calculated to determine reproductive quality. Results from phase 3 show that fish nutritionally programmed with SBM-A, had a higher weight gain percent when returned to SBM than fish from the other three diets, though not significant. Specifically, weight gain of SBM-A fed fish was 150 ± 31%, whereas other groups were 114 ± 24% (FM), 110 ± 26% (WG) and 118 ± 15% (SBM-B). Female reproductive quality was not affected by diet and results showed no significant differences between any of the parameters examined. However, growth during phase 4 was correlated with time to ovulation, increased GSI and mean egg weight.

Palm oil mill effluent (POME) has potential to contaminate the aquatic environment. This paper investigated the reproductive performance and gonad histopathology of female Nile tilapia (Oreochromis niloticus Linnaeus 1758) exposed to POME. Specifically, it examined changes in important parameters of reproductive performance (gonadosomatic index, fecundity, and oocyte diameter) and gonad histopathology. A chronic test was carried out experimentally using a completely randomized design consisting of four treatments with three replicates: treatment control (0 mg/L), treatment A (1.565 mg/L), treatment B (2.347 mg/L), and treatment C (3.130 mg/L). Results indicated that the POME exposure had no significant impact on fecundity of Nile tilapia. Nevertheless, exposure to POME triggered a decline in gonadosomatic index and shrunk the oocyte diameter of Nile tilapia. The histopathology test confirmed that exposure to POME impacted on the occurrence of follicular atresia, disorientation of gonad form, chinion layer depletion and yolk granular degeneration. Keywords: Gonadosomatic index, Fecundity, Oocyte diameter, Degeneration of yolk granule

As an alternative to perfluorooctane sulfonate (PFOS), 6:2 chlorinated polyfluorinated ether sulfonate (commercial name: F-53B) has been used in the Chinese chrome plating industry for over four decades. It has been increasingly detected in environmental matrices in recent years, causing great concern regarding its potential health risks to humans and wildlife. However, its adverse effects on biota remain largely unknown. To explore the chronic toxicity of F-53B on reproduction, a two-generational study was conducted using zebrafish (Danio rerio). Adult zebrafish (F0 generation) were chronically exposed to different concentrations of F-53B (0, 5, 50, and 500 μg/L) for 180 d using a flow-through exposure system, with F1 and F2 generations reared without exposure. The reproductive toxicity endpoints were assessed in F0 and F1 adult fish. Results showed that F-53B accumulated in the F0 gonads and transferred to the F1 generation via maternal eggs, and even remained in F1 adult fish and their eggs (F2) after 180 d depuration. In the F0 generation, F-53B exposure significantly inhibited growth and induced reproductive toxicity, including decreased gonadosomatic index and egg production/female, changes in the histological structure of the gonads, and increased serum testosterone levels. In particular, serum estradiol and vitellogenin levels were significantly increased in 5 μg/L F-53B-exposed adult males. The transcriptional levels of several genes along the hypothalamic-pituitary-gonadal axis were altered in F0 generation fish. Testis transcriptome analysis revealed that F-53B exposure disrupted spermatogenesis in F0 male zebrafish. Maternal transfer of F-53B also induced adverse effects on growth and reproduction in the F1 generation. Furthermore, the higher occurrence of malformation and lower survival in F1 and F2 embryos indicated that parental exposure to F-53B could impair the embryonic development of offspring. Taken together, this study demonstrated that F-53B could induce reproductive toxicity in zebrafish similar to that induced by legacy PFOS, and its potential adverse effects on offspring deserve further investigation.

The endocrine regulation of gonadal development and annual variation of key sex steroids is the basic knowledge to understand the reproductive cycle of teleost fish. Present study was aimed to investigate the levels of gonadotropins in relation to the follicular development and plasma steroids during the reproductive cycle of female Trichogaster fasciata. Female fish were sampled and ovarian development is described histologically throughout the year in relation to the seasonal variations of gonadosomatic index (GSI); follicle stimulating hormone (FSH) and luteinizing hormone (LH); three key steroids for folliculogenesis and maturation i.e. testosterone (T), 17β-estradiol (E2) and 17α20βdihydroxy4pregnen3one (17,20β-P). Relatively higher level of FSH was observed till the ovary reaches in late vitellogenic stage confirms that FSH regulates the early folliculogenesis of the ovary, whereas LH peak was observed in the postvitellogenic stage, which indicates that maturation and ovulation were controlled by LH. Seasonal steroid profiles show that both T and E2 reach its maximum level prior to the 17,20β-P which attain its peak value in the month of August. Thus, single peak values of LH and 17,20β-P coinciding with GSI peak, clearly indicates that T. fasciata breeds only once in a year. Furthermore, to elucidate the molecular basis of the reproductive cycle, this study analyzes the other key factors of ovarian function such as cyp19a1a gene expression, aromatase activity and SF-1 localization throughout the year. cyp19a1a gene expression and the aromatase activity were highest in vitellogenic stages indicate that relatively higher E2 production in this stage is regulated by FSH. Immunohistochemical localizations of aromatase and SF-1 in the cellular layer of oocytes demonstrated that aromatase is FSH-dependent and SF-1 could be regulated by both FSH and LH as relatively higher amount of aromatase was localized in the vitellogenic stage oocytes than the postvitellogenic and post germinal vesicle breakdown (post-GVBD) stages; whereas, high amount of SF-1 was observed in vitellogenic, postvitellogenic and post-GVBD stages. These data regarding the reproductive endocrinology of T. fasciata may be useful to understand the interaction between gonadotropins, steroids, aromatase and SF-1 in teleost fishes and may contribute to restoration of the ecologically important fish through artificial reproduction.

Tiger puffer (Takifugu rubripes) is a promising species for aquaculture production because of its high commercial value and limited supply. The growth performance and physiological metabolism of subadult tiger pufferfish reared in offshore sea cage aquaculture system (OSCS) and recirculating aquaculture system (RAS) were examined in this study. Results showed that the final body weight, specific growth rate and plasm growth hormone of the female tiger puffer reared in the OSCS were significantly higher than those of the fish reared in the RAS. The condition factor and gonadosomatic index of the female tiger puffer were significantly higher than those of the male tiger puffer cultured in the OSCS and the RAS. By contrast, the hepatosomatic index, viscerosomatic index and survival rate of the tiger puffer did not significantly change. Female fish reared in the OSCS with the significantly higher hepatic alkaline phosphatase activities and lower aspartate aminotransferase compared with those of fish reared in the RAS. The hepatic pyruvate kinase and Na+-K+ ATPase activities of the female or male fish in the OSCS were significantly higher than those of the female or male fish in the RAS, respectively. The mRNA expression of somatic growth axis-related genes (igf1, igf2, igf1r, igf2r, ghr1, ghr2) of the female tiger puffer reared in the OSCS was significantly higher than that of the fish reared in the RAS. These results indicated that the growth performance and metabolic state of the female tiger puffer reared in the OSCS were better than those of the fish in the RAS, the OSCS was more suitable than the RAS for the short-term culture of subadult tiger puffer. These findings enhanced our understanding of the combined land (RAS) and sea (OSCS) alternative aquaculture model of tiger puffer.

Among the pelagic egg spawning marine teleosts, spermatogonial transplantation techniques were first developed in the Nibe croaker Nibea mitsukurii ; however, production of donor-derived offspring had not yet been achieved. In salmonids, when triploid individuals were used as recipients, the resulting surrogate broodstock produced only donor-derived gametes, as the triploids were incapable of producing their own gametes. Therefore, in the present study, we determined the optimal parameters for cold-shock inducing triploidy through the suppression of meiosis II resulting in retention of the second polar body in fertilized Nibe croaker eggs. It was determined that cold-shock treatment, which was carried out at 10 °C for a period of 15 min beginning 5 min after fertilization, following pre-shock treatment at 22 °C achieved a 100% triploidization rate as well as hatching rates of which were high enough for practical application in the pelagic egg spawning marine teleost (16.4 ± 10.4%). Average chromosome numbers of cold-shock treated larvae counted using mitotic figures found on the fin membrane of 1 day post-hatch larvae were 67.3 ± 0.7, which was approximately 1.5 times larger than that of control larvae (46.8 ± 1.1), suggesting that triploidy had been induced. No differences in survival rates of hatched larvae during the rotifer-feeding stage existed between treated and non-treated groups. Gonadosomatic index and gametogenesis were impaired in both sexes of triploid Nibe croaker. Although triploids produced small amounts of gametes, no progeny from crosses between triploids and diploids survived later than 24 h subsequent to hatching. These results indicated that the triploid Nibe croaker developed in this study could be effectively used as surrogate recipients in spermatogonial transplantation. Statement of relevance In intraperitoneal germ-cell transplantation techniques in salmonids, donor-derived diploid germ cells proliferated and differentiated within triploid recipient gonads, and the surrogate recipients produced only donor-derived gametes, which were capable of generating viable offspring when used in fertilization. To date, germ-cell transplantation techniques have been developed for use in perciforms, including sciaenids, however, triploid recipients have not yet been utilized in marine fishes. In this study, triploid Nibe croaker was produced at high triploidization rates (~ 100%) using cold-shock treatments. Analysis of the gonadal development and gametogenesis of triploid Nibe croaker in two consecutive spawning seasons revealed that the triploid Nibe croaker was functionally sterile in both sexes and that the triploids would be suitable for use as surrogate recipients.

The commercial fishery for common whelk (Buccinum undatum L.) has expanded significantly in the Irish Sea since 1990 and continues to grow, particularly in Welsh waters and the Isle of Man territorial sea, with landings throughout the region increasing by 227% between 2011 and 2016. Whilst whelk populations are known to be vulnerable to localised overexploitation due to inherent life-history parameters, fisheries remain relatively unrestricted by conservation measures in comparison to other fisheries operating in the area. With the exception of the northernmost fishing ground between the Isle of Man and Scotland (Point of Ayre), the size-at-maturity (L50) estimate for populations sampled during peak-aGSI (the months in which adjusted gonadosomatic index is highest) indicates that whelk are being fished before the time at first spawning throughout the study area. A correlation was detected between the size (total shell length) and depth, with smaller whelks found in deeper waters where there generally is greater fishing effort, although effort data is not available at a resolution to investigate this relationship quantitatively. No clear link between benthic infauna biomass and the average size (total shell length) or reproductive capacity (aGSI) of whelk sampled throughout ICES Area VIIa was found, indicating that the ecological energetics of whelk populations are more likely to be a function of scavenging opportunities than predation on benthic communities. A mixed cohort analysis utilized length-based data to infer a size-at-age relationship in the absence of direct age observations (e.g. statolith rings), with whelk recruiting into the Isle of Man fishery five years after hatching. The evidence presented in this study suggests that, prior to recommending a MLS that will adequately protect the spawning stock biomass, L50 values should be adjusted for pre-spawning growth between the ideal time of assessment (when aGSI values are at a peak) and the spawning season (when aGSI values decrease).

Fecundity of marine fish species is highly variable, but trade-offs between fecundity and egg quality have rarely been observed at the individual level. We investigated spatial differences in reproductive investment of individual European sprat Sprattus sprattus (Linnaeus 1758) females by determining batch fecundity, condition indices (somatic condition index and gonadosomatic index) as well as oocyte dry weight, protein content, lipid content, spawning batch energy content, and fatty acid composition. Sampling was conducted in five different spawning areas within the Baltic Sea between March and May 2012. Spawning sprat from the Kiel Bight were in a better nutritional condition compared to sprat from the Arkona Basin, Bornholm Basin, and the Gdansk Deep. These females were also producing up to twice as many oocytes, and invested significantly more energy in reproduction, than their counterparts sampled in the eastern part of the Baltic Sea. Still, oocytes produced by Kiel Bight sprat contained significantly lower fractions of the essential fatty acids 20:4 (n-6) and 22:6 (n-3). A seasonal trade-off between oocyte weight/lipid content and fecundity was found for Baltic sprat, albeit the gross energy invested into spawning remained constant. Observed spatial and seasonal differences in sprat reproductive investment may be linked to hydrographic conditions and food availability and will impact the survival probability of yolk-sac and first feeding larvae. These findings indicate that Baltic sprat is able to adapt its reproductive tactics to the highly variable pelagic habitat of the Baltic Sea.

Short-term reproduction assays were conducted with fathead minnow (Pimephales promelas) and Japanese medaka (Oryzias latipes) to evaluate responses from atrazine exposure at environmentally relevant concentrations and above. Breeding groups of fish with multiple males and females were exposed to atrazine under flow-through conditions. Fathead minnows were exposed to mean measured concentrations of 1.0, 10, 26, 52, and 105 μg atrazine/L for 28 days. Medaka were exposed to mean measured concentrations of 9.4, 48, 74, 97, and 244 μg atrazine/L for 28 or 29 days. Fish were evaluated for survival, fecundity, fertility, total length, wet weight, secondary sex characteristics, gonadosomatic index (GSI) (P. promelas only), plasma or hepatic vitellogenin (VTG), and histopathology of gonads. General observations of health and behaviour were also conducted. There were no statistically significant effects (i.e., p 0.05) of atrazine on survival, size, reproduction, behaviour, GSI, VTG, or secondary sex characteristics in either species at any exposure level. In fathead minnows, there were no histopathological findings associated with atrazine exposure in male fish, but there was an increased proportion of Stage 4.0 ovaries accompanied by an increase in proportion of Grade 3 post-ovulatory follicles in females of the 105 μg/L treatment group. Without a concomitant increase in oocyte atresia, neither of these findings are considered adverse for the health of the fish. In medaka, there were no significant effects of atrazine exposure on histopathology in either sex. These data support current weight-of-evidence assessments that atrazine does not cause direct adverse effects on fish reproduction at environmentally realistic concentrations.

Follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh), secreted from pituitary, stimulate gonadal function by binding to their cognate receptors FSH receptor (FSHR), and LH/choriogonadotropin receptor (LHCGR). Rohu (Labeo rohita) is a commercially important seasonal breeder freshwater fish species, but till date, the regulation of expression of gonadotropins and their receptors gene during different phases of annual reproductive cycle has not been investigated. We envisaged the critical role of these molecules during seasonal gonadal development in this carp species. We cloned full- length cDNAs of fshra and lhcgrba from rohu testis using RACE (Rapid amplification of cDNA ends) and analyzed their expression along with fsh and lh by quantitative real time PCR (qRT-PCR) assay at various gonadal developmental stages of the annual reproductive cycle. Full-length rohu fshra and lhcgrba cDNA encodes 670 and 716 amino acids respectively, and in adult fish, they were widely expressed in brain, pituitary, gonad, liver, kidney, head kidney, heart, muscle, gill, fin, eye and intestine. In male, both fsh and fshra transcripts showed high level of expression during spermatogenesis, however, in female, expression level was found to be higher in the fully grown oocyte stages. The expression of rohu lh and lhcgrba mRNA increased with increment of gonadosomatic index and showed highest level during spermiation stage in male and fully matured oocyte stage in female. These results together may suggest the involvement of fshra and lhcgrba in regulating function of seasonal gonadal development in rohu.

Chitosan nanoparticles conjugated with 17α-methyltestosterone (CS + MT) were used for studying their effect on the testicular development of Clarias batrachus during different reproductive phases. The size of chitosan nanoparticles was 127.2 nm and the nano-conjugated 17α methyltestosterone (17α-MT) was 196.1 nm (20 mg/100 ml of chitosan). Single injections of CS + MT at different doses such as 0.01, 0.1 and 0.5 μg/g body weight were administered to adults during the pre-spawning, spawning and post-spawning phase. Nano-conjugated steroid was effective at the lower dose; showing an increase in the Gonadosomatic Index (GSI) and 11-ketotestosterone level compared to the control group. Histological observations confirmed the dose-dependent advancement in spermatogenesis. These findings indicate the possibility of using CS + MT for enhancing gonadal maturity of C. batrachus.

International audience; The development of predictive, sensitive and reliable biomarkers is of crucial importance for aquatic biomonitoring to assess the effects of chemical substances on aquatic organisms, especially when it comes to combined effects with other stressors (e.g. temperature). The first purpose of the present study was to evaluate the single and combined effects of 90 days of exposure to an environmental cadmium concentration (0.5 μg. L−1) and two water temperatures (16 and 21 °C) on different parameters. These parameters are involved in (i) the antioxidant system (superoxide dismutase activity –SOD– and total glutathione levels –GSH–), (ii) the energy metabolism, i.e. energy reserves (glycogen, lipids, proteins) and digestive enzymes (trypsin, amylase, intestinal alkaline phosphatase–IAP–), and (iii) biometric parameters (weight, length, Fulton’s condition factor, and the gonadosomatic index –GSI–) of threespine stickleback (Gasterosteus aculeatus). The second purpose was to determine the interest of the three digestive enzymes as biomarkers in comparison with the other parameters. The higher temperature (21 °C) impacted the anti-oxidant and energy reserve parameters. In liver, GSH levels increased on day 60, while SOD decreased on days 15 and 90, with a significant decrease of protein and lipid energy reserves on day 90. In muscle, the higher temperature decreased SOD activity only on day 90. G. aculeatus biometric parameters were also impacted by the higher temperature, which limited stickleback growth after 90 days of exposure. In female sticklebacks, the GSI peaked on day 60 and decreased sharply on day 90, while the highest values were reached at day 90 in the control groups, suggesting impaired reproduction in sticklebacks raised at 21 °C. These results suggest that 21 °C is an upper-limit temperature for long-term physiological processes in sticklebacks. In contrast, very low-concentration cadmium exposure had no effect on classical biomarkers (energy reserves, antioxidant parameters, biometric parameters). However, digestive enzymes showed an interesting sensitivity to cadmium, which was emphasized by high temperature. The activity of the three digestive enzymes decreased significantly on day 90 when sticklebacks were exposed to cadmium alone, while the decrease was stronger and was recorded earlier (from day 15) when they were exposed to the cadmium-temperature combination. Compared to conventional measurements, digestive enzymes responded rapidly. This could be an important advantage for them to be used as early warning tools to reflect the health status of organisms, particularly for trypsin and IAP activities.

Lake Mead National Recreational Area (LMNRA) serves as critical habitat for several federally listed species and supplies water for municipal, domestic, and agricultural use in the Southwestern U.S. Contaminant sources and concentrations vary among the sub-basins within LMNRA. To investigate whether exposure to environmental contaminants is associated with alterations in male common carp (Cyprinus carpio) gamete quality and endocrine- and reproductive parameters, data were collected among sub-basins over 7 years (1999–2006). Endpoints included sperm quality parameters of motility, viability, mitochondrial membrane potential, count, morphology, and DNA fragmentation; plasma components were vitellogenin (VTG), 17s-estradiol, 11-keto-testosterone, triiodothyronine, and thyroxine. Fish condition factor, gonadosomatic index, and gonadal histology parameters were also measured. Diminished biomarker effects were noted in 2006, and sub-basin differences were indicated by the irregular occurrences of contaminants and by several associations between chemicals (e.g., polychlorinated biphenyls, hexachlorobenzene, galaxolide, and methyl triclosan) and biomarkers (e.g., plasma thyroxine, sperm motility and DNA fragmentation). By 2006, sex steroid hormone and VTG levels decreased with subsequent reduced endocrine disrupting effects. The sperm quality bioassays developed and applied with carp complemented endocrine and reproductive data, and can be adapted for use with other species.

A 42-day feeding trial was carried out to investigate the effects of effects of five formulated feeds with different lipid sources (colza oil (CO), fish oil (FO), linseed oil (LO), soybean oil (SO), or palm oil (PO)) and kelp (Laminaria japonica) on the growth, gonad development, nutritional and organoleptic quality, transcription of fatty acid synthesis related genes, and antioxidant capacity during cold storage in adult sea urchin (Strongylocentrotus intermedius). Each diet was randomly allocated to 12 cages of sea urchins (initial weight: 60.76 ± 1.21 g). The results showed that the weight gain rate (WGR) in FO treatment was comparable to the CO and kelp, but was significantly higher than the PO, SO and LO. The WGR of S. intermedius fed SO and LO was significantly lower than that in the other dietary treatments. S. intermedius fed kelp had a significantly lower gonadosomatic index (GSI) than those fed the formulated feeds. The GSI of S. intermedius fed SO was comparable to that of sea urchins fed LO but was significantly lower than that of sea urchins fed FO, PO and CO. The percentage of gonads with market acceptable colors was highest in the PO treatment, followed by CO, FO and kelp, with the lowest value observed in SO and LO. The hardness of gonads in S. intermedius fed LO was comparable to that fed kelp, CO, and PO, but was significantly higher than that fed FO and SO. The total amino acid (AA), total sweet AA, and total umami AA were highest in the gonads of kelp treatment, which were only significantly higher than those in FO. FO contributed to the highest content of long-chain polyunsaturated fatty acids (LC-PUFAs) and ratio of EAA/TAA in the gonads. S. intermedius fed SO and LO had relatively higher ARA and EPA than the other plant oils, which could be due to the elevated transcription of fatty acid synthesis related genes. During cold storage (6–36 h), the MDA content in the gonads of S. intermedius fed FO was significantly higher than that in the other dietary treatments. In conclusion, PO and CO were most ideal lipid sources based on the growth, gonad increase and organoleptic characteristics. Although FO resulted in the highest nutritional value, it was most easily oxidized during cold storage. These results could contribute to adopting an effective and efficient feeding strategy to produce high quantity and quality gonads for adult S. intermedius.

Steroidogenic factor 1 (sf1) (officially designated as nuclear receptor subfamily 5 group A member 1 [NR5A1]) is an important regulator of gonad development. Previous studies on sf1 in fish have been limited to cloning and in vitro expression experiments. In this study, we used antisense RNA to down-regulate sf1 transcription and sf1 protein expression. Down-regulation of sf1 resulted in an increase in body weight and inhibition of gonadal development in both males and females with the consequent lower gonadosomatic index compared to fish in the control group. Hematoxylin-eosin staining of the gonads of fish with down-regulated sf1 revealed fewer seminiferous tubules and sperm in the testis of males. In addition, the oocytes were mainly stage II and many of them were atretic follicle. We conducted comparative transcriptome and proteome analyses between the sf1-down-regulated group and the control group. These analyses revealed multiple gene–protein pairs and pathways involved in regulating the observed changes, including 44 and 74 differently expressed genes and proteins in males and females, respectively. The results indicated that dysfunctional retinal metabolism and fatty acid metabolism could be causes of the observed weight gain and gonad abnormalities in sf1-down-regulated fish. These findings demonstrate the feasibility of using antisense RNA for gene editing in fish. This methodology allows the study gene function in species less amenable to gene editing as for example aquaculture species with long life cycles.

The edible tissue yield, proximate, fatty acid, and free amino acid composition were examined and compared among Chinese mitten crabs (Eriocheir sinensis) samples from Ya Lake over different months. Regardless of gender, the gonadosomatic index (GSI) was higher in May and June than that in August and September (P

Takifugu bimaculatus is a cultured marine teleost fish, distributed ranging from the southern Yellow Sea to the South China Sea. Understanding the mechanism of sex determination is essential for sex control breeding biotechnologies of T. bimaculatus. However, there lacks a rapid and accurate sex specific marker for the T. bimaculatus. In this study, whole genome resequencing was conducted on 71 individuals (including 49 females and 22 males), 331,190 high-quality polymorphic loci (34,435 INDEL, 296,755 single-nucleotide polymorphisms (SNPs)) were obtained through genome-wide association analysis (GWAS) by GEMMA (Genome-wide Efficient Mixed Model Association algorithm). 1403 loci on chromosome 7 were identified as sex significantly associated loci (P

We examined the annual reproductive cycle of both female and male hatchery-produced Pacific bluefin tuna (PBT, Thunnus orientalis) broodstock at 3 years of age, including the associated changes in plasma levels of sex steroid hormones and the gene expression of key endocrine factors. The females progressed to vitellogenesis in April, and approximately 50% of the females were observed in late vitellogenesis between June and July at water temperatures between 24.1 °C and 29.0 °C. Approximately 90% of the males were in spermiation for at least 7 months between April and October, which included the period when vitellogenic females were present. Furthermore, the gonadosomatic index of both females and males peaked between June and July. These results indicate that the reproductive season of hatchery-produced PBT peaks between June and July, which is in agreement with the reproductive season reported for PBT broodstock originating from wild-caught juveniles. Furthermore, the percentage of hatchery-reared females that reached late vitellogenesis in the present study was higher than that in wild-caught captive-reared females reported in previous literature. Analysis of plasma sex steroid levels and gene expression profiles suggested that oocyte and ovarian development were associated with 17β-estradiol (E2) control, whereas spermatogonial differentiation towards meiosis seemed to be mediated by 11-ketotestosterone (11-KT). Furthermore, the production of E2 and 11-KT is likely regulated by luteinizing hormone and follicle-stimulating hormone, respectively, via their related receptors. The findings of this study are expected to contribute to improvements of technologies for obtaining fertilized eggs from hatchery-produced PBT broodstock.

This study compared the nutritional quality and nutrient compositions of female mud crabs cultured in the coastal area around the Bohai Sea (BMC), the East China Sea (EMC), and the South China Sea (SMC). The results showed that BMC had the highest hepatopancreas index and meat yield and EMC had the highest gonadosomatic index and total edible yield. The protein content in the edible tissues of EMC and SMC was significantly higher than that of BMC. The essential amino acid index in the muscle and gonads of three-sourced female crabs was quantitatively higher than 70, meaning that the amino acid compositions in the muscle and gonads of BMC, EMC, and SMC showed good performance. The mineral element data revealed that they were all excellent mineral sources, especially the Zn content in the gonads, which was approximately 15 mg 100 g−1. Meanwhile, the polyunsaturated fatty acid contents of BMC were significantly higher than those of EMC and SMC, and BMC also had abundant eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), particularly in the muscle. Hence, although EMC and SMC contained more protein than BMC, the nutritional quality and nutrient composition of BMC was slightly better than those of EMC and SMC.

The present study to identify the best lipid source and optimum level of incorporation in the maturation diet of koi was carried out in 2 experimental trials. The first trial was conducted to evaluate the effect of selected lipid sources viz, commercial vegetable oil, fish oil, palm oil and groundnut oil on the reproductive performance of koi. The first trial was undertaken for 105 days and fed 35% crude protein diets and 7% lipid. The lipid sources used were Fish oil (T1), Palm oil (T2) and Groundnut oil (T3) and Commercial vegetable oil as the Control (C). The reproductive performance of the First trial experimental fish was assessed by the following factors viz, Gonadosomatic Index (GSI), fecundity, fertilization rate, hatching rate, and survival rate. GSI was found to be maximum in T2 (10.4 ± 2.80%) followed by T3 (10.15 ± 2.10%) and minimum in C (9.89 ± 1.22%). Maximum fecundity was observed in T3 (61,985 ± 2388) followed by other treatment animals viz T1 (55,160 ± 5988), T2 (52,839 ± 4636) and C (47,832 ± 1658). GSI was observed to be positively correlated with fertilization rate as observed by maximum fertilization rate (58.58 ± 2.35%) and hatching rate (50.91 ± 1.53%) in T3. Maximum survival rate was observed in T3 (20.51 ± 0.89%) followed by T2 (18.80 ± 1.06%), T1 (18.25 ± 1.06%) and C (15.89 ± 1.41%) during the ten days (upto early fry stage) nursery phase. The second trial was conducted until the animals in any treatment showed signs of good maturity, which was a maximum of 60 days. The best-performed lipid source, from the first trial, i.e., groundnut oil was taken and diets formulated at different lipid levels viz, 5% (T4), 7% (T5) and 10% (T6) with commercial vegetable oil (7%) as control diet (C). From the reproductive performance of the second trial experimental fish, it could be observed that T4 diet-fed fishes have shown significantly (p

The gonadosomatic index (GSI) is an economically important trait in the large yellow croaker ( Larimichthys crocea ), a mariculture fish species with high commercial value in Southeast China. However, progress in the genetic research on this species is relatively lacking. To identify the relevant genes and chromosome regions associated with the GSI, we performed a genome-wide association study (GWAS) on a population of 500 individuals (237 males and 263 females), using single marker analysis and Bayesian methods. The genotyping-by-sequencing method was used to construct the libraries, and 29,748 SNPs were subsequently found in the genome of Larimichthys crocea . A total of six different SNPs, located on LG3, LG6, LG8, and LG16, were determined to be significantly associated with the GSI. Among them, only two SNPs were found by both GWAS methods. By integrating the results of two GWAS methods with the biological functions of the genes, six candidate genes (viz., FZD3 , DDX4 , EDC3 , CITED3 , SOX9-b, and LOC106602108 ) were revealed to be associated with the GSI in the large yellow croaker. These functional genes are involved in gonadal development or gonadogenesis, providing the basis for further study on genetic mechanisms and marker-assisted selection in this fish species. In this study, we found that the combination of single marker analysis and Bayesian methods could identify more SNP loci associated with the phenotypes. Thus, we suggest performing these two methods simultaneously in GWAS.

Special issue Vectors of change in the marine environment.-- 11 pages, 7 figures, 1 table, supplementary data https://doi.org/10.1016/j.ecss.2016.01.002, Investigations on sexual reproduction of jellyfish are essential to understanding mechanisms and patterns of outbreaks formation. Pelagia noctiluca (Forskål, 1775) (Scyphozoa) is known as the predominant jellyfish species with direct development in Western and Central Mediterranean Sea. In this paper we used integrated morphometric, histological, and biochemical approaches to investigate the annual reproductive biology of P. noctiluca from the Strait of Messina (South Thyrrenian Sea), a key proliferation area for this species due to favourable temperatures and high productivity. From November 2011 to September 2012, P. noctiluca sexual reproduction occurred throughout the year, with two seasonal peaks (autumn, spring) of spawning and embryonic development. Gonads of female P. noctiluca were characterized by a large amount of mature eggs of small size (diameter < 200 μm) during high food availability, whereas fewer, larger eggs (diameter > 200 μm) were detected during low availability of prey. Two morphometric indexes were applied: the Gonad-Somatic Index (GSI, gonadal/somatic tissue dry weight ratio) and Fecundity Index (FI, n° eggs mm−2 * gonadal dry weight). The FI showed longer spawning periods than the GSI, providing a better causal-mechanistic explanation for the year-round occurrence of P. noctiluca in the Strait of Messina. Protein contents of the gonads changed seasonally, with the highest concentrations during the pre-spawning periods. We suggest that investigations on jellyfish sexual reproduction can provide biological information relevant for understanding mechanisms of jellyfish blooms as well as for the management of coastal zones affected by outbreaks of gelatinous species, The research leading to these results received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under Grant Agreement No. 266445 for the project Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors (VECTORS – http://www.marine-vectors.eu)

The objective of this study was to evaluate the effect of dietary supplementation with vitamin C (0, 261, 599 and 942 mg/kg diet, analyzed values) (ascorbyl monophosphate) on reproductive efficiency and egg and larvae quality of Nile tilapia ( Oreochromis niloticus ) through morphometric measurements, air exposure tests of newly hatched larvae (40 and 50 min), and incubation of larvae during the lecithotrophic period in different salinities (0 to 6 g of salt/L). A higher gonadosomatic index and greater egg weight and larval measurements were found for 599 and 942 mg vitamin C/kg diets. The hepatosomatic index and total and relative fecundity were highest for females receiving a 599 mg vitamin C/kg diet. The lowest values for egg diameters (largest and smallest) and morphometric measurements of larvae at 120 h after hatching were observed for those from females fed a diet without vitamin C. Increased hatching rate and egg and larvae production per female were directly related to increasing levels of vitamin C. Haematocrit, erythrocytes, leukocytes and total plasma protein were lower in females that did not receive vitamin C. The lowest glucose concentrations were detected after the reproductive period with the 942 mg vitamin C/kg diet, while the highest concentrations were observed with the 0 mg vitamin C/kg diet. When eggs were incubated at different salinities, the lowest survival rate occurred with the 0 mg vitamin C/kg diet at the end of 120 h of incubation. In the tests of exposure to air for 40 and 50 min, the resistance to stress by newly hatched larvae was greatest for those individuals from females receiving the 942 mg vitamin C/kg diet, intermediate with the 599 mg vitamin C/kg diet and lowest with the 0 and 261 mg vitamin C/kg diets. It was concluded that the addition of a minimum 599 vitamin C/kg to the diet optimized reproductive parameters, blood variables and quality of eggs and larvae of Nile tilapia.

The common snook, Centropomus undecimalis, is an emerging species for intensive fish culture, however, some reproductive aspects of this species, especially the development of the testes and the action of androgen hormones on spermatogenesis have not been studied. The objective of this study was to evaluate the effects of 17α-methyltestosterone (MT) on spermatogenesis and steroidogenesis during the first sexual maturation of the common snook. The fish, which were reproduced in captivity, had a body weight of 305.80 ± 35.60 g and a total length of 34,11 ± 1,08 cm. We used ethylene-vinyl-acetate (EVAc) implants with four concentrations of the hormone MT: T1 (0.3 mg/kg); T2 (3.0 mg/kg); T3 (15.0 mg/kg) and T4 (30.0 mg/kg), and a control group that did not receive the hormone. The gonads increased (P

Sufficient, clean and secure energy is the main driver for a worldwide growing welfare and economic development of a society. Environmental concerns on the expansion of offshore renewable energy and its impact on marine organisms need to be scientifically assessed for risks and consequences. In order to observe the effects of an operating wind farm on fish, we studied the rather stationary and benthic-living fish species viviparous eelpout (Zoarces viviparous) as model indicator organisms. We compared local populations of viviparous eelpout in the Lillgrund Offshore Wind Farm (OWF) with natural sites in the Oresund strait in Sweden. Eelpout studies on population dynamics, biometrics, reproductive success and fry development were conducted in 2011 and 2012. Condition index, histosomatic index, gonadosomatic index were measured additionally. Our findings showed that Lillgrund OWF neither had an impact on the condition index (CI), nor on brood development of female viviparous eelpout. Furthermore, populations size estimates in Lillgrund indicated that eelpout neither specifically aggregated in nor avoided the offshore wind farm, and no clear reef effect attracting eelpout to the foundations and scour protections of the OWF was observed. Our conclusion is that the operating wind farm did not have any potentially negative effects, since we did not observe any negative effects neither on the individual health of eelpout nor of the reproductive performance. We suggest that eelpout which may also be used as an indicator species for the environmental status of Lillgrund, as well as for other offshore wind farms and marine renewable energy installations, both in the Baltic and coastal waters in northern Europe.

Made available in DSpace on 2018-12-11T17:16:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Tebuthiuron is a phenylurea herbicide widely used in agriculture that can reach the aquatic environments, possibly posing negative effects to the aquatic biota. Phenylurea herbicides, such as diuron, are known to cause estrogenic and anti-androgenic effects in fish, but no such effects were yet reported for tebuthiuron exposure. Thus, the aim of this study was to evaluate if tebuthiuron, at environmentally relevant concentrations (100 and 200 ng/L) and after 25 days of exposure have estrogenic and/or anti-androgenic effects on male of Nile tilapia (Oreochromis niloticus), through the evaluation of plasmatic testosterone (T) and estradiol (E2) levels, brain aromatase (CYP19) levels (western-blot), and by evaluating the histology of the testicles. When compared to the control group, plasmatic T levels decreased about 76% in the animals exposed to 200 ng/L of tebuthiuron, while E2 levels increased about 94%, which could be related to a significant increase (77%) in CYP19A1 levels, an enzyme that catalyzes the conversion of androgens into estrogens. Histological analyses of the testicles also demonstrated that tebuthiuron at both tested concentrations caused a decrease in the diameter of the seminiferous tubules and in the diameter of the lumen. Therefore, the gonadosomatic index (GSI) was reduced by 36% % in the animals exposed 200 ng/L to tebuthiuron. Indeed, the relative frequency of spermatocytes and spermatids increased respectively 73% (200 ng/L) and 61% (100 ng/L) in the tebuthiuron exposed animals, possibly due to the impairment of sperm release into the lumen, that was decreased 93% (200 ng/L) in the treated animals compared to the control. These results confirm that tebuthiuron causes estrogenic and anti-androgenic effects in Nile tilapias at environmentally relevant concentrations. Department of Chemistry and Environmental Science Universidade Estadual Paulista (IBILCE/UNESP), Rua Critóvão Colombo, 2265 Rio Preto Universitary Center UNIRP, Rua Ivete Gabriel Atique, 45 Medical School of São José do Rio Preto FACERES, Av. Anísio Haddad 6751 Department of Aquaculture Universidade Estadual Paulista (CAUNESP), Via de Acesso Prof. Paulo Donato Castelane, s/n. Department of Natural Sciences Fundação Universidade Regional de Blumenau FURB, Av. Antonio da Veiga 140, Itoupava Seca Department of Chemistry and Environmental Science Universidade Estadual Paulista (IBILCE/UNESP), Rua Critóvão Colombo, 2265 Department of Aquaculture Universidade Estadual Paulista (CAUNESP), Via de Acesso Prof. Paulo Donato Castelane, s/n. CNPq: 401884/2012-0

The current study was carried out to study the effect of zinc oxide (ZnO) supported on kaolinite (ZnO-K) on biological parameters, reproduction indices, semen quality, lipid profile and oxidative biomarkers for broodstock of Nile tilapia. Four tested diets were formulated; Diet 1 was control diet without addition. Diet 2, Diet 3 Diet 4 were supplemented with 30, 60 and 90 mg ZnO-K kg−1, respectively. Sixty females with average weight of 135.19 ± 3.91 g and twenty-four males with average weight of 212.51 ± 13.4 g of Nile tilapia (Oreochromis niloticus) were used. All broodstock fish were hand fed experimental diets up to apparent satiation three times daily (9:00, 12.00 and 14.00) for 4 weeks before mating. The highest hepatosomatic index (HSI %) and gonadosomatic index (GSI %) (P