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Industrial and municipal effluents regularly pollute water bodies and cause various toxic effects to aquatic life. Because of the diverse nature of industrial processes and domestic products, urban effluents are often tainted with various anthropogenic endocrine disrupting chemicals that may interfere with the reproductive physiology of aquatic fauna. In this study, we tested effluents from the City of Bulawayo for the presence of estrogenic endocrine disrupting chemicals and their effects on fish gonads and fecundity. Effluents were collected from two sewage treatment plants (STPs), which receive largest volume of industrial effluents from the City, and from a textile factory. Male and female zebrafish (Danio rerio) were exposed to effluents and analyzed for vitellogenin induction, gonad alterations, and fertility. Male zebrafish exposed to effluent from Thorngrove STP had significantly higher (p ≤ 0.05) vitellogenin compared to control. Textile effluent caused adverse gonad alterations such as oocyte atresia (females) and increased proportion of spermatogonia (males) which could lead to reduced fertility. Textile effluent (5% v/v) and Thorngrove effluent also caused a decline in fertilization success of breeding groups of zebrafish. The results of this study show the potential effects of effluent pollution and the occurrence of EDCs in developing countries. This underscores the need to effectively prevent pollution of environmental water bodies from industrial and municipal sewage treatment plant effluents. We recommend a follow-up study to monitor the effects of the effluents on feral fish in effluent polluted downstream dams of Bulawayo., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Fecundity is an important parameter in fisheries that predicts the reproductive capability of fish stock. Information on the fecundity of Common carp is helpful in estimating the amount of offspring produced in spawning season, which is essential for the stock assessment of the species. Assessment of the fecundity of a fish is essential for evaluating the commercial potentialities of its stock, life history, practical culture and actual management of the fishery. Common carp is a commercially important fish which has the potential to meet the demand of food in the country. Scanty of data is available on fecundity parameter of common carp in Kashmir waters. Therefore, this research work aims to estimate the fecundity of Common carp collected from the Dal lake of Kashmir. Methods: The present study aims to estimate the fecundity of Common carp, [Cyprinus carpio var. communis] existing in Dal Lake, Kashmir. The 30 fish samples were collected once every month from the month of January 2018 to December 2018. Fishes were brought to Fisheries Resource Management (FRM), Faculty of Fisheries, SKUAST-K Laboratory for the estimation of total length, weight of fishes and weight of ovaries. Gravimetric and actual counting method was used for the estimation of fecundity. Result: It was observed that the number of eggs varied from 16650 (for a fish with total length 180mm and total weight 120 g) to 129000 (for a fish with total length 430 mm and total weight 1300 g. The mean absolute fecundity was recorded as 68864.07±6563.59 for a fish with a mean total length of 301.43±13.93 mm and mean total weight of 435.1±66.51 g. The relative fecundity ranged from 99.2-240.8 and the mean relative fecundity was 185.96. Significant positive correlation was found between fish weight and absolute fecundity. (r= 0.907, p<0.01), fish length and absolute fecundity (r= 0.976, p<0.01), Ovary weight and absolute fecundity (r= 0.998, p<0.01). Relative fecundity showed a significant negative correlation with weight, length and absolute fecundity (r= -0.747, p<0.01; r= -0.419, p<0.05 and r= -0.460, p<0.05 respectively. [ABSTRACT FROM AUTHOR]

Climbing perch Anabas testudineus is a freshwater fish that has economic value and has been cultivated in Indonesia. However, the fish farmers face problems with high-quality larvae supply because the breeding technology for this species is not well developed. Sperm and oocyte storage technology is important information in fish breeding. Therefore, this research aims to determine the best storage temperature using the dry storage method. Six levels of storage temperatures were tested in this study, namely: 29°C (room temperature as a control), 8°C, 4°C, 0°C, - 4°C, and -8°C. The oocytes are stored at the treatment temperature for 120 minutes, where every 30 minutes the quality of the oocytes is analyzed based on fertilization and hatchability parameters. The results showed that storage temperature had a significant effect on fertility (P<0.05) but had no significant effect on hatchability or the normality of larvae (P>0.05). The highest percentage of fertility was obtained in treatment B (8°C) at 30 minutes, with a value of 50.33%; this value was significantly different with other treatments. The highest hatchability percentage value was also obtained in treatment B (8°C) at 30 minutes, with a value of 12%. This value was significantly different in treatments E (-4°C) and F (-8°C), but not significantly different with treatments A (29°C), C (4°C), and D (0°C) (P > 0.05). The direct observations on the normality of the hatched larvae showed that all larvae had a normal morphology. In general, fertility and hatchability rate decrease with decreasing temperatures. Therefore, it is concluded that climbing perch fish eggs stored using the dry method can only be stored for less than 30 minutes, where the recommended temperature was 8°C. [ABSTRACT FROM AUTHOR]

Hoplias intermedius, of the Characiformes order and Erytrinidae family, is widely distributed across South America. This commercially interesting species can reach a length of 100 cm and a weight of 15–20 kg. To evaluate the reproductive biology of H. intermedius in the São Francisco River, Brazil, 154 males and 190 females were captured bi‐monthly between September 2018 and August 2019 from the downstream regions of the Três Marias dam. Gillnets with differently sized meshes were deployed at distances of 34–54 km after the confluence with the Abaeté River (18°00′49″ S, 45°10′51″ W). Biometric data, gonadosomatic index (GSI), Fulton condition factor (K) and absolute fecundity (AF) were determined for each specimen. Gonad maturation stages and the spawning season were also established. The biometric data, GSI and K average values were relatively higher in females than in males. The reproductive peak for both sexes was reached around January/February. The mean AF was 4300.5 ± 1451.2 follicles per female. Fully developed vitellogenic follicles had a mean diameter of 1014.8 ± 250.7 μm, which is characteristic of fish with moderate fecundity. Fish of all maturation stages, from mature, spawned and spermed, occurred in all bimesters, indicating that this species reproduced throughout the year. The high frequency of spawning females throughout the year and the histological characteristics of spawned ovaries indicated that trairão H. intermedius' spawning type is partial. [ABSTRACT FROM AUTHOR]

Background: Steroid hormones play an essential role in many reproductive processes of vertebrates. Previous studies revealed that teleost-specific Cyp17a2 (cytochrome P450 family 17 subfamily a 2) might be required for the production of cortisol in the head-kidney and 17a,20b-dihydroxy-4-pregnen-3-one (DHP) in ovary during oocyte maturation. However, the role of Cyp17a2 in male reproduction remains to be largely unknown. The aim of this study was to explore the essentiality of cyp17a2 gene in male steroidogenesis, spermatogenesis, and male fertility. Methods: A homozygous mutation line of cyp17a2 gene was constructed in tilapia by CRISPR/Cas9 gene editing technology. The expression level of germ cell and meiosis-related genes and steroidogenic enzymes were detected by qRT-PCR, IHC, and Western blotting. EIA and LC-MS/MS assays were used to measure the steroid production levels. And sperm quality was examined by Sperm Quality Analyzer software. Results: In this study, cyp17a2 gene mutation resulted in the significant decline of serum DHP and cortisol levels. On the contrary, significant increases in intermediate products of cortisol and DHP were found in cyp17a2-/- male fish. The deficiency of cyp17a2 led to the arrest of meiotic initiation in male fish revealing as the reduction of the expression of germ cell-related genes (vasa, piwil, oct4) and meiosis-related genes (spo11 and sycp3) by 90 dah. Afterwards, spermatogenesis was gradually recovered with the development of testis in cyp17a2-/- males, but it showed a lower sperm motility and reduced fertility compared to cyp17a2+/+ XY fish. Deletion of cyp17a2 led to the abnormal upregulation of steroidogenic enzymes for cortisol production in the headkidney. Moreover, unaltered serum androgens and estrogens, as well as unchanged related steroidogenic enzymes were found in the testis of cyp17a2-/- male fish. Conclusion: This study proved that, for the fist time, Cyp17a2 is indispensable for cortisol and DHP production, and cyp17a2 deficiency associated curtailed meiotic initiation and subfertility suggesting the essentiality of DHP and cortisol in the male fertility of fish. [ABSTRACT FROM AUTHOR]

In mice, CD9 expression on the egg is required for efficient sperm-egg fusion and no effects on ovulation or male fertility are observed in CD9 null animals. Here we show that cd9b knockout zebrafish also appear to have fertility defects. In contrast to mice, fewer eggs were laid by cd9b knockout zebrafish pairs and, of the eggs laid, a lower percentage were fertilised. These effects could not be linked to primordial germ cell numbers or migration as these were not altered in the cd9b mutants. The decrease in egg numbers could be rescued by exchanging either cd9b knockout partner, male or female, for a wildtype partner. However, the fertilisation defect was only rescued by crossing a cd9b knockout female with a wildtype male. To exclude effects of mating behaviour we analysed clutch size and fertilisation using in vitro fertilisation techniques. Number of eggs and fertilisation rates were significantly reduced in the cd9b mutants suggesting the fertility defects are not solely due to courtship behaviours. Our results indicate that CD9 plays a more complex role in fish fertility than in mammals, with effects in both males and females. [ABSTRACT FROM AUTHOR]

Aspects of the reproductive biology of Atlantic chub mackerel Scomber colias are reported here based on data from random samples of artisanal fish landings from Ghana. The specimens were between 13.7 cm and 40.7 cm total length (TL), and both sexes matured at a mean length (Lm50) of approximately 25 cm TL. An overall sex ratio of 1:1 was estimated for the population. Absolute fecundity of the fish ranged between 10 220 and 155 791 eggs (mean 48 238 [SE 2 324] eggs) in individuals measuring between 22.8 and 36.5 cm TL and weighing 104.3 to 525.3 g. Monthly variations in the gonadosomatic index and the proportion of fish with ripe gonads in the samples indicated the occurrence of spawning activities during two periods, March–April and June–August, the latter period of which coincided with the coastal upwelling season in Ghanaian waters. These findings are compared with those for chub mackerel from the northwestern and southwestern coasts of Africa. The results of this study will help inform the management of this small pelagic species in Ghana. [ABSTRACT FROM AUTHOR]

Background: Parastromateus niger, is one of the important fish species from economic point of view in Gwadar, Balochistan-Pakistan. This study was carried out to determine the growth and fecundity of Parastromateus niger. Methods: Growth of P. niger was determined by applying Le Cren formula while mean fecundity and relative fecundity of this fish was calculated by using equation of Yelden and Avsar. Result: Relationship between fish weight and ovary weight was found as 0.384 and 0.898 respectively in 1st and 2nd year of research. Annual mean fecundity of P. niger was calculated as 43165.4 eggs with relative fecundity of 73.7 in 2017-18 and annual mean fecundity in 2018-19 was 39759.5 eggs with 50.2 relative fecundity. Value of R2 in first year of research between fecundity and ovary weight was 0.751, for mean fecundity and relative fecundity was 0.545, in term of fecundity and total length of fish was 0.60 and for fish total weight and fecundity was 0.596. Value of R2 between fecundity and weight of ovary was 0.951, with mean fecundity and relative fecundity as 0.968, between fish fecundity and total length was 0.578 and in case of fecundity and total body weight was found 0.809 in second year of research period. [ABSTRACT FROM AUTHOR]

This present study provides an overview of the reproductive traits, including ovarian development, spawning season, size at maturity (Lm), and fecundity of Acentrogobius viridipunctatus - a high economic value fish in the Vietnamese Mekong Delta (VMD). A total of 432 females were collected using trawl nets from January to December 2020 at four sites, including Long Huu-Tra Vinh (LHTV), Trung Binh-Soc Trang (TBST), Dien Hai-Bac Lieu (DHBL), and Tan Thuan-Ca Mau (TTCM). The ovarian diameter was seen to increase from 2.09 (stage I) to 6.57 mm (stage V). Histological analysis showed that the goby was a multi-spawner due to the different oocyte stages found in stages IV and V of ovaries. It can release eggs all year-round due to the monthly appearance of ovarian stages IV and V during the study period, with the main peak in the 2-4 months of the wet season noted with the highest value of gonadosomatic index at that time. The Lm increased from 6.6 cm at TBST to 9.4 cm at TTCM. This species displayed relatively high fecundity, ranging from 5,481 to 130,683 eggs/female. The average fecundity of this fish was 27,698 ± 7,983 eggs/female at LHTV, 46,592 ± 7,264 eggs/female at TBST, 23,271 ± 4,985 eggs/female at DHBL, and 31,408 ± 2,515 eggs/female at TTCM. Egg diameter ranged from 0.45 ± 0.01 at DHBL to 0.50 ± 0.01 at TBST. For sustainable exploitation, local governments should ask the fishers to avoid catching fish during the main spawning period, and the fish length at first capture should be >Lm. [ABSTRACT FROM AUTHOR]

Steroidogenic acute regulatory protein (Star) plays an essential role in the biosynthesis of corticosteroids and sex steroids by mediating the transport of cholesterol from the outer to the inner membrane of mitochondria. Two duplicated Star genes, namely star1 and star2 , have been identified in non-mammalian vertebrates. To investigate the roles of star genes in fish steriodogenesis, we generated two mutation lines of star1 −/− and star1 −/− /star2 −/− in Nile tilapia (Oreochromis niloticus). Previous studies revealed that deficiency of star2 gene caused delayed spermatogenesis, sperm apoptosis and sterility in male tilapia. Our present data revealed that mutation of star genes impaired male fertility. Disordered seminiferous lobules and spermatic duct obstruction were found in the testis of both types of mutants. Moreover, significant decline in semen volume, sperm abnormality and impaired fertility were also detected in star1 −/− and star1 −/− /star2 −/− males. In star1 −/− male fish, lipid accumulation, up-regulation of steroidogenic enzymes, and significant decline of androgens were found. Additionally, hyperplasic interrenal cells, elevated steroidogenic gene expression level and decline of serum glucocorticoids were detected in star1 mutants. Intriguingly, either 11-KT or cortisol supplementation successfully rescued the impaired fertility of the star1 −/− mutants. Taken together, these results further indicate that Star1 might play critical roles in the production of both 11-KT and glucocorticoids, which are indispensable for the maintenance of male fertility in fish. [Display omitted] • Star1 plays critical roles in androgen and glucocorticoids synthesis in tilapia. • Star1 and star1 / star2 gene mutation impaired male fertility in tilapia. • 11-keto-testosterone and cortisol can restore male fertility in star1 mutant tilapia. [ABSTRACT FROM AUTHOR]

• The RNA-seq results revealed the overall changes of genes related to circadian rhythm and disease-linked signaling pathways. • The deficiency of Rln3a resulted in up-regulation of GnRH1 and kisspeptin 2 in the brain. • Mutation of Rln3a led to the alteration serum dopamine level and its synthase in hypothalamus. Relaxin3 (rln3) has been associated with various emotional and cognitive processes, including stress, anxiety, learning, memory, motivational behavior, and circadian rhythm. Notably, previous report revealed that Rln3a played an indispensable role in testicular development and male fertility in Nile tilapia (Oreochromis niloticus). However, the underlying molecular mechanisms remain largely unknown. We found that Rln3a is expressed exclusively in the diencephalon* (Di*) of the brain. Deficiency of Rln3a resulted in a significant increase in serum dopamine level and an upregulation of gene expression of gnrh1 and kisspeptin2. To further elucidate the role of Rln3a in fish fertility, we collected two different regions of Di* and hypothalamus (Hyp) tissues for subsequent RNA-seq analysis of both wild-type (rln3a +/+) and rln3a -/- male tilapia. Upon the transcriptomic data, 1136 and 755 differentially expressed genes (DEGs) were identified in the Di* and Hyp tissues, respectively. In Di*, the up-regulated genes were enriched in circadian rhythm, chemical carcinogenesis, while the down-regulated genes were enriched in type II diabetes mellitus, dopaminergic synapse, and other pathways. In Hyp, the up-regulated genes were enriched in circadian rhythm, pyrimidine metabolism, while the down-regulated genes were enriched in type I diabetes mellitus, autoimmune thyroid disease, and other pathways. Subsequently, the results of both qRT-PCR and FISH assays highlighted a pronounced up-regulation of core circadian rhythm genes, cry1b and per3 , whereas genes such as clocka , clockb , and arntl exhibited down-regulation. Furthermore, the genes associated with dopamine biosynthesis were significantly increased in the Hyp. In summary, the mutation of rln3a in male tilapia resulted in notable changes in circadian rhythm and disease-linked signaling pathways in the Di* and Hyp. These changes might account for the fertility defects observed in rln3a -/- male mutants in tilapia. [ABSTRACT FROM AUTHOR]

Populations of Periophthalmus chrysospilos, the Gold‐spotted mudskipper, within the Mekong Delta are facing extirpation risks due to indiscriminate harvesting for the growing aquarium and food‐fish trade. This study provides some of the first information on reproductive ecology—such as spawning type and season, length at first maturity, and batch fecundity—of this species, to be used in their management. The sex ratio of wild populations, based on 1031 individuals (523 males and 508 females) is 1:1. The gonadosomatic index (GSI) values are exhibit a non‐normal distribution and changed with gender, season, and site. A combination of GSIs and the monthly appearance of mature gonads suggest that this species reproduces throughout the year, with peak from July to October. This species exhibits sexual and spatial variation in size at first maturity (Lm) as Lm is 6.2–8.6 cm in males and 6.4–7.3 cm in females. The batch fecundity (F = 2614 to 23,465 eggs/female) exhibits non‐normal distribution and varies with site, with the highest values at Dam Doi, Ca Mau (13,336 ± 1,279 SE) and the lowest at Tran De, Soc Trang (6654 ± 851 SE). In addition, batch fecundity is directly proportional to body size due to high determination relationships between batch fecundity and fish size (r2 > 0.64 for all cases). Information derived on the reproductive biology of this species can inform its conservation, sustainable exploitation, and ex situ propagation. [ABSTRACT FROM AUTHOR]

Chromosomal ploidy manipulation is one of the means to create excellent germplasm. Triploid fish could provide an ideal sterile model for searching of a underlying mechanism of abnormality in meiosis. The complete understanding of the coding and noncoding RNAs regulating sterility caused by meiosis abnormality is still not well understood. By high-throughput sequencing, we compared the expression profiles of gonadal mRNA, long non-coding RNA (lncRNA), and microRNA (miRNA) at three different developmental stages between the diploid (XX) and triploid (XXX) female rainbow trout. These stages were gonads before differentiation (65 days post fertilisation, dpf), at the beginning of morphological differences (180 dpf) and showing clear difference between diploids and triploids (600 dpf), respectively. A majority of differentially expressed (DE) RNAs were identified, and 22 DE mRNAs related to oocyte meiosis and homologous recombination were characterized. The predicted miRNA-mRNA/lncRNA networks of 3 developmental stages were constructed based on the target pairs of DE lncRNA-miRNA and DE mRNA-miRNA. According to the networks, meiosis-related gene of ccne1 was targeted by dre-miR-15a-5p_R + 1, and 6 targeted DE lncRNAs were identified. Also, qRT-PCR was performed to validate the credibility of the network. Overall, this study explored the potential interplay between coding and noncoding RNAs during the gonadal development of polyploid fish. The mRNA, lncRNA and miRNA screened in this study may be helpful to identify the functional elements regulating fertility of rainbow trout, which may provide reference for character improvement in aquaculture. • miRNA-mRNA/lncRNA interaction networks of gonadal development in triploid fishes. • 22 genes were related to oocyte meiosis and homologous recombination. • 6 lncRNAs regulate meiosis as the target of miR-15a-5p. • Polyploidy-associated effects on fertility of fish. [ABSTRACT FROM AUTHOR]

Capoeta aculeata (Valenciennes, 1844) is native to Iran and little is known about its biology. Some biological characteristics of this species were examined in 120 male and 257 female specimens collected monthly from the Gizehrud River of Lorestan Province (Tigris basin, Iran) during July 2014-June 2015. The maximum age of the specimens, based on scale reading, was 6+ years for both males and females. The most frequent age group was 4+ in both sexes. Fork length ranged from 12.2 to 20.8 cm (17.4±1.2SD) and weight ranged between 32-188 g (93.6±21.8SD). Sex ratio was 1M:2.1F. Based on macroscopic gonad observation, maturation cycle consisted of four stages: Developing, spawning, regressing and regeneration phases. The GSI index indicated that reproduction of C. aculeata in Gizehrud occurred between April and May, with the highest value average of 6.37 for males and 11.91 for females in May. Oocyte diameters ranged from 0.57 to 1.88 mm, with a mean value of 0.87 mm. Absolute fecundity ranged between 3000 and 19500 (8300±3400) eggs. Absolute fecundity and fish size (fork length and total weight) were moderately correlated. Relative fecundity varied from 50 to 140 (80±20) eggs per gram of total body weight. This fish is a synchronous spawner. [ABSTRACT FROM AUTHOR]

A new fish species, alien to Armenia, was discovered in the surroundings of Areni in the Arpa River. Based on the comparison of morphological characteristics, this species status was determined as a sharpbelly Hemiculter leucisculus. The morphological characteristics, characteristics of reproduction and fertility of this fish in new habitats have been studied. It is assumed that the sharpbelly could penetrate into the River Arpa from River Araks, where it had been noted earlier. Considering the ecological flexibility and high fertility of the sharpbelly, it is feasible to inhabit other freshwaters of Armenia soon. [ABSTRACT FROM AUTHOR]

The exterior and fecundity of Baikal omul (Coregonus migratorius, G.) of the pelagic morpho-ecological group have been studied. A comparative analysis has been made, which has shown that in the studied gild, the filtering apparatus develops better, and the average weight, the commercial length, the median length, the maximum body depth, and the absolute individual fecundity increase. The average median length of the specimens, regardless of their sex, has been 384 ± 2 mm, with an average weight of 623 ± 10 g; with that, the females have had a length of 388 ± 2 mm and a weight of 660 ± 12 g, the males -- 379 ± 4 mm and 560 ± 15 g, respectively. It has been noted that with age, some relative traits decrease. A veracious increase in the length and weight of the fish is observed. It has been found that fecundity increases with age. The absolute fecundity has been 21, 061 ± 656 eggs. [ABSTRACT FROM AUTHOR]

Fecundity of fish is influenced by several factors, including body length, condition, population density, and environmental conditions. It follows that fecundity of fish populations can exhibit spatiotemporal variability; thus, periodic quantification of length–fecundity relationships is important for management. We hypothesized that average fecundity of Cisco Coregonus artedi in the upper Laurentian Great Lakes would be lower in Lake Superior than in Lakes Huron and Michigan. The trophic status of these lakes recently converged, but Lakes Huron and Michigan currently support lower Cisco densities; thus, we expected that they would reach larger sizes and have greater fecundity owing to lower intraspecific competition. Ovaries were collected from prespawn Cisco during 2008–2010 to test this hypothesis. We also compared length–fecundity relationships for 2008–2010 to those of precollapse (1930s–1950s) populations to explore how relationships have changed. Average fecundity of Cisco during 2008–2010 was lower in Lake Superior compared to Lakes Huron and Michigan; length–fecundity relationships in the latter two lakes did not vary significantly, so they were combined. Body condition was highest in Lakes Huron and Michigan. We used otoliths to determine age and found that body condition was domed shaped with respect to age in Lakes Huron and Superior. There were no females older than age 5 in our samples from Lake Michigan because that population was just beginning to recover from very low levels. Females of intermediate age had the highest fecundities in both Lake Huron (ages 7–13) and Lake Superior (ages 8–18). We hypothesize that differences in body morphometry may also influence fecundity, with deeper‐bodied C. artedi albus, the predominant form in Lakes Michigan and Huron, having greater fecundity than shallower‐bodied C. artedi artedi in Lake Superior. Moreover, varying Cisco diets and seasonal movement patterns across lakes may have also contributed to differences. Females in Lakes Superior and Michigan are currently more fecund than their precollapse counterparts. [ABSTRACT FROM AUTHOR]

To investigate the variability in the reproductive tactics of Acıgöl killifish (Aphanius transgrediens), one of the most seriously threatened freshwater teleost species, this study compared its reproductive ecology in two contrasting habitats that differ substantially in terms of stability of environmental parameters, particularly salinity regime (stable vs. unstable). Fish were sampled monthly from October 2013 to September 2014 with the aim of testing whether the reproductive life‐history response of fish to stable and unstable conditions differed. The reproductive effort (gonad weight) of both sexes did not differ significantly between the two habitats, but females in the unstable habitat had significantly lower fecundity and larger eggs. The relationship between fecundity and fish size was stronger in the stable habitat, whereas the relationship was quite variable and uncertain in the unstable habitat. Fish born in the unstable habitat reached their first maturity at a smaller size than those in the stable habitat. The gonado‐somatic index and the duration of hydrated eggs showed that reproduction continued from February to May in both habitats; nonetheless, a second spawning event occurred during July and August in the unstable habitat, which included the reproductive contributions of YOY individuals and older generations. This study's results suggest that A. transgrediens employs varying reproductive strategies against environmental instability in its restricted unique range. This may have further implications for the ways in which habitat‐specific conservation methods are used. [ABSTRACT FROM AUTHOR]

Intra-and interannual variability of fecundity and egg size of lumpfish (Cyclopterus lumpus) were assessed for 2009 and for 2014-2019 and compared with fecundity estimates from 1967 and 1969. Downregulation of fecundity was apparent throughout ovary development, but the intensity was reduced close to spawning. The fecundity of fish spawning later in the year was higher than that of fish that spawned earlier. Carcass weight was a better predictor of fecundity than length. The model was improved through the addition of liver weight, but this led to an increase of <1.0% in the explained variance in fecundity. Variation in fecundity between the periods studied (2009 and 2014-2019) was low; however, fecundity in these study periods was higher than in 1967 and lower than in 1969. Whether these differences were due to differences in methods could not be ruled out. Average egg diameter was positively correlated with fish size and decreased from the first to the second batch, and only limited variation between years was observed in this characteristic. [ABSTRACT FROM AUTHOR]

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. • The process of oocyte recruitment has rarely been examined in detail in a quantitative manner within the spawning cycle. • Oocyte recruitment occurred in a stepwise manner within the spawning cycle in an indeterminate batch spawning fish. • Spawning of the advanced batch and oocyte recruitment were synchronized, keeping the ovary in a state of dynamic equilibrium. [ABSTRACT FROM AUTHOR]

Variation in the degree of sexual size dimorphism (SSD) among taxa is generally considered to arise from differences in the relative intensity of male–male competition and fecundity selection. One might predict, therefore, that SSD will vary systematically with (1) the intensity of sexual selection for increased male size, and (2) the intensity of fecundity selection for increased female size. To test these two fundamental hypotheses, we conducted a phylogenetic comparative analysis of SSD in fish. Specifically, using records of body length at first sexual maturity from FishBase, we quantified variation in the magnitude and direction of SSD in more than 600 diverse freshwater and marine fish species, from sticklebacks to sharks. Although female-biased SSD was common, and thought to be driven primarily by fecundity selection, variation in SSD was not dependent on either the allometric scaling of reproductive energy output or fecundity in female fish. Instead, systematic patterns based on habitat and life-history characteristics associated with varying degrees of male–male competition and paternal care strongly suggest that adaptive variation in SSD is driven by the intensity of sexual selection for increased male size. [ABSTRACT FROM AUTHOR]

Hybrid catfish (female Channel Catfish Ictalurus punctatus × male Blue Catfish I. furcatus) fry are produced by hormone‐induced spawning of Channel Catfish in hatcheries. Anesthetics are used routinely to reduce handling stress by limiting the activation of the hypothalamic–pituitary–interrenal axis hormones. As a comparison, the present study determined the efficacy of electrosedation using a portable electrosedation system (PES) and its feasibility for possible application in hybrid catfish hatcheries. The PES was evaluated at 100 V and a 25% duty cycle at 30, 60, 90, or 100 Hz to anesthetize mature Channel Catfish to stage IV of sedation. The PES was compared to the chemical sedatives tricaine methanesulfonate (MS‐222; 200 mg/L) and metomidate hydrochloride (Aquacalm; 6 mg/L). The PES at 30 Hz anesthetized Channel Catfish in 4 s, significantly faster than the 120 s needed for MS‐222. However, the mean (±SE) time to recover from anesthesia and mean plasma cortisol response were similar (P > 0.05) with MS‐222 (104 ± 9 s; 35 ng/mL) and the PES (119 ± 15 s; 32 ng/mL). Relative fecundity of fish sedated by the PES and MS‐222 averaged 5,222 and 5,593 eggs/kg of body weight (BW), respectively; percent hatch averaged 46.9% and 50.4%, respectively; and hybrid catfish fry production averaged 1,644 and 1,711 fry/kg BW, respectively. Relative fecundity, percent hatch, and hybrid fry production were not significantly different between the PES and MS‐222 groups (P > 0.05). No internal injuries were noted in any of the fish subjected to electrosedation. The PES at 30 Hz effectively anesthetized female Channel Catfish with a quicker induction time, provided moderate time to recover from anesthesia, and elicited a cortisol response, with no known internal injuries. The results suggest that the PES has the potential to replace MS‐222 usage in hybrid catfish hatcheries. The PES is environmentally safe, does not expire or degrade, and requires no disposal or withdrawal period. [ABSTRACT FROM AUTHOR]

The gonadosomatic index (GSI) and fecundity of the threatened Cirrhinus reba (Hamilton) was studied over a period of one year from January to December 2015 in the Ganges River (northwest Bangladesh). The GSI index indicated that the C. reba breeding season in the Ganges was from June to September with the peak in August. Fish fecundity increased with increasing fish length and weight, and the highest fecundity (265,042.23) was recorded in a fish with a total length, a body weight, and an ovary weight of 23.80 cm, 136.00 g and 45.00 g, respectively. There was a linear relationship between fecundity and total length (r = 0.871), body weight (r = 0.872), and ovary weight (r = 0.879), with that between ovary weight and fecundity being the strongest. [ABSTRACT FROM AUTHOR]

Abstract The reproductive performance of farmed Arctic charr exhibits substantial individual variation. The causes behind this variation have not yet been properly explained, despite the species relatively long history in aquaculture. The aim of the present study was to provide better understanding of the issue by evaluating parent and gamete traits in relation to fertility and offspring viability under routine hatchery conditions. Are losses mainly due to failed fertilisation or mortality? Are maternal or paternal factor more predominant? The study covered sex hormone status of the broodstock, egg traits (egg size and wateriness of egg batches), milt traits (volume, density, and sperm motility characteristics), and symmetry of early cell division. We found that the majority of offspring loss occurred as embryo mortality, although a significant additional loss could be assigned fertilisation failure. Fertilisation and mortality rates were not inter-correlated. Neither of the evaluated egg traits, egg size and wateriness of newly stripped egg batches, proved to be useful indicators of egg quality. With regard to sperm traits, milt density as well as several computer assisted sperm analysis (CASA) parameters, i.e. swimming speed (VAP, VSL, and VCL) and beat cross frequency (BCF), were correlated with reproductive performance and could potentially be used as quality indicators for Arctic charr. Together, male 17,20β-P levels and BCF explained 69.5% of the between male variation in proportion of successfully eyed eggs. The results support previous indications that post-ovulatory aging of oocytes is contributing to the impairment of reproductive performance in farmed Arctic charr. In addition, a significant paternal factor to this impairment has been exposed. However, the cause and mechanism involved are still far from clear. Highlights • Broodstock and gamete traits were evaluated together with fertility and embryo viability under routine hatchery conditions. • Embryo mortality, rather than failed fertilisation, was the main cause for egg loss in the studied Arctic charr broodstock. • Besides post-ovulatory aging of oocytes, paternal fertility issues, which needs to be investigated further, were revealed. [ABSTRACT FROM AUTHOR]

• An assay to assess inhibition of oocyte maturation was developed. • TBCO decreased fecundity of Japanese medaka. • TBCO impaired oocyte maturation, in vitro and ex vivo. • Impaired oocyte maturation is a mechanism of decreased fecundity of Japanese medaka exposed to TBCO. Inhibition of oocyte maturation is an understudied mechanism by which chemical stressors can impair fecundity of female fishes. The primary objective of the present study was to develop an assay to assess oocyte maturation disruption by chemical stressors in Japanese medaka (Oryzias latipes). First, an in vitro assay to assess maturation inducing hormone (MIH)-stimulated oocyte maturation in zebrafish was validated for use with Japanese medaka. Next, using the brominated flame retardant, 1,2,5,6-tetrabromocyclooctane (TBCO), which previously was shown to decrease fecundity of Japanese medaka and inhibit oocyte maturation in zebrafish, effects on oocyte maturation were quantified using in vitro and in vivo exposure. Adaptation of the protocol for in vitro MIH-stimulated maturation of stage IV oocytes from zebrafish was successful in inducing greater than 80% of stage IX oocytes from female Japanese medaka to mature. To assess effects of in vitro exposure, stage IX oocytes were exposed to 0, 2, 20, and 200 μg/L of TBCO, followed by exposure to MIH. The in vitro exposure caused a significant decrease in maturation of oocytes exposed to 20 and 200 μg/L of TBCO. To assess effects of TBCO on fecundity and oocyte maturation following in vivo exposure, sexually mature fish were fed a control, 100 μg/g, or 1000 μg/g concentration of TBCO-spiked fish food for 21 days, where fecundity was measured daily, and following the exposure, stage IX oocytes were excised to assess MIH-stimulated maturation. Fecundity and oocyte maturation were significantly decreased at either concentration of TBCO. Plasma concentrations of 17β-estradiol (E2) and hepatic abundances of transcripts of vitellogenin (vtgI and vtgII) were quantified, but there were no significant differences between treatments. Results suggest that inhibition of oocyte maturation is a mechanism by which TBCO decreases fecundity, and that in vitro assays of oocyte maturation might be predictive of fecundity in this species. [ABSTRACT FROM AUTHOR]

Sex allocation theory predicts that parents bias the offspring sex ratio strategically. In avian species, the offspring sex ratio can be biased at multiple growth stages, although the mechanisms are not well known. It is crucial to reveal a cause and timing of biased offspring sex ratio. We investigated (i) offspring sex ratio at multiple growth stages, from laying to fledging; and (ii) the stage at which offspring sex ratio became biased; and (iii) the cause of biased offspring sex ratio in Eurasian tree sparrows Passer montanus. Sex determination of 218 offspring, including hatchlings and unhatched eggs from 41 clutches, suggested that the offspring sex ratio was not biased at the egg-laying stage but was significantly female-biased after the laying stage due to higher mortality of male embryos. Half of the unhatched eggs showed no sign of embryo development (37/74, 50.00%), and most undeveloped eggs were male (36/37, 97.30%). Additional experiments using an incubator suggested that the cause of embryo developmental failure was a lack of developmental ability within the egg, rather than a failure of incubation. This study highlights the importance of clarifying offspring sex ratio at multiple stages and suggests that offspring sex ratio is adjusted after fertilization. [ABSTRACT FROM AUTHOR]

Fertility of backcross triploid hybrids containing one genome of Prussian carp and two genomes of common carp is investigated. The females of hybrids of Prussian carp and common carp (Prussian × common carp) are prolific and produce diploid gametes. Since males of such hybrids are sterile, their reproduction is realized by means of induced gynogenesis. Triploid progeny is obtained by backcrossing female Prussian × common carp with carp males. Among triploids obtained from hybrids F and among hybrids of the first gynogenetic generation, there were no prolific specimens. However, in reproduction of diploid hybrids by means of gynogenesis during six generations, the female fertility in the backcross progeny is restored. From backcross triploid females (daughters of Prussian × common carp of the sixth gynogenetic generation), a viable triploid gynogenetic progeny and a tetraploid backcross (by carp) progeny are obtained. The obtained data may be considered as the experimental proof of the hypothesis of reticular speciation. [ABSTRACT FROM AUTHOR]

Exposure to estrogenic endocrine disruptors (EDCs) during development affects fertility, reproductive and non-reproductive behavior in mammals and fish. These effects can also be transferred to coming generations. In fish, the effects of developmental EDC exposure on non-reproductive behavior are less well studied. Here, we analyze the effects of 17α-ethinylestradiol (EE 2 ) on anxiety, shoaling behavior and fertility in zebrafish after developmental treatment and remediation in clean water until adulthood. Zebrafish embryos were exposed from day 1 to day 80 post fertilization to actual concentrations of 1.2 and 1.6 ng/L EE 2 . After remediation for 82 days non-reproductive behavior and fertilization success were analyzed in both sexes. Males and females from the 1.2 ng/L group, as well as control males and females, were bred, and behavior of the untreated F1 offspring was tested as adults. Developmental treatment with 1.2 and 1.6 ng/L EE 2 significantly increased anxiety in the novel tank test and increased shoaling intensity in both sexes. Fertilization success was significantly reduced by EE 2 in both sexes when mated with untreated fish of opposite sex. Progeny of fish treated with 1.2 ng/L EE 2 showed increased anxiety in the novel tank test and increased light avoidance in the scototaxis test compared to control offspring. In conclusion, developmental exposure of zebrafish to low doses of EE 2 resulted in persistent changes in behavior and fertility. The behavior of unexposed progeny was affected by their parents' exposure, which might suggest transgenerational effects. [ABSTRACT FROM AUTHOR]

Fecundity of redfish Sebastes mentella and Sebastes norvegicus in the Irminger Sea and Icelandic waters was analyzed in relation to several maternal features and oocyte developmental stages. The mean potential fecundity in S. norvegicus was estimated to be 123,300 oocytes and relative fecundity averaged 116 oocytes g-1. Mean potential fecundity in S. mentella was 50,013 oocytes and relative fecundity was 64 oocytes g-1. Strong fecundity down-regulation (50% on average) was observed during oocyte development estimated from September to November, when oocytes reached the advanced stage of vitellogenesis. This result implies that fecundity can only be comparable between individuals presenting the same stage of oocyte development. However, the development rates differed between species and between stocks, and therefore the same stage is reached at a different time of the year. Fecundity varied significantly with female weight and length, while condition had little influence on fecundity variation. [ABSTRACT FROM AUTHOR]

Accurate fecundity estimates are necessary for the proper assessment of fish stocks. Despite all recent investigations of the reproductive biology of Rhinoptera bonasus (Cownose Ray) indicating a maximum fecundity of 2 embryos per brood, maximum fecundity estimates of 6 per brood persist. All reports of 6 embryos per brood seem to stem from a single account. It is the purpose of this paper to present evidence indicating that the report of 6 embryos is based upon a misidentification in the field, and that maximum fecundity estimates for the Cownose Ray are therefore up to six-fold higher than actually observed. [ABSTRACT FROM AUTHOR]

Distant hybridization can combine together the genomes of different species, which leads to changes of the offspring in phenotypes and genotypes. In this study, we successfully establish a fertile hybrid lineage by intergeneric hybridization of female blunt snout bream (BSB, Megalobrama amblycephala ) × male topmouth culter (TC, Culter alburnus ) and investigate some important biological traits of this lineage including the morphological traits, chromosomal number, karyotype, DNA content, gonadal development, egg and milt yield, sperm shape and density, fertilization rate and early survival rate. The results show that: (1) the diploid and triploid hybrids coexist in F 1 and only diploid hybrids are found in F 2 , in which the diploid hybrids of F 1 and F 2 possess 48 chromosomes with one chromosome set of BSB and one chromosome set of TC, and the triploid hybrids of F 1 possess 72 chromosomes with two chromosome sets of BSB and one chromosome set of TC. (2) All the tested males and females of the diploid F 1 and F 2 hybrids have the normal gonadal development and produce mature sperm and egg, respectively, which are fertilized with each other to form F 2 and F 3 hybrids, respectively, and finally form a diploid hybrid lineage (F 1 –F 3 ). (3) The good fertility of the F 1 and F 2 hybrids of female BSB × male TC potentially provides reproductive base to make the hybrid lineage propagate from one generation to another. The formation of the hybrid lineage (F 1 –F 3 ) also provides an ideal model to research the reproductive rules of distant hybrid progeny. [ABSTRACT FROM AUTHOR]

Sperm DNA damage is one of the many factors that have been associated with male infertility. However, sperm DNA fragmentation (SDF) assessment has been challenging because protamines render the nuclear chromatin highly compacted. For those fish species having sperm with protamines, one hypothesis is that the less compacted DNA could be more vulnerable to iatrogenic damage when used in artificial reproduction. The present investigation included three objectives: 1) apply the Sperm Chromatin Dispersion (SCD) technique using the Halomax-SCD test kit (Halotech DNA, Madrid, Spain) for the rapid assessment of SDF in zebrafish ( Danio rerio ); 2) assess the dynamic aspects of SCD to determine zebrafish sperm DNA longevity in both activated and unactivated samples; and 3) to analyze if the dynamic level of zebrafish sperm DNA fragmentation has any impact on fertility and embryo viability. The results demonstrate the use of the Halomax-SCD test for assessing SDF in zebrafish and are congruent with results of DNA Breakage Detection-Fluorescence In Situ Hybridization (DBD-FISH) and Comet Assay. The averaged SDF values derived from 10 individuals were low immediately after sperm motility activation (1.4% ± 0.96) compared to 15 min later (10.6% ± 9.96), with increasing and very high rates of SDF (r-SDF), 0.6% units/min. Although SDF did not significantly influence oocyte fertilization capacity, it significantly impacted later embryo development and overall reproductive success, i.e. , fertility rates higher than embryo viability values. [ABSTRACT FROM AUTHOR]

The catfish Sorubim cuspicaudus cryopreservation semen was evaluated using three levels (5, 10, 15 %) of ethylene glycol (ETG). Males (n = 13) undergoing spermiation and in final maturation females (n = 6) were induced with 0.4 ml Ovaprim®/Kg, after 12 and 14 post-induction the semen was collected in 2 ml Eppendorf vials. The different cryoprotectants solutions were prepared with glucose 6 % (w/v) skimmed milk powder 5 % (w/v) and distilled water. The semen was diluted in ratio 1:3 (semen:extender), packed in macrotubes of 2.5 ml and frozen in liquid nitrogen (NL) vapor for 30 minutes, then the macrotubes were stored in cryogenic tanks submerged directly in NL (-196 °C). The sperm were thawed in serological bath to 35 °C for 90 seconds. The total motility, total progressivity and velocities in fresh and thawed semen were analyzed with the Sperm Class Analyzer software SCA® (Microptic SL, Spain). Fertility and hatching rates were assessed with 1.0-1.5 g of oocytes in experimental up flow incubators two liters, a completely randomized design was used. The hatching rate of fresh semen was 51,8±21 %, with no significant differences with semen cryopreserved with ETG 5 % (38.6 ± 13.9 %) (p> 0,05), while ETG 15 % (9.6 ± 2.9 %), recorded the lower hatching rate (p <0.05). The results suggest that the cryoprotectant solution composed of ETG 5 %, glucose 6 % and powdered milk 5 % is a viable alternative for semen cryopreservation of the catfish Sorubim cuspkaudus. [ABSTRACT FROM AUTHOR]

Abstract: Harvest weight is the main trait in Nile tilapia (Oreochromis niloticus) breeding programmes. The effects of selection for harvest weight on female reproductive traits are unknown. In this paper we estimate genetic parameters for reproductive traits and their correlation with harvest weight using females from the generation 12 of the GIFT strain of Nile tilapia in the Mekong Delta of Viet Nam. Spawning records were obtained from single pair mating as well as group mating experiments. The traits were categorised into two groups: fecundity-related traits and fertility-related traits. Fecundity traits were: number of eggs (NEGG), relative fecundity as the ratio of number of eggs to female spawning weight (RFEC), egg weight (EGGW) and egg diameter (EGGD); fertility traits were: number of fertilised eggs (FEGG), number of hatched eggs (HAT), number of swim-up fry (SWUP), and fertilisation rate (FER, in %). Heritability estimates for fecundity traits were low, ranging from 0.05 to 0.08. Heritability estimates for fertility traits were also low, ranging from 0.06 to 0.12. Genetic correlations for HW with NEGG and TEGGW were positive (0.51 and 0.42, respectively), while correlations for HW with RFEC, EGGW, and EGGD were negative (−0.72, −0.48, and −0.50, respectively). The same trend was observed for body weight at spawning (SPW), but genetic correlations between SPW and fecundity traits were higher than those between HW and fecundity traits. Genetic correlations between HW and fertility traits were all moderate to high (0.46 to 0.69), except for FER (0.15±0.24). Genetic correlations between SPW and fertility traits were even higher (0.69 to 0.93). We conclude that both HW and SPW have favourable genetic correlations with NEGG, RFEC, and SWUP, which are the desired characteristics for Nile tilapia seed production. Selection for HW does not affect these traits. However, Nile tilapia females selected for large HW tend to produce smaller eggs. We recommend monitoring the phenotypic and/or genetic trend in this trait, as smaller eggs might, on the longer term, lead to lower fry survival. [Copyright &y& Elsevier]

Understanding the mechanisms of coexistence of sperm-dependent asexuals and their sexual hosts requires an empirical evaluation of their relative fitness. We evaluated the fecundity, egg viability, and hatchling growth rate of the sperm-dependent asexual hybrid species Phoxinus eos-neogaeus and its sexually-reproducing parental species, P. eos and P. neogaeus. Three comparisons between asexual and sexual Phoxinus suggested a fitness advantage in the asexuals: absolute fecundity was higher in P. eos-neogaeus than P. eos, but this advantage disappeared when fecundity differences were scaled to differences in body size; a higher fraction of P. eos-neogaeus eggs than P. eos eggs were viable post-fertilization; P. eos-neogaeus grew faster in the first 60 days post-hatching than both their P. eos and P. neogaeus hosts. All other comparisons showed no difference in fitness between P. eos-neogaeus and the parental species. Overall, our data suggest, at best, a weak fitness advantage for the asexuals, which suggests that other factors, such as niche separation or male preference for sexually-reproducing females during mating, are critical to the maintenance of asexual-sexual lineages. [ABSTRACT FROM AUTHOR]

Population studies on terrestrial isopods, particularly those examining temperate and certain tropical species, are often performed through an investigation of life history traits, such as size at sexual maturity, fecundity and life span. In this study, some of the life history traits of Benthana cairensis Sokolowicz, Araujo, and Boelter, 2008, a neotropical species, were evaluated and tested against the hypothesis that this species has an iteroparous mode of reproduction, with females' reproduction occurring year-round. Samples were collected over an 18-month period from a small area in southern Brazil. Reproduction of B. cairensis peaked in the spring, females' mean fecundity was 10.4 ± 2.73 eggs (Mean ± SD) and mean reproductive allocation was 17% ± 4.08 (Mean ± SD). Females attain sexual maturity when they are approximately five months old and live over one and a half year. Males grow faster, reach smaller sizes and live approximately 13 months. We determined that a female only reproduces for one season, although it is capable of having more than one brood during this season; this result confirms that B. cairensis exhibits an iteroparous mode of reproduction and that reproduction is concentrated in the warmer months. [ABSTRACT FROM AUTHOR]

1. Selfish genetic elements (SGEs) are universal and can have major evolutionary and ecological impacts, but their ecology is not well understood. Most SGEs have stable population dynamics, but the reasons for this are rarely known. Several SGEs are distributed along latitudinal frequency clines, providing an opportunity to examine why these clines are stable. 2. Latitudinal temperature changes are a strong contender for an underlying environmental cause of such clines. Both SGEs and extreme temperatures commonly affect male fertility. If these factors interact to reduce male fertility, this could be the cause of the observed latitudinal clines. 3. The meiotic driving X-chromosome sex ratio ( SR), found in the fruit fly Drosophila pseudoobscura, is distributed in a cline across North America, being absent in Canada and increasing in frequency southward to 30% at the Mexico/USA border. This cline has been stable for at least 50 years, despite considerable gene flow between populations. If SR males have decreased fertility in the colder Northern populations, this could undermine the success of SR and cause this cline. 4. Here, we examine the fertility of males reared at high and low temperatures. We find that both SR and non- SR males have reduced fertility at high temperatures. However, SR males show disproportionally lower fertility at high temperatures than non- SR males. 5. The geographical distribution of SR suggests the opposite should be true; SR males should be more successful at high temperatures than low ones, as SR is more common in the South, hence the observed temperature-related fertility differences of males cannot be the cause of the cline in SR in nature. 6. This study finds that the reduction in male fertility commonly caused by SGEs is temperature dependent. However, although these interactions are likely to be important for the ecology of SGEs, they do not necessarily provide the explanation for the observed latitudinal clines in SR. [ABSTRACT FROM AUTHOR]

Recent theoretical models predict that the relative allocation to advertisement and parental care depends on whether paternal care is necessary for offspring survival: In species with exclusive male care, male investment in attraction is expected to reliably indicate paternal care effort and male phenotypic quality. Previous research, yielding contrasting results, has considered how one trait involved in mate attraction interacts with parental care or a specific aspect of male quality. In the blenny Salaria pavo, we perform a comprehensive analysis of the interplay between overall male attractiveness and male quality, the latter in terms of fertility, condition, and parental care. In this fish, males are larger than females, exhibit two sexually dimorphic traits (head crest and anal glands), and solely care for eggs. We generated a male attractiveness index through principal component analyses of morphological traits and quantified parental effort as the total time spent in egg care. In addition, we analyzed the relationships between specific components of attractiveness and male qualities. In agreement with theory predictions, we found that male overall attractiveness is a reliable indicator of fertility, in terms of sperm number, but is unrelated to body condition and parental care effort, with males able to perform high levels of care regardless of their level of advertisement. However, the relative expression of head crest area appears positively related to sperm number but is traded-off with parental care effort. These findings underline the need, in addressing real patterns, to consider interactions between multiple aspects of male display and quality. [ABSTRACT FROM AUTHOR]

Abstract: Xiphophorus fishes are well-established models for biomedical research of spontaneous or induced tumors, and their use in research dates back to the 1930s. Currently, 58 well-pedigreed lines exist among 24 Xiphophorus species housed as live animals at the Xiphophorus Genetic Stock Center. The technique of sperm cryopreservation has been applied to preserve these valuable genetic resources, and production of offspring has been reported with cryopreserved sperm in two species (X. helleri and X. couchianus). The goal of this research was to establish protocols for sperm cryopreservation and artificial insemination that yield live young in X. maculatus, a widely used research species. The objectives were to: 1) collect basic biological characteristics of males, and quantify the sperm production yield after crushing of dissected testis; 2) cryopreserve sperm from X. maculatus by adapting as necessary the protocols for sperm cryopreservation of X. helleri and X. couchianus; 3) use cryopreserved sperm to inseminate virgin females of X maculatus and other species (X. helleri and X. couchianus), and 4) compare experimental trials over a 3-year period to identify opportunities for improving female fecundity. In total, 117 males were used in this study with a standard length of 2.5±0.3cm (mean±SD), body weight of 0.474±0.149g, and dissected testis weight of 7.1 ±3.7mg. Calculation of sperm availability showed 5.9±2.8×106 sperm cells per mg of testis weight. Offspring were produced from cryopreserved sperm. Male-to-male variation (1–70%) was observed in post-thaw motility despite little variation in motility before freezing (60–90%) or genetic variation (~100 generations of sib-mating). Comparisons of biological factors of males did not have significant correlations with the production of live young, and the influence of females on production of young was identified from the comparison of artificial insemination over 3years. Overall, this study describes offspring production from cryopreserved sperm in a third species of Xiphophorus fishes, and identifies the opportunities for improving female fecundity which is essential for establishment of germplasm repositories for Xiphophorus fishes. [Copyright &y& Elsevier]

Abstract: The deleterious effects of tributyltin (TBT) on spermiation in fish have been attributed to its role in inhibiting aromatisation of androgens to estrogens, and the critical role of the latter in sperm development. We test this hypothesis by examining sperm parameters, fertilisation and hatching success in males of two fish species exposed throughout life to doses of Fadrozole, a non-steroidal aromatase inhibitor (AI), provided in their diets. AI-treatment caused 100% male development in zebrafish, but only partial masculinisation in medaka, in both cases supporting previous studies and suggesting different roles of estrogen in sexual differentiation in the two species. Milt volume, initial sperm motility, maximum sperm swimming duration and sperm morphology did not differ significantly between Control and AI-dosed fish in either species, after excluding low milt volumes in sex-changed females in medaka. Fertilisation rates were also unaffected by the aromatase inhibition, but hatching success in medaka was 31% lower than in Control males, suggesting a previously unreported effect of aromatase on sperm quality. The slight effect of aromatase inhibition on sperm parameters in general contrasts with the marked effect of TBT on fish sperm, and suggests that a mechanism other than depressed estrogen levels is involved. [Copyright &y& Elsevier]

Abstract: Groups of maiden or repeat spawning Atlantic salmon were maintained during vitellogenesis in austral autumn at either 14°C or 22°C through until April when all fish were transferred to a spawning temperature of 8°C. There was no difference in body weight within groups for maidens and repeats, with repeats being consistently larger than maidens, no difference in condition factor amongst groups, but consistently higher gonad weight in repeats than maidens. Gonadosomatic index (GSI) and follicle diameter were suppressed in both maidens and repeats at 22°C, with the effect being most marked in repeat spawners. Relative fecundity (eggkg−1) determined from ovarian tissue samples also showed depression in repeats at 22°C. Fish from both age classes held at 22°C had a higher proportion of atretic follicles. Plasma levels of estradiol-17β (E2) were strongly depressed in both maidens and repeats exposed to 22°C throughout autumn but there was some evidence of recovery amongst maiden fish by late April. A similar effect was seen on plasma testosterone (T) levels. Plasma cortisol levels were generally low and typical of levels in unstressed fish indicating that stress did not account for the inhibitory effects observed. Hepatic zona pellucida protein gene expression was significantly inhibited in both maiden and repeat spawning fish reared at 22°C, but with some evidence of recovery after temperature reduction to 8°C. Hepatic vitellogenin (Vtg) gene expression was also lower in both maiden and repeat spawning fish exposed to 22°C and this was accompanied by reduced plasma Vtg levels in maidens, but not repeats at 22°C. Maidens at 14°C began ovulating first followed by repeats at 14°C, then repeats at 22°C followed by maidens at 22°C. There was reduced fertility in maidens at 22°C relative to both maidens and repeats at 14°C, whereas repeats at 22°C showed intermediate fertility between 14°C fish and 22°C maidens. Survival to the eyed egg stage was highest in maidens at 14°C, significantly suppressed at 22°C in maidens, and at intermediate levels in repeats at both temperatures. This suggests that repeat spawning Atlantic salmon may be more robust in the face of thermal insult which combined with their larger size and egg production, could make their use desirable under production situations where there was any threat of exposure to higher than normal temperature. [Copyright &y& Elsevier]

Abstract: In effluent treatment systems, a major concern is how to maintain culture of local zooplankton species (Daphnia carinata and Moina australiensis), particularly with the impact of un-ionized ammonia on their life cycle response. Hence the impact of un-ionized ammonia present in digested piggery effluent on the reproductive physiology and survival of D. carinata and M. australiensis was evaluated in this study. Both species were cultured in diluted digested piggery effluent and supplied with algae, Chlorella vulgaris as food. The effects of different un-ionized ammonia concentrations on total fertility, number of clutches, clutch size and survival were recorded every 24h. The lethal concentration of unionized ammonia, with 50% survival after 24h exposure to (24hr LC50 values) un-ionized ammonia was determined for each species relative to total ammonia nitrogen, pH and temperature. M. australiensis had greater tolerance at higher levels of un-ionized ammonia than D. carinata. However, older neonates (<48h old) could survive at a higher concentration of un-ionized ammonia nitrogen (up to 2.8mg/l D. carinata and 8.8mg/l M. australiensis) than younger neonates (2.2mg/l D. carinata and 7.5mg/l M. australiensis). The net reproduction rates (R 0) were derived from fertility and survival while the intrinsic rates of increases (r) were calculated with net reproduction rate and generation time. M. australiensis has a maximum R 0 (189.84) and r (0.54) at 4.5 and 6.5mg/l NH3–N, respectively, while D. carinata has a maximum R 0 (100.46) and r (0.39) at 0.5 and 1.0mg/l NH3–N. Hence, M. australiensis is a faster growing species than D. carinata when cultured in digested piggery effluent. [Copyright &y& Elsevier]

Neosalanx taihuensis were sampled from the Tian-e-zhou Oxbow from March 2006 through November 2007. Two separate spawning seasons were identified based on the annual reproductive cycles of the females, designated as the autumn-spawning season and the spring-spawning season. Lifespan of the offspring of the spring-spawning fish was 1 year, with them dying after the subsequent spring spawning. Autumn-spawned females seem to be the offspring of the spring-spawning fish, based on monthly changes in the length–frequency distributions. Spring-mature females had higher absolute fecundity, gonadosomatic index, and relative condition factor in 2007 than in 2006. Relative condition factor of the immature female offspring of spring-spawning fish was higher in 2007 than in 2006, portending a further increase in reproductive investment during the spring spawning of 2008. The increasing reproductive investment suggests that the population of N. taihuensis in the Tian-e-zhou Oxbow may be recovering from its recent decline. [ABSTRACT FROM AUTHOR]

Gonçalves, P., Costa, A. M., and Murta, A. G. 2009. Estimates of batch fecundity, and spawning fraction for the southern stock of horse mackerel (Trachurus trachurus) in ICES Division IXa. – ICES Journal of Marine Science, 66: 617–622. Since 1995 the annual egg production method has been applied triennially to the southern stock of horse mackerel (Trachurus trachurus) in the Northeast Atlantic (ICES Division IXa). This method assumes that fecundity is determinate, but increasing evidence indicates that horse mackerel are indeterminate spawners. The daily egg production method (DEPM) does not rely on the assumption of determinate fecundity, making it the appropriate method for this species. Therefore, we reanalysed samples collected from previous surveys (2002, 2004, 2005, and 2007) to obtain estimates for batch fecundity and spawning fraction, which are important DEPM parameters. The estimates of batch fecundity are around 200 oocytes g−1 of female (total ovary-free weight). Several criteria were used to estimate spawning fraction (migratory nucleus stage, hydrated oocytes, and post-ovulatory follicles) and all showed the same trend among years, varying between 0.10 and 0.30 d−1. The estimates were significantly different among methods, but those differences were similar across surveys, indicating that a consistent bias would be reflected in the final spawning-stock biomass (SSB) estimates obtained from the DEPM. Until further information is available regarding the accuracy of the criteria used to estimate spawning fraction, the southern horse mackerel SSB estimates from the DEPM should only be taken as indicative of trends rather than measures of absolute abundance. [ABSTRACT FROM PUBLISHER]

The objective of the study was to determine some reproductive parameters in the golden grey mullet ( Liza aurata Risso, 1810) during two periods half a decade apart while also trying from limited data to identify changes in fecundity over the past half century. Maturity and fecundity of golden grey mullet caught in Iranian waters of the Caspian Sea is not well documented and were thus studied during several seasonal cycles during 2002–2004 to establish basic data on reproduction in the area. The fork length (FL) of 462 sampled fish was between 22.1 and 51.9 cm. The fork length–weight relationship derived from all fish was W = 0.0118FL2.964. Overall male to female ratio was 1 : 1.42. The reproductive season extended from October to December. Fifty percent of sexual maturity was at FL 26.0 cm. Mature gonads were present in 20% of fish at age 3, 63% at age 4, 88% at age 5, and 97% at age 6. Individual absolute fecundity of the golden grey mullet ranged from 113 386 to 1.47 million eggs, with a mean (±SD) of 451 963 (±274,114.2). An overlap exists between the spawning and fishing seasons. Therefore, the start of the fishing season should be delayed for 1 month in order for stocks to complete their spawning. [ABSTRACT FROM AUTHOR]

The life history characteristics of an invasive cyprinid fish, the Prussian carp ( Carassius gibelio) were examined in Lake Chimaditis (northern Greece). The population is dominated by females that are able to reproduce gynogenetically. Fish samples were collected using trammel nets from August 2004 to July 2005. Their total length (TL) ranged between 21.9 and 37.0 cm. The length–weight relationship was W = 0.0336TL2.81 ( r2 = 0.92, n = 600) and the mean Fulton condition factor exhibited monthly variation from 0.172 (May) to 0.186 (August). According to the annual growth marks present, the lifespan of the Prussian carp in Lake Chimaditis is 6 years. The growth parameters were estimated as L∞ = 34.46 cm, K = 0.297 year−1, t0 = −1.994 year. Absolute fecundity ( FA) ranged between 26 000 and 176 600 oocytes (mean = 66990) and relative fecundity between 78 and 251 oocytes per gram of total weight (mean = 158). Absolute fecundity increased exponentially with length ( FA = 0.286 × TL3.66, r2 = 0.66) and weight ( FA = 17.93 × W1.36, r2 = 0.73) of the fish. [ABSTRACT FROM AUTHOR]

Anadromous Coilia ectenes was sampled from the Yangtze estuary at Chongming and two of the primary upstream spawning grounds at Jingjiang and Anqing in April, May, June and August 2006. Gonad development was analyzed for females. In April, fish were collected in the estuary and at Jingjiang, but not at Anqing. No female was mature (gonad at stages IV or V) at either location. In May, 45% of the females were mature in the estuary, 9% at Jingjiang and 5% at Anqing. In June, 86% were mature in the estuary, 83% at Jingjiang and 7% at Anqing. In August, C. ectenes was absent at Jingjiang. No female was mature in the estuary, and all females were mature at Anqing. Absolute fecundity ( AF) increased significantly with standard length ( SL) by a power function AF = 2.27 × 10−6 × SL2.67 ( r2 = 0.57, n = 48, P < 0.05). Mature females in the estuary were smaller than those at Jingjiang and Anqing. Conservation of spawners in the upstream spawning grounds is important because they have a size-related fecundity advantage over the smaller spawners in the estuary. [ABSTRACT FROM AUTHOR]

1. Classical theory predicts that colonizing ability should increase with fecundity. Additionally, it has recently been shown that successful establishment of birds was correlated with relative brain size, which was suggested as possibly universal among vertebrates. 2. I conducted a comparative study of establishment success in global fish introductions, controlling for regional geographic differences, to test these hypothesized correlates. 3. In 133 introductions of 17 fish species, establishment success was negatively associated with fecundity while there was no evidence for an effect of relative brain size. In analysis of partially overlapping data, there was no evidence of a correlation between relative brain size and establishment rate across 39 species. 4. One explanation for the negative association with fecundity is that parental investment might be more important to establishment than fecundity. In 126 introductions of 14 species, reproductive behaviours associated with parental investment were significantly associated with establishment success. These results suggest that the correlation between brain size and establishment success is not universal. [ABSTRACT FROM AUTHOR]

Boulcott, P., Wright, P. J., Gibb, F. M., Jensen, H., and Gibb, I. M. 2007. Regional variation in maturation of sandeels in the North Sea. – ICES Journal of Marine Science, 64: 369–376. The current assessment of lesser sandeel (Ammodytes marinus) in the North Sea assumes a single stock and a knife-edge maturity ogive. However, there is evidence that the North Sea stock consists of several reproductively isolated components, raising the possibility of demographic differences among regional aggregations. We examine regional variation in size- and age-at-maturity in four components of the North Sea stock. Surveys in 1999 indicated pronounced regional differences in length- and weight-at-age, implying a disparity in growth rate across the North Sea. Logistic regression revealed that the onset of maturity was significantly related to regional distribution, in addition to length and age, with a tendency for fish off the UK's northeast coast to mature later and smaller than elsewhere. No significant effect of year on either growth or length-at-maturity was revealed from a comparison with other data collected in 2004. The results show that important regional phenotypic variation not currently represented in stock assessments could have implications for the local sustainability of sandeel aggregations. [ABSTRACT FROM PUBLISHER]