Relative Fecundity Research Articles

Reproductive characteristics of the giant gurami sago strain ( Osphronemus goramy Lacepède, 1801): basic knowledge for a future hatchery development strategy

Background: The giant gourami sago strain ( Osphronemus goramy Lacepède) has been approved in 2018 as a candidate for freshwater aquaculture in Indonesia. However, information on the species’ reproduction is minimal. This study analyzed the reproductive characteristics of the gourami sago strain broodfish to provide basic knowledge for a future hatchery development strategy. Methods: A total of 10 female and 10 male mature gourami sago strain broodfish were measured for body weight and length, and were evaluated for their reproductive characteristics. Breeding fish were spawned naturally in a 2×1×0.6 m concrete pond with a male-female sex ratio of 1:1. Egg weight and diameter were measured in 25 eggs per female using, respectively, ACIS AD- 600i scales with 0.01 g accuracy, and a microscope (Labo model L-711) using Canon Digital Camera Software 3 . Semen was collected using plastic syringes in 3 mL aliquots, then placed in an insulated ice-cooled container, and analyzed within two hours of collection. Results: Average weights of female and male broodfish before spawning were 2180±159.78 g and 3060±134.99 g, respectively. The relative fecundity and egg diameter were 1029±36 eggs kg -1 and 2.42±0.05 mm, respectively. The hatching rate and embryo survival to an eyed-egg stage were respectively 76.40±2.27% and 94.76±0.42%. Sperm characteristics showed that volume was 0.60±0.12 ml kg -1 and percentage of motile sperm was 70.04±2.27%. Female broodfish weight after spawning was strongly correlated with the weight before spawned ( r 2 = 0.999) and absolute fecundity was also strongly correlated with female broodfish weight before spawning ( r 2= 0.921). Sperm concentration was moderately correlated with sperm motility ( r 2 = 0.556) and duration of sperm motility ( r 2 = 0.502). Conclusions: The gourami sago strain broodfish has suitable reproductive characteristics for the development of hatcheries. Successful natural spawning should be followed by larval weaning and feeding technology to increase growth and survival.

Reproductive biology of Gattan females Barbus xanthopterus (Heckel, 1843) used for artificial breeding in Fish Hatchery of Marine Science Center

Some aspects of reproductive biology of Gattan Barbus xanthopterus females were studied from 15-30 March, 2009. These fishes were coughed from Huweiza Marsh, Southern Iraq and from Therthar Reservoir, Western Iraq, and used for artificial breeding in Marine Science Center Hatchery. Total lengths ranged between 550-806 mm, total weights ranged between 3100-7250 g, and their age ranged from 3-6 years. It had been found that all examined ovaries were in ripe stage that means females cached from Huweiza Marsh were ready for artificial breeding and possess suitable (3.64- 11.03) gonado somatic index (GSI), while females collected from Therthar Reservoir had low GSI (1.15-1.33). Average of eggs diameters was 1.56 mm for fish of 550 mm total length and 3400 g, while it was 2.09 mm for fish of 802 mm total length and 7005 g. However, generally there was positive relationship between total lengths and eggs diameters with no significant correlation (r = o.47, P<0.01). Absolute fecundity for Gattan was ranged between 1494191-518650 eggs, and relative fecundity was between 85.8-286.2 egg/g, while there was low positive relation between absolute fecundity and total fish weight with no significant correlation (r= 0.33, P<0.01).

Some reproductive characters of the fantail goldfish Carassius auratus auratus females from rearing ponds in Basrah, Southern Iraq.

This study was carried out to determine some reproductive characteristics of the fantail goldfish Carassius auratus auratus females (standard length 69-224 mm. and total weight 21.1- 255.35 g.) from rearing ponds in Basrah province, Southern Iraq. Standard length, total weight, gonad weight, absolute fecundity, relative fecundity, gonadosomatic index (GSI) and egg diameter were determined from October 2010 to April 2011 in 77 fantail goldfish females. Results showed that the studied reproductive parameters increased gradually from October, to attain peak in March and decreased again thereafter. Absolute fecundity ranged between 2877- 357246 eggs, GSI 7.28-19.11 and egg diameter 298-1006 micron. Regression relationships between the various studied morphometric and reproductive parameters were calculated and the importance of these results to the culturists of this commercially important ornamental fish species was discussed.

Length-weight Relationship and Fecundity of Parastromateus niger from Gwadar Port Balochistan Province, Pakistan

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.

Life-History traits of Hollandichthys multifasciatus (Eigenmann & Norris, 1900) (Characiformes: Characidae) in coastal Atlantic Forest blackwater streams from Southeastern Brazil

Ecological and life history traits have been used to understand the basic ecology of fishes. This study aimed to examine the existence of plasticity in life history traits of populations of Hollandichthys multifasciatus in ten blackwater streams. This is an inseminating Characidae, endemic to the Atlantic coastal drainages of Brazil. Different aspects of the life-history of the species, such as mean length, sex ratio, absolute and relative fecundity, gonadosomatic index, condition factor, length-weight relationship and the growth parameter (b) of 185 specimens were studied during the period of low precipitation (June-September). Fish samples were obtained along a 100 m stretch of each stream, and some habitat variables recorded. ANOVA and Kruskal-Wallis tests indicated a similarity in most of the analyzed traits, with exception of the mean length of immatures, Gonadosomatic Index of mature males and condition factor of immatures and mature adults. Also, slope tests of the length-weight relationship were significantly different for immatures. The observed differences were attributed to heterogeneity in food availability and/or other site-specific factors, which may influence growth and/or breeding aspects among the studied localities. The approach used herein may improve understanding of trait plasticity under natural conditions, helping to understand fish-community responses to anthropogenic changes.

Patterns and Scaling of Reproductive Output in Paddlefish Polyodon spathula and Its Conservation Implications

AbstractWe used a large, three‐state data set to investigate if larger female Paddlefish Polyodon spathula reproduce disproportionately more than smaller females. The approach was to assess the relation between fecundity F, expressed as raw egg weight, and fish weight W, in the expression F = aWb. We compared results among three fisheries for Paddlefish harvested in the three states and between two stocks and compared results between total fish weight and total raw egg weight with results across taxa presented in other studies. Paddlefish from all three state‐managed fisheries (Montana, North Dakota, and Oklahoma) showed hyperallometric increases in fecundity, expressed as raw egg weight, with fish weight (i.e., b > 1). For Montana females, hyperallometry was greatest (b = 1.75; n = 8,487), followed by North Dakota (b = 1.61; n = 9,549) and Oklahoma (b = 1.47; n = 14,294). Paddlefish from Montana and North Dakota in general allocated a lower percentage of their total weight to egg weight (asymptotic gonadosomatic index [GSI∞]) than did Oklahoma Paddlefish (Montana: 21.46%; North Dakota: 20.01%; and Oklahoma: 24.22%). The hyperallometric increases in raw egg weight with fish weight reported here depict only one of several conservation benefits associated with maintaining larger and older fish in the populations. Conclusions about weight–fecundity relationships for a particular species should be considered with an adequate understanding of the complete life history and factors which would affect somatic growth versus fecundity tradeoffs.

Artificial reproduction of Caspian roach, Rutilus caspicus following stimulating ovulation with Ovaprim, Ovopel, and their combinations under controlled conditions

The aim of this study was to evaluate the efficiency of different hormonal agents and their combinations for spawning induction of females Caspian roach, Rutilus caspicus. Five groups of fish were injected intraperitoneally as follows: two injections of Ovaprim (T1), two injections of Ovopel (T2), a priming dose of Ovopel with a resolving dose of Ovaprim (T3), a priming dose of Ovaprim with a resolving dose of Ovopel (T4), and two injections of sterile 0.9% NaCl solution as a control group. The results showed that no fish ovulated in the control group. In hormone-treated groups, no differences were observed in ovulation success (P > 0.05). The shortest latency time and highest working and relative fecundities were observed in fish stimulated with two injections of Ovaprim (T1 group). The mean values of fertilization success in treated fish were in the range of 87.9–93.1% and the highest values were observed in T3 and T1 groups (P < 0.05). The best results in terms of ovulation index (92.1%), hatching rate (93.7%), and survival up to the eyed egg stage (89.4%) were achieved after administering two injections of Ovaprim (T1 group). There were no significant differences in the incubation time and embryos survival rates up to absorbing the yolk sac among different groups (P > 0.05). Overall, the best results of controlled reproduction of Caspian roach were obtained after using two injections of Ovaprim. Consequently, the Ovaprim is more suitable for restocking and aquaculture purposes of endangered populations of Caspian roach.

Trial on artificial breeding and laviculture of giant razor clams (Cultellus maximus Gmelin, 1791)

The study was carried out with the aim of determining the reproductive parameters and performing the rearing of giant razor clams (Cultellus maximus Gmelin, 1791) at larval stage and postlarval stage with different diets. The results showed that the spawning rate was 62.22 ± 3.85%, the fecundity was 7.98 ± 0.67 million eggs/female, the relative fecundity was 48,081 ± 5,826 eggs/g female, the fertilization rate was 42.67 ± 4.47%, and the hatching rate was 44.19 ± 4.02%. The rearing at larval stage with different diets of algae was investigated ((T1.1): Nanochloropsis oculata + Isochrysis galbana; (T1.2): N. oculata + Chaetoceros muelleri; and (T1.3): N. oculata + Isochrysis galbana + C. muelleri). The results showed that T1.3 gave the survival rate, length and width of larvae, reaching 5.3 ± 0.91%; 1525.60 ± 48.90 μm and 918.20 ± 28.00 μm, respectively. The parameters obtained from T1.3 was significantly higher (P &lt; 0.05) than that of T1.1 and T1.2. The rearing at postlarval stage with different diets was also studied as follow: (T2.1): N. oculata + I. galbana + C. muelleri; (T2.2): using commercial feed (Lansy and Frippak); and (T2.3): combination of 50% of T2.1 + 50% of T2.2. The results showed that T2.1 gave the survival rate, growth in length and width of postlarvae, reaching 11.83 ± 3.89%; 5.72 ± 0.61 mm and 3.31 ± 0.14 mm respectively. Growth parameters of T2.1 were significantly higher (P &lt; 0.05) compared to that of T2.2 and T2.3.

Spatiotemporal variability in the reproductive biology of yellowfin tuna (Thunnus albacares) in the eastern Pacific Ocean

The reproductive biology of yellowfin tuna (Thunnus albacares) was investigated through at-sea sampling of ovaries from 1728 females, across 12 length classes from 40 to 160 cm fork length, from four spatial strata (northern (N), central coastal (CC), central offshore (CO), and southern (S)) of the eastern Pacific Ocean, caught by purse-seine vessels from January 2009 to November 2016. Histological evaluations of the ovarian tissues provided the foundation for the estimates of length-specific reproductive characteristics. Spawning was widespread from about 25°N to 16°S between 78°W and 148°W, occurring throughout the year from 5°N to 15°N. North of 20°N, spawning took place during April–December, and south of 5°S, spawning took place during January–June. Spawning was observed for fish captured in dolphin, floating-object, and unassociated sets. Although spawning occurred at sea-surface temperatures from 25 °C to 32 °C, 73.0% of the spawning took place between 27.0 °C and 29.0 °C. Results of fitting a general additive model (GAM) to the maturity-at-length data indicated significant spatial variation in maturity, with estimated lengths at 50% mature of 90.6 cm in the S area, 83.2 cm in the N area, 78.6 cm in the CC area, 70.9 cm in the CO area, and 81.6 cm for the combined data. Results of fitting GAMs to maturity-at-length data sets from the current study and from a previous study executed during 1987–1989, indicated significant temporal variation for the CO, CC, and S areas, and the combined data sets. The estimated lengths at 50% mature for the combined data, for the same spatial strata, from the earlier samples and from those in the current study were 90.4 cm and 78.6 cm, respectively. The observed batch fecundities from 146 fish, based on counts of late-stage migratory-nucleus or hydrated stages of oocytes, ranged from about 54 thousand oocytes for an 87 cm female to about 7.2 million oocytes for a 153 cm female. The average size of the 146 females was 118 cm, and the average batch fecundity was about 2.3 million oocytes. The estimated mean relative fecundity for 136 females, which were weighed, was 60.95 oocytes per gram of body weight. The fraction of all mature females with postovulatory follicles was 0.56, equivalent to a mean spawning interval of 1.79 d, whereas for reproductively active females the fraction spawning per day was 0.81, equivalent to a mean spawning interval of 1.23 d.

A multidisciplinary method to assess the reproductive biology of Mystus bleekeri

The study aims to afford a deeper knowledge on reproductive biology of Mystus bleekeri from Surma River, Bangladesh in a multidisciplinary way. Though, the species is in demand as food and ornamental fish in Bangladesh but still now comprehensive details on reproductive biology of this species is scanty. Total 600 fish samples were derived from commercial catches from July 2018 to June 2019. Periodic differences in sex ratio, size distribution, condition factor (Kn), fecundity, gonadosomatic index and gonadal maturation cycle were assessed. The results showed 384 (64%) female and 216 (36%) male with an overall sex ratio of 1.77: 1 (female: male). Mean total length (TL) and body weight (BW) of all fish studied were 14.85 ± 3.38 cm TL and 27.54 ± 15.76 g, respectively. The Kn varied with length groups, the highest (1.45 ± 0.23) and lowest (0.89 ± 0.18) values obtained in 16.0–16.9 and 10.0–10.9 cm TL groups, respectively. The highest Kn was documented in October while the lowest was in January. Monthly GSI values showed two peaks in July and November for both the sexes. The fecundity was found to vary from 1120 to 14790 eggs with average value of 4968 ± 3047 with 14.4–18.3 cm in TL and 19.97–34.7g in BW. The relationship of fecundity with TL and BW was F = 1.385TL13.405, r2 = 0.885 and F = 5.201BW4.827, r2 = 0.944. Partial behavior of spawning together with allochronic oocytes development has also been found through histology. The results of this study could be used for predicting the response of populations of fish in Surma River and/or other where to human interferences and environmental change.

Hormonal induction and synchronization in the reproduction of nile tilapia (Oreochromis Niloticus)

The present study aims to evaluate the sexual synchronization of Nile tilapia (Oreochromis Niloticus) breeding herds under different distributions and days. This study was carried out during, a period of 21 experimental days. It was conducted in a randomized block design (DBC), in a factorial scheme 2 × 2 × 3, (male and female, with and without hormone induction, and three times blocks of 7, 14 and 21 days). A total of 324 fish were used, 180 females and 144 males, previously microchipped with approximately 250 ± 12.25 g of body weight.. Each tank contained 36 animals, with every three tanks comprising a block of which were repeated in time. Each of the tanks was composed of only males, another with 12 males and 24 females separated by a glass and a screen on the bottom and the third tank with only females. In each treatment, half of the animals (male and female) were applied the hCG hormone, in a single dose at a concentration of 5 IU / gram fish live weight. The animals were evaluated at 7, 14, and 21 days. After 667 hours-degree after application of the hormone was made extrusion and spermatozoa by celomatic massage. It was observed females that showed ease of extrusion of gametes. For the females, spawning index, absolute and relative fecundity, oocyte weight per 1 g, diameters, and germinal vesicle peripheral position were evaluated; the sperm concentration, volume (ml), motility (%), duration of sperm motility (min) and integrity were evaluated in males. The data were submitted to analysis of variance at the 5% level of significance. For females at 14 days there was greater ease of extrusion when separated from males, with hormone application . The distribution influenced the spawning weight, the larger diameter, and for the diameters smaller the days and induction presented interference. In males, the days interfered in the increase in volume and duration of semen motility independent of induction and environment, and finally, the environment interfered significantly in semen concentration.

Fecundity and Gonadosomatic Index of Sucker Throat Catfish, Pseudecheneis sulcata (McClelland, 1842) from the Snow-fed Tamor River in Eastern Nepal

&#x0D; &#x0D; &#x0D; &#x0D; In comparison to other nations, the Nepalese information on the reproductive biology of hill-stream fish is limited. So, the purpose of the present study was to provide information related to reproductive biology of a hill-stream sucker throat catfish Pseudecheneis sulcata from the snow-fed Tamor River, Nepal. The study was carried out from June 2018 to May 2019. A total of 57 female fish was collected. The fecundity of 22 females was assessed, while the gonadosomatic index was determined using all the collected samples. The absolute fecundity ranged from 2,316 to 7,597 eggs, with an average of 3,660 ± 210. This range of absolute fecundity indicates that Pseudecheneis sulcata is a moderately fecund fish when compared to certain low fecund species and some exceptionally fecund fish with tens of thousands of eggs. Relative fecundity ranged from 65.47 to 129.11 with a mean of 88.98 ± 4.35. The present study demonstrated that absolute fecundity was moderately correlated with total length (r = 0.45) and strongly linked with body weight (r = 0.78), and ovary weight (r = 0.80). Mean gonadosomatic index (GSI) was recorded the highest in January (15.7 ± 1.22%), and showed a decrease in the subsequent month of February (10.3 ± 0.75%), March (6.25 ± 0.28%) and April (1.66 ± 0.40%). The trends of GSI might have indicated that the sucker throat catfish was a batch spawner, with spawning season occuring between January and March.&#x0D; &#x0D; &#x0D; &#x0D;

Reproductive Parameters and Larval Growth of Bighead Catfish (Clarias microcephalus Günther, 1864) from Wild and Cultured Broodstock Strains

Bighead catfish, Clarias macrocephalus, is an important species for aquaculture. Nevertheless, information on population variation in their reproductive characteristics and larval growth is limited. This research aimed to evaluate the reproductive performance and larval growth of three bighead catfish broodstock strains collected in Ca Mau (CM) and Hau Giang (HG) provinces (wild strains), and Can Tho (CT, domesticated strain) in the Mekong Delta, Vietnam. The three groups of fish were cultured under optimal maturation conditions in a recirculating system for three months. Then, 16-18 pairs from each broodstock source were artificially propagated. Relative fecundity differed among the sources, from 48,600 (CM) to 69,300 (CT) eggs/kg female (P&lt; 0.05). The three broodstock sources also differed in fertilization and hatching rates. In addition, wild breeders (CM and HG) had slightly larger eggs, and their offspring had larger sizes at hatching and larger yolk sac volumes than those of cultured (CT) breeders (P&lt; 0.05 for all tests, except for egg sizes). In the larval rearing experiment, 2 day-old larvae were stocked in 40 L-rectangle tanks (1,000 individuals/tank) in a recirculating water system. Larvae were fed with Moina combined with commercial feed. After 40 days, survival rates of the three fish groups ranged from 46.7% (CT) to 54.7% (HG). The final weights varied from 177 mg (CM) to 201 mg (HG) and 202 mg (CT). However, the effects of broodstock sources on the growth and survival rates of the offspring were not statistically significant (P&gt; 0.05).

Maturation and Fecundity of Barbus cyclolepis from the Stryama River of the Maritsa River Drainage Basin in Bulgaria

A field-based study of the reproductive aspects of Round-scaled barbel biology took place in the Stryama River, during the autumnal season of the period 2010–2011. This is the first study of the reproduction of this species. A total of 202 Round-scaled barbels were caught by electrofishing. The study found that both sexes reach sexual maturity in their second year. Females became sexually mature, once they reach 94 mm length and 13 g weight. Males became sexually mature once they reach 60 mm length and 12 g weight. Fecundity ranged from 460 to 18.420 eggs. Average fecundity was 6.944 eggs. Absolute fertility was positively correlated with the growth of fish length and mass. Consequently, five years old fish had the highest fertility rate. The average values of relative fecundity were 210 eggs per kilo. The reproductive parameters are an indicator of the growth conditions of the river, as well as the reproductive patterns and state of the fish population. The population parameters, established by this study, now represent a reference point, enabling a monitoring of the species’ population dynamics.

Досвід отримання зрілої ікри сибірського осетра (Acipenser baerii (Brandt, 1869)) у нетрадиційні рибницькі строки

Purpose. To investigate the peculiarities of obtaining ovulated eggs of the Siberian sturgeon in hatchery conditions in non-traditional (winter) period and determine major features of brood fish used for the experiments. Methodology. The material for the study were age-10+ Siberian sturgeon females with body weights of 6.20-8.24 kg grown in conditions of floating cages in a water body with natural temperature regime of the forest-steppe zone of Ukraine. The experiments were conducted with a regulated water temperature regime in the third decade of January with the use of natural gonadotropic drugs for the stimulation of egg maturation in fish. Brood fish were prepared for the experiment in the recirculating aquaculture system. Measurement of fisheries parameters and study of physicochemical factors of the aquatic medium were performed according to generally accepted methods. Experiment results were assessed statistically using standard software. Findings. With water temperature of 14-15оС, depending on the dosage of the gonadotropic drug, different efficiencies of gonad maturation in experimental groups of fish were detected. More than 85% of females matured after dosing of gonadotropic drugs 3.5 and 4.5 mg / kg. In the version with a minimum dose of gonadotropic substance 2.5 mg / kg responded positively to hormonal stimulation 57% of females. The average weight of eggs obtained in some groups of brood fish was 819.5-1079.0 g. Average working fecundity and relative working fecundity in experimental groups of the Siberian sturgeon females varied within 47.95-52.64 thousand eggs and 6.93-7.17 thousand eggs/kg of fish body weight, respectively. The duration of maturation after the second (resolving) administration of the gonadotropic drug until the moment of the occurrence of the ovulation process varied mainly within 15-20 hours. Originality. The peculiarities of obtaining mature eggs of the Siberian sturgeon with the use of methods of industrial reproduction of sturgeons, which are new for the aquaculture of Ukraine, were studied. Practical value. The study results are of interest for the development of modern methods of sturgeon aquaculture in conditions of fish farms of industrial type. Key words: brood Siberian sturgeon, industrial aquaculture, non-traditional technologies, eggs, ovulation, fisheries parameters.

Age, growth, reproductive biology and mortality of Cranoglanis multiradiatus , a threatened freshwater fish in Hainan Island, China

Age, growth, reproductive biology and mortality of Cranoglanis multiradiatus were studied in the present study. A total of 731 specimens were collected monthly using the benthic fyke nets and gillnets from October 2019 to September 2020 in Nandu River. Sagittal otolith was used for age determination, and the maximum age for both female and male was estimated to be 5 years. Female and male C. multiradiatus showed different growth pattern, which was expressed as Lt = 304.48 × (1 + e−0.39 (t + 0.30))−1 and Lt = 273.31 × (1 + e−0.60 (t + 0.29))−1, respectively. The overall sex ratio was 1: 0.56 (male: female). Female attained sex maturity at 3 years (239.00 mm body length). Month variation of gonad-somatic index indicated that the spawning period occurred from April to September. The absolute fecundity was estimated at 2545 ± 1482 eggs per ind. and the relative fecundity was 16.18 ± 9.39 per g. The fishing mortality was 1.05, and the exploitation rate was 0.66, which indicated C. multiradiatus was very likely under overfishing. This study provided data on the key life history traits of C. multiradiatus, which has been not known previously and is essential for conservation strategy and policy development.

Age, Growth, Reproduction and Fecundity of the Sharpsnout Seabream (Diplodus puntazzo Walbaum, 1792) in the Black Sea Region

In this study, the Sharpsnout Seabream (Diplodus puntazzo) population parameters (age, sex composition, length-weight relationship (LWR), age-length relationship, growth parameters, condition factor, gonadosomatic index, reproductive) of the sharpsnout seabream (Diplodus puntazzo) in the southern Black Sea Region have been investigated. In the study carried out between April 2018 and March 2019, 276 sharpsnout seabream were sampled and the average length and weight were calculated as 30.0 cm and 463.9 g, respectively. Male and female ratio was determined as 1:1.32 (P&gt;0.05). Age of fish varied between 0-9 years. The von Bertalanffy growth parameters were L∞=48.1 cm, k=0.2656 year-1 and t0=-1.6587 year for all individuals. The LWR was found as W=0.0399 L2.7212 for all individuals. Total mortality rate (Z=0.560), natural mortality rate (M=0.501) and fishing mortality rate (F=0.059), growth performance index (φ'=2.73) and condition factor value (K=1.55) were calculated. The maximum GSI value was 6.83 in September. Mean relative fecundity was calculated as 14695.4 eggs / 1g. The mean egg diameter was calculated as 486.83µm. This study is very important in terms of being the first study on this species in the Black Sea and will provide a source for future studies.

Experimental evidence for population variability of reproductive traits in Japanese anchovy Engraulis japonicus

Small pelagic fishes show spatiotemporal variations in reproductive traits due probably to responses to varying environmental conditions, but potential genetic contributions to such variations have received little attention. This study compared several reproductive traits of Japanese anchovy between two geographically isolated populations, from the central Seto Inland Sea and Omura Bay, western Japan, under common environmental conditions over three generations. There were no significant differences in age and standard length at sexual maturation between populations. Temperature-mediated variation in egg size was found in the two populations with decrease in egg size as temperature increased. However, regression analysis showed that the relationship between egg size and temperature differed significantly between the two populations over three generations. There was also a significant difference in the relative batch fecundity of the F1 and F2 generations between populations. Hence, females from the central Seto Inland Sea could produce a larger number of smaller eggs than females from Omura Bay. Variation in egg size appears to reflect significant differences in larval size at hatch and the onset of feeding in waters of different temperatures. These findings suggest that the thermal reaction norms of egg size observed in the two populations could have genetic contributions and that their egg traits may mediate a possible difference in offspring viability during early life stages.

Analysis of reproductive patterns of Sardinella longiceps (Valenciennes, 1847) from the Mumbai Sea, Maharashtra, India

In developing countries, management of fisheries resources is directly or indirectly dependent on fish reproductive biology &amp; conservation of the breeding grounds. Indian Oil Sardine fishery is a commercially important pelagic fishery along the coast of Mumbai. A Ganado-somatic index value of females was maximum (8.20) in September and minimum (0.38) in January. For males, the maximum Gonado-somatic index was 8.36 in September and the minimum 0.29 in February. Based on sex ratios month-wise, females were slightly more dominant in all months. There is a significant difference in the length-wise distribution of sexes, with a large number of females in higher length groups. Females attain the length at first maturity at 166.5 mm, and matured ovaries were seen in September and October, with a maximum percentage in September. It is estimated that the absolute fecundity ranged between 28,860 and 52,646, and the relative fecundity ranged between 450 and 684 number eggs per gram of fish weight.

Reproductive strategy of yellow squat lobster (Cervimunida johni Porter, 1903): re-evaluating the maturity criteria

ABSTRACT Studying the basic biology of heavily fished marine species is essential to achieving conservation and sustainable exploitation. Yellow squat lobster (Cervimunida johni) is a demersal crustacean with a long fishing history in the Southeast Pacific. However, knowledge of its reproductive biology is still fragmented, and these traits have never been validated at the gonad level. In this context, we assessed the reproductive traits of this species for the first time based on gonadal development using data from a research survey conducted during 2018 off the Chilean coast. A total of 117 and 376 gonads were assessed based on histological and macroscopic analyses, respectively. The functional and effective criteria (a combination of functional and physiological maturity) were used to estimate the maturity ogives. Using a total of 113 females, fecundity (F) and relative fecundity (RF) at length were estimated using the autodiametric method. We determined that females of yellow squat lobster possess group-synchronous ovary development with indeterminate fecundity. Histological analysis revealed that 59% of non-ovigerous females had mature ovaries and were therefore misclassified as immature based on the functional criterion. Similarly, maturity ogives derived from the effective criterion were displaced to smaller sizes and varied significantly from those estimated using the functional criterion (P < 0.05). In addition, the effects of female size on F and RF were significant (P < 0.05). A warning on the use of functional criteria for assessing maturity status is issued, and the importance of adult females on the per capita contribution to population renewal in this crustacean species is discussed .