Relative Fecundity Research Articles

Sex ratio and fecundity of Chrysichthys nigrodigitatus (Family - Claroteidae) from Asejire Lake, Nigeria

Sex ratio and fecundity of Chrysichthys nigrodigitatus from Asejire Lake were examined. The length-weight relationship showed that weight was curvilinearly related to standard length. The logarithm transformation of weight against standard length gave a straight-line graph represented by the following equation: Log W = -0.66 + 2.13 Log sl r2= 0.854; (p<0.001) n = 209
 Males were generally more with a male : female ratio of 1:0.18. The average fish weight was 88.97g (16.28 cm standard length). Sexual maturity was attained at an average size of 45.0g (14.0 cm standard length). Relative fecundity was dependent on body weight and standard length (P< 0.05 and P < 0.01 respectively). Chrysichthys nigrodigitatus expended between 0.75% - 27.30% of body weight in egg production. The condition factor values showed that a female specimen of equal length with a male specimen is heavier. Six gonad maturity stages were identified, ovary and gonad weights increased with stage of maturity.

Does habitat otherness affect weatherfish Misgurnus fossilis reproductive traits?

The fecundity and sexual structure of weatherfish (Misgurnus fossilis) population, an inperilled and protected freshwater fish with a poorly known life history, was studied in three waterbodies: the River Ner, the Południowy canal and the Nowy Rów canal (Poland) differing in hydrological character. We compared reproductive traits; i.e. sex ratio, absolute and relative fecundity, oocyte size, gonado-somatic index and body condition. In all study sites, the sex ratio of weatherfish did not differ from parity (1: 1), though in the River Ner, the highest GSI values were recorded for females whilst male GSI did not differ among sites. The absolute (FA = 2860 ± 2065) and relative fecundity (FR = 120 ± 55 eggs per g of female body weight) in the River Ner were significantly lower than in the other two sites. In the River Ner the frequency distribution of oocyte diameter, decomposed using the Bhattacharya method, showed two distinct groups in equal numbers. Oocytes that were ready to spawn were larger in the River Ner than in the Południowy and Nowy Rów canals. Fish in the River Ner were also characterized by the lowest Fulton condition index (mean K = 0.36 ± 0.1). The trade-off between impaired fecundity and increased egg diameter may result from the different nature of the studied watercourses or levels of endocrine-disrupting chemicals (EDCs), such as steroid compounds.

Research progress in fecundity study of Coleoidea (Cephalopoda)

Cephalopods are characterized by fast growth, short generation replacement and high abundance. These species live in all oceans of the world with the exception of the Black Sea, not only playing an important role in the trophic webs of the marine ecosystem but also being one of the most important fishery resources in the world. It is important to well study the fecundity of cephalopods, which can improve our understandings of their life history, and more importantly can promote to realize their population dynamics and recruitment processes. Herein, the fecundity of Coleoidea (Cephalopoda) was summarized in details, including the definitions and their determination methodologies, the values of fecundity among species, and the changeable characteristics of fecundity in relation to species body size, egg diameter and living habitats. The potential fecundity was one of the most popular approaches to determine the reproductive value, and represented the theoretical value that one species could produce during its lifecycle. Other approaches such as actual realized fecundity, effective fecundity, and relative fecundity were also used to estimate the fecundity of cephalopod species. It showed that there was species-specific fecundity for Coleoida species. The maximum potential fecundity was reported for <italic>Dosidicus gigas</italic>, and the minimum was reported for <italic>Pareledone turqueti</italic>. The fecundity of Coleoidea was generally found a linear relation to adult body size, indicating a larger body size with a higher fecundity value. At the guild level, there was a significantly negative relationship between the fecundity and egg size for both Octopoda and Teuthoidea. In contrast, there was a slightly positive relationship between the fecundity and egg size for Sepioidea. Generally, species living at lower latitudes exhibited a relatively higher fecundity, and those living at higher latitudes had a relatively lower fecundity. Meanwhile, such fecundity characteristics were also detected at the species level. Water temperature and primary production appeared to be the most important environmental factors that influenced the latitudinal trend of fecundity among the species. It is worthy to note that Coleoida species is semelparous reproduction and the fecundity is associated with the pattern and amount of energy allocation to reproduction. The reproductive investment strategy would determine the actual fecundity of a species and subsequently the biomass of recruitment, and hence studies on the potential reproductive investment will be an important area for better understanding of the fecundity characteristics of cephalopods. Increasingly, the importance of cephalopods has been recognized not only in their ecological roles as trophic indicators but also in their high abundance supporting global fisheries. Therefore, it is necessary to deeply understand the fecundity characteristics of cephalopods, which will largely increase our knowledge about their ecological roles and also assist the sustainable exploitation and the policy-making of resource assessment and management.

Variability of growth, maturation and fecundity of gibel carp (carassius gibelio) in different environments of Uzbekistan

The goal of present study was to examine gibel carp, Carassius gibelio (Bloch, 1782) growth, maturation, fecundity and ripe eggs size under pond fish culture conditions and conditions of natural water bodies of the River Syrdarya, Uzbekistan. Gibel carp originally came from the River Amur (Russia), it was introduced to Uzbekistan in 1950s. Recently, it is wide spread species in local ichthyofauna. Females matured for the first time at age 2 years: in ponds in 8-10 cm in standard length, in the river in 18-20 cm. The GSI increased to spawning up to 2.9 – 25%. In fish farm ponds absolute fecundity was 1,4 – 51,300 eggs, in the River Syrdarya - 9,2 – 91,400 eggs. Relative fecundity in all populations was 21 – 590 eggs/g in weight of gutted fish. In April, there were two peaks of ripe and yolk eggs size: 1st - 0.89 – 1.69 mm, 2nd – 0.69-0.9 mm.

Differences in the reproductive traits of Pacific bluefin tuna Thunnus orientalis among three fishing grounds in the Sea of Japan

Differences in the reproductive traits of Pacific bluefin tunaThunnus orientalis(PBF) in the Sea of Japan (SOJ) were investigated to evaluate the reproductive potential in 3 fishing grounds (i.e. northern, central and southern areas). The size distribution of PBF differed among the fishing grounds, with smaller fish (100-130 cm in fork length, FL) being caught in the central and northern areas of the SOJ. Spawning-capable females were found at sea surface temperatures (SSTs) between 17 and 25°C, with most SSTs &gt;21°C. Seasonal changes in SST differed among the fishing grounds, and the period when SST exceeded 21°C differed in each fishing ground. Spawning-capable females were found at different times among the fishing grounds, and were observed throughout the fishing season in the southern area of the SOJ. The mean ± SD relative batch fecundity was estimated to be 69.8 ± 45.3 and 92.7 ± 43.1 oocytes g-1in the central and southern areas of the SOJ, respectively. The total spawning fraction was 0.2, 0.38 and 0.73 in the northern, central and southern areas of the SOJ, respectively. SST and FL were positively correlated with the batch fecundity. In addition, FL, SST and location affected the probability of occurrence of spawning-capable fish among mature fish. Therefore, the difference in the observed reproductive potential of PBF among fishing grounds in the SOJ can be linked to the differences in seasonal increases in SST and the size distribution of adult fish.

Importance of Depth and Artificial Structure as Predictors of Female Red Snapper Reproductive Parameters

AbstractThe Red Snapper Lutjanus campechanus is a structure‐associated species occurring across a wide depth range in the northern Gulf of Mexico. We used the random forest machine learning algorithm to understand which habitat and individual fish characteristics could predict reproductive parameters of female Red Snapper. We evaluated fish captured from 2016 to 2018 on three artificial structure types with various structure heights at depths of 100 m or less. Overall, we found that depth and month were important predictors for most reproductive parameters, but the type of structure (artificial reefs, oil platforms, and rigs‐to‐reefs structures) was not important. Maturity was correctly classified in 88.9% of the cases when using the random forest ensemble model, with important predictors including FL, depth, structure height, and month of collection. Spawning seasonality (measured as gonadosomatic index [GSI]) was correctly classified in 59.5% of the cases when using histology reproductive phase, FL, month, and depth variables. Reproductively active or inactive females were correctly classified in 89.3% of the cases using GSI, month, FL, and depth, while females in the developing versus spawning capable phases were correctly classified in 82.2% of the cases using GSI, FL, month, and depth. Histological indicators that show potential spawning within a 36‐h period were correctly classified 61.5% of the time, with the best predictors being depth, FL, GSI, and month. Stepwise regression indicated that month was the only factor that significantly predicted contrasts in relative batch fecundity, with significantly greater values in August compared to all other months. Our findings suggest that female Red Snapper reproductive effort is not consistently or well predicted by artificial structure type or height but that a combination of fish FL, month, and depth can predict reproductive characteristics of female Red Snapper.

Influencia del tamaño, variedad y relación hembra macho en la producción de huevos de tilapias (Oreochromis spp.) en tanques de concreto en el pie de monte andino venezolano

The aim of this study was examine the effect of the variety, size and male female ratio in the egg production of tilapia Chitralada (CH: Oreochromis niloticus) and Taiwanese Red (TR: O. mossambicus x O. niloticus) reared in tanks of concrete. The study was conducted in a fish farm located at the Venezuelan Andean foothill of Trujillo state, Venezuela. A 2x2x3 factorial arrangement was applied: two varieties (CH and TR), two sizes (small and large) and three sexual relations (1♀ : 1♂; 2♀: 1♂; 3♀: 1♂). The data were processed by analysis of variance using the general linear model of the SAS. The CH females produced 1.5 times more eggs, which weighed 1.6 times more and had a fecundity 1.6 greater than the TR (P 0.05), while large CH females produced a greater egg volume (8.91 ± 0.79 versus 6, 20 ± 0.79; P<0.01) and egg mass (7.99 ± 0.67 versus 5.65 ± 0.67; P<0.01), and were more fertile (1210.5 ± 113,4 versus 911.4 ± 113.5; P<0.10) than the smaller ones. In addition, large CH tilapia were reproductively more efficient than the same category of TR. In CH females the sex ratios did not affect most of the variables studied, with the exception of relative fecundity that was greater in the 2:1 ratio than in the 1:1 and 2:1 (154.4 ± 21, 4 versus 129.9 ± 18.1 and 133.1 ± 14.6 respectively; P<0.01). In contrast, in the TR females that were in a 3:1 sex proportion, the reproductive performance was considerably lower than those that were in a 1:1 or 2:1 sex ratio, and even, their performance was significantly lower than CH females of the same proportion (P<0.01). In conclusion, CH tilapias and females of larger size and weight were reproductively more efficient than those of the variety TR and those of smaller size; whereas the reproductive activity was not affected by the sex ratios considered in the study.

The first data on the population parameters and morphometry of Mesogobius batrachocephalus (Pallas 1814) (Family: Gobiidae) in the southern Black Sea

Knout goby, Mesogobius batrachocephalus Pallas, 1814, which belongs to Gobiidae, inhabits in the Black Sea, Sea of Azov, the Caspian Sea and the rivers that flow in these three seas. The major population parameters and morphometry of Mesogobius batrachocephalus from the coasts of the southern Black Sea were investigated in this study. A total of 641 individuals were sampled between January 2019 and December 2019 between the depths of 2 to 120 m depth by using a trammel net with a mesh size of 17-24 mm. The average length and weight values were calculated as 23.1 cm (5.3-34.0) and 130.1 g (1.34-377.54) respectively. The male to female ratio of the population was found as 1:0.91 (P&gt;0.05). Age of sampled 641 individuals varies between zero and seven. For all the sampled individuals, the von Bertalanffy growth parameters were calculated as; L∞ = 38.2 cm, k = 0.245 year-1 and t0 = -1.873 year and the length-weight relationship was found as W = 0.0058 TL3.148. Total mortality (0.481), natural mortality (0.466), fishing mortality (0.015), growth performance index (2.55) and condition factor (0.913) were calculated. The maximum value of gonadosomatic index was reached in March. Average relative fecundity was found to be 118.3 eggs per g (78.9-234.5), while the average diameter of the eggs was found as 2733.0 µm ±221.18 (2287.1-3097.8). This study provides the first data on the population parameters and the morphometry of Mesogobius batrachocephalus. These data could contribute to the establishment of a sustainable management plan for fisheries resources in the Black Sea.

FECUNDITY IN THE CALICO SURFPERCH, AMPHISTICHUS KOELZI (TELEOSTEI: EMBIOTOCIDAE)

The Calico Surfperch (Amphistichus koelzi) shares a similar size, morphology and feeding habitat with its 2 widely-sympatric congeners, the Barred Surfperch (Amphistichus argenteus) and Redtail Surfperch (Amphistichus rhodoterus). Like the other 2 species, A. koelzi is an important commercial and recreational resource, but unlike these species, A. koelzi has received virtually no attention in the scientific literature. We found average relative fecundity to be significantly higher than in A. koelzi's 2 congeners, A. argenteus and A. rhodoterus, and the slope of the regression of brood count on female size in A. koelzi was steeper and translated to the left of the same slopes representing the 2 congeners.

Biology and fishery of pond smelt Hypomesus olidus in the Amur River basin

In the Amur River, there are two ecological forms of pond smelt Hypomesus olidus: anadromous and freshwater. Generalized information about biology and fishery of the anadromous form of pond smelt is presented. The smelt migrate to the Amur for spawning in winter and spring, and for wintering in autumn. The most remote point of their spawning migration is Bolbinsky cliff (375 km from the mouth). The spawning herd is represented by three age groups: 2-, 3-, and 4-year-old fish; the two-year-old fish are the most numerous. The sex ratio of spawning smelt is close to 1 : 1, though females prevail slightly. Body length of the pubescent fish ranges from year to year from 7.6 to 13.2 cm, body weight — from 3.05 to 16.04 g; females are slightly larger than males. Absolute fecundity of pond smelt ranges from 0.7 to 12.4 thousand eggs, relative fecundity — from 199 to 1287 eggs/g. During migration to the spawning grounds, the smelt practically do not feed, but they go to active feeding after spawning. Pond smelt is a popular object of fishery in the Amur basin: on average 1569.2 t were caught annually in 2010–2019, during the spawning migration, mainly in the lower Amur River between Nikolayevsk-on-Amur and Bogorodskoe.

Comparative characteristics of growth of the scales from pink salmon in returns to Sakhalin Island (southeast coast) and Iturup Island in 2017 and 2018

Iturup Island (in southern Kuril Islands) and southeastern Sakhalin Island are known by the highest catches of salmons within the Sakhalin-Kuril region. The timing of pink salmon mass return to Iturup is 5–10 days later than to Sakhalin, and the females returned to Iturup have higher relative individual fecundity, on average. In 2014, an unexpected increase of pink salmon catches occurred on southeastern Sakhalin Island, with a simultaneous sharp decrease of the catches on Iturup Island. Assumption on appearance of Kuril pink salmon in the Sakhalin waters was confirmed by analysis of the scale parameters (number of sclerites and intercirculi distance in the first-year scale zone), dynamics of catches, and individual fecundity of females. Sharp opposite changes of the pink salmon catch dynamics were noted again for these areas in 2017 and 2018. Such changes of pink salmon abundance could be reasoned by environmental conditions of reproduction in these areas or new redistribution between two areas. To clarify the issue, complex analysis (same as for 2014) was applied for pink salmon at southeastern Sakhalin and Iturup in 2017 and 2018 (187 and 215 fish samples from Sakhalin and 194 and 152 fish samples from Iturup in these two years, respectively). The results were interpreted following the hypothesis of fluctuating stocks. Taking into account the complex of traits, there is concluded that the assumption about redistribution of pink salmon between southeastern Sakhalin and Iturup Island in 2017 and 2018 is untenable.

A first assessment of atresia in the Chilean jack mackerel &lt;i&gt;Trachurus murphyi&lt;/i&gt; (Teleostei, Carangidae) from the South-eastern Pacific Ocean

The Chilean jack mackerel Trachurus murphyi support an important fishery in the South-eastern Pacific Ocean and has declined considerably over time. T. murphyi have asynchronous ovarian development with an oceanic spawning (September to January). Despite the economic importance of this resource critical issue such as characteristics and dynamics of atresia, which affect the reproductive output, are unknown. Females of T. murphyi caught in different spawning seasons were analysed to describe patterns of prevalence and intensity of atresia. General linear models (GLM) were performed by using prevalence and intensity atresia as response variables and gonadosomatic index, condition factor, sea surface temperature, postovulatory follicles and month/year as explanatory variables. The batch fecundity and relative fecundity were compared between females showing atresia, postovulatory follicles and non-atretic females. The stages of atresia identified were alpha, beta and gamma. The GLM showed that variations in the prevalence and intensity of atresia were explained for all variables, except condition factor for prevalence, and gonadosomatic index for intensity of atresia. According to our results, the dynamic of alpha and beta atresia could be considered a potential proxy for any disruption of spawning season. The batch fecundity and relative fecundity were lowest compared with other Trachurus spp. This is the first assessment comparing fecundity between atretic and not atretic females for this species.

Standardization of oocyte size during artificial fertilization and optimization of stocking density during indoor larval and outdoor nursery rearing of captive spotted scat (Scatophagus argus) for a viable juvenile production system

The present study describes the viable and efficient hatchery seed production technique to maximize spotted scat (Scatophagus argus) juvenile production in captivity during the breeding season. Broodstock fish maintained in the earthen pond of hatchery were selected according to varying mean oocyte diameter (MOD) ranging from 351 to 400 (T1), 401–450 (T2), 451–500 (T3), and > 500 μm (T4) according to natural vitellogenesis progression. Breeding pairs were formed as two males: one female. Females (n = 24) were induced with a double dose of hCG (2000 IU kg−1 body weight day−1) and a single dose of LHRHa (400 μg kg−1 body weight) each at 24 h interval, whereas males (n = 48) received a single dose of LHRHa (200 μg kg−1 body weight). Females in T4 were spawned through dry stripping earliest at 30 h post hormone induction, whereas females of the T1 group spawned last at 33 h. The largest (P < 0.005) diameter (718.33 ± 3.28 μm) of fertilized eggs was observed in T4, whereas the smallest (652.33 ± 18.68 μm) fertilized eggs were observed in T1 post-fertilization. Significantly highest absolute and relative fecundity was found in T5 (1060.67 ± 45.36 and 213,239.7 ± 17,324.9, respectively), whereas T1 and T2 exhibited no significant difference. The dry stripped eggs were fertilized with milt and incubated for 22 h for hatching. Females in T4 achieved the greatest fertilization (98.67 ± 0.88) and hatching (97 ± 2.08) percentages significantly. The initial oocyte size range of 351–400 μm in T1 led to the lowest fertilization (17 ± 3.46) and hatching (10.67 ± 3.92) percentage. Subsequently, scat juvenile production techniques were standardized by conducting two experiments on stocking densities of larvae and fry. Hatchlings were first reared in the mesocosm larval rearing system in an indoor hatchery with four different stocking density of 2 (SD2), 4 (SD4), 6 (SD6), 8 (SD8) larvae L−1 for 30 days. Stocking density of 4 and 6 larvae L−1 achieved the highest survival of 53.05 ± 1.01% and 51.03 ± 1.23%, respectively. On completion of metamorphosis (30 dph), fry were shifted to hapa based rearing in a pond with three different stocking density of 2000 (SD2000), 3000 (SD3000), 5000 (SD5000) fry m−3 for 30 days. Highest survival percentage of 78.94 ± 2.78 found in SD3000. Present study standardized the operation protocol for a commercial hatchery aiming for juvenile scat production by selecting females with initial oocyte size >500 μm diameter for artificial fertilization. Seed production can be optimized by adopting a stocking density of 4–6 larvae L−1 in the indoor larval rearing and 3000 fry m−3 in outdoor hapa based nursery systems.

FECUNDITY ANALYSIS OF A FRESHWATER FISH MASTACEMBELUS ARMATUS (LACEPEDE) FROM RIVER NAYAR, UTTARAKHAND

Mastacembelus armatus (Lacepede) is one of the most important eel like hillstream fish belonging to order Mastacembeliformes and family Mastacembelidae. During last few decades, the population of this species is considerably declining due to overfishing and other anthropogenic activities. Present investigation is an attempt towards conservation of this species in which reproductive power of the fish is estimated and preferred habitat and breeding grounds of fish were studied. The fish is monsoon breeder with maximum fecundity 11810.667±1716.994, observed in a fish size of 42.233±1.365 cm and body weight 153.333±7.638 g. The size of mature egg ranges from 1.2-1.6 mm. With the help of regression analysis, the relationship of fecundity with different body parameters was also traced out. It is suggested that avoiding fish catch during breeding season will be very helpful in conservation of species.

Common carp maturation and fecundity and reproduction optimization in Uzbekistan

Reproductive biology of cultured common carp in Uzbekistan was studied. The ages, total lengths of the samples studied ranged 1-5 years, 5.0 - 87.0 cm in standard length. In spring, 1-year-old fish (8.0-25.0) cm had gonads at stage I; 2-years-old females (18.0 – 33.0 cm) had gonads at stage I (23 %) and II (77 %); 3-years-old females (25.6–47.1 cm) had ovaries at stage II (43 %) and III-IV (57 %); all 4-year-old and 5-year-old females were mature. Females mature when they reached 32 cm in standard length. Absolute fecundity varied 131–1830 thousand eggs, relative fecundity was 190.5–344.0 eggs/g of gutted fish body, real fecundity was 200.0–1300.0 thousand eggs. Average individual ripe egg size varied 1.32–1.52 mm. Positive correlation between maturation, absolute fecundity and growth was determined. For broodstock forming optimization, additional (to body size) fish characteristic should be entered to selection; fish growth could be recommended as such measure. Annual artificial selection of fishes with standard length at different ages (at least SL1 – 13 cm; SL2 - 25 cm; SL3 – 32 cm) would form broodstock which mature at 3-years-old age with real fecundity 800 – 1300 thousand eggs.

Cultivation of Triple Hybrids of Russian, Siberian, and Amur Sturgeons at a Warm-Water Fish Farm

This study provides biological, fishery, and production characteristic of spawning females of a triple hybrid between the Russian sturgeon, Siberian sturgeon, and Amur sturgeon (RS × SS) × AS and other commercial hybrid sturgeon forms grown in the cages of a warm-water fish farm in Primorsky Krai, Russia. The survival rate of larvae and juveniles of the triple hybrid in conditions of warm-water pools and the survival rate of marketable-size sturgeon was higher than those of Amur sturgeon and hybrids between the Russian and Siberian sturgeons. The weights of the triple hybrid individuals at an age of 3 and 4 years were 1.58 and 2.36 kg, respectively. These values were higher than those recorded for the hybrids between Russian and Siberian sturgeons and close to the standard values for Amur sturgeon. The fish productivity reached 94 kg/m2 of cage, or 134 kg/m2 of cage taking fish that were sold into account. The values of this index were much higher than the standard values not only for Amur sturgeon, but also for other sturgeon species and hybrids. Up to 93% of the females reached maturity after being treated with a hormone-stimulating drug. The first female of the triple hybrid sturgeon became mature at an age of 9 years with a body weight of 13.1 kg. Maturation of the other females of the same year-class was stretched in time and lasted for 7 years, up to 16 years of age. Approximately 75% of them reached maturity at an age of 10–12 years. The maximum recorded weight of a female triple hybrid was 29 kg at an age of 14 years. The inter-spawning interval for 97% of females was 1–2 years. The average annual yield of hard roe obtained from one female at an age of 9–16 years per spawning event was 2.28 kg; the weight of one egg was 17.6 mg; the fecundity was 132 000 eggs; the relative working fecundity was 7440 eggs/kg; the oosomatic index was 12.8%. The values of most of the production indices for the female triple hybrids were intermediate between those characteristic of the initial species used for crossbreeding. For three or four spawning seasons, an average of 5.25 kg of hard roe, or 30% of body weight, was obtained from one female triple hybrid. The roe yield from the most productive females was 10.8–11.0 kg, or 55–73% of body weight. The roe of the triple hybrid sturgeon was distinguished by high quality and was used for manufacturing food products. Females were technologically well adapted for roe stripping and showed a high survival rate of approximately 98% during long-term exploitation. Thus, the triple hybrid of the Russian, Siberian, and Amur sturgeons can be recommended for commercial cultivation with a high production output at warm-water sturgeon farms. Female triple hybrids can be used for the production of quite large amounts of high-quality food caviar. Their roe yield is lower than that in Amur sturgeon and does not differ significantly from the roe yield in the hybrid between the Russian and Siberian sturgeons.

Fitness cost of imidacloprid resistance in the cotton-staining bug, Dysdercus koenigii

Dysdercus koenigii, a serious cotton-staining insect pest in many countries, has shown high resistance to imidacloprid, a systemic neonicotinoid insecticide used to control sap-sucking pests. With the aim of creating an effective management strategy, the biological traits of susceptible (SS) and imidacloprid-resistant (Imida-RS) D. koenigii, as well as their reciprocal crosses (CR1 and CR2), were investigated here using a life table established on age, stage, and two-sex patterns. Compared with SS D. koenigii, Imida-RS and CR1 strains had lower relative fitness (0.80 and 0.47, respectively) and fecundity (eggs per female); prolonged egg duration and a prolonged adult preoviposition period; shorter nymphal duration, male/female total longevity, and oviposition days, and a shorter total preoviposition period. However, there were no differences among strains in nymphal survival rates and female ratio. The CR2 D. koenigii had similar relative fitness value (1.09), suggested no fitness cost in most of the parameters. Demographic parameters, including net reproductive rate, were lower in the Imida-RS strain than in SS and CR2 D. koenigii. Similarly, the Imida-RS and CR1 strains had shorter generation time and doubling time, lower reproductive value and life expectancy relative to the SS and CR2 D. koenigii. In addition, age-specific fecundity was negatively affected in the CR1 strain compared with the other strains. These findings could help facilitate the development of rational D. koenigii control strategies.

Effect of hormonal stimulation on captive broodstock maturation, induced breeding and spawning performance of striped snakehead, Channa striata (Bloch, 1793)

In the present study, there was assessment of effects of gonadotropin treatments on broodstock maturation, induced breeding, and spawning outcomes of striped snakehead in captivity. The striped snakehead (n = 128) were equally distributed in four concrete tanks (15 m2) and hormone implants (500 IU human chorionic gonadotropin (hCG)/kg body weight) were inserted intramuscularly and striped snakehead broodstock administered this treatment were confined in two tanks and striped snakehead of a non-implanted group were confined in two tanks. The hormone implanted striped snakehead had a greater (P < 0.05) gonadosomatic index (GSI) and oocyte diameter in comparison to non-implanted striped snakehead. In a subsequent experiment, hCG and carp pituitary homogenate (CPH) were evaluated for inducing breeding. Dosages of hCG used were, 2,000 (TH1), 3000 (TH2), and 4000 (TH3) IU hCG/kg body weight of females. Dosages of CPH were, 20 (TP1), 30 (TP2), and 40 (TP3) mg CPH/kg body weight of females. Males were administered 0.75 of the dosage administered to females. The values for reproductive variables were estimated. Fertilization (89.0 ± 3.0 %) and hatching (92.0 ± 1.0 %) rates were greater (P < 0.05) in the TH1 group of implanted striped snakehead. Relative fecundity (19,023 ± 2211), as well as fertilization (96.2 ± 2.4 %), and hatching (96.6 ± 1.7 %) rates were greater in the TP2 group of the implanted striped snakehead. The results from the present study indicate broodstock treated with gonadotropins had greater spawning outcomes which might facilitate mass scale breeding and fertilized egg as well as juvenile production of striped snakehead in captivity.

Effectiveness of Curcumin Supplementation in feed on liver productivity and reproductive performance of female carp Cyprinus carpio L.

The availability of quality seeds, on time with large amounts is a major problem in freshwater aquaculture. Supplementation of curcumin in female carp aims to increase the reproductive productivity of fish through increased activity of the liver in the synthesis of vitellogenin, a precursor of egg yolk, that play a role in the growth and development of eggs until larvae. This study used 25 female carp, which supplemented with curcuminat several doses: 0; 2.5; 5; 10; and 20 g of curcumin/kg of feed. The collected data was analyzed using a completely randomized design (CRD). The results showed that supplementation of curcumin female carp significantly (p&lt;0.05) affected the malondialdehyde(MDA) concentration of liver, estradiol hormone in the blood, gonadosomatic index, relative fecundity, and larval survival, but did not significantly (p&gt;0.05) affect the superoxide dismutase (SOD), vitellogenin concentration in blood and egg diameter. The study showed that the supplementation of curcumin prevents liver damage showed by a decreased level of liver MDA. The supplementation of curcumin with a dose of 5 g/kg of feed optimizes the productivity and reproductive performance of carp by increasing the production of vitellogenin, the diameter of egg, and the number of survival larva through optimizing the performance of the fish liver.

Reproductive Cycle and Fecundity Tristramella simonies (Gunther, 1864) (Teleostei: Cichlidae) in the Northern Great River (Lattakia, Syria)

This research was conducted to study the reproductive cycle and fecundity of the fish Tristramella simonis in the Northern Great River (Nahr Alkabeer Alshmali) north of Lattakia city. 263 individuals were collected from the northern great river, during the period between July 2017 and June 2018. Samples were collected every 15 days using gill nets, which its pores diameter ranged from 16 to 20 mm and using cages (1 × 1 × 1 m). The total length of the collected fish ranged from 9.5 to 16.5 cm, and their weights ranged from 19.5 to 112.27 g. Samples contained (128 females) and (88 males) and (47) undetected. Results of Gonado Somatic Index (GSI) showed that the reproduction period was between April and August with three obvious peaks of maturity. Where the highest value of GSI was (10.06±8.46) % for females and (0.13 ± 0.05) % for males. Results of Hepato Somatic Index (HSI) was concurrence highly with the ecological and physiological changes, which result from changes in sexual activity during the reproductive cycle. Where the highest value of HSI attained 3.79 ± 1.86 % for females and attained 3.95 ± 1.38 % for males. In the first sexual maturity, the length attained 13.31 cm for females and (14.87 cm) for males. The sexual rate was (1: 0.7), which means 40.7 % males and 59.3 % females in the population. The absolute fecundity ranged from 940 to 1229 egg. While the relative fecundity ranged between 158- 215 egg/ g of ovary weight. Egg diameter during reproduction season ranged between 2.4- 4 mm, with several sizes, which mean a relatively long reproduction term.