Spawning Rate Research Articles

Effects of Temperature on Reproductive Performance, Embryonic Quality, and Embryonic Development of Chinese Mitten Crab

To explore the effects of temperature on the reproductive performance and embryonic development of female Eriocheir sinensis broodstock, the reproduction experiments of broodstock crabs under different temperatures (6, 9, 12, 15, 18, and 21°C) were carried out. Each temperature was replicated in three parallel tanks, with 5 male and 10 female crabs stocked in each tank for feeding. The results showed that with the rising of temperature, the mating rate of broodstock crabs increased gradually, the spawning rate, spawning amount, fecundity and reproductive index increased first and then decreased. At 15°C, the spawning rate, spawning amount, fecundity and reproductive index of the broodstock reached the highest and significantly higher than other temperature groups (p < 0.05). At 18°C, the egg diameter of embryos reached the largest. At 18°C, the contents of crude protein, triglyceride (TG) and total cholesterol (CHL) of embryos in E. sinensis were the highest. With the rising of temperature, the embryonic development rate of E. sinensis accelerated, the embryonic development time of the crabs was shortened and the effective cumulative temperature was gradually decreased. At 6°C, embryos stagnate at the fertilized egg stage, while at 9°C, they develop to the multicell stage but cease division thereafter. In conclusion, the best reproductive performance of the Chinese mitten crab was achieved at 15°C and the quality of embryos produced at 18°C was relatively good. The results of this study not only provided basic data for the breeding biology of E. sinensis but also provided scientific support for the conservation of fishery resources in the Yangtze River Estuary.

Effects of Geographical Origin and Timing of Broodstock Collection on Hatchery Conditioning of the Clam Ruditapes decussatus (L. 1758).

The grooved carpet shell clam (Ruditapes decussatus), widely found along Morocco's coasts and estuaries, is a key economic resource due to its high market value. However, clam production has declined over recent decades, largely due to the overexploitation of natural beds, and recruitment failures, leading to a limited wild spat availability. This study examined how the broodstock collection season (winter vs. summer) and origin (South Atlantic vs. North Mediterranean) affect broodstock performances in hatcheries. The maturity development (condition index (CI) and gonadal condition index (GCI)), histological examination, and reproductive output were evaluated. The results showed that Mediterranean clams achieved a higher maturity during winter conditioning (CI = 13.60 ± 1.02, GCI = 6.01 ± 0.90) than the Atlantic population (CI = 11.51 ± 1.50, GCI = 5.31 ± 1.14). Moreover, Mediterranean clams produced more oocytes per female (2.34 million), despite the lower spawning rate (42%), compared to the Atlantic clams (1.68 million) with a 69% spawning rate by the end of the winter conditioning. These findings highlight the importance of selecting broodstock by geographic origin to optimize shellfish hatchery production.

The endoplasmic reticulum as an active liquid network

The peripheral endoplasmic reticulum (ER) forms a dense, interconnected, and constantly evolving network of membrane-bound tubules in eukaryotic cells. While individual structural elements and the morphogens that stabilize them have been described, a quantitative understanding of the dynamic large-scale network topology remains elusive. We develop a physical model of the ER as an active liquid network, governed by a balance of tension-driven shrinking and new tubule growth. This minimalist model gives rise to steady-state network structures with density and rearrangement timescales predicted from the junction mobility and tubule spawning rate. Several parameter-independent geometric features of the liquid network model are shown to be representative of ER architecture in live mammalian cells. The liquid network model connects the timescales of distinct dynamic features such as ring closure and new tubule growth in the ER. Furthermore, it demonstrates how the steady-state network morphology on a cellular scale arises from the balance of microscopic dynamic rearrangements.

Hormone-Driven Temperature Optimization for Elevated Reproduction in Goldfish (Carassius auratus) under Laboratory Conditions.

This study investigates the efficacy of hormone-induced artificial reproduction in goldfish (Carassius auratus) under controlled temperatures. Ovaprim injections significantly enhanced ovulation and sperm production compared to controls. Medium temperature (22 °C) produced the highest ovulation rates, fastest ovulation timing, and optimal sperm quality (motility and morphology) compared to high (28 °C) and low (16 °C) temperature groups. The low-temperature group exhibited reduced sperm motility duration and higher rates of sperm and larvae damage. The sperm volume of the high-temperature group was higher, but their post-injection survival rates were lower. Furthermore, the lowest spawning rate and low egg quality were noted in the high temperature. Cryopreservation using extender E4 (15% DMSO) exhibited superior post-thaw sperm motility and achieved higher fertilization rates. Fertilization rates, embryo development, and larval survival were all highest at the medium temperature. Larvae hatched from fresh sperm at medium temperature exhibited faster growth and fewer deformities. These findings suggest that hormone stimulation coupled with a medium temperature regimen is critical for successful artificial reproduction in goldfish. Cryopreservation with extender E4 holds promise for sperm banking; however, further optimization is necessary to improve fertilization success with thawed sperm. Future research could explore the influence of temperature on sperm physiology and refine cryopreservation protocols to enhance fertilization rates.

Administration of Arginine Vasotocin and modified Isotocin improve artificial propagation and post-spawning survival of female yellow catfish

Low rate of spawning and high percentage of death after artificial propagation are frequently observed in catfish, which do harms to the long-term population stability and genetic breeding programs in aquaculture. In this study, yellow catfish (Pelteobagrus fulvidraco), an important freshwater species in China was used as a research model, since the farmed female yellow catfish had poor reproduction performance and a high death rate after treatment with the traditional exogenous hormones, luteinizing hormone releasing hormone analogues2 (LHRH-A2) and human chorionic gonadotropin (HCG). We tried to investigate the roles of the Arginine Vasotocin (AVT)/ Isotocin (IT) neuropeptide family in reproduction and design an optimal strategy for inducing artificial propagation in yellow catfish. Two copies of pro-avt and pro-it were detected in hypothalamus and ovaries of yellow catfish, and their mRNA levels gradually increased during spring-summer season. Furthermore, the transcript levels of pro-avt and pro-it in hypothalamus significantly increased after injection of LHRH-A2 and HCG. Although AVT could not induce germinal vesicle breakdown (GVBD) in female yellow catfish, administration of AVT significantly stimulated premature ovulation in a dose-dependent manner and induced the expression of ovulation-related genes, ptgs2a and acvr1. Furthermore, there is a significant up-regulation of serum prostaglandin E2 (PGE2) and luteinizing hormone (LH) in female fish after AVT treatment, whereas no difference was observed in follicle stimulating hormone (FSH). Since IT of yellow catfish was insoluble in saline, a rigid peptide segment was added at the end of IT (the modified IT was named IT-M), which could greatly improve its solubility and induce ovulation in female yellow catfish. Subsequently, we demonstrated that adding carp pituitary extraction (CPE) to the second injection of traditional methods could efficiently improve the spawned fish, eggs production, fertilization rate, hatching rate and post-spawning survival of female yellow catfish, despite at a relatively high cost in hormones. We further discovered that IT-M + AVT could substitute for HCG + CPE in the second injection and had high efficiency in artificial propagation, reducing the hormone costs to less than one-third. Altogether, we provide an effective and affordable combination of exogenous hormones to improve reproduction performances and post-spawning survival rate in yellow catfish.

Genetic parentage reveals the (un)natural history of Central Valley hatchery steelhead.

Populations composed of individuals descended from multiple distinct genetic lineages often feature significant differences in phenotypic frequencies. We considered hatchery production of steelhead, the migratory anadromous form of the salmonid species Oncorhynchus mykiss, and investigated how differences among genetic lineages and environmental variation impacted life history traits. We genotyped 23,670 steelhead returning to the four California Central Valley hatcheries over 9 years from 2011 to 2019, confidently assigning parentage to 13,576 individuals to determine age and date of spawning and rates of iteroparity and repeat spawning within each year. We found steelhead from different genetic lineages showed significant differences in adult life history traits despite inhabiting similar environments. Differences between coastal and Central Valley steelhead lineages contributed to significant differences in age at return, timing of spawning, and rates of iteroparity among programs. In addition, adaptive genomic variation associated with life history development in this species varied among hatchery programs and was associated with the age of steelhead spawners only in the coastal lineage population. Environmental variation likely contributed to variations in phenotypic patterns observed over time, as our study period spanned both a marine heatwave and a serious drought in California. Our results highlight evidence of a strong genetic component underlying known phenotypic differences in life history traits between two steelhead lineages.

Persilangan Ikan Nila (Oreochromis niloticus) Dari Berbagai Varietas Serta Ikan Mujahir (Oreochromis mossambicus) Untuk Mendapatkan Benih Bersifat Unggul

This research aims to produce seeds from the crossbreeding of nile tilapia (Oreochromis niloticus) of the jabir, nirwana, and sultana strains, as well as Mozambique tilapia (Oreochromis mossambicus). The crosses involved using male jabir nile tilapia with female nirwana nile tilapia and male mozambique tilapia with female sultana nile tilapia. The breeding was conducted in a 1:3 ratio of male to female. The spawning process occurred over a 16-day cycle, followed by a 28-day period of larval rearing. Crossbreeding between jabir and nirwana resulted in a higher spawning rate (17%) compared to the crossbreeding of mozambique and sultana (7%). The specific growth rate of seeds from the jabir and nirwana cross (14%) was not significantly different from the mozambique and sultana cross (13%). The survival rate of seeds from the jabir and nirwana cross (80%) was higher than from the mozambique and sultana cross (70%). Crossbreeding between male jabir nile tilapia and female nirwana nile tilapia exhibited better performance compared to the crossbreeding of male mozambique tilapia and female sultana nile tilapia.

Growing (Pleurotus Pulmonarius) on Various Local Substrates in the Kurdistan Region of Iraq

In this study the effect of five locally sourced organic substrates as raw material and supplemented with CaSO4 2%, CaCO3 2% and wheat bran10% and three levels of spawning rates (5, 10, and 15%) on growth, morphological characteristics and chemical composition of Pleurotus Pulmonarius mushrooms were examined. These organic ingredients include: (Wheat straw (WS), Rice straw (RS), cardboard, Populus Canadensis sawdust (PC), and Salix Alba sawdust(WW). The study found that organic substrates, such as wheat straw and rice straw, had a significant effect on the mushrooms’ fresh weight 1087.33g and 1030.67g respectively. Supplements increased the fruit content of crude protein15.3%, nitrogen2.44%, fiber15.44%, and carbohydrates 50.44% without affecting vitamin C 3.38 mg/100 g. It also found that a spawn rate of 15% was optimal for protein19.62%, nitrogen 3.13%, carbohydrates 52.26%, and vitamin C 4.1 mg/100 g content in the fruits, while the lowest content was observed at a spawn rate of 5% protein 8.87%, nitrogen 1.42%, carbohydrates 46.31%, and vitamin C 2.6 mg/100 g content in the fruits.

Gonad maturation and spawning performance of the sand sea cucumber (Holothuria scabra) by Oodev® dan Ovaprim® administration

Sea cucumber (Holothuria scabra) contains lots of collagen and vitamin E for the pharmaceutical and cosmetic industries. H. scabra have high economic value. The price in the local market is IDR 400,000–1,200,000/kg and internationally it is IDR 500,000–IDR 5,000,000/kg dry weight. The level of exploitation is high, and it is suspected that there has been overfishing in several areas. Cultivation efforts need to be done to maintain the population in nature. The natural rate of gonad maturation and spawning in H. scabra broodstock is relatively slow, so efforts are needed to speed it up, among other things by administering hormones. This study aimed to stimulate (1) gonad maturation and (2) H. scabra spawning. The study used a completely randomized design (CRD) with 3 treatments and 3 replications in 2 stages using broodstock measuring 250–350 g/head. Stage 1: (1) Treatment A: without immersing the H. scabra in hormone solution, (2) Treatment B: immersing the H. scabra in the Oodev®/Oocyte developer dose of 1 mL/kg weight, and (3) Treatment C: soaking sea cucumber broodstock in Oodev® dose of 2 mL/kg weight. Stage 2: (1) without immersion of the broodstock in hormone solution, (2) immersion of the broodstock in Ovaprim® doses of 1 mL/kg weight. The data obtained were analyzed by analysis of variance. The results showed that immersion of H. scabra broodstock in Oodev® and ovaprim® was not successful in stimulating gonad maturation and spawning in H. scabra broodstock. The spawning behavior of sea cucumbers that were successfully observed included body movements such as writhing, coiling like a ball, sticking to walls, partially erecting their bodies, actively crawling, and being more active at night.Keywords: Gonad; Holothuria scabra; Oodev®; Ovaprim®; Spawning; Sea cucumber.

Potential Influence of Shading in Freshwater Ponds on the Water Quality Parameters and the Hematological and Biochemical Profiles of Nile tilapia (Oreochromis niloticus Linnaeus, 1758)

Nile tilapia is a high-demand commodity in most developing countries including the Philippines, but its production is hampered by fluctuating water temperature (WT) and dissolved oxygen (DO) concentrations, which are mostly influenced by temperature warming. Net shading has been demonstrated to reduce pond temperature and increase the rate of spawning in cultured tilapia. The current study aimed to investigate the potential effects of shading on the water quality parameters, blood indices, and serum biochemical profiles of cultured Nile tilapia. Fish were collected from unshaded (control) and shaded (experimental) ponds in three breeding cycles. WT and DO concentrations were measured, while hematological and biochemical analyses were performed. The results showed that the average WT was considerably decreased in the shaded pond with no significant difference in the DO concentrations. Red blood cells, hemoglobin, and lymphocyte counts were significantly lower in fish raised in shaded ponds, although mean corpuscular volume and neutrophil counts were significantly higher. Likewise, Chole, TP, and Alb values were significantly affected by the interaction of cycle and shading setup. Cortisol, Glb, K+, Cl−, Mg2+, and TCa values showed significant differences and were only affected by the cycle. Similarly, AST and ALT values showed significant differences and were affected by both cycle and shading setup. Water quality parameters (WT and DO), hematological blood indices, and serum biochemical variables were correlated positively with each other. In brief, prior data imply that net shading can reduce WT in aquaculture ponds, reduce stress in Nile tilapia, and lessen the consequences of temperature warming on species production.

Attempts for increasing Astyanax altiparanae spawning rates and percentage of responsive oocytes

In this study, we aimed to propose changes in the protocol of cultured Astyanax altiparanae hypophysation to increase the maximum ovulation rate of 60% registered previously. To that two consecutive experiments were conducted. In the first experiment, three carp pituitary homogenate (CPH) doses (3, 6, and 9 mg/kg) were administered in a single injection, while in the second experiment, the 6 mg/kg CPH dose was tested either in single or double injections. In the first experiment, a single injection of 3 mg/kg CPH did not induce final oocyte maturation or spawning, while a dose of 6 mg/kg CPH resulted in an increase in the plasma level of prostaglandin (PGF2α) at ovulation. The single higher dose of 9 mg/kg CPH did not improve reproductive performance and even though anticipated the resumption of meiosis it was detrimental to the spawning rate. In the second experiment, the dose of 6 mg/kg CPH fractionated into two injections led to a higher spawning rate, spawning volume per female body mass, frequency of post-ovulatory complexes, and PGF2α concentration at ovulation compared to the single injection. The most effective treatment remained the 6 mg/kg of CPH fractionated into two injections, but still providing very low proportion of ovulated females (∼40 %). Overall, this study indicates that the spawning protocols for this species need to be improved to induce ovulation in a larger number of females and be more potent in those females that respond positively.

Effects of cadmium exposure during the breeding period on development and reproductive functions in rare minnow (Gobiocypris rarus).

Cadmium is a common reproductive toxin in aquatic systems. Cd exposure of fish species at high concentrations can severely affect the reproductive function of fish. However, the underlying toxicity of cadmium exposure at low concentrations on the reproductive function in parental fish remains unclear. To investigate the impacts of cadmium exposure on reproductive capability, eighty-one male and eighty-one female rare minnows (Gobiocypris rarus) were exposed to cadmium at 0 (control group), 5 and 10μg/L for 28days, and then transferred into clean water to pair spawn. The results showed that cadmium exposure at 5 or 10μg/L for 28days in rare minnows could reduce the success rates of pair spawning in parent rare minnows, lessen no-spawning activities, and prolong the time for first spawning. Furthermore, the mean egg production of the cadmium exposure group increased. The fertility rate of the control group was significantly higher than that of the 5μg/L cadmium exposure group. Anatomical and histological data further revealed that the intensity of atretic vitellogenic follicles significantly increased and spermatozoa vacuolated after cadmium exposure (p < 0.05), but slightly increased the condition factor (CF), and relatively stable gonadosomatic index (GSI) values were also observed in the cadmium exposure groups. These observed results indicated that cadmium exposure at 5 or 10μg/L affected the reproductive activity of paired rare minnow by accumulating Cd in the gonads, and the effect diminished over time. The reproductive risk of low-dose cadmium exposure to fish species remains a cause for concern.

Redclaw, Cherax quadricarinatus sex-separated rearing strategy enhances reproduction in females

Redclaw crayfish Cherax quadricarinatus, a tropical freshwater species, native to Northern Australia and is regarded as a promising species for global expansion of aquaculture. However, poor female fertility is a hindrance towards the commercial production of redclaw. The present study investigated if dissociated; pre-exposure of female redclaw to males can stimulate spawning and increase reproductive efficiency. The study was conducted in dissociated (111 days) and associated (34 days) phases. Redclaw were held in vertical recirculating aquaculture systems with each system consisting of 42 individual compartments (45 cm length x 33 cm width x 25 cm height) arranged as six compartments horizontally and seven compartments vertically. The average body weight of females was 66 ± 2.2 g. In the dissociated phase, females were either kept alone (0M, n = 36) or were exposed to either 1 (1M, n = 36) or 2 (2M, n = 36) males suspended in the uppermost row of the system. During the associated phase, females (n = 108) were maintained at a sex ratio of 1M:1F. During the dissociated phase, the spawning rate was less in the control compared to the male exposed groups (2.8%, 1/36, 18.1%, 13/72 respectively; p = 0.026). However, the moulting rate was greater in the control compared to the male exposed groups (22.2%, 8/36; 5.6%, 4/72 respectively; p = 0.009). During the associated phase, there were no significant differences in spawning rate (22.2%, 8/36 and 33.3%, 24/72), mean days to spawning (21.88 ± 3.06 and 16.38 ± 2.35), moulting rate (11.1%, 4/36 and 6.9%, 5/72) and mean days to moulting (24.50 ± 3.97 and 22.40 ± 3.93) in the control and male exposed groups, respectively (p > 0.05). However, the mean total number of eggs (670.9 ± 26.0 and 507.0 ± 29.36), fecundity (11.00 ± 0.59 and 6.14 ± 0.47), the hatching rate (89.70 ± 1.31% and 77.50 ± 9.24%) and the total number of juveniles produced (545.70 ± 42.50 and 343.30 ± 37.47) during the associated phase were greater in the male exposed groups compared to the control group respectively; p < 0.05). It was concluded that pre-exposure of redclaw females to males in a dissociated recirculation system, increases spawning rate during a dissociated phase, and after exposure to males improves egg and juvenile production during an associated phase. Such a breeding strategy has potential to increase hatchery productivity.

Gene Editing of the Follicle-Stimulating Hormone Gene to Sterilize Channel Catfish, Ictalurus punctatus, Using a Modified Transcription Activator-like Effector Nuclease Technology with Electroporation

Follicle-stimulating hormone (fsh) plays an important role in sexual maturation in catfish. Knocking out the fsh gene in the fish zygote should suppress the reproduction of channel catfish (Ictalurus punctatus). In this study, transcription activator-like effector nuclease (TALEN) plasmids targeting the fsh gene were electroporated into fertilized eggs with the standard double electroporation technique. Targeted fsh cleavage efficiency was 63.2% in P1fsh-knockout catfish. Ten of fifteen (66.7%) control pairs spawned, and their eggs had 32.3-74.3% average hatch rates in 2016 and 2017. Without hormone therapy, the spawning rates of P1 mutants ranged from 33.3 to 40.0%, with an average egg hatching rate of 0.75%. After confirmation of the low fertility of P1 mutants in 2016, human chorionic gonadotropin (HCG) hormone therapy improved the spawning rates by 80% for female mutants and 88.9% for male mutants, and the mean hatch rate was 35.0% for F1 embryos, similar to that of the controls (p > 0.05). Polymerase chain reaction (PCR) identification showed no potential TALEN plasmid integration into the P1 channel catfish genome. Neither the P1 nor the F1 mutant fish showed any noticeable changes in in body weight, survival rate, and hatching rate when the reproductive gene was knocked out. F1 families had a mean inheritance rate of 50.3%. The results brought us one step closer to allowing implementation of certain genetic techniques to aquaculture and fisheries management, while essentially eliminating the potential environment risk posed by transgenic, hybrid, and exotic fish as well as domestic fish.

Reproductive and Developmental Alterations on Zebrafish (Danio rerio) Upon Long-Term Exposure of Di-ethyl phthalate (DEP), Di-isononyl phthalate (DINP) and Di (2-ethylhexyl) phthalate (DEHP)

Di (2-ethylhexyl) phthalate (DEHP), di-ethyl phthalate (DEP) and di-isononyl phthalate (DINP) are all endocrine disrupting chemicals (EDCs) for organisms. However, little research has been done on the effects of long-term EDC exposure. The present study found that the zebrafish barely grew during the 7months of DINP exposure. The fecundity rate (%) of female spawning was lower in the DEHP treatment by 4months compared to other exposure groups. Zebrafish treated with 12.5-25.0ppm of DEP for 4months presented no spawning. Gonadal-somatic index (GSI) levels significantly decreased, and there were more oocytes in the atresia and peri-nucleus stage compared to the control group. In addition, the hatching rate of embryos were 71.02%, 56.92%, and 21.70% for females treated with DINP, DEHP and DEP, respectively. There were also abnormal craniofacial chondrogenesis development on 72hpf embryos upon females treated with the three EDCs. In conclusion, long term exposure of DEHP, DINP, and DEP did not only affect the reproductive capacity of female zebrafish, but the 3 plasticizers also influence craniofacial cartilage development of its offspring.

Invasive Australian swamp stonecrop (Crassula helmsii) negatively affects spawning but accelerates larval growth of the endangered natterjack toad (Epidalea calamita)

The invasive Crassula helmsii is rapidly expanding in Europe. Several ecological effects are described, most of which focus on ecosystem functioning and native vegetation but rarely on fauna. In North-western Europe, C. helmsii often invades the breeding habitat of endangered amphibians, such as Epidalea calamita. The spawning rate, egg survival and the speed of larval growth of this toad species in relation to the presence of C. helmsii were studied. In order to unravel causal mechanisms, effects on natterjack toads were related to the effects of C. helmsii presence/absence on temperature and chemical properties of the water. Spawning and egg survival were significantly lower under C. helmsii dominance compared to bare soil conditions, and negatively affected the population size of E. calamita. However, larval growth rate was significantly higher in C. helmsii dominated treatments, which could be beneficial. Differences in water temperature and chemistry were a possible explanation for these effects. It remains unclear whether the population viability of E. calamita is negatively affected when C. helmsii is present. In many areas, however, this plant species completely overgrows and causes desiccation of waterbodies. Therefore, appropriate management measures will be required to protect this toad against this invader.

A state‐space model to estimate spawning rates in a Ruditapes philippinarum population

AbstractThe Ruditapes philippinarum catch in Japan has drastically declined and its recovery is a major challenge. The spawning rates and egg output need to be estimated to discuss stock management strategies. However, it is difficult to observe these directly in a field survey. This study proposes a state‐space model to estimate spawning rates in an R. philippinarum population using the number of individuals at each developmental stage based on traditional histological observations of the gonads. An example of its application to monthly observed data of an R. philippinarum population on the western Japanese coast is also presented. The spawning seasons were quantitatively detected in spring and fall, and the durations were estimated to be 2.8 months in spring and 3.0–3.5 months in fall, based on the spawning rates. The mean condition factor was lower in fall than in spring, but females with a high condition factor were also found in fall. The egg output of these individuals during the fall may be large. The spawning frequency per individual was estimated to be 6.5 times per year based on the model, indicating that R. philippinarum is an r‐strategy species capable of multiple spawning. Questioning how the spawning rates vary with individual size/age and environmental conditions is essential for estimating egg output in R. philippinarum populations. The state‐space model in this study can contribute to the quantification of spawning rates. The results will contribute to estimating the egg output and stock management strategies.

Biological structure and abundance dynamics of Pacific rainbow smelt Osmerus dentex (Osmeridae) of the Amur river

Data on spawning migrations, biology and abundance of the spawning group of the pacific rainbow smelt Osmerus dentex of the Amur River in the period from 2014 to 2021 are presented. According to the data of mass labeling of producers, the smelt extracted in the Amur estuary and the Amur riverbed belongs to one unit of stock, the migration routes of producers and the spawning rate have been clarified, and a decrease in the number of spawning herds has been recorded. Analysis of the main biological indicators revealed a significantly significant (p&lt;0.001) decrease in size and mass characteristics, a change in age structure, and a tendency to increase the proportion of females in the spawning herd. The analysis of fertility dynamics revealed a decrease in the indicators of individual and relative fertility of fish of the spawning herd in 2017 (p&lt;0,001), however, in general, the observed changes fit into the range of average long-term fluctuations.

The reproductive response of Cornu aspersum to different hibernation conditions

ABSTRACT This study was conducted between February and May 2019 on mature Cornu aspersum in the Black Sea region, Turkey to investigate the effects of different hibernation situations on reproductive responses. Three snail groups were studied: NH (natural hibernation), ASH (artificial short hibernation) and ALH (artificial long hibernation). NH showed inactive behaviour and had no reproductive activity while ASH and ALH performed intensive reproduction. During the experiment, the mean spawning rate (SpR), egg number (EgN), hatching rate (HR) and offspring number (OfN) were 20.50 ± 1.69%, 100.10 ± 5.22, 85.63 ± 2.36 and 80.69 ± 5.44 in the ASH group; 23.43 ± 3.36%, 122.33 ± 7.62, 61.55 ± 10.76 and 70.26 ± 11.60 in the ALH group, respectively. In conclusion, the high temperatures in the winter months of 2019 may have caused NH snails to become reproductively inactive, or it could simply be a consequence of their life-history strategy. Snails in the ASH and ALH groups represented a resource allocation trade-off between fecundity and survival to carry the genetic information to the next generation. This study leads to a better understanding of land snail reproductive physiology and behavioural responses to different hibernation conditions.

The effects of recombinant GnRH with dopamine antagonist on reproduction performance, sex steroid levels, and stress response in female koi carp (Cyprinus carpio)

In this study, the effect of different doses of recombinant gonadotropin-releasing hormone (rGnRH) and ovaprim (OVP) was investigated on reproductive function, sex steroid levels, and stress response in female koi carp, Cyprinus carpio, females. For this purpose, female koi carps (980.66 ± 23.46 g) were divided into five experimental groups and injected with the following preparation procedure: 0.9% NaCl with 5 mg/kg body weight (BW) of domperidone (Dop) (Control, C), 0.5 ml/kg BW of ovaprim (OVP); 10 μg kg BW−1 of rGnRH with 5 mg/kg of Dop (rGn10), 25 μg/kg BW of rGnRH with 5 mg/kg of Dop (rGn25), and 50 μg/kg BW of rGnRH 5 with mg/kg of Dop (rGn50). To evaluate sex steroids and stress indicators in the females, blood samples were collected before injection and 6, 12, and 24 h post-injection. The results indicated that the females were significantly different in terms of the number of spawned females, with the highest numbers in OVP and rGn25 treatments and the lowest number in the control treatment. Significant differences were observed between hormone-treated fish at the latency period, and the highest latency was obtained in the rGn10 treatment compared to shorter latencies in the other treatments. Sex steroid levels 17β estradiol (E2), testosterone (T), and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) were affected by the hormonal treatments. Levels of E2 decreased in rGnRH and OVP treatments at 6 and 12 h after the injection. T and DHP levels increased in rGnRH and OVP treatments at 6 and 12 h after the injection and then decreased at 24 h post-injection. Cortisol levels increased at 6 and 12 h post-injection and decreased 24 h after the injection. No changes were observed in lactate and glucose levels at 6 h after the injection, but its levels were significantly higher in hormone-injected treatments than in the control treatment at 12 h after the injection. rGnRH could induce spawning, and the highest spawning rate and efficiency were measured in the rGn25 treatment. According to the results, rGnRH may be suggested as an alternative to other hormones used for artificial propagation in koi carp.