Common Carp Populations Research Articles

Single-Nucleus RNA Sequencing Reveals the Transcriptome Profiling of Ovarian Cells in Adolescent Cyprinus carpio

The common carp (Cyprinus carpio) is a crucial freshwater species cultivated worldwide for food consumption. Female carp have better growth performance than males, which fascinates scholars to uncover the mechanism of gonadal differentiation and produce mono-sex populations. However, the mechanism of ovarian development at single-cell resolution is limited. Here, we conducted single-nucleus RNA sequencing in adolescent common carp ovaries. Our study obtained transcriptional profiles of 13,155 nuclei and revealed 13 distinct cell clusters in the ovaries, including three subtypes of germ cells and four subtypes of granulosa cells. We subsequently performed pseudotime trajectory analysis to delineate potential mechanisms underlying the development of germ cells and granulosa cells. We identified 1250 dynamic expression genes in germ cells and 1815 in granulosa cells (q-value < 0.01), including zp3, eif4a2 and aspm in germ cells and fshr and esr1 in granulosa cells. The functional annotation showed that dynamic expression genes in germ cells were involved in sperm–egg recognition and some terms related to meiosis, such as sister chromatid segregation and homologous recombination. Genes expressed dynamically in granulosa cells were related to the TGF-β signaling pathway, response to gonadotropin, and development of primary female sexual characteristics. In addition, the dynamic genes expressed in granulosa cells might relate to the complex communication between different cell types. In summary, our study provided a transcriptome profile of common carp ovaries at single-nucleus resolution, and we further revealed the potential cell type-specific mechanisms underlying oogenesis and the differentiation of granulosa cells, which will facilitate breeding all-female common carp populations.

Effects of sampling effort and data sources on precision of common carp and bigmouth buffalo population estimates

Biologists often manage abundant invasive Common Carp (Cyprinus carpio) populations for suppression below population density or biomass thresholds via commercial harvest that also removes large numbers of native Bigmouth Buffalo (Ictiobus cyprinellus). Thus, biologists need population estimates to monitor abundance but often avoid them due to the time and effort required to produce population estimates and pervading estimate imprecision. While population abundance of these fishes can be challenging to estimate, commercial fishers harvest large numbers of fish that could improve population estimates with less effort from biologists. Yet, how population estimates from fishery-dependent and fishery-independent data sources compare is unknown. We compared the precision of Schnabel fishery-independent (electrofishing) and Lincoln-Petersen fishery-dependent (commercial harvest) population estimates for Common Carp and Bigmouth Buffalo in seven northwest Iowa lakes. We then assessed how sampling effort and environmental factors affected the number of fish recaptured by electrofishing and how the number of fish marked and recaptured affected estimate variability. Lincoln-Petersen estimates were more precise and provided similar abundance estimates compared with Schnabel estimates for Bigmouth Buffalo, while both models provided comparable population estimates and precision for Common Carp. Common Carp electrofishing recaptures were positively related to electrofishing effort, number of fish tagged, lake size, and water temperature. Bigmouth Buffalo recaptures were positively related to number of fish tagged and negatively related to lake area and water temperature. Coefficient of variation for fishery-dependent estimates declined with number of fish tagged and recaptured; 750 Common Carp and 150 Bigmouth Buffalo needed to be marked at large to obtain precision of CV ≤ 0.25. Our results suggest Lincoln-Petersen estimates with fishery-dependent data represent an improvement over fishery-independent estimates for Bigmouth Buffalo while both techniques provided comparable estimates for Common Carp. Incorporating harvest data into population estimates can reduce sampling effort while improving or maintaining precision.

Histopathology and transcriptome profiling reveal features of immune responses in gills and intestine induced by Spring viremia of carp virus

The immune system of bony fish closely resembles that of mammals, comprising both specific (adaptive) and non-specific (innate) components. Notably, the mucosa-associated lymphoid tissue (MALT) serves as the first line of defense within the non-specific immune system, playing a critical role in protecting these aquatic organisms against invading pathogens. MALT encompasses a network of immune cells strategically distributed throughout the gills and intestines, forming an integral part of the mucosal barrier that interfaces directly with the surrounding aquatic environment. Spring Viremia of Carp Virus（SVCV）, a highly pathogenic agent causing substantial harm to common carp populations, has been designated as a Class 2 animal disease by the Ministry of Agriculture and Rural Affairs of China. Utilizing a comprehensive array of research techniques, including Hematoxylin and Eosin (HE)、Alcian Blue Periodic Acid-Schiff (AB-PAS)、transcriptome analysis for global gene expression profiling and Reverse Transcription-Polymerase Chain Reaction (RT-qPCR), this study uncovered several key findings: SVCV is capable of compromising the mucosal architecture in the gill and intestinal tissues of carp, and stimulate the proliferation of mucous cells both in gill and intestinal tissues. Critically, the study revealed that SVCV's invasion elicits a robust response from the carp's mucosal immune system, demonstrating the organism's capacity to resist SVCV invasion despite the challenges posed by the pathogen.

Effect of long-term temperature-controlled rearing on growth traits and sexual maturity of common carp (Cyprinus carpio)

Many economically important fish have a long sexual maturation cycle, with the first sexual maturation time exceeding four years, which poses a long-term challenge for the cultivation of excellent varieties of these fish. Gonadal development and reproductive timing of fish are closely related to changes in environmental temperature. This study used the common carp as an economic fish model and set up three aquaculture modes for a one-month old common carp population: constant temperature test group (CTTG), normal temperature control group (NTCG), and variable temperature control group (VTCG). A long-term (approximately 11 months), temperature-controlled aquaculture experiment was conducted. The results of growth traits and gonadal development tests showed that at 10 months, the body length and weight of the CTTG were significantly higher than those of the other two groups. At seven months, the gonadosomatic index (GSI) value of CTTG was also significantly higher than that of the other two groups; At 10 months, the serum estradiol (E2) concentration of CTTG was significantly higher than that of the other two groups, while the testosterone (T) levels of VTCG and CTTG were significantly higher than those of NTCG, and only the 11-ketotestosterone (11-KT) concentration of VTCG was significantly higher than that of the other two groups. Simultaneously, qPCR analysis of sex hormone regulatory genes revealed that the expression of Cyp19a1a in CTTG ovaries was significantly higher than that in NTCG and VTCG ovaries, whereas the expression of Cyp11b and Hsd11b2 in VTCG ovaries was significantly higher than that in NTCG and CTTG ovaries. At 12 months, artificial reproduction revealed that only fish from the CTTG (66.67%) successfully laid eggs and fertilized normally. The results indicate that long-term constant temperature cultivation at 28 °C starting from the juvenile stage is not only beneficial for the body growth of common carp, but also promotes their gonadal development. This may be due to the conversion of T into E2 by Cyp19a1a in the common carp, ultimately facilitating the functional development of gonadal tissue under hypothalamus-pituitary-gonadal (HPG) axis regulation, normal egg laying, and fertilization. This study reduced the normal first sexual maturation time of common carp by at least 50% and provides a reference for the rapid cultivation of excellent varieties of other economically important fishes.

In Search of a Target Gene for a Desirable Phenotype in Aquaculture: Genome Editing of Cyprinidae and Salmonidae Species.

Aquaculture supplies the world food market with a significant amount of valuable protein. Highly productive aquaculture fishes can be derived by utilizing genome-editing methods, and the main problem is to choose a target gene to obtain the desirable phenotype. This paper presents a review of the studies of genome editing for genes controlling body development, growth, pigmentation and sex determination in five key aquaculture Salmonidae and Cyprinidae species, such as rainbow trout (Onchorhynchus mykiss), Atlantic salmon (Salmo salar), common carp (Cyprinus carpio), goldfish (Carassius auratus), Gibel carp (Carassius gibelio) and the model fish zebrafish (Danio rerio). Among the genes studied, the most applicable for aquaculture are mstnba, pomc, and acvr2, the knockout of which leads to enhanced muscle growth; runx2b, mutants of which do not form bones in myoseptae; lepr, whose lack of function makes fish fast-growing; fads2, Δ6abc/5Mt, and Δ6bcMt, affecting the composition of fatty acids in fish meat; dnd mettl3, and wnt4a, mutants of which are sterile; and disease-susceptibility genes prmt7, gab3, gcJAM-A, and cxcr3.2. Schemes for obtaining common carp populations consisting of only large females are promising for use in aquaculture. The immobilized and uncolored zebrafish line is of interest for laboratory use.

Genetic diversity of the common carp black strain population based on mtDNA (D-loop and cytb)

The common strain black carp (Cyprinus carpio var. baisenensis) is a culturally important carp strain that is raised and cultured in Guangxi Province, China. Its color reflects the interactions between the Burau people and their surrounding environment. The population of the common carp black strain was isolated and cultured in a rice-fish integration system. To explore the genetic diversity and protection of germplasm resources, we analyzed mitochondrial DNA (mtDNA) sequences, specifically the displacement loop (D-loop) and cytochrome b (Cytb), using single-nucleotide polymorphisms (SNP). We compared these sequences with those from four other local common carp populations. The study included a total of 136 adult common carps from five strain populations: the common black carp strain (HJ = 31), Jian (F = 30), Heilongjiang (H = 10), Songpu (S = 31), and Saijiang (SJ = 34). The results of the Cytb and D-loop analyses showed that the Heilongjiang carp (H) and Saijiang (SJ) populations had the highest levels of haplotype diversity (0.867 ± 0.034785) and nucleotide diversity (π = 0.0063 ± 0.000137 and 0.0093 ± 0.000411), respectively. On the other hand, the Common carp black strain population (HJ) exhibited the lowest haplotype diversity in both Cytb and D-loop, with haplotype 2 being the most commonly observed among the populations. Private haplotypes dominated the five common carp populations, which were significantly different at P<0.001. Furthermore, analyzing the coefficient of genetic differentiation (Fst), the highest genetic difference was observed between Saijiang (SJ) and Heilongjiang (H) (Fst = 0.963), whereas the lowest was observed between Songpu (S) and the Common carp black strain population (HJ) (Fst = 0.019) for the Cytb gene sequences. For the D-loop, the Common carp black strain population (HJ) and Songpu (S) (Fst = 0.7) had the highest values, and Heilongjiang (H) and Common black carp strain (HJ) had an Fst of 0.125. Additionally, the AMOVA analysis revealed a higher level of variance for the Cytb and D-loop genes, indicating lower genetic diversity within the local carp community. On the other hand, the phylogenetic tree analysis showed that the five carp populations were closely related and formed a distinct cluster. The distinct cluster of populations suggests a common ancestor or recent gene flow, possibly due to geographic proximity or migration history, and unique genetic characteristics, possibly due to adaptations or selective pressures. The results of this study provide valuable insights into the genetic diversity of the common strain black carp, which can have implications for conservation, breeding programs, evolutionary studies, and fisheries management.

Genetic diversity of common carp Cyprinus carpio in the base population of a selective breeding programme in India

A selective breeding program for developing a suitable strain of Cyprinus carpio (Linnaeus, 1758) for inland saline aquaculture in India is in progress. At ICAR-CIFE, various geographical populations of common carp of India, viz. Madhya Pradesh (MP), Haryana (HR), Tripura (TR), Andhra Pradesh (AP), Manipur (MN), and Maharashtra (MH) formed the base population for selective breeding. The present study assesses the genetic diversity of these stocks using truss morphometry and mitochondrial DNA D loop marker analysis. The images of 600 fish were captured and digitized. The landmarks were identified, and an image network was constructed for truss analysis using tpsDig2 and PAST software. The data was subjected to scale transformation and factor analysis using SAS for Academics. The top 3 factors could explain 85.40% of the total variation. The results indicate stock-wise and sex-wise groupings. The mitochondrial DNA (D-loop) sequence analysis was conducted on 169 samples using MEGA6 software. The overall average haplotype and nucleotide diversity of the population were 0.08129 and 0.01134, respectively. Among stocks, the MP stock had a maximum of four haplotypes. The AMOVA results reveal that the stock AP is unique, and the other stocks form a single grouping. The information generated from the present study delineates genetic diversity among stocks and will aid in designing breeding plans.

Uncommon life history and winter spawning of common carp (Cyprinus carpio) in a natural thermal spring, under temperate climate.

Common carp female generally matures at age 4-5 years old and spawns between April and July under the temperate climate. Contrary to a range of 0-28 °C of temperate freshwaters, the water temperature of Lake Hévíz (Hungary, Central Europe), the largest natural bathable thermal lake in the world, varies between 26 and 35 °C seasonally. The specific environmental conditions (continuously warm water and its individual chemical composition, special nutrient base, lack of natural lakeside spawning substrate compared to usual spawning grounds, continuous high human disturbance, etc.) suggest that the carp population here may also differ in reproductive characteristics from their counterparts in surrounding waters. Our findings suggest that the self-sustaining dwarf common carp population of Lake Hévíz matures 2 to 4 years earlier (at the age of one) and spawns 1 to 3 months before (between February and April, at 27-30 °C water temperature) than carp typically do in the temperate zone (16-20 °C). Successful winter spawning was verified by rearing larvae from the collected eggs and in situ induced propagation.

The hidden world of fish fungal pathogens: molecular identification and phylogenetic analysis in common carp, Cyprinus carpio.

Fungal infections pose a significant threat to aquaculture, causing substantial economic losses and ecological disruptions. The common carp (Cyprinus carpio), as a crucial farmed fish, requires in-depth research to uncover the underlying fungal pathogens affecting its health. In this study, we analyzed 150 samples of C. carpio to identify the fungal pathogens responsible for the infections based on clinical signs and symptoms. Further, we assessed fungal diversity and prevalence in the infected fish. The infected fish exhibited varying degrees of gross pathogenicity, with fins and skin heavily affected, intermediate infection observed in the head and gills, and the least infection found in the operculum. Morphological examination revealed distinct characteristics such as necrosis, lesions on the skin, fins, and gills, as well as loss of scales, hemorrhagic lesions, and red spots. Furthermore, the presence of gray and white cottony patches on the body confirmed ascomycete and zygomycete infections, while a dark white cottony mass indicated phycomycete infection. Some fish exhibited severe fungal infections, presenting prominently curved spines and necrosis with red spots on the skin. These isolates belonged to various fungal groups, including ascomycetes, zygomycetes, phycomycetes, deuteromycetes, and basidiomycetes. Among these, Fusarium oxysporum emerged as the most prevalent fungal pathogen, followed by Fusarium solani, Saprolegnia delica, and Saprolegnia parasitica. Molecular identification based on ITS and LSU rRNA sequences confirmed the presence of Saprolegnia delica, Mucor hiemalis, Coniothyrium telephii, Rhodotorula mucilaginosa, Penicillium cellarum, and Fusarium californicum in the fish samples. Phylogenetic analysis further supported the morphological and molecular data, providing insights into the relationship between the isolated fungal strains and known species from various geographical regions. Our study enhances our understanding of the diversity and prevalence of fish fungal pathogens in common carp, emphasizing the significance of employing molecular techniques for accurate identification. These comprehensive findings offer essential insights into the impact of fungal infections on common carp populations, laying the groundwork for targeted control measures to mitigate their effects on global aquaculture.

Annual changes in water quality and sportfish community structure following commercial harvest of common carp and bigmouth buffalo

Martin A. Simonson, Michael J. Weber, Grace M. Wilkinson and Andrew R. Annear. 2023. Annual changes in water quality and sportfish community structure following commercial harvest of common carp and bigmouth buffalo. Lake Reserv Manage. XX:XXX–XXX. Commercial harvest of common carp (Cyprinus carpio; hereafter carp) and bigmouth buffalo (Ictiobus cyprinellus; hereafter buffalo) populations had little detectable effect on shallow lake ecosystems. We tested whether carp and buffalo biomass removal affects limnological variables and fish community metrics across 6 shallow, natural lakes of northwestern Iowa using mixed effects models. Annual commercial harvest of carp ranged from 0 to 71 kg/ha; annual harvest of buffalo ranged from 0 to 356 kg/ha. Biomanipulation (i.e., commercial harvest) of carp was associated with decreases in soluble phosphorus and nitrogen concentrations, but not total phosphorus or nitrogen. Buffalo harvest was unrelated to annual changes in nutrient concentrations but was associated with reductions in chlorophyll a and phycocyanin concentrations. Secchi disk transparency and total suspended solids were unrelated to carp and buffalo harvest. Carp harvest was associated with reduced biomass of large cladocerans but no other zooplankton biomass densities; buffalo harvest was unrelated to zooplankton biomass. Species richness and rake density of aquatic macrophytes were unrelated to carp and buffalo harvest. Carp and buffalo harvest was unrelated to changes in most indices of sportfish abundance, condition, and size distribution. Our results suggest harvest of carp and buffalo <71 kg/ha has little effect on abiotic and biotic ecosystem components on short time scales and highlights the challenges associated with shallow lake restoration.

Intra‐Annual Variability of Common Carp and Bigmouth Buffalo Electrofishing Data in Shallow Lakes

AbstractCommon Carp Cyprinus carpio and Bigmouth Buffalo Ictiobus cyprinellus are widespread across the Midwest, where they can achieve high population densities in shallow lakes. Despite their contrasting statuses as invasive and native fishes, these species are commonly managed together due to their capacity to have deleterious effects on water quality. However, intra‐annual sampling variability is poorly understood for both species, making it difficult to track population changes. We compared boat electrofishing CPUE and proportional size distribution (PSD) of Common Carp and Bigmouth Buffalo during May–October 2018–2020 in seven shallow northwestern Iowa lakes. We also estimated sampling effort necessary to reach targets of fish captured (100) and precision (relative standard error &lt; 25%) and to detect 25% and 50% differences in CPUE between samples. Common Carp CPUE peaked in June (29 fish/h), declined across the summer, and was lowest in October (9 fish/h). Bigmouth Buffalo CPUE exhibited bimodal peaks in May (16 fish/h) and October (12 fish/h), with low catches during August (2 fish/h). Common Carp size structure was largest during October (PSD of preferred‐size fish [PSD‐P] = 92) and smallest in July (PSD‐P = 58). Bigmouth Buffalo size structure was smaller in June (PSD‐P = 20) than in all other months (PSD‐P = 34). Our targets for number of fish captured and precision were typically reached within twenty‐five 15‐min electrofishing transects for Common Carp during periods of high catch rates but were not reached after 100 transects for Bigmouth Buffalo in most cases. Our results suggest that timing of sampling is important for reliably and efficiently assessing Common Carp and Bigmouth Buffalo populations. We recommend the sampling of Common Carp with electrofishing during June and the sampling of Bigmouth Buffalo during May in Midwestern shallow lakes to maximize catch rates while minimizing the influence of seasonal sampling variability.

Mitochondrial diversity and genetic structure of common carp (Cyprinus carpio) in Pearl River and Nandujiang River.

Common carp (Cyprinus carpio) is an important valuable cyprinid in China and has been a popular cultured aquaculture species around the globe. Understanding the genetic diversity of wild native common carp not only provides basic data for the protection and utilisation of common carp resources but also assesses the effect of human activities on the genetic diversity of this species. In this study, genetic diversity and population structure of the common carp from 15 sampling populations in the Pearl River and Nandujiang River were determined using a coalescent mitochondrial locus (MLS), including mitochondrial cytochrome b gene (Cytb) and a control region (D-loop) segment. The haplotype diversity and nucleotide diversity were 0.962 and 0.00628 in the Pearl River and 0.808 and 0.00376 in the Nandujiang River, respectively. Phylogenetic and haplotype network analyses indicated that three sub-species (a) C. c. rubrofuscus, (b) C. c. haematopterus and (c) C. c. carpio all occur in both rivers. AMOVA revealed that the variation within populations (86.2%) was the main source of the total variation. Statistically significant genetic differentiation among different Pearl River populations of C. c. rubrofuscus (Fst = 0.05-0.25) and relatively high genetic differentiation between the Nandujiang River population and the Pearl River populations (Fst > 0.238) are apparent. Bayesian clustering analyses detected that global populations consisted of eight genetic clusters and examined that Nandujiang River population included relatively pure genetic clusters. Neutrality tests suggested that native populations experienced recent population expansion, and Extended Bayesian Skyline Plot indicated that the common carp populations likely experienced a historical expansion during 0.125-0.250MYA. Artificial fish propagation and release, escape from fish farms and Fang Sheng may explain the invasion of non-native sub-species in many river sections, such as Laibin, Rongjiang, Huizhou, Heyuan and Zhaoqing. To conserve the native common carp populations, release station should be established to culture native common carp fry. Overall, the findings can be contributed to complementing scientific knowledge for conservation and management of the wild native common carp.

The resistance of the synthetic population of Indonesian common carp (Cyprinus carpio) to Koi Herpesvirus (KHV)

One of the effects of a decrease in the genetic quality of common carp is a decrease in resistance to disease. Establishing a synthetic population, blended from 5 strains, namely Rajadanu, Majalaya, Sutisna, Wildan, and Sinyonya, is expected to increase the disease resistance in the Indonesian common carp population. This study aims to evaluate the resistance of this synthetic population to Koi Herpesvirus (KHV) disease. The three common carp strains, Majalaya carp, Subang carp, and Cangkringan carp, were challenged with a cohabitation approach compared to the synthetic population. The water temperature was adjusted to the optimum condition for KHV development, which ranged from 20 – 22 °C. The result showed that KHV infection started on day three and peaked on days 6 to 10 after cohabitation. At the end of the challenge test, the survival rate of the synthetic population was 62.0 %, significantly higher than other strains (P&lt;0.05), which ranged from 20.0 to 26.7 % of the constituent populations. The results of this challenge test indicated that the synthetic population of common carp had better resistance to KHV infection than other strains of common carp cultured by farmers.

A comparison of growth of a vulnerable species, common carp, Cyprinus carpio (Actinopteri: Cyprinidae), from two different reservoir types in the same river basin

Context The mechanisms underlying regional differences in growth parameters of common carp, Cyprinus carpio Linnaeus, 1758 (Actinopteri: Cyprinidae), are not yet fully understood, because comparisons among them have been made post hoc. Aims To simultaneously compare growth of common carp between sexes and between regions: Demirköprü Reservoir (DR) and Marmara Lake (ML), which have different structures (lowland type vs highland type) and are proximate to each other in the same river basin (Gediz River Basin). Methods Length-frequency distributions, length–weight relationships and three growth models (von Bertalanffy growth function (VBGF), Gompertz growth function (GGF) and Robertson growth function (RGF)) were used for both sexes and all individuals in reservoirs. Key results As none of the best-fitting models used among these growth models clearly suggested a ‘clear winner’ (Akaike’s weight (wi) &gt; 0.9), the model-averaged multi-model inference (MMI) was used for the first time for common carp. Conclusions Asymptotic length obtained from MMI for all individuals in ML (lowland type) was statistically higher than that in DR (highland type) (P &lt; 0.05). Implications Based on the maximum observed length and the mean L∞ obtained from MMI, the common carp population in the DR can be considered threatened by overfishing.

Origin of domesticated Qingtian paddy-field carp and its genetic differentiation from wild common carp populations

Common carp is the first domesticated fish species in the world, which is the main fish candidate for being cocultured with rice in paddy fields. There are several strains of rice field-domesticated common carp in China, such as Qingtian (paddy-field) carp, Congjiang Carp, Wuyi Carp etc. Unfortunately, their geographical origins were unclear and the adaptability to rice field of these common carp varieties have not yet been well studied. Here we used 2b-RAD simplified genome sequencing to obtain 108,813 SNP markers from two paddy-field carp populations (Qingtian and Wuyi Mountain) and eight wild carp populations to explore the phylogenetic relationship and differences between the Qingtian paddy field carp and the other neighboring wild and domesticated carp populations. Compared with the wild carp populations, the levels of nucleotide diversity of the two paddy-field carp populations were lower. The neighbor-joining (NJ) tree, principal component analysis (PCA), and population structure analysis all showed three clusters of the carp populations: Qingtian paddy-field carps as one of the clusters, paddy-field carps from Wuyi Mountain areas the second and all the wild common carp populations the third. Qingtian paddy-field carps were clearly separated from other populations, which was consistent with the population differentiation index (Fst) analysis. All these analyses indicated that Qingtian paddy-field carps showed the closest relationship with the Oujiang wild carp population (OJ), and less close to all other populations, providing clear evidence of the geographical origin of Qingtian paddy-field carp from Oujiang River. With wild carps as the control group and paddy-field carps as the selection group, 180 genes with a selection signature were obtained. The gene ontology (GO) classification and enrichment analysis showed that the genes with a selection signature were enriched in the pathway related to signal transduction function. We can thus conclude that Qingtian paddy field carp of the Asia first GIAHS rice-fish coculture system were originated from the domestication from the local Oujiang wild common carp population, which showed a clear genetic adaptive evolution in genes with function in signal transduction. These findings will help us to further disclose the domestication effects on fish that leading us better understanding the adaptive mechanism of fish to the rice field environment.

Genotyping-by-Sequencing Reveals the Impact of Restocking on Wild Common Carp Populations of the Southern Caspian Basin

Understanding the population structure and level of genetic diversity of wild populations is fundamental for appropriate stock management and species conservation. The common carp (Cyprinus carpio) is one of the most important bony fish throughout the Southern coastline of the Caspian Sea, but captures of this species have seen a dramatic reduction during the last decade. As a consequence, a restocking program has been put in place to maintain C. carpio populations, but its impact is not clear. In the present study, the population structure and genetic diversity of C. carpio in the Southern Caspian basin was determined using 17,828 single-nucleotide polymorphism (SNP) markers. A total of 117 individuals collected from four different locations in the southern Caspian basin and a farm were genotyped by genotyping-by-sequencing. The overall Fst obtained was 0.04, indicating a low level of differentiation between populations, and most genetic diversity was attributed to within population variation (97%). The low Fst values suggest that frequent migration events between different locations occur, and three migration events were inferred in the present study. However, each population still showed a distinct genetic profile, which allowed distinguishing the origin of the fish. This indicates that the ongoing restocking program is maintaining the differences between populations to some extent. Nonetheless, high inbreeding and low heterozygosity were detected in all populations, suggesting that additional conservation efforts are required to protect C. carpio populations in the Southern coast of the Caspian Sea.

Empirical evidence on the effects of climate on the viability of common carp (Cyprinus carpio) populations in European lakes

Empirical evidence on the effects of climate on the viability of common carp (Cyprinus carpio) populations in European lakes

Comparative analysis of brain in relation to the body length and weight of common carp (Cyprinus carpio) in captive (hatchery) and wild (river system) populations.

Cyprinus carpio is the member of family cyprinidae commonly called common carp. This study was aimed to find out the comparison of brain of wild (river system) and captive (hatchery reared) population of common carp. A total of thirty samples (15 from hatchery and 15 from river Swat) were collected. All the specimens were examined in Laboratory of Parasitoloy, Zoology Department, University of Malakand. Findings indicated that wild population were greater in brain size and weight as compared to hatchery reared population. The fish samples collected from captive environment (hatchery) were showing more weight and length as compared to wild population of common carps. The mean value of total weight of hatchery fishes 345±48.68 and the mean value of brain weight of hatchery reared fishes 0.28±0.047. The mean value of wild fish's total body weight 195.16±52.58 and the mean value of brain weight of wild fishes are 0.45±0.14. Present research calls for the fact that fish in dependent environmental conditions possess brain larger in size as compared to its captive population, it is due to use and disuse of brain in their environmental requirements.

CARP EDEMA VIRUS DISEASE IN SERBIA - DISEASE OUT OF CONTROL

A poxvirus named carp edema virus (CEV), is the causative agent of carp edema virus disease (CEVD), which is an emerging disease of global concern that may cause high rates of morbidity and mortality in ornamental koi and common carp and. Common carp (Cyprinus carpio) is the most important fish species for warm‐water aquaculture in Serbia. CEVD was first time detected in Serbia in 2017. During 2017-2020 period, increasing number of CEVD outbreaks in carp farms is reported. Carp were collected from farms in different regions of Serbia from 2017 to 2020. The fish were sampled for disease diagnosis because they exhibited lethargy and anorexia, which eventually led to mortality. Mortality started with clinical signs of hypoxia while fish swam slowly without escaping reactions. The gills were pale and covered with a thick mucus layer. In advanced cases, the lesions in the gills turned into a necrotizing form. A moderate to high amount of opportunistic freshwater bacteria were isolated from gills of diseased fish. By performing real-time PCR, CEV was detected in 38 samples of diseased carps from 21 carp farms. These outbreaks further confirm the spread of CEVD and the need for practitioners to be vigilant for outbreaks of this disease. To prevent further spreading of the disease, it is very important to introduce CEV testing before fish movement. To avoid further transmission of the virus to common carp populations in Serbia, testing of CEV should become part of fish disease surveillance programs. Fish health service should be aware of the presence of CEV in Serbia which may result in high losses in carp aquaculture. Action should be taken also to prevent transmission of CEV to carp populations in open waters.

It is everywhere-A survey on the presence of carp edema virus in carp populations in Germany.

Carp edema virus (CEV) is the causative agent of koi sleepy disease (KSD), a serious gill disease affecting common carp, Cyprinus carpio, and its ornamental variety, koi. After recent detections of the virus in various countries around the world, KSD has emerged as a new global disease in carp. However, the prevalence of the infection in carp populations in a given geographical region has not been studied thoroughly. The present communication reports an investigation into the presence of CEV in carp and koi populations in Germany. For this purpose, gill samples collected from carp and koi populations suffering from gill diseases or collected for a routine examination of their health status were tested for the presence of CEV by PCR. In total, 651 fish samples from 401 carp or koi cases were examined in 2015 and 2016, additional 118 samples from previous studies were included in the examination. CEV was detected in archive samples from carp dating back to 2007, and in koi samples dating back to 2009. From 2015 to 2016, CEV was detected in 69% of cases from carp populations examined from the main carp-producing areas in Germany, and in 41% of the examined cases from koi populations from all over Germany. Clinical KSD occurred mainly from April to June in carp populations at water temperatures ranging from 8 to 12°C and in koi populations at water temperatures ranging from 18 to 22°C. Most fish from clinically affected carp or koi populations harboured high virus loads of above 10,000 copies of CEV-specific DNA per 250 ng DNA, while gills from fish of other fish species from the ponds, including goldfish, grass carp and European perch were found CEV negative or harboured a low virus load. A phylogenetic analysis revealed the presence of multiple CEV variants from genogroup I in carp and genogroup II in koi populations in Germany. Genetically identical genogroup I isolates were detected in carp from different geographical locations in Germany and in other European carp populations. Some German genogroup II variants were identical to variants previously recorded from koi in Asian and other European countries. The data presented here show that CEV is highly prevalent in German common carp and koi populations and implies the spreading of this virus by intense trading of common carp and koi without necessary risk mitigating measures. As infections with this virus may induce serious disease, CEV diagnostic should be included in health surveillance and disease monitoring programmes.