Carp Reproduction Research Articles

Invasive Carp Reproduction Phenology in Tributaries of the Upper Mississippi River

AbstractInvasive Bighead Carp Hypophthalmichthys nobilis, Silver Carp H. molitrix, and Grass Carp Ctenopharyngodon idella are expanding throughout the upper Mississippi River (UMR) basin. Spawning has occurred in the main‐stem UMR but could be limited to high‐discharge events when dam operations create a free‐flowing river. Alternatively, naturally free‐flowing tributaries could offer alternative habitat for successful reproduction. Our objectives were to examine temporal and spatial variation in adult gonad development, ichthyoplankton densities, and back‐calculated spawn dates of invasive carp collected in three UMR tributaries. We compared ichthyoplankton densities between the upstream and mouth reaches of tributaries and densities between the UMR and adjacent tributaries. Ichthyoplankton samples were collected every 10 d, and adult invasive carp were sampled monthly at nine sites throughout the Des Moines, Skunk, Iowa, Cedar, and Mississippi rivers during April–October 2014 and 2015. Peaks in adult gonadosomatic index, an increase in postspawn females, and ichthyoplankton collections suggested that peak spawning occurred during late May through June, when water temperatures were 18–30°C and channel velocities were at least 0.7 m/s. However, reproduction occurred as late as August in some tributaries. Ichthyoplankton densities were highest in the Des Moines River among tributaries, but tributary densities were similar to the UMR densities, suggesting that both tributaries and main‐stem sites provide suitable spawning locations. Invasive carp reproduction in UMR tributaries provides additional sources of potential recruitment for further population expansion upstream in the UMR and should be considered when devising plans for controlling populations along the leading edge of the invasion.

Evaluating the potential role of bioactive chemicals on the distribution of invasive Asian carp upstream and downstream from river mile 278 in the Illinois waterway

Two non-native carp species have invaded the Illinois Waterway and are a threat to Great Lakes ecosystems. Poor water quality in the upper Illinois Waterway may be a factor contributing to the stalling of the carp population front near river mile 278. In 2015, the U.S. Geological Survey collected 4 sets of water samples from two sites upstream and 4 sites downstream from river mile 278, and one tributary. Each sample was analyzed for up to 649 unique constituents of which 287 were detected including 96 pesticides, 62 pharmaceuticals, 39 wastewater indicator chemicals, 29 metals, 19 volatile organic compounds (VOCs), 6 disinfection by-products (DBPs), 5 hormones, and 5 carboxylic acids. Potential for bioactivity was estimated by comparing chemical concentrations to aquatic life or human health criteria and to in-vitro bioactivity screening results in the U.S Environmental Protection Agency ToxCast™ database. The resulting hazard quotients and exposure-activity ratios (EARs) are toxicity indexes that can be used to rank potential bioactivity of individual chemicals and chemical mixtures. This analysis indicates that several bioactive chemicals (BCs) including: carbendazim, 2,4-D, metolachlor, terbuthylazine, and acetochlor (pesticides); 1,4-dioxane (VOC); metformin, diphenhydramine, sulfamethoxazole, tramadol, fexofenadine, and the anti-depressants (pharmaceuticals); bisphenol A, 4-nonylphenol, galaxolide, 4-tert-octylphenol (wastewater indicator chemical); lead and boron (metals); and estrone (hormone) all occur in the upper Illinois Waterway at concentrations that produce elevated EARs values and may be adversely affecting carp reproduction and health. The clear differences in water quality upstream and downstream from river mile 278 with higher contaminant concentrations and potential bioactivity upstream could represent a barrier to carp range expansion.

Morphological Identification of Bighead Carp, Silver Carp, and Grass Carp Eggs Using Random Forests Machine Learning Classification

AbstractVisual identification of fish eggs is difficult and unreliable due to a lack of information on the morphological egg characteristics of many species. We used random forests machine learning to predict the identity of genetically identified Bighead Carp Hypophthalmichthys nobilis, Grass Carp Ctenopharyngodon idella, and Silver Carp H. molitrix eggs based on egg morphometric and environmental characteristics. Family, genus, and species taxonomic‐level random forests models were explored to assess the performance and accuracy of the predictor variables. The egg characteristics of Bighead Carp, Grass Carp, and Silver Carp were similar, and they were difficult to distinguish from one another. When combined into a single invasive carp class, the random forests models were ≥ 97% accurate at identifying invasive carp eggs, with a ≤5% false positive rate. Egg membrane diameter was the most important predictive variable, but the addition of ten other variables resulted in a 98% success rate for identifying invasive carp eggs from 26 other upper Mississippi River basin species. Our results revealed that a combination of morphometric and environmental measurements can be used to identify invasive carp eggs. Similar machine learning approaches could be used to identify the eggs of other fishes. These results will help managers more easily and quickly assess invasive carp reproduction.

Gonad development and reproductive hormones of invasive silver carp (Hypophthalmichthys molitrix) in the Illinois River.

Reproduction is a major component of an animal's life history strategy. Species with plasticity in their reproductive biology are likely to be successful as an invasive species, as they can adapt their reproductive effort during various phases of a biological invasion. Silver carp (Hypophthalmicthys molitrix), an invasive cyprinid in North America, display wide variation in reproductive strategies across both their native and introduced ranges, though the specifics of silver carp reproduction in the Illinois River have not been established. We assessed reproductive status using histological and endocrinological methods in silver carp between April and October 2018, with additional histological data from August to October 2017. Here, we show that female silver carp are batch spawners with asynchronous, indeterminate oocyte recruitment, while male silver carp utilize a determinate pattern of spermatogenesis which ceases in the early summer. High plasma testosterone levels in females could be responsible for regulating oocyte development. Our results suggest that silver carp have high spawning activity in the early summer (May-June), but outside of the peak spawning period, female silver carp can maintain spawning-capable status by adjusting rates of gametogenesis and atresia in response to environmental conditions, while males regress their gonads as early as July. The results of this study are compared to reports of silver carp reproduction in other North American rivers as well as in Asia.

Factors limiting successful reproduction in wild silver carp, Hypophthalmichtys molitrix, in Kherrata Reservoir, Algeria

Abstract Silver carp, Hypophthalmichtys molitrix (Cyprinidae), is the most important freshwater fish in Algerian aquaculture. No natural spawning is observed in Algerian water bodies. This study was conducted with the aim of investigating silver carp reproduction in the wild in Algeria. This investigation can contribute tools to facilitate successful artificial reproduction. Macroscopic and histological analysis of the gonads was conducted, and the monthly distribution of maturity stages and oocyte diameters were monitored in an aggregate sample of 130 male and female silver carp, H. molitrix, (450-710 mm total length). The gonadosomatic index (GSI) ranged from 2.76 to 18.88% in females and from 0.34 to 1.85% in males. The female GSI values were the highest from June to August indicating the onset of the spawning season. The histological structures of the gonads revealed five different developmental stages in females and three stages in males. The oogenesis stages were the perinucleolar stage, the yolk vesicle stage, the primary yolk, the secondary yolk, and the tertiary yolk. Migratory nuclei and hydrated oocytes, which are considered to be the maturation stage, were not observed. Three different spermatogenesis phases (immature, maturing, and mature testis) were identified, which included final spermatozoa maturation.

Effects of short-time exposure to atrazine on miRNA expression profiles in the gonad of common carp (Cyprinus carpio)

BackgroundAtrazine is widely used in agriculture and is a known endocrine disrupting chemical. Atrazine can seep into the water body through surface, posing a potential threat to the aquatic ecological environment and human drinking water source. In vertebrate, studies have shown that it can affect reproduction and development seriously, but its molecular mechanism for aquatic animals is unknown. Aquaculture is very common in China, especially common carp, whose females grow faster than males. However, the effects of atrazine on the reproduction of carp, especially miRNA, have not been investigated.ResultsIn this study, common carp (Cyprinus carpio) at two key developmental stages were exposed to atrazine in vitro. Sex ratio was observed to analyze the effect of atrazine on the sex. MiRNA expression profiles were analysed to identify miRNAs related to gonad development and to reveal the atrazine mechanisms interfering with gonad differentiation. The results showed that the sex ratio was biased towards females. Atrazine exposure caused significant alteration of multiple miRNAs. Predicted targets of differently-expressed miRNAs were involved in many reproductive biology signalling pathways.ConclusionsOur results indicate that atrazine promoted the expression of female-biased genes by decreasing miRNAs in primordial gonad. In addition, our results indicate that atrazine can up-regulate aromatase expression through miRNAs, which supports the hypothesis that atrazine has endocrine-disrupting activity by altering the gene expression profile of the Hypothalamus-Pituitary-Gonad axis through its corresponding miRNAs.

Development of a quantitative PCR method for screening ichthyoplankton samples for bigheaded carps

Monitoring ichthyoplankton is useful for identifying reproductive fronts and spawning locations of bigheaded carps (Hypophthalmichthys spp.). Unfortunately, sorting and identifying ichthyoplankton to monitor for bigheaded carp reproduction is time consuming and expensive. Traditional methods require frequent egg-larvae sampling, sorting of all samples to obtain presumptively identified bigheaded carp, and genetic validation of presumptively identified eggs. Quantitative PCR (qPCR) has the potential to streamline this process by identifying samples that likely do or do not contain a target species. Our objective was to develop a genetic screening tool using qPCR with the duplex assays SCTM4/5 and BHTM1/2 to prioritize samples that have a higher likelihood of containing bigheaded carp eggs or larvae. We used tandem ichthyoplankton samples collected for monitoring bigheaded carps in the Upper Mississippi, Illinois, and St. Croix rivers to evaluate the effectiveness of qPCR as a screening tool. Samples with > 10,000 copies of DNA had 100% occurrence of bigheaded carp eggs or larvae in the traditionally sorted samples, whereas samples with < 10 copies of DNA had 0% occurrence of ichthyoplankton from these invasive species. We used a logistic regression model to calculate the probability of finding bigheaded carp eggs or larvae based upon the number of DNA copies; 406 copies corresponded with a 50% probability of having bigheaded carp ichthyoplankton present in a sample. These data can be used to inform management actions (i.e., control, containment) for these invasive fishes, and this tool could be adapted for monitoring for reproduction of other aquatic invasive species.

Ecological and genetic features of the Ukrainian Antoninsko- Zozulinetsky species of scaly carp (Cyprinus carpio L.) population

The main ecological and genetic features of growing in the internal reservoirs of Ukraine of promising populations of the Antonino-Zozulentskyi sparse carp are presented. A morphometric evaluation of the breeding material was conducted. The studied herd is homogeneous, the coefficients of variability are stable and correspond to the normative indexes of Ukrainian flint breed. According to the results of the analysis, the pedigrees were divided into classes, elite groups were isolated, from which the material material was formed for performing carp reproduction. Species-specific features of the genetic structure were revealed by distribution of allelic frequencies by albumin loci, esterase, transferrin. The analysis of the genetic structure showed the specificity of the distribution of allelic frequencies and genotypic composition of the protein loci. An analysis of the variety of genotypes of the studied populations in the context of the farms gave an opportunity to detect specific genotypes according to the transferrin locus, and the lack of some theoretically expected ones, namely TF АВ, ВВ snd DD. Specific in Medzhybizh fishpond, the genotypes of TF С1С1 were genotypes for scapular carps, the specifics of the TF С1С2 genotype, Antoninus — AC1 and AC2, were specific for carps from the Staraya Sinyava fishpond. The differences in terms of average heterozygosity are obtained, which makes it possible to control the level of variability in the genetic structure of the studied populations. A statistically significant excess of heterozygotes was found in most loci except TF and EST in the study group. The highest level of heterozygosity in the studied groups of carp is marked by loci ALB (78.8–82.8%) snd ME (72.7–82.8 %). The obtained data indicate that the optimal level of genetic heterogeneity (60–71%) in the carps of the «Medzhybizh» and «Antonina» sites is observed in comparison with the «Stara Synyava» section, where it is the lowest (57%). Data were obtained for the use of individual genetic-biochemical systems for differentiation and the conduct of permanent genetic monitoring of the populations of scaly carp. Promising and ecological safety of carp growing in Ukraine is proved.

Ontogenetic changes in swimming speed of silver carp, bighead carp, and grass carp larvae: implications for larval dispersal.

Bighead, silver, and grass carps are invasive in the waterways of central North America, and grass carp reproduction in tributaries of the Great Lakes has now been documented. Questions about recruitment potential motivate a need for accurate models of egg and larval dispersal. Quantitative data on swimming behaviors and capabilities during early ontogeny are needed to improve these dispersal models. We measured ontogenetic changes in routine and maximum swimming speeds of bighead, grass, and silver carp larvae. Daily measurements of routine swimming speed were taken for two weeks post-hatch using a still camera and the LARVEL program, a custom image-analysis software. Larval swimming speed was calculated using larval locations in subsequent image frames and time between images. Using an endurance chamber, we determined the maximum swimming speed of larvae (post-gas bladder inflation) for four to eight weeks post-hatch. For all species, larval swimming speeds showed similar trends with respect to ontogeny: increases in maximum speed, and decreases in routine speed. Maximum speeds of bighead and grass carp larvae were similar and generally faster than silver carp larvae. Routine swimming speeds of all larvae were highest before gas bladder inflation, most likely because gas bladder inflation allowed the fish to maintain position without swimming. Downward vertical velocities of pre-gas bladder inflation fish were faster than upward velocities. Among the three species, grass carp larvae had the highest swimming speeds in the pre-gas bladder inflation period, and the lowest speeds in the post-gas bladder inflation period. Knowledge of swimming capability of these species, along with hydraulic characteristics of a river, enables further refinement of models of embryonic and larval drift.

ЕСТЕСТВЕННОЕ ВОСПРОИЗВОДСТВО СЕРЕБРЯНОГО КАРАСЯ CARASSIUS AURATUS GIBELIO (BLOCH, 1782) В НИЗОВЬЯХ Р. ВОЛГИ В 2012-2013 ГГ

Observation of spawning of carp sires and fattening of larvae and fry in 2012-2013 was carried out by the staff of the Laboratory of Fish Reproduction Federal state scientific institution "CaspNIRKh" from April to July on the spring floods in the lower reaches to the Volga river, in the west part: in Gandurinski, Chief, Kirov banks; in the east: in Belinsky and Vasilevsky banks, using research vessels and cars. The studies took place on the spawning grounds of the lower reaches of the Volga. Estimation of carp juvenile abundance was conducted according to the results of registration survey of juveniles in the hollow period of flood water on the spawning grounds of the western and eastern parts of the Delta. Depending on the area of the studied reservoir there were selected at least 5 samples at different sites. The catch of carp juveniles was carried out with a 6-meter scraper made of sprat net with a rare gas bag. Hydrological parameters were provided by the researchers of the Laboratory of water problems and toxicology, Federal state scientific institution "CaspNIRKh". The reliable research data assert that more favourable conditions for crucian carp breeding were formed in 2013. The duration of flooding and spawning had a positive impact on the natural reproduction of carp. Low water level in the delta front and overgrowing of water bodies in recent years contribute to creation of favorable conditions for silver carp spawning, survival of juveniles, availability of food and increase in their number. In high water year of 2013 average weight and length of juveniles was higher in all locations, compared to 2012. In 2013 in all the spawning grounds under study a large proportion of crucian carp juveniles (84.09%) was characterized by viability (F and G stages), whereas in 2012 in the spring floods of the upper zone of the eastern part of the Volga the early larvae of stage C were registered. In 2013 on the spawning grounds of the Delta the average concentration of juveniles of crucian (33.4 thousand sp/ha) and abundance of juvenile carp were higher, compared to 2012 (2.1 and 2.6 times, accordingly).

Multistate models of bigheaded carps in the Illinois River reveal spatial dynamics of invasive species

Knowledge of the spatial distributions and dispersal characteristics of invasive species is necessary for managing the spread of highly mobile species, such as invasive bigheaded carps (Bighead Carp [Hypophthalmichthys nobilis] and Silver Carp [H. molitrix]). Management of invasive bigheaded carps in the Illinois River has focused on using human-made barriers and harvest to limit dispersal towards the Laurentian Great Lakes. Acoustic telemetry data were used to parameterize multistate models to examine the spatial dynamics of bigheaded carps in the Illinois River to (1) evaluate the effects of existing dams on movement, (2) identify how individuals distribute among pools, and (3) gauge the effects of reductions in movement towards the invasion front. Multistate models estimated that movement was generally less likely among upper river pools (Starved Rock, Marseilles, and Dresden Island) than the lower river (La Grange and Peoria) which matched the pattern of gated versus wicket style dams. Simulations using estimated movement probabilities indicated that Bighead Carp accumulate in La Grange Pool while Silver Carp accumulate in Alton Pool. Fewer Bighead Carp reached the upper river compared to Silver Carp during simulations. Reducing upstream movement probabilities (e.g., reduced propagule pressure) by ≥ 75% into any of the upper river pools could reduce upper river abundance with similar results regardless of location. Given bigheaded carp reproduction in the upper Illinois River is presently limited, reduced movement towards the invasion front coupled with removal of individuals reaching these areas could limit potential future dispersal towards the Great Lakes.

Molecular cloning and expression profiles of IGFBP-1a in common carp ( Cyprinus carpio ) and its expression regulation by growth hormone in hepatocytes

In this study, we cloned and determined IGFBP-1a cDNA from common carp (Cyprinus carpio) liver. The 1655 bp full-length cDNA consisted of a 96 bp 5-untranslated region (UTR), a 789 bp open reading frame encoding 262 amino acid residues and a 770 bp 3-UTR containing seven mRNA instability motifs. Northern blot revealed a 1.8 kb IGFBP-1a transcript. IGFBP-1a mRNA was widely distributed in all tissues examined and predominantly expressed in the liver. During embryogenesis, IGFBP-1a mRNA was firstly observed in blastula stage, and significant increases were observed in body segment stage, lens formation stage and blood cycling stage. After hatching, its expression increased more than twenty times. Furthermore, hypoxia could significantly up-regulate IGFBP-1a expression in the liver and brain. IGFBP-1a expression increased with ovarian maturation and decreased at regressed stage. In testis, IGFBP-1a mRNA maintained relatively higher levels at recrudescing and matured stages, while it sharply declined at regressed stage. In primary cultured hepatocytes, IGFBP-1a gene was greatly down-regulated by growth hormone via the MAPK and PI3 kinase signaling pathways. These results suggest that IGFBP-1a may be involved in the IGF system regulating growth, development and reproduction in common carp.

Reproductive characteristics of an invasive species Carassius gibelio (Bloch, 1782) in Ataturk Dam Lake, Turkey

In this study, sex composition, spawning period, fecundity and sexual maturity of the gibel carp, Carassius gibelio (Bloch, 1782), an invasive species in the Atatürk Dam Lake, on Euphrates River,Turkey were studied. C. gibelio specimens were analysed from Ataturk Dam Lake and the percentage of the males and females was 45.55% and 55.45% respectively out of the 110 specimens studied, ranging between age groups I -VI. The age at first maturity was three years for both females and males. The diameter of the egg was smallest in September, with a mean of 0.62 mm, while the mean egg diameter in June was greatest, at 1.54 mm. The absolute fecundity ranged from 1054 to 22548. Reproduction of gibel carp in Atatürk Dam Lake in Turkey was characterised by a young age at first maturity and high spawning capacity that would facilitate population expansion in aquatic environments.

БИОЛОГИЧЕСКАЯ МЕЛИОРАЦИЯ АЗОВСКИХ ЛИМАНОВ КРАСНОДАРСКОГО КРАЯ И ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ СРЕДСТВ, ПОЛУЧЕННЫХ В КАЧЕСТВЕ КОМПЕНСАЦИИ УЩЕРБА, НАНЕСЕННОГО ВОДНЫМ БИОЛОГИЧЕСКИМ РЕСУРСАМ

The author has carried out a retrospective analysis of environmental data about the Azov limans of the Krasnodar Krai. The increasing liman deterioration leading to their complete disappearance has been noted. Assessment of the priority of liman fish economy has been given. In terms of biological melioration there have been offered measures on stocking limans with herbivorous fish species of different age: grass carp Ctenopharyngodon idella and white silver carp Hypophthalmichthys molitrix , and determined necessary amounts of yearly stocking of the Azov limans. Modern data on the overgrowth in the water area of the Azov limans by higher aquatic vegetation have been presented in the context of the main groups of limans. The groups of limans were graded according to the priority of conducting biological melioration measures in them and practical recommendations were given on the quantity and places of stocking of the Azov limans grass carp and white silver carp depending on the degree of overgrowth. The necessity of using the funds received as compensation for the harm to water biological resources in the Krasnodar Krai for the artificial reproduction of grass carp and white silver carp and their introduction into the Azov limans has been substantiated. The article shows that stocking limans with herberous fish species will both ensure ameliorative effect and increase amount of fish commercial output.

Hydrology controls recruitment of two invasive cyprinids: bigheaded carp reproduction in a navigable large river.

In the Mississippi River Basin of North America, invasive bigheaded carp (silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis, also referred to as Asian carp) have spread rapidly over the past several decades. In the Illinois River, an important tributary of the Upper Mississippi River, reproduction appears to be sporadic and frequently unsuccessful, yet bigheaded carp densities in this river are among the highest recorded on the continent. Understanding the causative factors behind erratic recruitment in this commercially-harvested invasive species is important for both limiting their spread and managing their harvest. We analyzed weekly catch records from 15 years of a standardized monitoring program to document the emergence of age-0 bigheaded carp in relation to environmental conditions. The appearance of age-0 fish was generally linked to hydrographic attributes, which probably serve as a cue for spawning. However, we found profound differences in the number of age-0 fish among years, which varied by as much as five orders of magnitude in successive years. The strong link between summer flooding and age-0 fish production we observed emphasizes the importance of understanding the hydrologic context in which sustained invasions occur. Despite evidence of sporadic recruitment, bigheaded carp populations in the Illinois River appear to be consistent or increasing because of particularly strong, episodic year classes.

Using a Population Model to Inform the Management of River Flows and Invasive Carp (Cyprinus carpio).

Carp are a highly successful invasive fish species, now widespread, abundant and considered a pest in south-eastern Australia. To date, most management effort has been directed at reducing abundances of adult fish, with little consideration of population growth through reproduction. Environmental water allocations are now an important option for the rehabilitation of aquatic ecosystems, particularly in the Murray-Darling Basin. As carp respond to flows, there is concern that environmental watering may cause floodplain inundation and provide access to spawning habitats subsequently causing unwanted population increase. This is a management conundrum that needs to be carefully considered within the context of contemporary river flow management (natural, environmental, irrigation). This paper uses a population model to investigate flow-related carp population dynamics for three case studies in the Murray-Darling Basin: (1) river and terminal lakes; (2) wetlands and floodplain lakes; and (3) complex river channel and floodplain system. Results highlight distinctive outcomes depending on site characteristics. In particular, the terminal lakes maintain a significant source carp population regardless of river flow; hence any additional within-channel environmental flows are likely to have little impacton carp populations. In contrast, large-scale removal of carp from the lakes may be beneficial, especially in times of extended low river flows. Case studies 2 and 3 show how wetlands, floodplain lakes and the floodplain itself can now often be inundated for several months over the carp spawning season by high volume flows provided for irrigation or water transfers. Such inundations can be a major driver of carp populations, compared to within channel flows that have relatively little effecton recruitment. The use of a population model that incorporates river flows and different habitats for this flow-responsive species, allows for the comparison of likely population outcomes for differing hydrological scenarios to improve the management of risks relating to carp reproduction and flows.

Source of bigheaded carp (Hypophthalmichthys spp.) in Lake Balaton, Hungary: natural recruitment or continuous escapement from aquaculture?

The worldwide spread of bigheaded carp (Hypophthalmichthys spp.) is considered an ecological threat and problem in many countries. The aim of this study was to consider the likelihood of bigheaded carp reproduction in Lake Balaton and its catchment area (Hungary). The within-year trends of gonadosomatic index values show that female bigheaded carp increase ovary masses from spring until midsummer, after which a decline is typical. This trend may indicate bulk egg release, but the lack of a sharp drop in fecundity (number of eggs in the ovary) values during and after the potential spawning period suggests that a general and considerable ovary evacuation does not likely explain the declining gonadosomatic index values. Rather, it is more probable that female bigheaded carp resorb their eggs, supported by the presence of atretic oocytes in the ovaries after the potential spawning season. In turn, postovulatory follicles were present in the posterior ovary segments of 2 individuals, indicating that mature eggs were released by some females. The evidence of sporadic egg release does not necessarily imply that successful reproduction has occurred, however. The genetic analyses showed remarkable deviation from Hardy-Weinberg equilibrium within the stock, suggesting that bigheaded carp do not constitute a natural reproductive community in Lake Balaton. Thus, the present bigheaded carp stock in Lake Balaton likely derives primarily from external origin (i.e., from the surrounding fish ponds).

Spatiotemporal Reproduction and Larval Habitat Associations of Nonnative Silver Carp and Bighead Carp

AbstractThe establishment of nonnative Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis (collectively referred to as “bigheaded carp”) in the central United States may have negative ecological consequences and economic impacts. Our objectives were to quantify patterns and habitat associations of adult bigheaded carp reproduction, larval production, and habitat use; such information is important for control strategies and identifying recruitment sources. During May–August 2011, we sampled adults and larvae at 10 sites distributed adjacent to and within the main channel of the Mississippi River at Pool 26 (study area = 28 river kilometers). Female reproductive status, adult location, and larval density were compared to environmental conditions, including temperature, site velocity, and turbidity. Large females spawned earlier than their smaller counterparts. No clear spawning aggregations of adults were observed, suggesting plasticity in staging habitat. Larvae were distributed across all sites during flooding. Larval density was positively related to velocity and turbidity, suggesting that nondepositional areas may facilitate recruitment. Bigheaded carp larvae comprised 10% of the ichthyofauna. Although pooled reaches are a source of recruitment for bigheaded carp in the Mississippi River system, the low densities of bigheaded carp larvae relative to native larvae cannot explain the dominance of adults in this system. Our findings provide insights into the plastic nature of bigheaded carp reproduction and habitats associated with larval development. Control efforts that target large adult females should be conducted earlier during the spring spawn. To maintain fishing pressure, such control efforts would likely need to continue through the summer, when smaller individuals spawn, discharge decreases, and CPUE increases. However, we found no specific mass staging area or habitat type where adult females could be targeted.Received July 19, 2016; accepted December 14, 2016 Published online March 21, 2017

The Socialist Origins of Artificial Carp Reproduction in Maoist China

The Maoist era has often been portrayed as a hindrance to China’s biotechnological development due to Lysenko doctrine and the communist government’s animosity to basic academic research. Yet some of China’s most developed sectors in biotechnology have been made possible by socialist enterprises in agriculture and science under Mao. One such example is China’s world-leading aquaculture biotechnology and genetic research on Asian carp. Although some associated China’s success in the area with the booming Asian market and a globalised biotech industry, the field’s advancement has been deeply rooted in earlier socialist history in reforming aquaculture and science. This article takes one essential technology used by biotech and aquaculture industries–the hormone-aided method in artificial carp reproduction–as a major case. By tracing the political, scientific and sociocultural lineages that made its invention and dissemination possible, this article unpacks the complex local and historical underpinning that defies prevalent understanding about the method as simply a variation of biotechnology’s global form. Particularly, the initial invention of the method was catalysed not only by state economic concerns but also by a socialist understanding of fishery and Maoist attempts to remold scientists. The two successful breakthroughs described in the article demonstrate two ways that scientists and technicians of different social and professional standings have appropriated available scientific and political resources to achieve personal and institutional goals. The dissemination of the method was further cemented through mass involvement during the Cultural Revolution. By delineating the concrete processes that have ‘assembled’ and maintained the artificial carp propagation method, the article contrasts its entanglement with the socialist regime then with the way the method has become decontextualised in its current use.

Life history aspects of carp (Pisces : Cyprinidae) in a dam lake ecosystem: current status and future needs

An increase in aquaculture production may have positive effects on both food resources and a country’s economy. Carp (Cyprinus carpio L.) is the most common cyprinid species in Turkey and accounts for approximately one-fifth of total inland water aquaculture production. However, carp production in Turkey has decreased in recent years. Changes in carp population of Hirfanli Dam were compared with previous studies in similar and different habitats worldwide. The population structure, growth and reproduction of carp were investigated. The length–weight relationships for the carp population of Hirfanli Dam indicated negative allometric growth in males and females, but the condition factor was greater for these carp than carp elsewhere. Asymptotic length and the growth coefficient were 89.42cm and 0.071year–1. Fecundity was positively correlated with fork length, total weight, gonad weight and age. The carp population of Hirfanli Dam evaluated in the present study appeared to have a lower fecundity and smaller egg diameter compared with other carp populations.