Carp Reproduction Research Articles

Effect of melatonin on dopamine secretion in the hypothalamus of mature female common carp, Cyprinus carpio L

Background. The work was the continuation of previous study, which indicated that melatonin influences the inhibition of hypothalamic dopamine secretion in vitro. In the presently reported study, the influence of melatonin injection into the third cerebral ventricle on the release of dopamine was tested. The aim of this study was to investigate if and how melatonin affects dopamine secretion in the hypothalamus of mature female carp. Materials and methods. The concentration of dopamine in hypothalamic tissue was determined radioenzymatically. The experimental groups were fish deprived of melatonin by pinealectomy, fish that received intraventricular injections of melatonin, fish that received intraventricular injections of physiological saline, and intact fish (control treatment). The study was carried out in the summer during spawning and in the winter when fish gonads were regressed. Results. Melatonin injection resulted in an increase in dopamine concentration in the hypothalamus, which indicates that melatonin influenced aminergic nuclei inhibiting secretion of dopamine. Dopamine probably remained unreleased in the hypothalamic tissue, whereas in pinealectomized fish the lack of melatonin influenced continuous dopamine secretion, what was shown as the low dopamine level in the hypothalamus. The results confirmed the previous study effect of melatonin in mature female carp, and point to an inhibitory effect of intraventricularly injected melatonin on the release of dopamine from the hypothalamus. This effect occurred only in the summer experiment, indicating a seasonal impact of melatonin on the dopaminergic system. Conclusion. By inhibiting the release of hypothalamic dopamine, which blocks gonadotropin secretion, melatonin has a potential stimulatory effect on the release of LH and in this way may be involved in control of reproduction in carp.

Age composition, growth, and reproduction of koi carp (Cyprinus carpio) in the lower Waikato region, New Zealand

A total of 566 koi carp (Cyprinus carpio) from the lower Waikato region were aged from scales and opercular bones, and growth was modelled with the von Bertalanffy growth function. There was no difference in growth rate between male and female carp. Growth of koi carp between zero and 3 years of age was lower than that of common carp in Europe and Australia. However, after 5 years of age the growth of koi carp was higher than that of common carp in Europe, but still below that of carp in Australia. Males rarely lived in excess of 8 years, whereas females lived to 12 years. Mean total fecundity calculated from 44 running‐ripe females was 299000 oocytes (±195600 SD) (range 29800–771000). Relative fecundity ranged from 19300 to 216000 oocytes kg‐1 total body weight, with a mean of 97 200 (±35 000 SD) oocytes kg‐1. Feral koi carp in the Waikato are capable of multiple spawnings within their lifetimes. Within a spawning season, Waikato populations of feral koi carp contained females that spawned once, and females that had the potential to have spawned repeatedly. Female gonadosomatic index (GSI) varied with season and was negatively related to water temperature.

Exposure of spermatozoa to duroquinone may impair reproduction of the common carp ( Cyprinus carpio) through oxidative stress

Toxicity of many waterborne organic contaminants to aquatic organisms is mediated through oxidative damages resulting from the production of reactive oxygen species (ROS). Using duroquinone as a model ROS inducer, we carried out in vitro and in vivo experiments to test the hypothesis that reproduction in common carp ( Cyprinus carpio) can be impaired through oxidative damage of their spermatozoa. In vitro exposure of fish spermatozoa to 0, 12.5, 25, 50, 100 and 200 μM duroquinone for 2 h showed a significant increase in the level of ROS in a dose-dependant manner. Sperm motility was significantly reduced in all exposure groups, but lipid peroxidation (LPO) and DNA strand break (measured by comet assay) were only enhanced at 50 μM and above. A significant decrease in subsequent hatching rate was recorded in all the exposure groups, despite fertilization rate was not affected. In the in vivo experiment, spermatozoa were collected 24 and 72 h after fish received intra-peritoneal injections of 1.0 and 10 mg kg −1 body weight duroquinone. DNA damage was clearly evident in spermatozoa of all treatment groups after 72 h exposure, and ROS was significantly enhanced in the high concentration group. LPO however, remained unchanged in both treatment groups. The overall results of both our in vitro and in vivo experiments demonstrated that duroquinone can induce ROS production in spermatozoa, which may impair sperm quality and subsequently reproductive success through oxidative stress.

Acute Toxicity of Synthetic Pyrethroid Cypermethrin on the Common Carp (Cyprinus carpio L.) Embryos and Larvae

In this study, the toxic effects on the embryos and larvae of the common carp were used as a model to investigate the synthetic pyrethroid pesticide, cypermethrin, which contaminates aquatic ecosystems. Data obtained from the cypermethrin acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The control and eight test experiments were repeated five times. The number of dead embryos significantly increased in response to cypermethrin concentrations 0.0001, 0.001, 0.01, 0.1, 1, 2, 4 and 8 μg l−1 (p<0.05 for each case). The 48 h LC50 value (with 95% confidence limits) of cypermethrin for common carp embryos was estimated at 0.909 (0.256–5.074) μg l−1. Dose–response decreases in hatching success were recorded as 87.4, 85.0, 80.2, 71.4, 56.3, 48.6, 38.8 and 23.5%, respectively. The lowest concentration of cypermethrin (0.0001 μg l−1) produced a significant increase in the number of dead larvae compared to the control group (p<0.05). The number of dead larvae significantly increased with increasing cypermethrin concentrations exposed for 1–96 h (p<0.05). The highest concentration (8 μg l−1) showed the highest larvae mortality. The 96 h LC50 value (with 95% confidence limits) of cypermethrin for common carp larvae was estimated at 0.809 (0.530–1.308) μg l−1. The results of the study suggest that low levels of cypermethrin in the aquatic environment may have a significant effect on the reproduction and development of carp.

Acute toxicity of diazinon on the common carp ( Cyprinus carpio L.) embryos and larvae

In the present study, the toxic effects on the embryos and larvae of the common carp were used as a model to investigate the organophosphorus pesticide, diazinon, which contaminates aquatic ecosystems. Data obtained from the diazinon acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The control and six test experiments were repeated five times. The number of dead embryos significantly increased in response to diazinon concentrations 0.25, 0.5, 1, 2, 4, and 8 mg L −1 ( p < 0.05 for each case). The 48 h LC 50 value (with 95% confidence limits) of diazinon for common carp embryos was estimated at 0.999 (0.698–1.427) mg L −1. Dose–response decreases in hatching success were recorded as 84.60, 75.2, 54.1, 31.0, 6.0, and 0.0%, respectively ( p < 0.05). The number of dead larvae significantly increased with increasing diazinon concentrations exposed for 24–96 h ( p < 0.05). The 24, 48, 72, and 96 h LC 50 values (with 95% confidence limits) of diazinon for common carp larvae were estimated at 3.688 (2.464–8.495), 2.903 (2.019–5.433), 2.358 (1.672–4.005), and 1.530 (1.009–3.948) mg L −1, respectively. There were significant differences in the LC 50 values obtained at different exposure times ( p < 0.05). The results of the study suggest that low levels (0.25 mg L −1) of diazinon in the aquatic environment may have a significant effect on the reproduction and development of carp.

The toxic effects of pyrethroid deltamethrin on the common carp ( Cyprinus carpio L.) embryos and larvae

Deltamethrin, a synthetic pyrethroid pesticide contaminating aquatic ecosystems as a pollutant, was investigated in the present study for toxic effects on embryos and larvae of common carp, Cyprinus carpio as a model. The control and five test experiments were repeated five times. The water temperature in the experimental units was kept at 24 ± 1 °C. The number of dead embryos significantly increased in response to deltamethrin concentrations 0.005, 0.05, 0.5, 5, 25, and 50 μg L −1 ( p<0.05 for each cases). Dose–response decreases in hatching success were recorded as 75.2, 64.6, 47.4, 26.0, 14.4, and 9.0%, respectively. The lowest concentration of deltamethrin (0.005 μg L −1) produced a significantly decrease in number of dead larvae compared to control group ( p<0.05). With increasing deltamethrin concentrations, the larvae exposed duration 1–48 h significantly increased the number of dead larvae ( p<0.05 for each cases). The 48 h LC 50 values (with 95% confidence limits) of deltamethrin for common carp embryos and larvae were estimated as 0.213 (0.103–0.404) and 0.074 (0.011–0.260) μg L −1, respectively. The results provide evidence that deltamethrin pollution may have an adverse effect on the reproduction and development of carp, which should be considered when this chemical is used in agricultural areas near aquatic ecosystems.

Age, Growth, and Gonadal Characteristics of Adult Bighead Carp, Hypophthalmichthys nobilis, in the Lower Missouri River

Bighead carp were introduced into Arkansas in 1973 to improve water clarity in production ponds. Bighead carp subsequently escaped aquaculture facilities in the early 1980's and dispersed into the Mississippi and Missouri rivers. The first documentation of bighead carp reproduction in the Mississippi River system was in 1989. The population has increased in the Missouri River as is evident in their increased proportion in the commercial harvest since 1990. The effect of this exotic planktivore on native ecosystems of the U.S. has not been examined. Basic biological data on bighead carp Hypophthalmichthys nobilis in the Missouri River are needed to predict potential ecological problems and provide a foundation for manipulative studies. The objectives of this study were to assess age, growth, and gonadal characteristics of bighead carp in the Missouri River. Adult bighead carp in our sample varied from age 3 to age 7 and length varied from 475 to 1050 mm. There was a large variation in length at age, and overall bighead carp exhibited fast growth. For example, mean back-calculated length at age 3 was 556 mm. The sample was dominated by bighead carp from the 1994 year class. There was no difference in gonad development (i.e., gonadal somatic index, egg diameter) between winter and spring samples. Length of male bighead carp and GSI were not significantly correlated; however, females exhibited a positive linear relationship between length and GSI. In each ovary, egg diameter frequencies exhibited a bimodal distribution, indicating protracted spawning. Mean fecundity was 226 213, with a maximum fecundity of 769 964. Bighead carp in the Missouri River have similar life history characteristics to Asian and European populations. They have become well established in the Missouri River and it is likely that dispersal and population density will increase.

Genetic evidence for gonochoristic reproduction in gynogenetic silver crucian carp (Carassius auratus gibelio bloch) as revealed by RAPD assays.

Sex evolution has been a debating focus in evolutionary genetics. In lower vertebrates of reptiles, amphibians, and fish, a species or a bioform reproduces either sexually or asexually but never both. A few species were found to consist of all females in fish. These all-female species can propagate by asexual reproduction modes, such as gynogenesis and hybridogenesis. However, the coexistence of sexuality and asexuality in a single species was recently noted only in a cyprinid fish silver crucian carp, Carassius auratus gibelio. This fish had been demonstrated to be capable of gynogenesis stimulated by sperm from other related species. Surprisingly, natural populations of this fish consist of a minor but significant portion (approx. 20%) of males. As different clones with specific phenotypic and genetic characteristics have been found, and RAPD markers specific to each clone have recently been identified, this fish offers many advantages for analyzing whether or not genetic recombination occurs between different clones. In this study, artificial propagation was performed in clone F and clone D. Ovulated eggs from clone F were divided into two parts and respectively inseminated with sperm from a clone D male and from a red common carp (Cyprinus carpio) male. The control clone D individuals were selected from gynogenetic offspring of clone D activated by sperm of red common carp. The phenotype and sex ratio in the experimental groups were also observed. Using RAPD molecular markers, which allow for reliable discrimination and genetic analysis of different clones, we have revealed direct molecular evidence for gonochoristic reproduction in the gynogenetic silver crucian carp and confirmed a previous hypothesis that the silver crucian carp might reproduce both gynogenetically and gonochoristically. Therefore, we conclude that the silver crucian carp possesses two reproductive modes, i.e., gynogenetic and gonochoristic reproduction. The response mechanism of two reproductive development modes may be the first discovery in vertebrates. Additionally, we discuss the evolutionary implication between gynogenetic and gonochoristic reproduction modes and the contribution of the minor proportion of males to genetic flexibility in the gynogenetic silver crucian carp.

APPLICATIONS OF FACTOR-CRITERIA SYSTEM RECONSTRUCTION ANALYSIS IN THE REPRODUCTION RESEARCH ON GRASS CARP, BLACK CARP, SILVER CARP AND BIGHEAD IN THE YANGTZE RIVER

The natural reproduction of grass carp, black carp, silver carp, and bighead will be affected adversely by the Three Gorges Project in the Yangtze River. One of the methods to save the fish is to regulate the water levels, keeping them suited for the species to spawn. Nine factors associated with the scale of larvae-flood of the four species are classified into five levels, and the ranges of these factors producing larvae-floods are given by using the “factor-criteria system reconstruction analysis” method. Moderate beginning water levels and flow, with high daily increases in the rate of water level and flow, and a long duration of water level rising are important for the production of a large larvae-flood.

Artificial spawning of carp Cyprinus carpio L.: differences between the effects on reproduction in females of Israeli strain Dor-70 and its cross-breed treated with carp pituitary and Ovopel

The effects on carp reproduction were investigated in females of the Dor-70 strain and a cross-breed of this line with a Hungarian one of carp pituitary and Ovopel as ovulation stimulators. It was clear that, in the case of the Ovopel treatment, a higher percentage of females spawned, although the weight of eggs obtained was less than that yielded by hypophysed fish, the differences being highly significant (P ≤ 0.01) with respect to the weight in grams and to percentage of female body weight. No statistically significant differences were determined in the quality of eggs, measured by both the fertilization percentage and the percentage of living embryos, obtained after the two stimulators were used. Neither the provenance of females nor the interaction of female provenance and the stimulator has any effect on the traits investigated. The correlation between the percentage of fertilization and the percentage of live embryos was 0.54 for strain Dor-70 and 0.95 for the cross-breed. The multiple regression equations were calculated for strain Dor-70 and for cross-breed 5 separately, where the percentage of living embryos constituted a dependent variable and the mass of a female, mass of eggs in grams and the percentage of fertilization were independent variables. We appraised the regressions as significant for Dor-70 (P ≤ 0.04) and highly significant for the cross-breed (P ≤ 0.0001).

Biology of sperm and artificial reproduction in carp

Although the common carp, Cyprinus carpio, has been cultivated for several thousand years and is produced in large quantities, research on reproduction has been very limited. Traditionally, spawning occurred naturally in situ in rearing ponds. In slightly improved methods large breeding ponds stocked with brood fish were devoted to reproduction with fry collection in autumn, or in small spawning ponds with collection of larvae a few days after hatching. Controlled reproduction in hatcheries started only in the 1950s. This paper reviews some of the basic work on carp sperm and describes the technologies of artificial reproduction. The sperm is of a primitive type with uncondensed chromatin and a small midpiece. As in most teleost fish, the sperm is immotile in the male genital tract and in the semen and is activated after release into fresh water. The initiation of motility is due to the decrease in osmotic pressure. The structure of the flagellum is rapidly disorganized in fresh water and sperm stop moving after 30 s. When dilution occurs in a 50 mM NaCl solution, the osmotic change is sufficient to initiate motility, but the flagellum is not disorganized and swimming lasts a few minutes. Motility depends mainly on endogenous ATP stores, about 12 nmol 10 8 spermatozoa, and stops when 50–80% of the ATP is exhausted by hydrolysis. The procedure of artificial insemination includes collection of gametes (from “hypophysised” males and females), mixing in an extender (45 mM NaCl, 5 mM KCl, Tris 2.5 mM, glycine 19 mM, pH 8) in a ratio 1 litre of eggs to 1 litre of diluent and 1 ml of semen. Sperm motility can be triggered during collection by contamination of the semen with urine; this could interfere with fertilization and, if present, urine should be discarded by pouring out the top part of the tube. The sticky layer of the egg is removed by adding a “dissolving solution” (20 g urea/1 + 4g NaCl/1 of water) or milk (diluted 1 5 in water) to the fertilized egg and stirring. One hour later the swollen eggs are transferred to incubators (usually Zug bottles, sometimes 200 litre circular jars).

Mineral requirement in fish. XVIII Effect of deletion of several trace elements from a mineral mixture in fish meal diets on mineral composition of gonads in rainbow trout and carp.

The effect of deletion of various trace elements from the mineral mixture in the fish meal diets on mineral composition of gonads was examined by feeding fingerling of both rainbow trout and carp with various diets for 93 and 83 weeks, respectively. Deletion of one of each trace element or total deletion of trace metals from the mineral mixture in fish meal diets greatly affected the mineral compositions of both ovary and testis in rainbow trout and carp. Especially mineral compositions in gonads were found to be significantly affected by Zn or Mn deletion. The content of Zn in both testis and ovary of carp was three to four times higher than that of the rainbow trout. A similar result of Zn was also obtained in the concentration of Mn in testis, being higher in carp than in rainbow trout. However, the content of Mn in ovary of carp was much less that of rainbow trout. Thus, it is suggested that quality of eggs in terms of rate of eyed eggs and hatchability is affected by mineral status in broodstock and eggs through diets. These results have also demonstrated that although white fish meal containing various kinds of minerals is used as a protein source, a supplement of dietary trace elements is essential for normal growth and reproduction of both rainbow trout and carp.

Temperature regulation of ovarian steroid production in the common carp, Cyprinus carpio L., in vivo and in vitro

The effect of temperature on ovarian steroid production in the common carp, Cyprinus carpio L., has been studied in vitro with exogenous and endogenous precursors, and in fish held at three different temperatures in vivo. With radioactive testosterone as substrate, the major metabolite was testosterone glucuronide, but androstenedione and 5α-androstane-3β,17β-diol were also identified, 5α-Androstane-3β,7α,17β-triol was tentatively identified and two other polar metabolites were isolated, one of which was convertible to this triol. A significant increase in production of most metabolites occurred between 20 and 24°. Production of estradiol and testosterone from endogenous substrate under gonadotrophin stimulation in vitro showed a marked temperature dependence, but the response was closely related to ovarian maturity. Stage 4–5 ovaries produced testosterone, while late Stage 3 tissue produced only estradiol. Neither steroid was produced in significant quantities by less mature ovaries. The results indicate that the “switch off” of ovarian aromatase activity at the end of vitellogenesis is actuated by an ovarian rather than by a pituitary factor. Secretion of testosterone and estradiol showed a very significant change with temperature with the optimum at 24–29°. Profiles for individual fish show that this optimal range is extremely narrow, particularly for estradiol, where secretion may increase as much as twentyfold over 5°. The results in general correlate well with 24° as the most favourable temperature for reproduction in carp. Plasma concentrations of testosterone and estradiol closely paralleled the in vitro secretion rates of these hormones. Plasma testosterone levels were greatest in the most mature fish, whereas plasma estradiol was significantly higher in late Stage 3 fish than in those of greater or lesser ovarian maturity. More Stage 4 and 5 fish were found in the group held at 24° than at 20 or 29° for 4 weeks, but all groups contained a high proportion of early Stage 3 fish.

Sex Ratio, Age of Spawning Fish, and Duration of Spawning in the Carp, Cyprinus carpio (Linnaeus) in Lake Carl Blackwell, Oklahoma

lfitroduction The ubiquitous occurrence of carp in rivers and reservoirs west of the Rocky Mountains is mainly a function of a high ecological valence including adaptability to diverse abiotic factors, euryphagous feeding, and highly successful reproduction. Reasons for the latter lie in high fecundity, early age at first spawning, longevity, and adaptability to available spawning sites. Certain aspects of carp reproduction, induding time of spawning, size and age at time of spawning, spawning habitat and behavior have been described by Adams and Hankinson (1928), Buck and Cross (1951), Struthers (1931), Walden (1964), Breder and Rosen (1966), and others. Fecundity has been discussed by Hessel (1878), Frey (1940), Rehder (1959), and Swee and McCrimmon (1966) and others. Effects of fluctuating water levels on spawning success of carp have been reported by Rehder (1959) and Shields (1958). Mansueti and Hardy (1967), Smallwood and Smallwood (1931) and McCrimmon and Swee (1967) have studied embryology and development of the carp. The present report describes age at first spawning, duration of spawning, relationship between temperature and time of spawning, and sex ratios of a carp population in Lake Carl Blackwell, Oklahoma, southern Great Plains; Permian Redbeds physiographic region.

Experimental Control of Carp Reproduction through Water Drawdowns in Fort Randall Reservoir, South Dakota

Water drawdowns of 1 1/2 to 2 feet were effected at Fort Randall Reservoir immediately following periods of major carp spawning in 1955, 1956, and 1957. Eggs thus exposed were killed. Predictions of the time of spawning were based on gonadal conditions of mature fish, water temperature and weather forecasts. Major spawning occurred in shallow (less than 1 foot deep) flats during periods of warm, calm weather when open-water temperature first reached 62–68° F. Effectiveness of the drawdowns in limiting carp reproduction was judged by the size of the age class produced each year in comparison to a previous year and to other species sampled by the same methods of spot-poisoning, shoreline seining, gill netting and frame netting. Size of the age class of carp established each year was relatively small. It is concluded that the planned drawdowns were primarily responsible for poor reproduction.

Reproduction of Carp, Largemouth Bass, Bluegills, and Black Crappies in Small Rearing Ponds

about the year 1883. The popularity of this introduction, however, was short-lived, and control measures were quickly sought to prevent the carp from dominating the fish populations in many lakes and streams. Since that time, the detrimental effects of large carp populations on aquatic vegetation have been well documented (Cahn, 1929; Black, 1946; Moyle, 1949; Rose and Moen, 1953; Cahoon, 1953; and Threinen and Helm, 1954), but competition between carp and other fishes is not so clearly understood. Pairs of adult carp, when placed in small ponds without other species of fish present, produced abundant crops of young in each of the 13 trials conducted over a three-year period (Mraz and Cooper, 1957). The studies reported on here were designed to determine the success of natural reproduction and early survival of carp, largemouth bass (Micropterus salmoides), bluegills (Lepomis macrochirus), and black crappies (Pomoxis nigro-maculatus) in small ponds with mixed populations of adult fish at known densities. Four ponds at Delafield, Wisconsin, formerly used to rear largemouth bass and bluegills, were made available for these experiments. These ponds are referred to as numbers III, IV, V, and VI. Ponds I and II were unsuitable for use

Natural Reproduction and Survival of Carp in Small Ponds

From 1912 to 1954 inclusive, more than 200 million pounds of rough fish have been removed from Wisconsin waters. The major part of this total was carp (Cyprinus carpio). Analysis of the catch reports for some of the more heavily fished and more productive waters show the importance of strong year classes in the fishery (Hacker, 1952a, 1952b; Helm, 1951; Threinen, 1952). A tabulation of the size frequency of carp in the catch indicated that as much as 80 per cent of the catch were of one year class. In some instances this year class could be easily traced through a fishery for several years.