共查询到20条相似文献，搜索用时 31 毫秒
1.
2.
3.
Eggs stripped from Coregonus albula were incubated at different constant temperatures. The duration of embryogenesis varied from 183 days at 1.1°C to 45 days at 9.9°C. We describe the course of embryogenesis using 16 easily recognizable developmental stages (DS j). Development rate (DR j) for any given stage (DS j) is expressed as the reciprocal of time (in days) from fertilization to attainment of a given developmental stage. The generalized equation relating rate of development to stages DS j with respect to temperature (x) is The values of DR to the “eyed egg” stage and to 50% hatch, expressed as percentage per day of the total development period, were computed and tabulated for temperatures ranging from 0.1 to 9.9°C. To verify the derived regression model we observed the course of embryogenesis of C. albula eggs incubated in a commercial hatchery at fluctuating temperatures. The observed times of attainment of the successive developmental stages were compared to the predicted times based on mean daily water temperatures. The time observed agreed well with times predicted by the model; the only exception was the time of hatching, which was systematically overestimated (5 to 7 days) by the model. This was possibly due to the influence of dissolved oxygen on the time course of hatching processes, which was not considered in our regression model. 相似文献
4.
Anil Chatterji Z.A. Ansari B.S. Ingole A.H. Parulekar 《Aquaculture (Amsterdam, Netherlands)》1984,40(1):47-55
Growth of the green mussel, P. viridis L., was studied in a sea water circulating system for 12 months. The maximum growth rate was recorded during March–May, coinciding with the maximum abundance of phytoplankton. The other hydrological parameters did not show any marked correlation with growth rate, which was chiefly influenced by the availability of food. A significant relationship was noted between the shell length and total weight of the mussel, i.e. The maximum growth rate (91.62%) was recorded at an early stage and was followed by a sharp decline to 5.78%. The growth pattern of the mussel fitted well with the von Bertalanffy growth equation: 相似文献
5.
Brood stock of Atlantic salmon were sampled from 37 rivers or riversystems (strains) for three consecutive years. Each strain was represented by several full- and half-sib families. During the freshwater period each full-sib family was reared separately and each group was given as equal environmental conditions as possible. Fingerlings large enough to become 1-year-old smolt were freeze-branded and smolts from the different strains were sampled and transported to five salmon farms along the Norwegian coast. This paper deals with body weight and length of Atlantic salmon after a growth period of 2 years in the sea.Significant differences between strains were found for all three year classes. The interaction farm × strain was significant but accounted for only a small part of the total variation. It is concluded that genotype × environment interaction can be ignored when planning a selection programme for Altantic salmon for Norwegian farming conditions. A significant interaction sire × dam was found for the 1972 year-class, implying the presence of non-additive genetic variation. The heritabilities for body weight and length estimated from sire components (year-class 1973 and 1974) were quite high: 0.31 and 0.28, respectively. Genetic correlations between body weight and length were close to unity. The heritabilities for condition factor ( were small and none of the sire components were significant. It is concluded that the combination of weight and length used in calculating the K-factor has minor genetic basis.Genetic variation in body weight of Atlantic salmon is high, and about three times as high as for body length. 相似文献
6.
M.W. Eklund M.E. Peterson F.T. Poysky L.W. Peck J.F. Conrad 《Aquaculture (Amsterdam, Netherlands)》1982,27(1):1-11
Botulism type E was first recognized as a major cause of fish mortality in the United States in 1979. This disease caused an estimated loss of million juvenile salmon reared in earth-bottom ponds during the summer and fall of 1979 and 1980. The botulism outbreaks, preliminary laboratory results of experimental botulism, and precautions to be taken by fish farm employees are discussed. 相似文献
7.
8.
9.
For the safe maintenance of microalgae and rotifers in mass culture, it is necessary to know the exact threshold concentration of ammonia for rotifers. In order to determine this threshold concentration, the continuous culture technique was used as a sensitive method to determine the influence of ammonia on the reproduction rate of the rotifer Brachionus rubens. As expected, only unionized (free) ammonia affected the population growth. Up to a concentration of 3 mg the reproduction of Brachionus was unaffected. In the range of 3–5 mg the reproduction rate decreased, although no animals were killed. This decrease was reversible and could be overcome by lowering the NH3-N concentration. At concentrations over 5 mg the rotifers died within 2 days. 相似文献
10.
Colin E. Nash 《Aquaculture (Amsterdam, Netherlands)》1984,37(2):183-184
Oxygen consumption and ammonia production in elvers of varying growth rates were studied. The allometric equation describing the relationship between oxygen consumption and weight is y =00.638 x0,525, where y is the oxygen consumption (mg/h) and x is the mass (g). The weight specific allometric equation for the relationship between ammonia excretion and weight is . Slow growing elvers were found to have higher respiratory rates (0.737 mg O2 h?1 g?1) than would be expected for their size. 相似文献
11.
The serum half-disappearance time (), metabolic clearance rate and volume of distribution of intraperitoneally administered carp gonadotropin (cGtH) and endogenous GtH levels were determined in sexually mature male and female goldfish, Carassius auratus maintained at 12 ± 1°C or 20 ± 1°C. The results indicated that the rate of serum uptake of the injected cGtH from the peritoneal cavity was greater at 20°C than at 12°C in sexually mature male goldfish. Although increased endogenous serum GtH levels and decreased values of serum were associated with the elevated temperature, there was no difference in any of the parameters between sexually mature male and female goldfish acclimated to 12°C. 相似文献
12.
13.
Cortisol stimulates intestinal fluid uptake in Atlantic salmon (Salmo salar) in the post-smolt stage
Sean C. Cornell David M. Portesi Philip A. Veillette Kristina Sundell Jennifer L. Specker 《Fish physiology and biochemistry》1994,13(3):183-190
The fluid uptake rate of the posterior intestine of salmonids increases during the parr-smolt transformation. Intestinal fluid
uptake in post-smolt Atlantic salmon was investigated after treatment with cortisol and growth hormone (GH), alone or together.
Two replicate experiments were conducted in August 1991 and August 1992. Cortisol was emulsified in vegetable shortening and
vegetable oil (1:1) and implanted into the peritoneal cavity. GH was administered as intraperitoneal injections in a saline
vehicle on days 0 and 2. On days 5 and 6, plasma cortisol levels, gill Na+,K+-ATPase activity, andin vitro measurements of fluid transport rate (Jv) across the posterior intestine were measured. Implants of cortisol elevated the plasma cortisol levels within a physiological
range, and resulted in elevated gill Na+,K+-ATPase activity, as expected. The fluid uptake rate across the posterior intestine was roughly doubled by cortisol treatment.
GH treatment did not affect intestinal fluid transport, gill Na+,K+-ATPase activity, or plasma cortisol concentrations. The seawater-adapting increase in the rate of fluid uptake by the posterior
intestine of smolting salmon is probably stimulated by elevated plasma cortisol concentrations. 相似文献
14.
《Aquaculture (Amsterdam, Netherlands)》1987,65(1):7-14
A simple and rapid on site-test method was used to screen farmed chinook salmon (Oncorhynchus tschawytscha) broodstock for bacterial kidney disease (BKD) at the time of spawning. Kidney tissue and ovarian fluid smears were examined, using the indirect fluorescent antibody technique (IFAT). To check the validity of our field screening procedure, intra-ovum fluid, taken from random samples of 300 surface-sterile, fertilized eggs, was examined in the laboratory for the presence or absence of Renibacterium salmoninarum, using the IFAT. Prior to sampling, eggs were incubated at 15°C for 40 days in enrichment KDM-2 broth. R. salmoninarum cells were found in one out of 10 samples of pooled contents of eggs from fish showing no R. salmoninarum in the kidney tissue (these fish were assumed to have R. salmoninarum-free ovarian fluid); three out of 10 pooled samples from fish in which R. salmoninarum was detected in the kidney but not the ovarian fluid; all of the 10 pooled samples from fish with R. salmoninarum in both the kidney tissue and the ovarian fluid. The number of R. salmoninarum in the pooled egg contents was low (2–23 per 100 fields). Using the IFAT technique it was not possible to determine whether the BKD-bacteria in the eggs were alive or dead. Methods of BKD treatment and screening are discussed as is the validity of using these techniques to prevent vertical transmission of BKD in farmed salmon. 相似文献
15.
《水生生物资源》1998,11(6):387-394
A sperm cryopreservation protocol adapted from turbot, was tested on sea bass using either 250-μL straws or 1.5-mL cryovials. A dilution to 1/3 in Mounib s extender and a cooling rate of −65 °C·min−1 allowed frozen sperm to recover an initial motility similar to that of fresh sperm at thawing; however, significant differences in motility (P < 0.001, n = 10 fish semen) were observed at further post-activation times, the motility decrease being faster in thawed sperm. At the experimental scale, triplicate inseminations of 2-mL aliquots (approximately 2 000 eggs) showed a significant fertility decay of thawed sperm compared to that of fresh sperm (P < 0.01, n = 12 fish semen) when a discriminating 35·103 spermatozoa to egg ratio was applied. When 70·103 and 200·103 spermatozoa per egg were provided in the same experimental conditions, no significant difference appeared between the fertilisation rates of fresh and thawed sperm. In order to validate the procedure for production or cryobank purpose, a scaled-up protocol was established. Two and 50 mL batches of eggs (approximately 2·103 and 50·103 eggs, respectively) were inseminated in triplicate using either fresh or thawed individual sperms of 5 males with 200·103 spermatozoa per egg. The mean fertility decreased by 23.5 % due to cryopreservation. This decline was explained by the loss of fertility of only one sperm, and only in large-volume conditions, probably due to the delay of use after thawing. 相似文献
16.
R Billard 《Aquaculture (Amsterdam, Netherlands)》1978,14(3):187-198
The spermatozoa of various marine teleosts (sea bass, Dicentrarchus labrax; sea bream, Sparus auratus) or fresh water teleosts (trout, Salmo gairdneri; pike, Esox lucius; guppy, Poecilia reticulata) were diluted in media of different salinities. Motility, morphological changes and fertilizing ability were the criteria used in judging the effects of such treatments. The medium best adapted to dilution of sea-fish sperm had a salinity of about 20‰. Sperm motility was increased and prolonged, and fertilization rate was significantly improved (P<0.05) for the sea bass at a dilution. For freshwater fish (trout and pike), an extender with about 7‰ salinity increased motility time and fertility ability (P<0.01) as compared to freshwater. After dilution in fresh water the structure of trout spermatozoa was considerably altered (rupture of plasma membrane and mitochondrial swelling). When spermatozoa were diluted in the extender, there were no significant structural changes in trout, but alteration occurred in the mid-piece of the guppy spermatozoon. It is concluded that fresh water or sea water are not the best media for the practice of artificial insemination in freshwater or marine fish. Investigations should be carried out to define the best extender for use in techniques of artificial insemination in fish produced in aquaculture. 相似文献
17.
The paper describes some past and current work for the control and regulation of ovarian development. It reports on the induction of ovarian maturation out of season by manipulation of photoperiod and temperature cycle, and recommends conditions of constant temperature control at 21°C and photoperiod of for the best results using fish with oocytes in the refractory period. It also recommends salmon pituitary gonadotropin SG-G100 as the best ovulating agent for reliable results, but suggests further research with alternative gonadotropins and steroids. The paper describes some recent progress with the latter. 相似文献
18.
Gametogenesis, spawning and larval production of the European flat oyster Ostrea edulis L. were studied in sublittoral beds in Ballinakill Harbour and Kilkieran Bay, Co. Galway, from April 1977 to November 1978 and from November 1978 to May 1980 respectively. Histol ogical preparations of gonads and percentages of oysters brooding larvae were used to monitor breeding.Maturation began in March/April with ripe gametes appearing in some oysters in mid-May. Incubating oysters were observed from mid-June to August/September. Spent oysters were numerous in September. Gametogenesis was at a minimum from October to February depending on the year of study. Ripeness as measured by four different parameters was observed to peak around 29 June 1977 and 4 July 1978 in Ballinakill Harbour, and on 10 July 1979 in Kilkieran Bay. The onset of maximum ripeness in both populations could be predicted using the formula: where D is the thermal constant in degree-days, n = the number of days required to reach ripeness, ti = temperature to which the oysters were exposed daily (°C) and t0 is the developmental zero for gametogenesis. The mean thermal constant as calculated from the gametogenesis study was 554.52 ± 44.52 degree-days. Redevelopment of gametes began during late winter at mean seawater temperatures above approximately 7.0°C. 相似文献
19.
The effect of pre-freezing treatments as well as freezing of inseminated, not water-activated eggs from rainbow trout Salmo gairdneri, and coho salmon, Oncorhynchus kisutch, was investigated in relation to survival and further development.Effects above freezing temperatures included: the temperature at insemination, viability of inseminated and unactivated eggs after storage, suitability of an incubation medium and the tolerance of eggs to various levels of the cryoprotectant dimethylsulfoxide (DMSO). Freezing experiments included: investigating the action of DMSO (0, 1, 2 mole) and the tolerance of coho eggs to temperatures between ?4.6 to ?30°C. Insemination temperatures between 0.5°C and 9.8°C (coho eggs) as well as incubation in an artifical medium (1-0°C) for 80 min (rainbow trout eggs) and 170 min (coho eggs) did not influence subsequent fertility. Storage of inseminated and unactivated rainbow trout eggs for 135 min and beyond reduced egg fertility. DMSO at 2 and 4 mole was detrimental to coho eggs (1-0°C). One mole DMSO had no (coho) or reduced (rainbow trout) influence on egg fertility when it was added gradually.In the presence of 1 mole DMSO most eggs remained unfrozen (67–89%) when kept for 10 min in frozen artificial medium (?4.6%) and 27–32% subsequently reached the eyed stage (control = 100). Further cooling (0.3°C/min) to ?10°C was still tolerated (62% unfrozen, 22% eyed eggs) but not to ?20°C (6% unfrozen, no development) and ?30°C (no survival). Use of 2 mole DMSO did not improve the results. 相似文献
20.
Artificial induction of maturation and fertilization in the Japanese eel, Anguilla japonica 总被引：4，自引：0，他引：4
H. Ohta H. Kagawa H. Tanaka K. Okuzawa N. Iinuma K. Hirose 《Fish physiology and biochemistry》1997,17(1-6):163-169
Repeated injections of salmon pituitary extract (20 mg per fish per week) induced vitellogenesis in feminized, cultivated Japanese eels (Anguilla japonica). Oocytes were attained at the migratory nucleus stage after 11 or 12 injections. Addition of 17,20-dihydroxy-4-pregnen-3-one (DHP) into the incubation medium induced germinal vesicle breakdown (GVBD) in the oocytes at the migratory nucleus stage. An injection of DHP (2 µg g-1 BW), given 24h after an injection of salmon pituitary extract (20 mg fish-1), succeeded in inducing maturation and ovulation in females which contained occytes at the migratory nucleus stage. Most fish ovulated 15–18h following the DHP injection. Eggs that were ovulated within 15h after the DHP injection showed high fertility and hatchability, but eggs ovulated 18 or 21h after the DHP injection, showed considerably lower fertility and hatchability. A delay between ovulation and stripping of the eggs rapidly decreased both the fertility and hatchability within 6–9h after ovulation, indicating that artificial fertilization must be carried out immediately after ovulation. Repeated injections of human chorionic gonadotropin (hCG) at a concentration of 1 IU g-1 BW week-1 induced spermatogenesis, spermiation, and the acquisition of potential for sperm motility in cultivated males. Most males spermiated after the fifth or sixth injection of hCG, and the milt weight gradually increased and remained constant (1–2 g) from the 11th to 31th injection. Sperm motility peaked 24h after each weekly injection, and decreased from the 3rd day after the injection. Potassium ions are an essential constituent for the maintenance of motility in the eel spermatozoa. Artificial seminal plasma containing 15.2 mM KCl is applicable as a milt diluent. Using these techniques developed for female and male eels, we have succeeded in obtaining many fertilized eggs from cultivated eels. 相似文献