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1.
This study examined the pH sensitivity of steelhead, Oncorhynchus mykiss (Walbaum), sperm motility relative to the composition of incubation and activation media. The percentage of sperm that initiated motility following incubation in a sperm immobilizing solution (SI) titrated to different pH values and subsequent activation by dilution in buffered swimming medium (SM) at pH 8.5 or 50% ovarian fluid (OF) showed little or no pH sensitivity; sperm diluted in de‐ionized water (DI) showed no motility after incubation at any pH. In contrast, motility of sperm diluted in tap water (TAP) was highly sensitive to the pH of the incubation medium. Sperm incubated with buffered seminal plasma at high, but not low pH demonstrated high percent motility when diluted with DI. Sperm incubated in low‐pH SI demonstrated high motility only when diluted into high‐pH SM. The effects of the composition of incubation and activation media on sperm motility were generally reflected in comparable effects on fertility. Therefore, these data indicate that the pH sensitivity of sperm motility and fertility depends on the composition of commonly used incubation as well as activation media.  相似文献   

2.
The effects of different carbon dioxide (CO2) levels on the short-term storage of semen samples from hatchery-produced steelhead (Oncorhynchus mykiss) were evaluated. Sperm motility and fertilizing ability were significantly reduced following 4 h incubation under a relatively modest (0.9 kPa = 1%) amount of CO2. The dose-dependent reductions, however, were not the result of cell death as sperm viability was unaltered even at the highest (5.2 kPa = 5.6%) CO2 exposures. Reductions in sperm motility and fertilizing ability were reversible. Although previous work has indicated a direct relationship between salmonid sperm motility and sperm ATP content, the inhibitory effects of CO2 on sperm motility were not the result of reduced sperm ATP levels. Decreasing the pH of the seminal fluid (to below 7.5) significantly reduced sperm motility. However, this effect was only observed after prolonged (4 h) exposure; short-term (1 min) exposure to this lowered pH did not alter sperm motility. Moreover, acetazolamide, a carbonic anhydrase inhibitor, attenuated the inhibitory effects of CO2 on sperm motility. These results suggest that CO2 inhibits steelhead sperm motility and therefore fertility in a dose-dependent manner, by reversibly lowering intracellular pH.  相似文献   

3.
Sperm motility, pH and osmolality of seminal plasma varied throughout the reproductive season spanning the period from June to September. Initially, sperm motility was low, peaked in July and August and then fell again towards the end of the spawning season. While the pH of seminal plasma increased from pH 7.4 to 7.9 during the period of spermiation, the average seasonal pH (7.78 ± 0.03) remained close to an experimentally determined optimum pH range for ocean pout sperm motility (pH 8–9). Likewise, although the values for seminal plasma osmolality fell during the reproductive season, from 416–339 mmol kg-1, the average osmolality value 356 ± 3 was within the optimum for sperm motility (300–400 mmol kg-1). In comparing fluctuations in sperm motility with the biochemical composition of ocean pout seminal plasma during the spawning season, this analysis showed that increased Mg++ levels were correlated with the summer period of maximum sperm motility. A seasonal decline in Na+ and Cl− ion levels was reflected in lower seminal plasma osmolality values.  相似文献   

4.
Impact of bacteria on short-term storage of salmonid eggs   总被引：1，自引：0，他引：1  
Unfertilized eggs of steelhead, Oncorhynchus mykiss (Walbaum 1792), were stored at a low temperature (～0°C) with antibiotics (penicillin and streptomycin) for up to 22 days and fertility assessed. Unfertilized eggs of chinook salmon, Oncorhynchus tshawytscha (Walbaum 1792), were stored at a low temperature (～0°C) either with or without antibiotics for up to 24 days and fertility assessed. There were no significant decreases in fertility under these conditions. Steelhead eggs were maintained at 4°C for up to 15 days with or without added bacteria and with or without gentamicin. Gentamicin inhibited bacterial growth during storage at 4°C and its use resulted in a less pronounced decline in fertility with storage. These results suggest that low temperatures and antibiotics play an important role in extending the period over which salmonid eggs can be successfully stored.  相似文献   

5.
Gradually increasing levels of gill Na+K+ ATPase activity were observed in juvenile chinook, Oncorhynchus tshawytscha, and coho, Oncorhynchus kisutch, salmon and steelhead trout, Salmo gairdneri, undergoing parr-smolt transformation in artificial rearing facilities on the Columbia River. Portions of the same populations released to migrate seaward, however, generally showed much greater increases in enzyme activity with time and distance from the release point. After migrating 714 km to the Columbia River estuary, spring chinook salmon had a mean gill Na+K+ ATPase activity 2.5 times greater than fish retained at the hatchery and 1.9 times greater than fish adapted to 28 ppt seawater for 208 days. Similar observations were made on coho salmon.  相似文献   

6.
The present study investigated the effects of sequential collection of milt, time of post-mortem storage and anesthesia on rainbow trout (Oncorhynchus mykiss) sperm motility parameters (using computer-assisted sperm analysis – CASA) as well as seminal plasma osmolality and sperm concentration. The post-mortem storage and time of anesthesia altered motility characteristics of rainbow trout sperm to different extents. The moderate impact of time of anesthesia was manifested in a shortened duration of sperm motility after 10 min exposure of fish to anesthetic. The prolonged post-mortem storage (≥40–60 min), in addition to lowering sperm motility duration, also significantly influenced sperm motility parameters, such as sperm velocities, percentage of motile sperm and sperm trajectory parameters. These results clearly demonstrate that when milt from sacrificed fish is used for sperm motility studies, the time of post-mortem storage significantly alters sperm motility characteristics. Since sperm motility rate and swimming velocity could predict fertilizing ability, detrimental effects of prolonged post-mortem storage may lead to reduced fertilization success. Sperm concentration and seminal plasma osmolality were lower in the first fractions and increased with successive collections of milt. It suggests the presence of urine contamination of the first milt fractions which were collected by stripping. Therefore, testing of sperm concentration and/or seminal plasma osmolality should be mandatory while handling stored milt.  相似文献   

7.
Quality differences of testicular semen of the African catfish, Clarias gariepinus, and their influence on fertilization and hatching success were investigated. In accordance with an earlier study, two semen types of the African catfish were distinguished according to testicular maturity stage. Semen type I derived from males with white mature testes whereas type II semen derived from males with grey, partly mature testes. Semen volume, sperm cell concentration and seminal plasma pH was significantly higher in type I semen than in type II semen, while sperm motility was similar. Similar fertilization percentages were obtained with semen type I and semen type II. However, the hatching percentage was higher and the percentage of deformed hatched larvae was lower for type I semen. There were significant (P<0.01) positive correlations between sperm motility and fertilization percentage, seminal plasma pH and hatching percentage and a negative correlation between seminal plasma pH and percentage of deformed larvae. Therefore seminal plasma pH and sperm motility are useful to predict semen quality of the African catfish.  相似文献   

8.
In rainbow trout, Oncorhynchus mykiss, parameters to determine semen fitness for cryopreservation and quality control of cryopreserved semen were investigated. The following parameters can be used to evaluate semen fitness for cryopreservation as they are statistically significant (P < 0.01) correlated to the post-thaw fertilization rate: motility rate of fresh semen (y = 4.996x - 0.0958x2 + 0.0006x3 - 5 1.7363); sperm velocity of fresh semen (y = 6.741x - 0.036x2 - 268.37); seminal plasma osmolality (y = 0.539x - 125.59); seminal plasma pH (y = -82.768x + 728.133); seminal plasma triglyceride levels (y = 0.069x + 29.863); seminal plasma ß-D-glucuronidase activity (y = -1.112x + 0.0058x2 + 82.229); seminal [lasma lactate dehydrogenase activity (y = -0.096x + 0.00006x2 + 583.80); spermatozoan acid phosphatase activity (y = -132.51x + 126.38x2 + 66.48); spermatozoan adenylate kinase activity (y = 3.474x + 4.925). Quality of deep-frozen semen can be evaluated by motility parameters (P < 0.01): frozen/thawed semen motility rate and post-thaw fertilization rate: y = 1.943x + 28.002; sperm velocity and post-thaw fertilization rate: y = 0.8812x - 0.0059x2 + 24.9686.  相似文献   

9.
The effects of extracellular ions on the acquisition and maintenance of the potential for motility in the spermatozoa of the ayu, Plecoglossus altivelis Temminck et Schlegel (Osmeridae), were examined. Testicular spermatozoa and milt spermatozoa were obtained from fully matured males and diluted with buffered solution (BS, 20 mM HEPES–NaOH, pH 7.5). Testicular spermatozoa showed a significantly low rate of motility (0.8 ± 0.4%), whereas milt spermatozoa showed a high rate (89.4 ± 2.1%). The spermatozoa were incubated with various isotonic media for 2 h, diluted with BS, and changes in the rates of motility were then compared. When incubated for 2 h with artificial seminal plasma (ASP), corresponding in terms of ionic constituents to seminal plasma buffered at pH 8.0, both spermatozoa showed a high rate of motility. Testicular spermatozoa acquired and milt spermatozoa maintained the potential for motility in response to the HCO3– ion concentrations (between 0 and 20 mM) in the ASP. The differences in the pH of the ASP had a significant effect on the acquisition and maintenance of the potential for motility, and spermatozoa showed the highest rate of motility with the ASP at pH 8.0 and 8.5. These results suggest that the quality of milt in the ayu can be regulated by controlling the concentration of bicarbonate and the pH of the incubating media.  相似文献   

10.
The purpose of this study was to determine whether daily-elevated water temperature shifts during the embryonic period in spring-run chinook salmon (Oncorhynchus tshawytscha) could influence the phenotypic sex ratio. Three families of salmon embryos were divided into two groups; one was moved between 7.5 °C and 12 °C each day (6–8 hours) for 105 days while the other (control) remained at a constant 7.5 °C. Sex ratios varied between the three families, but no significant sex ratio differences were observed between the control and temperature shifted groups.  相似文献   

11.
Abstract. Five fish cell lines (CHSE-214, STE-137, RTG-2, EPC and FHM) were compared for sensitivity to infectious haematopoietic necrosis virus (IHNV) from samples obtained from naturally-infected fish. Infectious ovarian fluids were obtained from steelhead trout, Salmo gairdneri Richardson, at the Round Butte Hatchery in central Oregon and tissue homogenates were prepared from chinook salmon, Oncorhynchus tshawytscha (Walbaum), alevins during an IHN virus epizootic at the Elk River Hatchery in coastal Oregon. The only lines to show characteristic viral cytopathology by plaque or end-point dilution assay for the steelhead trout virus isolate were the EPC and FHM cell lines. The chinook salmon isolates produced CPE in CHSE-214, STE-137, FHM and EPC cells. The titre of the salmon virus isolate was 10-50-fold higher on FHM and EPC cells by both assay methods. Neither by end-point nor plaque assay did the Round Butte or Elk River isolates produce CPE on RTG-2 cells. With both virus isolants both cell lines showed that greater sensitivity was obtained with plaque assay than with end-point titration. Pre-treatment of the cells with the polycation, polybrene, did not increase the virus titre in either assay. However, a transient enhancement in virus titre was observed in polybrene-treated STE-137 and CHSE-214 cells.  相似文献   

12.
Sperm physiology, in vivo artificial insemination and spawning of the ocean pout (Macrozoarces americanus L.), a marine bottom fish, were studied. Milt was collected from the reproductive tract of mature males by suction using a catheter. The uncontaminated milt, having a very low sperm concentration, contains highly motile spermatozoa and sperm motility was retained in vitro at 4 °C for at least 24 h in both seminal plasma and ovarian slime collected from the oviduct of pre-spawning females. Instead of activating sperm, dilution in sea water instantly immobilized the spermatozoa of ocean pout. Osmolarity and pH of ocean pout seminal plasma were in the ranges 365–406 mOsM and 7.2–7.5, respectively. A study of the ionic composition of ocean pout seminal plasma demonstrated the presence of various ions including Na+, K+, Ca2+, Mg2+, and Cl−, with a remarkably lower K+ concentration compared to that from other fish species. Since injections of milt containing motile sperm into the ovaries of pre-spawning females, which spawned in the absence of males, yielded fertilized ocean pout eggs, it is concluded that the ocean pout exhibits internal fertilization. The larvae hatched after 3 months of egg incubation in ambient sea water (9–10 °C). With proper timing of in vivo artificial insemination of mature females, fertilized ocean pout eggs can be obtained from fish reared in captivity.  相似文献   

13.
Downstream passage for juvenile Chinook salmon Oncorhynchus tshawytscha (Walbaum) and steelhead Oncorhynchus mykiss (Walbaum) through the fish weir at Foster Dam, Oregon, was evaluated to assess the weir's efficacy as a long-term passage solution. Radio telemetry was used to estimate survival, passage and effectiveness for the fish weir, spillway and turbines. Survival of Chinook salmon through the fish weir varied by season and reservoir elevation (66%–87%), and passage proportions were low (8%–20%). Fish weir effectiveness was low to moderate (0.39–2.09). Steelhead survival was lower (57%–77%) but passed the fish weir in higher proportions (77%), and weir effectiveness was consistently high (2.96–5.49). The results indicate the existing fish weir will not be a suitable long-term passage solution for all species. However, because of the high passage proportions and effectiveness observed for steelhead, further development of the surface-flow concept appears to be promising for safely passing downstream-migrating fishes.  相似文献   

14.
Information on prey availability, diets, and trophic levels of fish predators and their prey provides a link between physical and biological changes in the ecosystem and subsequent productivity (growth and survival) of fish populations. In this study two long‐term data sets on summer diets of steelhead (Oncorhynchus mykiss) in international waters of the central North Pacific Ocean (CNP; 1991–2009) and Gulf of Alaska (GOA; 1993–2002) were evaluated to identify potential drivers of steelhead productivity in the North Pacific. Stable isotopes of steelhead muscle tissue were assessed to corroborate the results of stomach content analysis. We found the composition of steelhead diets varied by ocean age group, region, and year. In both the GOA and CNP, gonatid squid (Berryteuthis anonychus) were the most influential component of steelhead diets, leading to higher prey energy densities and stomach fullness. Stomach contents during an exceptionally warm year in the GOA and CNP (1997) were characterized by high diversity of prey with low energy density, few squid, and a large amount of potentially toxic debris (e.g., plastic). Indicators of good diets (high proportions of squid and high prey energy density) were negatively correlated with abundance of wild populations of eastern Kamchatka pink salmon (O. gorbuscha) in the CNP. In conclusion, interannual variations in climate, abundance of squid, and density‐dependent interactions with highly‐abundant stocks of pink salmon were identified as potential key drivers of steelhead productivity in these ecosystems. Additional research in genetic stock identification is needed to link these potential drivers of productivity to individual populations.  相似文献   

15.
Twelve full-sib families of chinook salmon, Oncorhynchus tshawytscha (Walbaum), reared in two environments, were examined for differences in disease resistance following a natural outbreak of vibriosis on a commercial salmon farm in British Columbia, Canada. The two replicate groups differed in early rearing conditions, time of introduction to sea water, and netpen environment. Family mortality data revealed a significant genetic component to disease resistance (sire and dam). Cumulative mortalities in the two replicate groups were significantly different, at 8.1% and 5.7%. There were no significant genotype-by-environment interactions, indicating that the genetic contribution to the disease resistance was stable across environments. Plasma lysozyme activity in both environmental groups was found to have a significant genetic component (sire). There was a significant positive correlation between plasma lysozyme activity and vibriosis mortality.  相似文献   

16.
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17.
Abstract. Carotenoid distribution was examined in muscle, ovary, integument and serum from red- and white-fleshed chinook salmon, Oncorhynchus tshawytscha (Walbaum), along with their muscle proximate compositions. There were no significant differences in muscle compositions of moisture, protein and lipid except for the carotenoid levels between red- and white-fleshed salmon. Similar carotenoid levels of ovaries were found between red- and white-fleshed chinook salmon, although the muscle carotenoid level of white-fleshed salmon was apparently low compared to red-fleshed salmon. This suggests that white-fleshed chinook salmon have the ability to accumulate the carotenoids in their ovaries but not muscle. The white-fleshed chinook salmon may be devoid of carotenoid receptors in their muscle and this seems to be the reason for the failure to accumulate the carotenoids in their muscle.  相似文献   

18.
Juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum), were held in 8–11°C freshwater, starved for 3 days and subjected to a low‐water stressor to determine the relationship between the general stress response and oxidative stress. Lipid peroxidation (LPO) levels (lipid hydroperoxides) were measured in kidney, liver and brain samples taken at the beginning of the experiment (0‐h unstressed controls) and at 6, 24 and 48 h after application of a continuous low‐water stressor. Tissue samples were also taken at 48 h from fish that had not been exposed to the stressor (48‐h unstressed controls). Exposure to the low‐water stressor affected LPO in kidney and brain tissues. In kidney, LPO decreased 6 h after imposition of the stressor; similar but less pronounced decreases also occurred in the liver and brain. At 48 h, LPO increased (in comparison with 6‐h stressed tissues) in the kidney and brain. In comparison with 48‐h unstressed controls, LPO levels were higher in the kidney and brain of stressed fish. Although preliminary, results suggest that stress can cause oxidative tissue damage in juvenile chinook salmon. Measures of oxidative stress have shown similar responses to stress in mammals; however, further research is needed to determine the extent of the stress–oxidative stress relationship and the underlying physiological mechanisms in fish.  相似文献   

19.
Oxytetracycline (OTC), a broad-spectrum antibiotic, is used widely to treat bacterial diseases in farmed fish. In the present study, the time course of OTC concentrations in freshwater rainbow trout, Oncorhynchus mykiss (Walbaum), and seawater chinook salmon, Oncorhynchus tshawytscha (Walbaum), were compared, tissue by tissue, after receiving a bolus dose of the antibiotic (5 mg kg–1 or 50 mg kg–1) intra-arterially (i.a.). The OTC concentration–time profiles of rainbow trout tissues were found to be very similar to those of the corresponding tissues in chinook salmon. Therefore, neither water salinity nor fish species seemed to play an important role in the disposition and elimination of OTC in these salmonids. In a separate experiment, rainbow trout were implanted surgically with a urinary cannula and received a single dose of OTC (50 mg kg–1) i.a. Urine was collected from the cannula daily for 13 days. The amount of OTC excreted into the bile was found to be larger than that eliminated by the urine. These results show the similarity of OTC pharmacokinetics in freshwater rainbow trout and seawater chinook salmon and render support in using a single fish species to study the pharmacokinetics of a drug for other species in the same taxon.  相似文献   

20.
In order to meet the demand of salmon market, Chinese scientists and entrepreneurs are working on salmon mariculture far offshore in the Yellow Sea, China. Rainbow, steelhead trout and Atlantic salmon were selected as the main culture species. The aims of the present study were as follows: (a) investigate the effect of the salinity acclimation method on the growth, osmoregulation and energy budget in two forms of Oncorhynchus mykiss, rainbow and steelhead trout and (b) explore the optimal size of steelhead trout for the seawater entry. In trial I, rainbow (mean = 99.44 g) and steelhead trout (mean = 99.01 g) were reared for 40 days after undergoing salinity acclimation at three rates: an abrupt increase in salinity from 0 to 30 g/L (T30); an abrupt increase in salinity to 14 g/L, followed by a daily increase of 2 g/L (T2) or 6 g/L (T6) until reaching 30 g/L; and no salinity exposure (control treatment) (T0). In trial II, steelhead trout with body weights of approximately 100 and 400 g were cultured for 60 days with two treatments, T0 and T2, and the specific growth rate (SGR) was calculated every 10 days. In trial I, in both kinds of fish, the optimal growth performance, survival rate, osmoregulation and energy budget were observed in the T0 treatment, followed by the T2 treatment. These results indicate that O. mykiss with a body weight of approximately 100 g can adapt to sea water with a gradual transition (T2), but they are still not suitable for the seawater entry because of low growth. Based on the recorded SGRs in trial II, our formulated regression formula revealed that approximately 200 g is the optimal size of steelhead trout for the transition to sea water.  相似文献   

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