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1.
Methods were developed to assess whole‐body immunoreactive corticosteroid concentrations (IRC) and plasma levels of cortisol in Atlantic cod subjected to several common, acute stressors. A measurable corticosteroid stress response was observed at the first sampling in whole bodies of 8‐day post‐hatch (dph) larvae. Two groups of juveniles (～5 and 30 g) were subjected to a 30 s net stressor and whole‐body IRC and plasma cortisol levels were determined. Post‐stressor IRC in smaller fish rose approximately 14‐fold, peaked at 1 h, were sustained for 3–6 h and returned to pre‐stressor levels within 24 h. Post‐stressor plasma cortisol levels in larger fish rose approximately 18‐fold, peaked at 0.5–1 h, were sustained for 1–3 h and then returned to near pre‐stressor levels after 24 h. Immunoreactive corticosteroid concentrations appeared to remain elevated longer than plasma cortisol levels suggesting that steroids other than cortisol were contributing to total immunoreactivity in homogenates. Juveniles exposed to either a grading procedure or high density transport had maximal IRC and plasma cortisol levels within 90 min which returned to pre‐stressor levels within 24–72 h. A reduction in water salinity (20 g L?1) did not moderate the corticosteroid response in juveniles. The results show that Atlantic cod respond to common, acute stressors in a manner similar to other teleosts. Whole‐body homogenates can be used to identify changes in IRC in response to acute stress in cod with the caveat that recovery IRC may differ from plasma cortisol concentrations.  相似文献   

2.
The effects of 60‐mg L?1 clove oil and 60‐mg L?1 tricaine methanesulphonate (MS‐222) on the blood chemistry of rainbow trout were compared after exposure to handling stress via caudal puncture blood sampling. Fish sampled by caudal puncture and subsequently exposed to anaesthetics showed a typical handling stress response over a 48‐h period. There were no significant differences between the responses of fish exposed to equal concentrations of clove oil and MS‐222, with the following exceptions: the blood glucose at full anaesthesia, and lactate at full recovery increased significantly in the clove oil‐exposed fish. In a subsequent experiment, the stress response observed in fish sampled by caudal puncture and exposed to clove oil and MS‐222 was compared with a non‐anaesthetized control group. The increases in plasma cortisol levels were significantly lower at recovery in fish treated with either anaesthetic compared with the control fish. Fish exposed to MS‐222 had significantly higher cortisol levels at 1 h. These findings show that few differences exist between the anaesthetic effects of clove oil and MS‐222 on the physiological response of fish to stress. However, clove oil is more effective at reducing the short‐term stress response induced by handling and blood sampling, and is recommended as an alternative fish anaesthetic.  相似文献   

3.
The golden shiner, Notemigonus crysoleucas, is a major bait and forage fish species in the USA. Farmers produce millions of golden shiners annually that are distributed live, many across state boundaries. Native over much of the eastern and central USA, this species is often present but rarely abundant in natural systems, as fish density is apparently controlled by predation rather than by food resources. Aquaculture of the golden shiner is a century‐old practice and culture methods have evolved over time, resulting in today's farm‐raised, certified specific pathogen– and aquatic nuisance species–free baitfish. Federal and state agencies and universities have a long history of developing culture methods and promoting baitfish culture to replace the indiscriminate and wasteful harvest of fish from natural waters. Despite advances in culture methods and the advantages of a farm‐raised species produced under controlled and biosecure conditions, golden shiner farming is only marginally profitable and remaining farmers survive on farm equity and increased market share from others exiting the business. Ironically, increasing regulations and restrictions leading to a reduction in the supply of farm‐raised baitfish could drive anglers back to harvesting bait from natural waters, the very concern that initiated government support for baitfish culture a century ago.  相似文献   

4.
This experiment was designed to investigate the effect of dietary supplemental ascorbic acid (AA) on the feed intake, growth, serum lysozyme, hepatic superoxide dismutase (SOD) and handling stress response in Chinese longsnout catfish (Leiocassis longirostris Günther) exposed to three levels of unionized ammonia nitrogen (UIA‐N). Juvenile Chinese longsnout catfish were reared in 54 fibreglass tanks with a 3 × 3 factorial design treatment consisting of three supplemental AA levels in ascorbyl 2‐monophosphate (38, 364 and 630 mg AA equivalent kg?1 diet) and three UIA‐N concentrations [0.004 (the control), 0.037 and 0.292 mg L?1]. The fish were sampled on the 11th, 32nd and 60th day. On the 62nd day, the remaining fish were subjected to an acute stress by being held in a dipnet out of water for 60 s, and sampled at 30 min post handling. The results showed that the specific growth rate (SGR) in 32 days significantly decreased with increased water UIA‐N (P=0.0476) but was not affected by dietary supplemental AA (P>0.05). After 60 days, SGR, feeding rate (FR) and feed conversion efficiency (FCE) significantly increased with increased dietary supplemental AA (P<0.001) while remaining unaffected by water UIA‐N (P>0.05). There was no significant interaction between dietary AA and UIA‐N for growth responses (P>0.05). The serum lysozyme activity on the 11th day and the hepatic SOD activity on the 32nd day were significantly affected at high (0.292 mg L?1) water UIA‐N. On the 62nd day, the increase in cortisol resulting from acute stress significantly decreased by higher UIA‐N (P=0.038). It is suggested that Chinese longsnout catfish displayed an adaptive response after long‐term UIA‐N exposure, and AA had beneficial effects on the growth and feed intake of catfish and alleviated the negative effects of chronic ammonia stress. A chronically higher ammonia level shows a tendency to inhibit the cortisol response to another acute stressor.  相似文献   

5.
Salt (NaCl) and gypsum (CaSO4) are used as water additives to mitigate fish stress and improve specimen survival. High stocking densities and the transportation of fish can increase aqueous ammonia, which can, in turn, alter fish cortisol secretion. The objectives of this study were to assess the effects of salt, gypsum, and aqueous ammonia on some stress‐induced physiological responses of jundiá, Rhamdia quelen, juveniles induced by captivity and handling, and to determine the lethal ammonia concentration for this species. Jundiá juveniles were subjected to the following five treatments: water only, water + ammonia (0.4 mg/L), water + NH3 + NaCl (6 g/L), water + NH3 + gypsum (150 mg/L), and water + NH3 + NaCl + gypsum. Blood samples were taken after intervals of 1, 5, 24, and 96 h, and the concentrations of cortisol, glucose, chloride, ammonia, and hematocrit were determined. The NH3 LC50 value after 96 h of exposure (LC50?96h) was measured to be 1.9 mg/L NH3. Either salt or gypsum reduced both cortisol and glucose levels during most of the experimental period, but the combination of both reduced these levels even further. The combined use of NaCl and CaSO4 demonstrates a synergic effect on mitigating stress responses induced by handling and aqueous ammonia in jundiá juveniles.  相似文献   

6.
The effects of handling on haematocrit, haemoglobin, plasma glucose, lactate and total amino acids, liver glycogen and hepatic activity of fructose 1,6‐bisphosphatase (FBPase) and alanine aminotransferase (AAT) were investigated in common dentex (Dentex dentex Linnaeus, 1758). A total of 42 fish (50‐g weight) were subjected to handling (netting and shaking in the air for 45 s). Six fish were sampled at 0, 0.5, 1, 2, 4, 8 and 12 h after handling. Six unstressed fish were also sacrificed at each time and used as controls. Handling resulted in a rise in plasma glucose and lactate levels, as well as in enhanced hepatic FBPase and AAT activities. In most cases values returned to control levels 8 h after handling. There were no significant changes in haematocrit, haemoglobin, plasma total amino acids and liver glycogen levels as a consequence of handling. The results suggest that dentex is rather tolerant to handling; apparently, sensitivity to handling is not the main factor responsible for the low survival exhibited by this species in aquaculture.  相似文献   

7.
A 12-wk feeding trial was conducted in a flow-through system to determine whether juvenile golden shiner Notemigonus crysoleucas have a dietary requirement for ascorbic acid. Triplicate groups of 30 fish each weighing 0.44 g initially were fed semi-purified (casein) diets supplemented with 0 or 250 mg ascorbic acid/kg, or practical (fish meal) diets supplemented with 0 or 250 mg ascorbic acid/kg. The form of ascorbic acid used was L-ascorbyl-2-polyphosphate. Survival was higher in fish fed the semi-purified diet with 250 mg ascorbic acid/kg than in those fed the unsupplemented semi-purified diet, while weight gain did not differ between treatments. Weight gain was higher in fish fed the practical (fish meal) diet supplemented with 250 mg ascorbic acid/kg than in those fed the unsupplemented practical diet, while survival did not differ between treatments. No other signs of ascorbic acid deficiency were observed, but fish fed the casein diets had skin and fin erosion indicative of a possible bacterial infection. Whole-body concentrations of ascorbic acid (total, reduced, and percent of reduced ascorbic acid) were higher in fish fed semi-purified or practical diets supplemented with 250 mg ascorbic acid/kg than in fish fed unsupplemented diets. Golden shiners appear to require a dietary source of ascorbic acid for growth or survival, depending on experimental conditions. The two main differences in the study were in diet composition (semi-purified versus practical diets) and apparent health status of fish fed the different diet types. Additional studies are needed to define requirements further.  相似文献   

8.
In this study the effects of exposure to two air temperatures (15 and 27.5 °C) and three graders commonly used in South Australia (Rotary, Flat Bed and Inside/Out) on Pacific oysters were investigated using post-exposure or post-grading catecholamine levels as a stress indicator. During the 48 h experimental period the circulating dopamine and noradrenaline levels of oysters exposed to 15 °C air temperature did not differ significantly from controls sampled directly from the 15 °C water tank. Conversely, in oysters exposed to 27.5 °C air temperature, dopamine and noradrenaline became significantly different from controls after 8 and 12 h air exposure, respectively, and then returned to the control levels at 24 h.Significant increases (P < 0.05) in circulating noradrenaline and dopamine levels were observed in oysters graded by the Flat Bed and the Inside/Out graders. The circulating noradrenaline concentrations in oysters subjected to the Flat Bed grader were significantly higher (P < 0.05) than those observed in the Rotary graded oysters and close to being significantly higher (P = 0.052) than those levels measured in the Inside/Out graded oysters. The circulating noradrenaline levels in oysters subjected to the Inside/Out grader were, in turn, significantly higher than those recorded in the Rotary graded oysters. These results suggest that in relation to the three graders used in South Australia, the Flat Bed induces the highest stress levels in oysters and the Rotary grader the lowest.  相似文献   

9.
The concentrations of monoamines in the hypothalamus were determined in yellow perch Perca flavescens before and after injection with lipopolysaccharide (LPS; 3 mg kg−1 fish weight) or saline to test for the presence of neurochemical changes potentially associated with changes in plasma cortisol characteristic of intraperitoneal (ip) challenge with LPS. In the first experiment, yellow perch were injected with saline or LPS and the hypothalamus removed and plasma sampled before and at 0.5, 1.5, 3.0, and 6 h after injection. Plasma cortisol was elevated in both saline- and LPS-injected fish through 1.5 h after injection and returned to levels resembling pre-injection by 3 h after injection. Significantly higher amounts of cortisol in plasma from LPS-injected relative to saline-injected fish were observed 6 h following injection. A significant decrease relative to levels observed 0.5–3 h after handling was observed in serotonin concentrations at 6 h following LPS and saline injection with a concomitant increase in the ratio of 5-hydroxyindoleacetic acid:serotonin. In the second experiment, hypothalamic monoamines were sampled before and at 3, 6, 9, 12, and 24 h after injection with LPS or saline. Significant increases from pre-injection levels were observed in the ratio 5-hydroxyindoleacetic acid:serotonin at 9, 12, and 24 h after injection, but no differences were detected between LPS- and saline-injected fish. These results support a model linking serotonergic system activation following handling stress, but no correlations with the sustained elevations of plasma cortisol associated with inflammatory challenge were observed.  相似文献   

10.
Understanding how gilthead sea bream, Sparus aurata L., an important Mediterranean Sea species for aquaculture, respond physiologically to stressors commonly encountered in intensive rearing is important for effective production, as managing for stress is a major factor in maintaining healthy fish stocks. Our objective was to determine whether holding juvenile gilthead sea bream at a high density (HD), as a chronic stressor, would affect their physiological responses to a subsequent acute handling stressor. After acclimation at a low density (LD) of 6 kg m?3 in 200‐L circular tanks containing 33–36 g L?1 recirculating seawater at 19°C under a normal photoperiod, juvenile 37‐g gilthead sea bream were confined for 14 days at a HD of 26 kg m?3 and then subjected to 30‐s aerial emersion in a dipnet. Plasma levels of cortisol, glucose, lactate, osmolality and chloride were determined in fish held in separate lots during LD (control) and HD confinement at 0, 1, 2, 7 and 14 days, and then after handling at 0, 1, 2, 4 and 8 h. Although plasma cortisol levels were similar in LD and HD fish groups after 14 d of confinement (15 and 23 ng mL?1, respectively), the cortisol response in fish from the HD treatment at 1 and 2 h following acute handling (70 and 37 ng mL?1, respectively) was only about half of that measured in the control group (139 and 102 ng mL?1); plasma cortisol was similar in both groups by 4 and 8 h. In contrast, plasma glucose elevations in response to handling were higher at 4 and 8 h in the HD‐held fish (94 and 72 mg dL?1, respectively) than in those from the LD treatment (59 and 51 mg dL?1); glucose responses were similar in both groups at 1 and 2 h after handling and throughout confinement. Plasma lactate levels were higher in LD fish than in the HD group at the beginning of the experiment but were similar after 14 d confinement and responses to handling were similar (e.g. 33 and 35 mg dL?1 at 1 h). Plasma osmolality showed increases during the first 2 h after acute handling but no differences were evident between the two density treatments at any time during confinement or posthandling. Plasma chloride levels did not change throughout the experiment. The reduced plasma cortisol response to acute handling likely resulted from negative feedback of mildly but chronically elevated circulating cortisol caused by the confinement stressor on the hypothalamic–pituitary–interrenal axis. While other post‐handling physiological changes also showed differences between treatment groups, the suppressed cortisol response in the HD‐held fish suggests a reduction in the gilthead sea bream's normal capacity to respond to an acute stressor.  相似文献   

11.
Understanding how released fish recover following capture is vital information for researchers examining the effects of angling on exploited populations. This information is virtually non‐existent for fish angled through the ice in winter, despite the popularity of ice‐angling in many northern areas. To address this gap, 60 northern pike, Esox lucius L., were angled through the ice from an impoundment in eastern Wisconsin, USA, and subjected to one of ten combinations of handling and recovery duration. Plasma samples were collected and analysed for cortisol, lactate and glucose. The results showed a delayed response in the elevation of plasma variables, and a significant interaction between air exposure and recovery time for plasma lactate. No fish suffered mortality during the period of holding. Collectively, these data suggest that northern pike are physiologically resilient to ice‐angling capture stress as long as air exposure times are kept at 4 min or less.  相似文献   

12.
Grading trials were performed in experimental and commercial catfish ponds to compare an in-pond horizontal floating bar grader to current live-car grading. Three replicate trials were conducted in experimental ponds at three different temperature ranges (warm, >26 °C; cool, 13–26 °C; cold, <13 °C) with catfish size groups stocked in ratios of either 75:25, 50:50, or 25:75 sub-marketable (<0.57 kg) to marketable fish (≥0.57 kg). Commercial pond trials were replicated three times at each temperature range with a fish size range typical of ponds ready to harvest. Stress experienced by fish during harvest and grading was measured by mean serum glucose and cortisol levels. Grading speed was greater (P < 0.05) with the UAPB grader (105–449 kg/min) than the traditional live-car grader (0.5–0.6 kg/min). The UAPB grader decreased (P < 0.05) the proportion of sub-marketable fish during all trials. In contrast, the live car did not reduce the proportion of sub-marketable fish with the experimental methods used in this study during commercial trials or in the 25:75 distributions during warm and cold temperature trials in experimental ponds. The UAPB grader returned an average two to four times (range of 2–52) more sub-marketable fish by weight to the pond than the traditional live car method. Glucose and cortisol levels in fish graded with the two technologies were not significantly different. The UAPB grader sorted fish more accurately, consistently, and quickly than the live car at all temperatures in both experimental and commercial trials.  相似文献   

13.
This study investigated the effect of different proportions of dietary docosahexaenoic acid (DHA) and arachidonic acid (ARA) on the growth, survival and stress response of curimba (Prochilodus lineatus Valenciennes) larvae, an omnivorous freshwater species, fed on enriched Artemia. Six different experimental emulsions were formulated to have two levels of ARA (A‐0.5 and A‐1.0), two levels of DHA (D‐0.5 and D‐1.0) two combinations of ARA and DHA (AD‐3:1 and AD‐1:3). There were no significant effects of treatments on curimba standard length and survival at the end of the experiment. The results showed a negative correlation between dietary DHA and whole‐body cortisol after 60 s of air exposure. The resting concentration of cortisol was not affected by the diets (p = .424). After air exposure, all treatments except for D‐1.0 (p = .137) and D‐0.5 (p = .545) exhibited a marked cortisol rise. These results showed that DHA supplementation can have an attenuating effect on cortisol response after air exposure.  相似文献   

14.
Effect of some repetitive factors on turbot stress response   总被引：2，自引：0，他引：2  
The stress response of the turbot, Scopthalmus maximus (L.), to repetitive factors including netting, air exposure, blood sampling and hand-stripping, were tested using two different tank sizes as well as two blood sampling techniques. Exposure of juvenile fish to air for 1-4 min had no immediate effect on plasma cortisol concentrations or haematocrit values. Similarly, the serial netting of immature fish from tanks did not significantly modify plasma cortisol concentrations, haematocrit or osmolarity values. Hand-stripping of mature males was more disturbing than air exposure. The cumulative effect on plasma cortisol levels and osmolarity of stress factors such as netting, air exposure, blood sampling and stripping applied simultaneously to mature males in a 16 m3 tank and repeated twice daily for several days was recorded. The level of cortisol increased from 5 ng ml-1 to 300 ng ml-1 after 10 days of treatment, while an osmoregulatory imbalance and fish death were observed. Moreover, adaptation of fish to smaller tanks seemed to improve the increased plasma cortisol levels and death rate. Reduction in the number of stress factors applied greatly decreased both the range of physiological responses and the death rate. In order to avoid a cumulative stress response, handling of fish should therefore be reduced to a minimum.  相似文献   

15.
Abstract.— A stressful environment induces cortisol that might affect fish breeding and reproduction. In the present work, which aimed to mimic aquacultural conditions of the jundia (Rhamdia quelen) hatcheries in southern South America, females were submitted to normal or stressful handling and the effects of cortisol on serum levels of 17β‐estradiol (E2) and testosterone (T) were determined. In addition, the effect of stress on reproductive parameters such as eggs and swim‐up fry production was also measured. Eight females from a group submitted to stressful handling (SH) conditions and eight females from a group with normal handling (NH) conditions were captured for blood sampling at D 0 and at D 1, 10, 20, 30, and 40 of the experiment. A typical cortisol response was observed in the SH females group in that they presented higher cortisol level in contrast to the NH female group, in all days sampled, except at D 0. In the 10th and 20th d, the E2 levels were lower in SH females, but cortisol levels were higher, suggesting an effect of cortisol on E2 production and/or release. Stressful handling appeared to affect both the number and the quality of the gametes because a lower number of oocytes was stripped from SH females, and from SH fertilized eggs, a lower number of viable swim‐up fry was obtained to be transferred to earthen larviculture ponds. Taken together, the results indicated that stressful handling of broodstock impairs R. quelen reproduction.  相似文献   

16.
Scientific information on baitfish effluents is important to provide a basis for the development of appropriate and cost-effective management practices that minimize environmental impacts. Effluents from 10 commercial golden shiner Notemigonus crysoleucas ponds in central Arkansas were sampled December 2000 through June 2001. Grab samples of the first and last 10% of pond volume were collected during intentional draining events. Effluents were sampled as they exited pond drainpipes and at the ends of drainage ditches just prior to stream discharge. Concurrent receiving stream samples were collected upstream and downstream of the discharge point. Total nitrogen (TN), total phosphorus (TP), 5-d biochemical oxygen demand (BODS), and total suspended solids (TSS) of each sample were measured. Mean whole effluent concentrations for the first 10% were 36 mg TSS/L, 9 mg/L BOD5, 2 mg TN/L, and 0.5 mg TP/L. The water quality of the first and last 10% of pond effluent were not significantly different ( P < 0.05). Filtering effluents through a 5-pm mesh screen did not significantly reduce nutrient concentrations. Serial fractionation of effluents resulted in small but significant decreases in TSS concentrations in samples filtered through the 10, 8, and 5-μm meshes ( P < 0.05). Effluent discharge through farm ditches generally did not improve effluent water quality. Effluents collected at ditch ends were significantly less than drainpipe samples in BOD, concentrations only ( P < 0.05). Limited data on receiving stream water quality indicated that only TP concentrations were greater in pond effluents than in receiving streams. Overall, baitfish pond effluents are similar in composition to effluents of other phytoplankton-based pond production systems.  相似文献   

17.
Behavioural and energetic responses of domesticated rainbow trout Oncorhynchus mykiss (Walbaum) (mean fork length=440±45 mm) to a brief transportation episode were investigated. Fish implanted with radio transmitters measuring muscle activity (electromyogram; EMGi) were transported in a standard commercial shipping tank for 50 min by truck, and then allowed to recuperate for 48 h in stationary culture tanks. The EMGi telemetry data indicated that vigorous swimming activity occurred during transportation. Telemetry recordings also indicated that the fish's swimming activity returned to baseline levels within the 48 h period after transport. However, even beyond the 48 h resting period, the swimming performance (measured as critical speed and endurance) of transported fish was still impaired relative to non‐transported controls (P<0.05). Respirometry measurements of fish taken after transportation indicated that oxygen consumption (Vo2) was significantly elevated. The rise in Vo2 of post‐transport fish could be attributed to handling procedures, as well as the intense swimming behaviour observed during transportation. Therefore, the behavioural responses of fish during transportation produced physiological consequences that persisted long after the transportation event. This study demonstrates the potential for utilizing behavioural measures, in concert with biotelemetry technologies, as tools to assess the impacts of routine aquacultural procedures on the health and welfare of captive fish.  相似文献   

18.
Predator‐prey interactions can be influenced by the behaviour of individual species as well as environmental factors. We conducted laboratory experiments to test for the influences of two abiotic factors (light intensity and habitat complexity) on predator–prey interactions between walleye Sander vitreus and two prey species, bluegill Lepomis macrochirus and golden shiner Notemigonus crysoleucas. Three light intensities were simulated (day, twilight and night) in the presence or absence of simulated vegetation. Observations of predator behaviour indicated that walleye increased activity and foraging success with decreasing light levels and had most success capturing dispersed, closer prey. While schooling could not be maintained as light levels diminished, prey decreased predation vulnerability by moving into vegetation or higher in the water column. Throughout all treatments, bluegill were more evasive to capture as the number of strikes was similar on both prey but capture rates were higher for golden shiner. Although light intensity and simulated habitat complexity affected predator and prey behaviour, these factors did not interact to influence foraging success of walleye. To fully understand predator and prey behaviours in fishes, an understanding of species‐specific responses to abiotic and biotic factors is necessary.  相似文献   

19.
The purpose of this study was to determine the cortisol response of spotted wolffish (Anarhichas minor) after exposure to air immersion and netting (acute stress) under a range of increasing densities (chronic stressor). In addition, the presence of a cumulative negative impact from chronic stress was assessed by the application of an additional acute stressor following rearing at various densities, and proxies of behavior were evaluated (feeding and aggression data). The stress response to air immersion and netting led to increasing plasma cortisol values at 0.5, 13, and 37 h post-stress, with the highest value achieved after 13 h. At 168 h, cortisol concentrations returned to similar pre-stress value. Changes in cortisol concentrations were relatively low after acute stress (five to six fold increases) and recovery time long lasting (>37 h). Prolonged rearing at 20, 30, and 40 kg m?2 showed a non-significant trend of increasing cortisol values with increasing density, and the cortisol response after the application of an additional acute stressor was significantly altered, i.e., higher cortisol levels were measured in unstressed (chronic stress only) compared to stressed fish (chronic stress + acute stress). Our results suggest that (1) spotted wolffish is a low responder that additionally displays a long-lasting cortisol elevation following an acute stressor; (2) fixed densities did not lead to significant differences of plasma cortisol concentration or aggression levels, although involved marked changes in daily feed intake and food conversion efficiency were observed; and (3) cortisol levels reached acute stress values after prolonged chronic stress. Although this species displays indications of being relatively resistant to handling disturbances during aquaculture practices, it is nevertheless responsive to chronic stress factors that could alter the physiological response to subsequent acute stressor.  相似文献   

20.
Of the many stressors in aquaculture, transportation of fish has remained poorly studied. The objective of this study was therefore to assess the effects of a (simulated) commercial transportation on stress physiology of market-size African catfish (Clarias gariepinus). Catfish weighing approximately 1.25 kg were returned to the farm after 3 h of truck-transportation, and stress-related parameters were measured for up to 72 h following return. Recovery from transportation was assessed through blood samples measuring plasma cortisol, glucose and non-esterified fatty acids (NEFA) and gill histology. Also, the number of skin lesions was compared before and after transport. Pre-transport handling and sorting elevated plasma cortisol levels compared to unhandled animals (before fasting). Plasma cortisol levels were further increased due to transportation. In control fish, plasma cortisol levels returned to baseline values within 6 h, whereas it took 48 h to reach baseline values in transported catfish. Plasma glucose and NEFA levels remained stable and were similar across all groups. Transported catfish did not, on average, have more skin lesions than the handling group, but the number of skin lesions had increased compared to unhandled animals. The macroscopic condition of the gills was similar in control, transported and unhandled catfish; however, light microscopy and immunohistochemistry revealed atypical morphology and chloride cell migration normally associated with adverse water conditions. From our data, we conclude that transportation may be considered a strong stressor to catfish that may add to other stressors and thus inflict upon the welfare of the fish.  相似文献   

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