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1.
The performance of all‐female diploid (AF2N) and triploid (AF3N) Atlantic salmon were compared in fresh water, under commercial production conditions in 1995 and 1996 year classes. The performance of the 1996 year class was also assessed for 14 months in a commercial sea farm. Freshwater mortality was higher in the triploid groups. The majority of losses occurred in the early stages of egg development and during the first feeding period, when the incidence of non‐feeding fry was consistently higher. In growth studies, although diploid fry were significantly heavier during first feeding there were no significant differences in weight between groups some 8 months after fertilization or in presmolt growth periods from February to April in 1996 and 1997. Smolting rates were high (range 93.5–95.3%) and the incidence of deformities was low (< 1%) in both groups. Marine survival was lower in the triploid group, largely as a consequence of higher losses sustained during a period of chronic stress, when triploid losses were 9% higher. Growth patterns were similar for the first 11 months in sea water. Although graded triploid salmon were heavier in January 1998 (AF3N 1.62 ± 0.033 kg, AF2N 1.46 ± 0.36 kg, P < 0.05), when the fish were harvested in May 1998 diploid salmon were significantly heavier than triploid salmon although there was no significant difference in weights after evisceration (AF3N 2.40 kg ± 0.04 AF2N 2.49 kg ±0.03). The increase in weight of the diploids between winter and harvest reflects the growth spurt that occurs in maturing fish in the spring. Overall yields of triploid salmon in salt water were lower as a result of inferior survival.  相似文献   

2.
Interest in land-based farms using recirculating aquaculture systems (RAS) for market-size Atlantic salmon (Salmo salar) continues to grow, and several commercial facilities are already rearing fish. Performance data for commercially available mixed-sex, all-female, and triploid all-female Atlantic salmon reared to market-size in freshwater land-based facilities, however, are limited, particularly for European strain fish. Accordingly, eight groups of European-sourced Atlantic salmon (five groups of diploid mixed-sex, two groups of diploid all-female, and one group of triploid all-female fish) were reared from eyed egg to market-size in a semi-commercial scale land-based aquaculture systems over five separate production cycles to quantify performance metrics. Fish reached market-size (4−5 kg) in 24.7–26.3 months post-hatch. Fish were reared at a mean water temperature of 12.3–13.7 °C from first feeding to a mean size of 466–1265 g, then 13.3–15.1 °C during growout. On average, all-female groups grew faster than mixed-sex groups; however, environmental conditions and performance of individual cohorts varied. In a comingled production cycle, diploid all-female salmon grew faster than triploid counterparts. Early maturation rates ranged from 0 % to 67 %, with a mean maturation rate of 34 % for diploid mixed-sex fish and 67 % and 13 % for two diploid all-female groups, respectively. Triploid all-female Atlantic salmon did not mature. This research confirms biological and technological feasibility of growing Atlantic salmon to market-size in land-based systems but controlling early maturation of diploid salmon remained a challenge under the conditions utilized in these trials. This research provides important data inputs to optimize operational and financial projections for existing and potential land-based Atlantic salmon farms.  相似文献   

3.
The migratory behaviour of adult wild and escaped farmed Atlantic salmon, Salmo salar L., before, during after spawning in the River Namsen, Norway, was analysed using radio telemetry. The fish were caught, radio tagged and released into the fjord between 7 and 25 km from the river mouth. A significantly higher proportion of wild (74%) than farmed (43%) salmon was subsequently recorded in the river. Wild salmon (33%) were more frequently captured in the sea and in rivers than farmed salmon (14%). The migration speed from release to passing a data logger 11 km upstream from the river mouth was not significantly different between wild (20.6 km day?1) and farmed (19.8 km day?1) salmon. Wild salmon tagged when water flow in the river was increasing had a significantly higher migration speed than wild salmon tagged when water flow was decreasing. This was not true for farmed salmon. Farmed salmon were distributed significantly higher up the river than wild salmon during spawning, although both types of fish were found together in spawning areas. Thus, there was no geographical isolation to prevent spawning between wild and escaped farmed salmon. Farmed salmon had significantly more and longer up- and downstream movements than wild salmon during the spawning period. Unlike farmed salmon, the number of riverine movements by wild salmon increased significantly when variation in water flow increased. A smaller proportion of wild (9%) than farmed (77%) salmon survived through the winter after spawning.  相似文献   

4.
This study was carried out to examine differences in microstructure and texture of fresh and smoked farmed Atlantic salmon Salmo salar L. fillets with different biological characteristics. The left fillet was analysed fresh and compared with the salted and smoked right fillet from each individual fish. Light microscopy and image analysing techniques were used to study both transversal and longitudinal sections of the muscle. The fish muscle fibres shrank during the salting and smoking process, but sarcomere length did not change. After smoking, a considerable number of fat globules were dispersed among the muscle fibres. The biological characteristics studied were based upon diploid and triploid fish held in both sea cages and land‐based tanks. Different starvation times were used and one group was stressed during slaughter. The cross‐sectional area of muscle fibres from triploid fish was found to be larger than from diploid fish, both in fresh and smoked fillets.  相似文献   

5.
Growth was found to be associated with the changes of trypsin activity in the pyloric caecal tissues and the level of plasma insulin in Atlantic salmon (Salmo salar L.). A decrease in trypsin activity accompanied by an increase in plasma insulin was detected one month before an enhanced growth was observed. There were significant relationships between weight specific consumption rate, plasma insulin levels and fish growth. The correlation of weight specific consumption rate was higher with growth rate (R2=0.7, p<0.0001) than with plasma insulin concentration (R2=0.4, p<0.0001).When the comparison was made between Atlantic salmon carrying and lacking the trypsin variant TRP-2*92, the fish with the variant had lower maintenance ration (p<0.05), higher capacity for protein synthesis in the white muscle (p<0.02), and a greater ability to utilize the feed at a restricted ration than the fish without the variant. In Atlantic salmon lacking the variant, both plasma insulin concentrations and growth rates were significantly lower (p<0.05) in the fish fed 0.5% bw day–1 than those fed 1% bw day–1. Whilst the growth rates of TRP-2*92 salmon fed the different rations became similar one month after similar levels of plasma insulin were observed between them. The TRP-2*92 salmon may be defined as a high protein growth efficiency fish with low protein turnover rate.Genetic variation in trypsin isozyme pattern affects feed utilization, plasma insulin levels and growth in Atlantic salmon.  相似文献   

6.
Endurance of farmed and sea-ranched Atlantic salmon Salmo salar L. males was analysed during spawning time. The fish were endurance tested at different swimming speeds (1.6–2.1 m s?1) in forced swim trials. The sea-ranched males (51-65 cm, n= 20) fatigued significantly earlier than the farmed males(59-72 cm, n= 20),although the sea-ranched males were significantly smaller than the farmed males. When the size difference between the two groups were corrected for, no significant difference in the endurance of the two groups was found. Farmed salmon had a significant higher fat content in white muscle (4.7%) than sea-ranched salmon (1.1%).  相似文献   

7.
The migration patterns of wild and released farmed Atlantic salmon, Salmo salar L., were studied by radio-telemetry during migration from entering a river to after spawning. The wild salmon were caught during return migration in bagnets and the farmed salmon were produced in a near by fish farm. Both groups were tagged and released at sea near the river mouth of the River Alta, North Norway. A pronounced individual variation in migration pattern was observed. No significant differences was found between wild and farmed salmon in the distance from entering the river mouth to the place of the first stop (recorded in the same pool for 5 days or longer) and the days from entering the river mouth to arrival at the first stop. For both wild and farmed salmon, mean migration speed was 2.6 km day1, varying from 0.4 to 11.0 km day-1. A larger proportion of farmed salmon distributed to the upper part of the river at spawning; mean distances from the river mouth were 30.1 and 19.1 km. respectively. Farmed salmon spent a significantly longer time from entering the river to reaching the area occupied during spawning.  相似文献   

8.
Triplicate groups of triploid and diploid Atlantic salmon were fed diets with a low (LP, total P: 7.1 g kg?1), medium (MP, total P: 9.4 g kg?1) or high (HP, total P: 16.3 g kg?1) phosphorous (P) level from first feeding (0.18 g) to transfer to sea water (~50 g, duration: 203 days) and subsequently fed a commercial diet in sea water for 426 days (~3 kg). This study examined the short‐ and long‐term effects of dietary P on freshwater performance (mortality, growth), vertebral deformities (radiology), bone cell activity (ALP and TRACP enzyme activity in vertebrae and scales, and fgf23, bgp and igf‐I relative gene expression in vertebrae), bone mineralization (ash content) and some parameters related to fish condition (heart and liver size). Irrespective of ploidy, at seawater transfer, fish fed the MP diet had significantly highest length and weight and those fed the LP diet significantly lowest length and weight, while those fed the HP diet had intermediate lengths and weights. Increased dietary phosphorus reduced deformities in both ploidies at seawater transfer; however, triploids fed the LP and MP diets had more deformities than diploids fed the respective diets, while there was no ploidy effect observed for fish fed the HP diet. The vertebral bone ash content at seawater transfer was significantly higher in diploids than in triploids when fed the MP diet only. Alkaline phosphatase (ALP) and tartrate‐resistant acid phosphatase (TRACP) enzyme activities and relative gene expression of bone hormones involved in metabolism of plasma phosphate (fgf23) and bone growth (bgp) were not affected by ploidy at seawater transfer, but by dietary P level; LP increased ALP activity and reduced TRACP activity and fgf23 and bgp expression levels in vertebral bone. In scales, LP increased both ALP and TRACP activity. At the termination of the seawater period, the group‐wise pattern in occurrence of vertebral deformities was the same as at seawater transfer. The present results on mortality, growth, bone mineralization and development of skeletal deformities all demonstrate that triploids have a higher P requirement than diploids in fresh water. This study shows that an optimalization of P nutrition for triploid Atlantic salmon can improve health and welfare and reduce down‐grading of triploid salmon.  相似文献   

9.
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10.
Heart deformities are a concern in aquaculture and are linked to egg incubation temperature. Diploid and triploid Atlantic salmon, Salmo salar L., were incubated at 6, 8 and 10 °C and analysed for aplasia of the septum transversum (n = 150 ploidy?1 incubation temperature?1). Heart morphology (size and shape) was assessed in fish incubated at 6 °C and in fish with and without aplasia of the septum transversum (n = 9 group?1) incubated at 10 °C. Egg mortality was significantly higher in triploids than in diploids at all incubation temperatures, and increased egg incubation temperatures increased mortality in both ploidy. Triploids grew quicker than diploids after egg incubation at 10 °C, but not at 6 °C. Aplasia of the septum transversum occurred only in triploid fish after incubation at 6 °C and 8 °C (0.7% and 3.3%, respectively) and was significantly greater (P ≤ 0.05) in triploids after incubation at 10 °C compared with diploids (30% and 18%, respectively). Aplasia of the septum transversum significantly increased heart mass and resulted in a long flat ventricle compared with fish displaying a septum transversum. The results suggest triploid salmon should be incubated below 8 °C.  相似文献   

11.
Arctic char, Salvelinus alpinus L., and Atlantic salmon, Salmo salar L., were fed a commercial diet with or without supplementation of 1.5% Na+-lactate. Dietary Na+-lactate enhanced growth of Arctic char, while that of salmon was unaffected. Dietary 14C-lactate was retained for significantly longer in the stomach of Arctic char than that of Atlantic salmon. Changes in intestinal cholytaurin hydrolase activity, a bacterially produced enzyme, may indicate that dietary lactate affects the intestinal microbiota of Arctic char but not that of Atlantic salmon. Analysis of bile acids of char showed that dietary Na+-Iactate influenced neither intestinal nor gallbladder bile acid composition. Although Arctic char possesses the classical entero-hepatic circulation pathway, no extra loss of bile acids from the fish was observed. It is concluded that the retention time of diet in the stomach of char is significantly longer than that of salmon. This may increase the antibacterial action of lactate in the former, favouring the colonization of lactic-acid-tolerant bacteria in the intestinal tract, some of which produce the enzyme cholytaurin hydrolase.  相似文献   

12.
Growth performance, survival and feed utilization of diploid (2n) and triploid (3n) sex‐reversed male and female Nile tilapia were evaluated at maintenance feeding (1% body weight (BW) day?1), fixed feeding (3% BW day?1) and apparent satiation feeding levels in a freshwater recirculation system comprised of thirty‐six 1‐m3 concrete tanks at the Asian Institute of Technology, Bangkok, Thailand. Triploid Nile tilapia (3n) was produced by subjecting fertilized diploid (2n) tilapia eggs to heat shock. After hatching, fish were sex‐reversed to all‐male and all‐female populations by oral administration of 17 α‐methyltestosterone (60 mg kg?1 feed) and ethynylestradiol (100 mg kg?1 feed) respectively. There was significantly higher growth with increased ration levels in both male and female groups. There were no significant differences in final BW, specific growth rate, survival rate, feed conversion ratio and protein efficiency ratio between diploid and triploid fish. Triploids had lower gonad weights than diploids, and this was particularly evident at the satiation feeding level. Triploid fish had a significantly higher apparent net protein utilization and percentage of gutted weight than diploids at all feeding levels. Higher protein utilization efficiency of triploids might be an advantage for commercial tilapia culture but further research is necessary to make such a conclusion.  相似文献   

13.
Reproductive variables from 1529 females and 168 males of Atlantic salmon Salmo salar L. 1758 were recorded individually during the 1995 spawning season at a salmon farm in the south of Chile. The spawning period occurred in autumn and lasted 43 days, with a peak occurring in the first week of May. Average mature female and male body weights were 6.4 ± 0.9 kg and 7.0 ± 1.0 kg respectively. Average total and relative fecundity of females were 5998 ± 1404 eggs and 946 ± 210 eggs kg?1 respectively. Female body weight showed a similar pattern of correlation with total and relative fecundity observed in other salmonids. Average total and relative volume of ejaculate of males were 47.7 ± 32.8 cm3 kg?1 and 7.26 ± 5.44 cm3 kg?1, respectively, with the latter being lower than the values reported in the literature. Furthermore, male weight showed a negative correlation with these variables, in contrast to a positive value reported for these correlations in the northern hemisphere. Ejaculate volume showed a positive correlation with date of stripping. Average sperm density (5.83 ± 3.75 sperm cm?3 10?9) was lower than the values found in the literature and could be explained by the higher ejaculate volumes.  相似文献   

14.
There is inconsistent evidence of resistance of Atlantic salmon, Salmo salar L., to amoebic gill disease (AGD). Here, evidence is presented that demonstrates that Atlantic salmon exposed and subsequently challenged with AGD are more resistant than naïve control fish. Seventy‐three per cent of Atlantic salmon previously exposed to AGD survived to day 35 post‐challenge compared with 26% exposed to Neoparamoeba sp. for the first time, yet the gill pathology of surviving naïve control or previously exposed fish was not significantly different. Development of resistance to AGD is associated with anti‐Neoparamoeba sp. antibodies that were detectable in serum of 50% of surviving Atlantic salmon previously exposed to AGD. However, anti‐Neoparamoeba sp. antibodies were not detectable in cutaneous mucus of resistant fish. Increased resistance of Atlantic salmon after secondary Neoparamoeba sp. infection and detection of specific serum antibodies provides support for the development of a vaccine for AGD.  相似文献   

15.
This study was undertaken to assess dorsal aorta cannulation as a method to evaluate alterations in diet composition and feeding protocol on pigment retention in salmonid fish. Temporal changes in blood astaxanthin concentrations of dorsal aortacannulated Atlantic salmon, Salmo salar L., were followed in relation to variations in dietary pigment concentration and fish-feeding husbandry protocol. The fish were held individually in 200-L fibreglass tanks supplied with running sea water. Each fish was forced to swim at 0.5 body lengths s?1 and was fed daily by hand to satiation. The fish had an average growth rate of 1% day?1. Blood astaxanthin concentrations were noted to be highly correlated (r= 0.995) with dietary levels of astaxanthin, but not as well correlated (r= 0.71) with total gut content of this pigment. Marked variations in blood astaxanthin concentration were noted between individual fish at each dietary pigment concentration, but the ranking of the fish was generally unaffected between each dietary pigment level. After cessation of feeding a diet supplemented with 75 mg of astaxanthin kg?1, salmon fed a diet with no pigment showed more-rapid blood pigment clearance than those that were starved. Likely, feed remaining in the alimentary tract of the starved fish functioned as a reservoir of pigment for the blood until the intestinal tract was empty. Blood pigment levels were not depressed in salmon fed a diet supplemented with 75 mg of astaxanthin kg?1 once daily instead of twice daily.  相似文献   

16.
Three levels of gelatinized wheat, 70, 140 and 210 g kg?1, were included in diets for Atlantic salmon, Salmo salar, L., of mean initial weight around 270 g. The experiment was run for 10.5 months and there was an eight- to nine-fold increase in fish weight. No significant differences in weight increase were found between fish. No negative physiological effects, such as hyperglycaemia or excessive hepatic glycogen accumulation were observed. Concentrations of pancreatic hormones were not affected by diet, but positive correlations were found between glucagon-like peptide (GLP) and glucagon, and between insulin and glucagon. Gelatinized wheat in diets for Atlantic salmon did not seem to affect organoleptic traits of the fish flesh in any undesired way.  相似文献   

17.
Multiple greyish‐white visceral nodules containing abundant rapidly growing and acid‐fast bacteria, subsequently identified as Mycobacterium salmoniphilum, were detected in moribund and newly dead market‐sized fish during a period of increased mortality in an Atlantic salmon, Salmo salar, farm in western Norway. Isolates cultured from diseased fish were phenotypically consistent with Mycobacterium sp. previously isolated from Atlantic salmon [MT 1890 (= NCIMB13533), MT1892, MT1900 and MT1901] in the Shetland Isles, Scotland. Partial sequences of 16S rDNA, ribosomal RNA internal transcribed spacer (ITS1), 65‐kDa heat‐shock protein (Hsp65) and β subunit of RNA polymerase (rpoB) revealed 97‐99% similarity with M. salmoniphilum type strain ATCC 13758T. The source of infection was not confirmed. Koch’s postulates were fulfilled following experimental challenge of Atlantic salmon with field isolate NVI6598 ( FJ616988 ). Mortality was recorded in experimentally infected fish; however, the infection remained subclinical in the majority of affected fish over the 131‐day challenge period.  相似文献   

18.
The long‐term adipose homeostasis seen in mammals gives rise to a ‘lipostatic’ model in which signals produced in proportion to fat stores serve to regulate energy intake. An extension of this predicts an impact of these signals on growth; downregulation of feeding in animals with increased adiposity should result in reduced growth. This was tested by monitoring fat deposition and growth in Atlantic salmon Salmo salar L. provided with feeds that differed in fat content. Salmon parr (mass c. 20 g) were fed either high‐ (H: 34%) or low‐fat (L: 22%) feeds, based on either fish (F) or vegetable (V) oils for 6 months to create groups of fish that differed in adiposity (10–12% and 5–7% body fat) at parr–smolt transformation (mass c. 130 g). Fish fed the high‐fat feeds deposited more body fat, and this was confirmed by measurement of fat concentrations in the fillet, viscera and remaining carcass. The fish were then grown‐on in sea water (c. 35 g L?1, 8 °C, 24L:0D) for 14 weeks while being fed either high‐ or low‐fat feed formulated with fish oil to give the following treatments: HF→ H, HF→ L, LF→ L, LF→ H, HV→ H, HV→ L, LV→ L, LV→ H. Although fish exposed to the various feed treatments did not differ markedly in growth rate (SGR range 1–1.14% day?1) over the 14 weeks of rearing in sea water, the results were in general agreement with predictions from the ‘lipostatic’ model, i.e. fish with the greatest fat reserves after the parr–smolt transformation grew more slowly than fish that were ‘leaner’ at this time. This suggests that adiposity, or ‘fatness’, may exert a negative feedback on feeding in salmon, thereby having an influence upon growth.  相似文献   

19.
Suboptimal egg incubation temperature is a risk factor for the development of skeletal deformities in teleosts. Triplicate diploid and triploid Atlantic salmon, Salmo salar L., egg batches were incubated at 6, 8 and 10 °C up until first feeding, whereupon fish were reared on a natural temperature before examination for externally visible skeletal deformities (jaw and spine) and radiographed for vertebral deformities and morphology at the parr stage. Increasing incubation temperatures and triploidy increased the number of fish showing one or more deformed vertebrae. Triploids had significantly higher mean vertebrae cranio‐caudal length (L) and dorsal‐ventral height (H) ratio at 6 and 10 °C than diploids, but triploidy had no effect on mean vertebrae centra area. Triploids demonstrated an increase in lower jaw deformities with increased incubation temperature, whereas jaw deformities were rare in diploids. Fish incubated at 10 °C had a significantly lower mean vertebral number than fish incubated at 6 °C, and triploids had lower mean vertebral numbers than diploids. Diploid fish with 58 vertebrae had a significantly higher mean vertebral centra area than fish with 59 vertebrae, but vertebral number did not affect the mean vertebral L/H ratio. The results are discussed with respect to the welfare and production of farmed salmonids.  相似文献   

20.
Inter-stage survival of wild juvenile Atlantic salmon, Salmo salar L.   总被引：1，自引：0，他引：1  
A biological model was developed to calculate annual survival between life stages of juvenile Atlantic salmon, Salmo salar L., in Catamaran Brook, a small stream basin (52 km2) in the Miramichi River catchment in New Brunswick, Canada. Seven years’ data (1990–1996) were used in the model. Input variables included: daily fish counts and measurements of parr (3–4 age classes), smolts, and adult salmon at a fish-counting fence near the stream mouth; biennial quantification of all habitat types along the watercourse; fish density estimated by electric fishing at 30 sites; and estimates of young-of-the-year emigration via stream drift. Continuous recording of stream discharge provided data to assist in interpretation of survival estimates. Annual survival for juvenile salmon in their first 3 years of life in the stream averaged between 31% and 34%. The greatest annual variation (CV = 0.699) occurred at the egg to 0+ (summer) stage with a low of 9.2% survival recorded for a winter with an atypical midwinter flood event; parr and pre-smolt survival were similarly affected. Survival from egg deposition (after correction for losses caused by predation and retention/non-fertilization) to smolt emigration was between 0.16% and 0.52%, which is low relative to estimates from many other studies. Survival of smolts to returning 1-sea-winter adults (grilse) averaged 8.5%. Potential errors in the computation of the model are discussed, e.g. inaccurate counts of spawning adults during high autumn stream flow. A possible explanation for the low egg to smolt survival was the environmental conditions experienced during various winters. Mean egg survival was 1.3 times higher (39.3%) and egg to smolt survival increased to 1.03% when the two winters characterized by extremely low discharge or midwinter freshets were excluded from the calculation. Density-dependent factors related to a beaver dam, which limited spawning distribution, may also have contributed to poor survival and increased fry emigration in one year. Environmental factors, particularly winter conditions, in streams such as Catamaran Brook may act as bottlenecks to natural production of Atlantic salmon.  相似文献   

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