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1.
The present study evaluates if abdominal dis-tension caused by a water-filled stomach in seawater farmed rainbow trout, Oncorhynchus mykiss (Walbaum), and Atlantic salmon, Salmo salar L., could be provoked experimentally by live chilling in sea water (0.5 °C). Fifty rainbow trout and 50 salmon were visually classified, either as normal or suffering from the condition. Prior to chilling, no rainbow trout or salmon suffered from a water-filled stomach. During chilling, 25% of the rainbow trout and 2.5% of the salmon developed water-filled stomach. Affected rainbow trout had significantly higher blood plasma osmolality and significantly lower body weight than normal trout. The frequency of trout with a water-filled stomach increased significantly with increasing chilling time and increasing plasma osmolality. The regression coefficients revealed that the proportion of affected rainbow trout in-creased by 0.82% h−1 of chilling and by 0.46% per unit increase in mosmol L−1. The present study revealed that abdominal distension in seawater farmed rainbow trout was far more severe than in Atlantic salmon and could be provoked experimentally by osmoregulatory stress. This is consistent with the observation that water-filled stomach appear only occasionally in seawater farmed Atlantic salmon.  相似文献   

2.
The oilseed Camelina sativa has been studied as a lipid source for farmed salmonids, but recommended inclusion as a protein source has not been determined. This study evaluated low inclusion of camelina high‐oil residue meal (HORM) at 20, 40 and 60 g/kg of the diet, to determine an adequate level for Atlantic salmon parr (Salmo salar) and rainbow trout (Oncorhynchus mykiss). Salmon and trout were fed experimental diets containing up to 60 g/kg HORM for 16 weeks. At 40 g/kg HORM, trout and salmon growth performance were similar to those fed a control diet. However, at 60 g/kg HORM, trout showed lower final weight, weight gain and feed intake than those fed the control diet. Rainbow trout fed 40 and 60 g/kg HORM showed significantly lower whole body ash (p = .005), slightly lower whole body protein levels and higher fat than the control. In salmon fed 60 g/kg HORM diets, whole body ash (p = .024), and the submucosal layer of the intestine was thicker than the control (p = .007). Current results indicate that up to 40 g/kg HORM can be included in diets for rainbow trout and salmon juveniles.  相似文献   

3.
Plasma levels of insulin in rainbow trout,Oncorhynchus mykiss, Atlantic salmon,Salmo salar, and Pacific coho salmon,Oncorhynchus kisutch and plasma circulating levels of glucagon and glucagon-like peptide, in rainbow trout and Atlantic salmon, were measured by homologous radioimmunoassays. Hormonal levels were compared against the average body weight of the same group of fish. Plasma insulin levels were significantly correlated (r=0.56, 0.46 and 0.42 respectively) with body weight in all three salmonid species. Moreover, rainbow trout from fast-growing families had significantly higher (p<0.005) plasma insulin levels than did fish from slow-growing families. Plasma titres of glucagon and glucagon-like peptide were always lower than insulin titres and did not correlate with body weight.Reported in part at Satellite Symposium on Applications of Comparative Endocrinology to Fish Culture, Almunecar, Spain (Sundby, 1989).  相似文献   

4.
Abstract. Underwater television was used to observe the distribution and swimming behaviour of groups of farmed rainbow trout, Salmo gairdneri Richardson, in marine net cages. Undisturbed rainbow trout (mean total length 240 mm) aggregated near the surface, remaining motionless in slack water and formed polarized shoals at higher current velocities. Larger fish (mean total length 317 mm) occupied deeper parts of the cage and were more active during periods of slack water. The results are compared with previous work on farmed Atlantic salmon, Salmo salar L., and discussed in relation to the biology of wild rainbow trout and recent work on exercise, growth and condition in salmonids.  相似文献   

5.
The present paper describes, for the first time, clinical signs and pathological findings of pancreas disease (PD) in farmed Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), in sea water in Norway. Similarities and differences with reports of PD from Ireland and Scotland are discussed. Samples of 68 rainbow trout from disease outbreaks on 14 farms and from 155 Atlantic salmon from outbreaks on 20 farms collected from 1996 to 2004 were included in the present study. The histopathological findings of PD in Atlantic salmon and rainbow trout in sea water were similar. Acute PD, characterized by acute necrosis of exocrine pancreatic tissues, was detected in nine Atlantic salmon and three rainbow trout. Salmonid alphavirus (SAV) was identified in acute pancreatic necroses by immunohistochemistry. Most fish showed severe loss of exocrine pancreatic tissue combined with chronic myositis. Myocarditis was often but not consistently found. Kidneys from 40% and 64% of the rainbow trout and Atlantic salmon, respectively, had cells along the sinusoids that were packed with cytoplasmic eosinophilic granules. These cells resembled hypertrophied endothelial cells or elongated mast cell analogues. Histochemical staining properties and electron microscopy of these cells are presented. SAV was identified by RT-PCR and neutralizing antibodies against SAV were detected in blood samples.  相似文献   

6.
The first alphavirus to be isolated from fish was recorded in 1995 with the isolation of salmon pancreas disease virus from Atlantic salmon, Salmo salar L., in Ireland. Subsequently, the closely related sleeping disease virus was isolated from rainbow trout, Oncorhynchus mykiss (Walbaum), in France. More recently Norwegian salmonid alphavirus (SAV) has been isolated from marine phase production of Atlantic salmon and rainbow trout in Norway. These three viruses are closely related and are now considered to represent three subtypes of SAV, a new member of the genus Alphavirus within the family Togaviridae. SAVs are recognized as serious pathogens of farmed Atlantic salmon and rainbow trout in Europe. This paper aims to draw together both historical and current knowledge of the diseases caused by SAVs, the viruses, their diagnosis and control, and to discuss the differential diagnosis of similar pathologies seen in cardiomyopathy syndrome and heart and skeletal muscle inflammation of Atlantic salmon.  相似文献   

7.
The infectious salmon anaemia virus (ISAV) has not been observed to cause natural disease in farmed rainbow trout, Onchorhynchus mykiss (Walbaum), but may cause high mortality in farmed Atlantic salmon, Salmo salar L. In this study, ISAV was passaged 10 times in succession by intraperitoneal injections of serum from previous passage into naïve rainbow trout. The serum viraemia was monitored by real‐time qPCR. The rainbow trout in this study became infected but did not develop ISA. No clinical signs were observed in the rainbow trout in any passage, but replication of ISAV was detected from Day 4 post‐infection (p.i.). Neither increased relative virus loads nor histopathological and immunohistochemical findings consistent with ISA were observed. However, the expression of interferon type I and Mx genes were slightly up‐regulated in the hearts of some individual fish at day 17 p.i. Sequencing of all open reading frames in the ISAV genome of the 10th passage revealed two nucleotide mutations, one in segment 6 coding for the haemagglutinin–esterase (HE) and one in segment 1 coding for the basic polymerase 2 (PB2). The mutation in HE resulted in an amino acid substitution T/K312.  相似文献   

8.
Although non‐native species can sometimes threaten the value of ecosystem services, their presence can contribute to the benefits derived from the environment. In the Great Lakes, non‐native brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) support substantial recreational fisheries. With current efforts underway to restore once‐native Atlantic salmon (Salmo salar) to Lake Ontario, there is some concern that Atlantic salmon will impede non‐native contributions to the recreational fishery because Atlantic salmon exhibit niche overlap with brown trout and rainbow trout, particularly during the juvenile life stage. We therefore examined competition and growth of juvenile Atlantic salmon, brown trout and rainbow trout in semi‐natural streams. We found that brown trout were the most dominant and had the greatest growth rate regardless of what other species were present. Rainbow trout were more dominant than Atlantic salmon and consumed the most food of the three species. However, in the presence of brown trout, rainbow trout fed less frequently and exhibited negative growth as compared to when the rainbow trout were present with only Atlantic salmon. These data suggest that, outside of density‐dependent effects, Atlantic salmon will not impact stream production of brown trout and rainbow trout.  相似文献   

9.
Abstract. Sporadic cases of a systemic protozoal infection with cells resembling Dermocystidium sp. are described from cultured rainbow trout, Salmo gairdneri Richardson, from France and brown trout, Salmo trutta L., and Atlantic salmon, Salmo salar L., from Ireland. Classical proliferative kidney disease was additionally found in the rainbow trout and PKX-like cells were also seen in the brown trout and salmon.  相似文献   

10.
Growth rates of Atlantic salmon, pink salmon, Arctic char, sea trout and rainbow trout were compared under Norwegian farming conditions. During the juvenile, freshwater period, growth was fastest in pink salmon, followed by rainbow trout and Arctic char. Freshwater growth of sea trout and, especially, Atlantic salmon, was slow. After transfer of smolts or fingerling to sea water, Arctic char failed to survive the autumn. Sea water growth of sea trout was slow, but the three species, rainbow trout, Atlantic salmon and pink salmon, all grew rapidly through all seasons. When in sea water, rainbow trout and pink salmon were regularly attacked by vibriosis, while Atlantic salmon were rarely attacked, and sea trout never. It is concluded that, for commercial farming in Norway, rainbow trout are of value for production of fish of any size up to 3–4 kg, and pink salmon for production of small fish of 0.5–1.5 kg. Atlantic salmon is the only species suitable for production of a very large salmonid, i.e., more than 4–5 kg.  相似文献   

11.
This is the first comprehensive study on the occurrence and distribution of piscine reovirus (PRV) in Atlantic salmon, Salmo salar L., caught in Norwegian rivers. PRV is a newly discovered reovirus associated with heart and skeletal muscle inflammation (HSMI), a serious and commercially important disease affecting farmed Atlantic salmon in Norway. A cross‐sectional survey based on real‐time RT‐PCR screening of head kidney samples from wild, cultivated and escaped farmed Atlantic salmon caught from 2007 to 2009 in Norwegian rivers has been conducted. In addition, anadromous trout (sea‐trout), Salmo trutta L., caught from 2007 to 2010, and anadromous Arctic char, Salvelinus alpinus (L.), caught from 2007 to 2009, were tested. PRV was detected in Atlantic salmon from all counties included in the study and in 31 of 36 examined rivers. PRV was also detected in sea‐trout but not in anadromous Arctic char. In this study, the mean proportion of PRV positives was 13.4% in wild Atlantic salmon, 24.0% in salmon released for stock enhancement purposes and 55.2% in escaped farmed salmon. Histopathological examination of hearts from 21 PRV‐positive wild and one cultivated salmon (Ct values ranging from 17.0 to 39.8) revealed no HSMI‐related lesions. Thus, it seems that PRV is widespread in Atlantic salmon returning to Norwegian rivers, and that the virus can be present in high titres without causing lesions traditionally associated with HSMI.  相似文献   

12.
Attempts were made to complete all possible interspecific hybrid crosses between Atlantic salmon (Salmo salar), rainbow trout (Salmo gairdneri), brook trout (Salvelinus fontinalis), lake trout (Salvelinus namaycush), and Arctic char (Salvelinus alpinus). Survival was appreciable only in (giving female first) lake × brook, salmon × char, brook × char and char × brook hybrids. Growth rates over a weight increment of 3–30 g averaged 2.14% wet weight/day for all species and hybrids (14.5–17.0°C — excess rations). The highest growth rate, 2.74%, was obtained with the brook (female) × char (male) hybrid and the lowest, 1.63%, in lake trout. Salmon (female) × char (male) hybrids grew faster than salmon; brook trout (female) × char (male) hybrids grew faster than brook trout. Salmo species grew no faster than Salvelinus species but became silvery and had greater salinity tolerance at a smaller size and earlier age. Intergeneric hybrids between female Salmo spp. and male Salvelinus spp. more closely resembled the female parent in processes related to smoltification (silvering and salinity tolerance).  相似文献   

13.
Methemoglobin is hemoglobin containing ferric iron. Methemoglobin cannot bind to oxygen and at high concentrations causes tissue hypoxia. Brook trout (Salvelinus fontinalis) develop significantly greater methemoglobinemia than Atlantic salmon (Salmo salar) or rainbow trout (Oncorhynchus mykiss) following general anesthesia with benzocaine or tricaine methanesulfonate. The objective of this study was to compare the activity of the major methemoglobin reducing enzyme, NADH-dependent cytochrome b5 reductase (CB5R), in brook trout erythrocytes to the activity of CB5R in Atlantic salmon and rainbow trout erythrocytes. Methemoglobin levels were compared using co-oximetry following in vitro incubation of erythrocytes with sodium nitrite (NaNO2). The CB5R activity was measured using a ferricyanide assay. There was significantly greater methemoglobin at time 0 in brook trout erythrocytes than in rainbow trout or Atlantic salmon erythrocytes (2.79 ± 0.29 %, 2.19 ± 0.23 %, 2.08 ± 0.14 %), (P < 0.001). There was significantly greater methemoglobin induction by NaNO2 in brook trout erythrocytes (33.14 ± 3.32 %) than in rainbow trout or Atlantic salmon erythrocytes (28.73 ± 2.92 % and 24.85 ± 1.40 %, respectively), (P < 0.001). The CB5R activity was significantly less in brook trout erythrocytes (median of 3.05 μmol/min/μl) than in rainbow trout erythrocytes (median of 6.73 μmol/min/μl). The CB5R activity in Atlantic salmon erythrocytes (median 4.09 μmol/min/μl) was not significantly different than in brook or rainbow trout erythrocytes. Total methemoglobin at any one time is a balance between induction by oxidants and reduction by antioxidants. Lower CB5R activity in brook trout erythrocytes may contribute to a species-specific sensitivity to methemoglobin induction; however, there are likely additional factors.  相似文献   

14.
Infectious salmon anaemia (ISA) is a viral disease of farmed Atlantic salmon, Salmo salar L., in Norway. However, in laboratory experiments, the virus has also been found to propagate in trout, Salmo trutta L., where it is a persistent infection. It is crucial for the management of ISA in Norway, and for the prevention of spread to fish in other countries, that possible carriers of the virus are found. Another possible salmonid reservoir species is the rainbow trout, Oncorhynchus mykiss (Walbaum). After experimental infection, the ISA virus was found to be present in O. mykiss as late 28 days after infection, with a peak around day 20. The infection resulted in a significant drop in the haematocrit and haemorrhages on the liver in some specimens. The ISA virus was seen budding from endothelial cells lining blood vessels in the heart ventricle of challenged rainbow trout. It is concluded that the ISA virus is able to propagate in O. mykiss and that this species may function as a reservoir when cultured in areas where the virus is found. The virus does not seem to cause any significant mortalities of infected rainbow trout.  相似文献   

15.
Competition with non‐native species may impede the restoration of native species, but differences in competitive abilities among intraspecific native populations may make some populations more suitable for reintroduction than others. Here, juvenile Atlantic salmon (Salmo salar) from two allopatric populations (LaHave and Sebago) being used for reintroduction into Lake Ontario were placed into two natural stream sites differing in the presence of ecologically similar rainbow trout (Oncorhynchus mykiss). We assessed the effects of competition in the natural streams on fitness‐related traits and habitat use of the Atlantic salmon. We then compared these effects to those observed in artificial streams from a previous study. Atlantic salmon in natural streams had reduced fitness‐related traits that were associated with suboptimal microhabitats in the presence of rainbow trout, but utilised optimal microhabitats in their absence. In the presence of rainbow trout, the two Atlantic salmon populations exhibited comparable recapture proportions to each other, but the individuals from the Sebago population had better performance (body size and condition) than those from the LaHave population. Responses of both Atlantic salmon populations to competition with rainbow trout were generally similar in both direction and magnitude when compared to results from the artificial stream study. The combined results suggest that native species restoration efforts should be focused on candidate populations that are ecologically suitable to reintroduction environments, as well as on suitable habitats that do not contain exotic competitors. Moreover, this study highlights the value of controlled experiments in artificial environments for predicting fitness‐related performance in natural environments.  相似文献   

16.
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17.
The substantial growth of the farmed salmon industry in Europe since the 1970s has highlighted concerns regarding the genetic impact of escaped farmed salmon on wild salmonid stocks. High incidences of salmon × trout hybrids have been recorded in rivers situated near intensive salmon farming in Norway and Scotland, which may be indicative of a breakdown in reproductive isolation between salmon, Salmo salar L., and brown trout, Salmo trutta L. In the present study, salmonid fry and 0+ parr were collected from rivers in western Ireland. Allozyme and minisatellite DNA analysis were carried out on fry to determine the frequency of F1 hybrids from 10 rivers located within 38 km of salmon farms and three rivers at least 80 km from salmon farms. A total of 49 hybrids were recorded from 4135 salmonid fry (frequency = 1.2%). Mitochondrial DNA analysis showed that all hybrids arose from Atlantic salmon female × brown trout male crosses. Hybrid parr were recorded from one of the low-risk rivers (1.0%), but were present in seven out of the 10 catchments located within 38 km of salmon farms, with frequencies ranging from 0.7% to 3.1%. The results of the present survey, which represents the first extensive record of the levels of salmon-trout hybridization in Ireland, are discussed in relation to the continued growth of salmon farming in this country.  相似文献   

18.
2000～2009年,全球鲑科鱼类养殖产量合计达1989万t,2010年养殖产量已达到240万t以上,产量一直在稳步上升。十年累计产量超过10万t的有大西洋鲑（Sdmosdar）、虹鳟（Oncorhynchttsmykiss）、银大麻哈鱼（0．kisutch）、大鳞大麻哈鱼（0．tshawytscha）、褐鳟（Sdmotrutta）,能够形成单独统计产量的有5属13种,大西洋鲑、虹鳟、银大麻哈鱼占鲑科鱼类养殖总产量的97％。养殖产量居前三位的是挪威、智利、英国。全球共有67个国家和2个地区（台湾、法属留尼旺岛）开展鲑科鱼类养殖,其中欧洲33个国家、美洲13个国家、亚洲11个国家和1个地区、非洲6个国家和1个地区、大洋洲4个国家,虹鳟是养殖最普遍的种类,遍布5大洲的64个国家和2个地区。  相似文献   

19.
Abstract. An enzootic, Australian, atypical strain of Aeromonas salmonicida isolated from diseased goldfish, Carassius auratus (L.), was inoculated into Atlantic salmon, Salmo salar L., brown trout, S. trutta L., rainbow trout, S. gairdneri Richardson, and brook trout, Salvelinus fontinalis (Mitchill), fingerlings by intraperitoneal injection (i.p.) and by bath challenge, the latter with and without prior abrasion of skin. The 10-day LD50 (i.p.) was estimated to be 7·4 × 10-3 colony forming units (cfu) for Atlantic salmon, 3·0 × 10-2 cfu for brown trout, 3·7 × 102 cfu for brook trout and 6·4 × 103 cfu for rainbow trout. Brown, rainbow and brook trout succumbed to bath challenges with between 105–106 cfu/ml, developing ulcers of the skin and septicaemia. The organism was trasmitted from inoculated fish to five of 195 within-tank control fish via water and established a carrier state in one of 14 Atlantic salmon. It was concluded that the organism poses a significant threat to the salmonid farming industry and wild salmonid fisheries in Australia.  相似文献   

20.
Bile salt‐dependent lipase (BSDL) is assumed to be the predominant lipid hydrolase in fish digestive tracts where it hydrolyses dietary triacylglycerols (TAG), sterol esters (SE) and wax esters (WE). BSDL is known to hydrolyse TAG at much faster rates than SE and WE in both fish and mammals. An assay for BSDL has previously been developed for rainbow trout (Oncorhynchus mykiss). However, this setup may not be valid in other fish species. Accordingly, the present study aimed at optimizing previous assays in rainbow trout for use on intestinal luminal contents of Atlantic salmon (Salmo salar L.). Crude intestinal extracts from midgut were desalted before the assay and concentrated bile salts supplemented. In general, the rank order for the degree of hydrolysis in Atlantic salmon was TAG > WE > SE. The optimal assay conditions were determined as being 100 μg protein, 125 μm lipid substrate and 20 mM bile salt (taurocholate) during the 4 h of incubation. Atlantic salmon and rainbow trout of 1500 g showed similar lipolytic activity, while salmon smolts of 300 g showed a significantly lower activity. Furthermore, the inhibition of intestinal lipase activities, especially triacylglycerol hydrolase and sterol ester hydrolase, observed in trout intestinal extracts at bile salt concentrations around 10 mm , was not observed in salmon. This could indicate that the activities in these two salmonids may display different enzyme biochemistry.  相似文献   

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