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1.
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
2.
Abstract. Analyses of the Sr-contenl in scales of Atlantic salmon, Salmo saiar L ., smolts from two hatcheries revealed significant ( P < 0·001) differences. These differences were reflected in the Sr-conients of their respective diets. Sr-values in scale samples taken from wild salmon smolts from 10 Norwegian rivers showed a considerable variation. Analysis of variance showed that sampling site was the major source of variation. In general the Sr-content in scales cannot be used to distinguish between hatchery-reared and wild salmon smolls, although the present results nevertheless suggest that such a distinction is possible in some localities.
The Sr-contenl of the vertebrae was somewhat lower than that of the scales in both hatchery-reared and wild smolls. The Sr-conient of the scales of sea trout, Salmo trutta L., smolts from one of the sampling sites was significantly ( P < 0·001) higher than that of scales of Atlantic salmon smolts from the same site. The Sr-content of the scales of all the salmon smolts sampled from a lake was higher than the values recorded for sea trout and salmon after their stay in the sea. Use of the Sr-contenl of the scales todistinguish between migratory and resident individuals should therefore be done with care. 相似文献
The Sr-contenl of the vertebrae was somewhat lower than that of the scales in both hatchery-reared and wild smolls. The Sr-conient of the scales of sea trout, Salmo trutta L., smolts from one of the sampling sites was significantly ( P < 0·001) higher than that of scales of Atlantic salmon smolts from the same site. The Sr-content of the scales of all the salmon smolts sampled from a lake was higher than the values recorded for sea trout and salmon after their stay in the sea. Use of the Sr-contenl of the scales todistinguish between migratory and resident individuals should therefore be done with care. 相似文献
3.
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
4.
The population dynamics of Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.) were compared in a small tributary of the River Scorff (Brittany, France) from spawning time to the beginning of the third growing season. The spawning and fry emergence of the two species took place at approximately the same time. In the first autumn, the densityof 0+ juveniles and settling rate from the egg stage were much higher in trout than in salmon. The emigration rate from 0+ population was much higher in trout than in salmon. The size of resident and migrating fish was always smaller in salmon than in trout, whatever the age. The low level of salmon production in the brook, compared with trout, was the result of low survival from egg to 0+ stage in autumn, combined with the small proportion of juveniles migrating after the first growing season. This was not compensated by a high number of migrants the next year. The role of physical habitat, inter-and intraspecific competition, predation and migration dependence on size and early sexual maturity is discussed. Indications are that small tributaries of the type studied are of great value for recruitment in trout but not very productive for juvenile salmon. 相似文献
5.
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
6.
Abstract. A natural bath challenge method has been developed for furunculosis using Atlantic salmon, Salmo salar L., and rainbow trout, Salmo gairdneri Richardson. Fish were placed in an enclosed, continuously circulating tank system, supplemented with additional oxygen, the temperature raised gradually (overnight) to 15–16°C, a low dose of Aeromonas salmonicida (strain 184/186) introduced into the tank and the challenge maintained for 14 days. The challenge strain was characterized with respect to possible virulence factors and possessed an A-layer, ability to auto-agglutinate, haemagglutinate, adhere to Atlantic salmon cells and resist destruction by serum. No caseinase activity was detected. LD50 for salmon using this method was 1.8×103 cells per millilitre while trout had an LD50 of 9.5×104 cells per millilitre. Onset of the disease appeared to depend on fish size with larger trout (50 g) taking up to 10 days to show signs of the disease while mortalities in smaller trout (8.5g) commenced on day 1 post-challenge. 相似文献
7.
Bjarne Gjerde 《Aquaculture (Amsterdam, Netherlands)》1984,40(2):109-114
The variation in semen production among farmed Atlantic salmon (Salmo salar) and rainbow trout (Salmo gairdneri) has been studied. Both species were stripped at weekly intervals, the Atlantic salmon four times and the rainbow trout three times.The individual variation in volume of semen was very high, particularly in rainbow trout. The total volume of semen obtained was 137 ml (20 ml/kg body weight) in Atlantic salmon and 23 ml (5 ml/kg body weight) in rainbow trout. The intraclass correlation for volume of semen was estimated at 0.73 in Atlantic salmon and at 0.59 in rainbow trout. The correlations between volume of semen and body size (weight and length) were all positive. They were all significant and medium in Atlantic salmon whereas in rainbow trout they were all low and significant only for volume of semen at first stripping.The number of males needed to supply the Norwegian fish farming industry with semen is discussed. It is concluded that the possibility of disseminating genetic improvement throughout the whole population of farmed Atlantic salmon and rainbow trout by transport of semen from selected males is considerable. 相似文献
8.
The variation of virulence of Renibacterium salmoninarum , the causative agent of bacterial kidney disease (BKD) in salmonid fish, was studied by infecting rainbow trout, Oncorhynchus mykiss (Walbaum), with two isolates (strains 325 and 932) from diseased Atlantic salmon, Salmo salar L., and one isolate (strain 4366) from an apparently healthy Atlantic salmon. Coho salmon, Oncorhynchus kisutch (Walbaum), were injected with the strain 932 to estimate difference in fish species resistance. Fish were removed by random sampling for other study purposes, a study design possible with analysis of lifetime distributions incorporating both sampling-, death- and survival-times. At the end of the experiment, the rainbow trout infected with strains 325, 932 and 4366 had a survival probability of 33%, 51% and 72%, respectively. The coho salmon infected with strain 932 had a 26% survival probability. The strain differences were significant according to the log-rank test, and the risk ratio between the strains ranged from 1·8 to 5·4. The strain from the apparently healthy fish was least virulent. The survival of the fish species was different over time. Rainbow trout were more likely to die early in the time course, but high numbers of coho died later, resulting in an overall risk of mortality of 1·4 in favour of rainbow trout. Differences in virulence may reflect changed selective pressure on R. salmoninarum when introduced from feral stocks into the environment of fish farms. 相似文献
9.
Despite long‐standing interest in foraging modes as an important element of animal space use, few studies document and compare individual foraging mode differences among species and ecological conditions in the wild. We observed and compared foraging modes of 61 wild Arctic charr, Salvelinus alpinus, 42 brown trout, Salmo trutta, and 50 Atlantic salmon, Salmo salar, in their first growing season over a range of habitats in 10 Icelandic streams. We found that although stream salmonids typically sit‐and‐wait to ambush prey from short distances, Arctic charr were more mobile during prey search and prior to prey attack than Atlantic salmon, whereas brown trout were intermediate. In all three species, individuals that were mobile during search were more likely to be moving when initiating attacks on prey, although the strength and the slope of this relationship differed among species. Arctic charr also differed from salmon and trout as more mobile individuals travelled longer distances during prey pursuits. Finally, coupled with published data from the literature, salmonid foraging mobility (both during search and prior to attack) clearly decreased from still water habitats (e.g., brook charr), to slow‐running waters (e.g., Arctic charr) to fast‐running waters (e.g., Atlantic salmon). Hence, our study suggests that foraging mode of young salmonids can vary distinctly among related species and furthers our understanding of the behavioural mechanisms shaping the geographical distribution of wild salmonids. 相似文献
10.
Rainbow trout, Oncorhynchus mykiss (Walbaum), sea trout, Salmo trutta L., and Atlantic salmon, Salmo salar L., were experimentally infected with Flavobacterium psychrophilum in order to evaluate any species differences in susceptibility to the bacterium. Furthermore, differences in pathological changes and distribution of the bacteria in internal organs were studied. The bacteria were injected intraperitoneally in two doses, high dose (Hd) 1 x 10(7) colony forming units (CFU) fish(-1) and low dose (Ld) 1 x 10(6) CFU fish(-1). The mortalities in the Ld groups varied between 0 and 7.5% and in the Hd groups between 55-70%. No significant differences in mortality between the species were recorded. Clinical signs and pathological findings were similar in the three species and in accordance with those of rainbow trout fry syndrome. Rainbow trout showed more pronounced lesions in the spleen compared with the other species. Necrosis of renal tubular epithelium and haematopoietic tissue was most prominent in rainbow trout and Atlantic salmon. Intracellular eosinophilic droplets in the kidney tubular epithelium were a prominent finding in rainbow trout and sea trout surviving the infection. The distribution of the bacteria in internal organs was similar in the three species, as studied with immunohistochemistry. 相似文献
11.
12.
Å. H. Garseth C. Fritsvold M. Opheim E. Skjerve E. Biering 《Journal of fish diseases》2013,36(5):483-493
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
13.
Abstract – This review of stream trout research literature for the 1987–2006 period covered >1300 papers dealing with 22 relevant topics, when compared with <400 papers on 18 topics in the previous one (1967–1986). The percentage of experimental approaches here quantified for both research reviews was 18% in the 1967–1976 period, increased to 21% in 1977–1986, to 39% in 1987–1996, and up to 43% in 1997–2006. Particular journals in the recent two decadal period published high percentages of experimental papers ( The Journal of Animal Ecology and Canadian Journal of Fisheries and Aquatic Sciences ; 62.9% and 62.4%, respectively), others, intermediate percentages ( Nordic Journal of Fisheries Research , Transactions of the American Fisheries Society , North American Journal of Fisheries Management and Ecology of Freshwater Fish : 44.1%, 42.4%, 40.5%, and 35.6%, respectively); the remainder covered ≤33%. Research papers on stream 'trouts' published over the last two decades were classified into 22 subject areas for nine major journals separately and combined for 55 other journals. Subject areas dealing with the biology and ecology of trout redds, egg development, alevin emergence and onto fry and parr were the most heavily reported in nine major journals, as well as in all other journals combined. Habitat characteristics and cover use by trout were the next. Atlantic salmon and brown trout were the species with highest publication coverage in nearly all subject areas, with low coverage for all salvelinid (charr) species except brook charr. Research on Atlantic salmon in the UK used experimental approaches in nearly 60% of publications and in mid to high 30% for those on Atlantic salmon and brown trout in Scandinavian countries. Consideration is given to future research needs for stream trouts. 相似文献
14.
R. J. Scott M. S. Poos D. L. G. Noakes F. W. H. Beamish 《Ecology of Freshwater Fish》2005,14(3):283-288
Abstract – We examined the effects of two salmonid species, chinook salmon ( Oncorhynchus tschwaytscha ) and brown trout ( Salmo trutta ), both exotic species to Lake Ontario, on behaviour and foraging success of juvenile Atlantic salmon ( S. salar ), a native species to Lake Ontario, in an artificial stream. We found that both exotic species have effects on Atlantic salmon behaviour, but that neither had an effect on foraging success. These results may explain why the Atlantic salmon re-introduction programme in Lake Ontario has had little success, as more than 3 million exotic salmonids are released in Lake Ontario streams annually. 相似文献
15.
There is concern that expanding beaver (Castor fiber) populations will negatively impact the important economic, recreational and ecological resources of Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) populations in Europe. We studied how beaver dams influenced habitat, food resources, growth and movement of juvenile Atlantic salmon and trout on three paired beaver-dammed and beaver-free (control) tributaries of important salmon rivers in central Norway. Lotic reaches of beaver-dammed and control sites were similar in habitat and benthic prey abundance, and ponds were small (<3,000 m2). Though few juvenile salmonids were detected in ponds, trout and salmon were present in habitats below and above ponds (comprising 9%–31% and 0%–57% of the fish collected respectively). Trout dominated control sites (79%–99%), but the greatest proportion of Atlantic salmon were upstream of beaver ponds (0%–57%). Growth rates were highly variable, with no differences in growth between lotic reaches of beaver-dammed and control sites. The condition and densities of juvenile salmon and trout were similar in lotic reaches of beaver-dammed and control sites, though one beaver-dammed site with fine sediment had very few juvenile salmonids. Beaver dams did not block the movement of juvenile salmonids or their ability to use upstream habitats. However, the degree of repeated movements and the overall proportion of fish moving varied between beaver-dammed and control sites. The small scale of habitat alteration and the fact that fish were able to move past dams makes it unlikely that beaver dams negatively impact the juvenile stage of salmon or trout populations. 相似文献
16.
R. J. Gibson 《Ecology of Freshwater Fish》2002,11(4):207-222
Abstract – The required freshwater habitats of juvenile Atlantic salmon ( Salmo salar ) are, in general, well known, but vary in quality, related to interacting effects of several variables, which may depend on different parts of a river system. Examples are given of ranges of densities and growth that can be found at various sites in eastern Canada, illustrating the biological and physico-chemical factors affecting production of juvenile salmon. Relative growth rates can indicate habitat quality and population densities. Salmon parr have negative effects on brook trout in riffle habitats. The effects of migrations within the river and of changes with stream succession on juvenile salmon production are illustrated with examples from a Newfoundland river. Migration of age-classes can be quantified from 'self-thinning' curves. Lakes have enhancing effects on downstream fluvial habitats, and, at least in Newfoundland, and probably in many boreal areas, the lacustrine proportion of the basin can be used as an index for deriving estimates of required spawning escapement. The factors described should be taken into account for more refined estimates of river production and management of the salmon resource. 相似文献
17.
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
18.
Abstract– The utilization of lakes, and inlet and outlet streams by juvenile Atlantic salmon ( Salmo salar L.), brown trout ( Salmo trutta L.) and Arctic charr ( Salvelinus alpinus (L.), were investigated in 16 watercourses northern Norway, all known to inhabit salmon stocks. In lakes, fish were caught by small mesh size gill nets, while in rivers fish were caught electrofishing. In the shallow littoral (0-3 m depth) there were juvenile salmon in 15 of 19 investigated lakes, juvenile trout in 17 and juvenile charr in seven. Trout dominated significantly in numbers in the shallow littoral of seven lakes, while salmon and charr dominated in three lakes each. When trout and salmon were frequent in the shallow littoral, charr was usually not present in this habitat, but were found in the profundal zone in most of the lakes. Atlantic salmon parr utilized both shallow and deep lakes, and used both stones and macrophytic vegetation as shelter. The utilization of lakes by salmon parr seemed to be closely related to utilization of small inlet streams for spawning. In most inlet and outlet streams salmon dominated over trout in numbers, while charr were absent. This is the first documentation of lake-use by naturally occurring salmon parr in Scandinavia. 相似文献
19.
Taksdal T Olsen AB Bjerkås I Hjortaas MJ Dannevig BH Graham DA McLoughlin MF 《Journal of fish diseases》2007,30(9):545-558
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
20.
Abstract. An ulcerative dermal necrosis-like salmon disease appeared in Laukaa Central Fish Culture Station in Middle-Finland in autumn 1976 showing lesions in different sites on diseased landlocked salmon Salmo salar L., sea trout Salmo trutta trutta L. and brown trout Salmo trutta lacustris L. Lesions from the diseased landlocked salmon were studied by transmission and scanning electron microscopy.
Both aquatic bacteria and fungi grew in abundance in the lesions, changing the fine structure of the epidermis.
In all of the lesions studied virus-like particles 30–33 nm in diameter were found. The relationship of these particles to the disease is still unresolved. 相似文献
Both aquatic bacteria and fungi grew in abundance in the lesions, changing the fine structure of the epidermis.
In all of the lesions studied virus-like particles 30–33 nm in diameter were found. The relationship of these particles to the disease is still unresolved. 相似文献