Rainbow Trout Oncorhynchus Mykiss (rainbow + trout_oncorhynchu_mykiss)

Distribution by Scientific Domains


Selected Abstracts


Effects of Oral Administration of Specific Antibodies to Rainbow Trout Oncorhynchus mykiss

JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2003
Michael Engelbrecht Nielsen
A new product called oralized fish serum concentrate (OFSC) was evaluated for a possible effect against various bacterial pathogens in rainbow trout. The OFSC produced from immune trout sera was found to contain fully functional antibodies and complement component C3. The antibodies detected in the serum concentrate were specific to Vibrio anguillarum (O1 and O2) and Aeromonas salmonicida, which had been used for vaccination of the fish prior to serum collection. The functionality of the specific antibodies in OFSC was not reduced after 6 wk storage at -20 C, 5 C, and 20 C. The serum was mixed with commercial trout feed and used for feeding rainbow trout fry (first feed period). After oral delivery of OFSC to rainbow trout for 1 mo, samples of gut content and gut tissue contained functional antibodies. In gutted fish no functional antibodies were found. This suggests that antibodies from OFSC are unable to be transferred across the gut wall in a functional state. Oral administration of OFSC did not increase survival of rainbow trout in an immersion challenge with Vibrio anguillarum. [source]


A trial of two trouts: comparing the impacts of rainbow and brown trout on a native galaxiid

ANIMAL CONSERVATION, Issue 4 2010
K. A. Young
Abstract Rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta are the world's two most widespread exotic fishes, dominate the fish communities of most cold-temperate waters in the southern hemisphere and are implicated in the decline and extirpation of native fish species. Here, we provide the first direct comparison of the impacts of rainbow and brown trout on populations of a native fish by quantifying three components of exotic species impact: range, abundance and effect. We surveyed 54 small streams on the island of Chiloé in Chilean Patagonia and found that the rainbow trout has colonized significantly more streams and has a wider geographic range than brown trout. The two species had similar post-yearling abundances in allopatry and sympatry, and their abundances depended similarly on reach-level variation in the physical habitat. The species appeared to have dramatically different effects on native drift-feeding Aplochiton spp., which were virtually absent from streams invaded by brown trout but shared a broad sympatric range with rainbow trout. Within this range, the species' post-yearling abundances varied independently before and after controlling for variation in the physical habitat. In the north of the island, Aplochiton spp. inhabited streams uninvaded by exotic trouts. Our results provide a context for investigating the mechanisms responsible for apparent differences in rainbow and brown trout invasion biology and can help inform conservation strategies for native fishes in Chiloé and elsewhere. [source]


Swimming activity and energetic expenditure of captive rainbow trout Oncorhynchus mykiss (Walbaum) estimated by electromyogram telemetry

AQUACULTURE RESEARCH, Issue 6 2000
S J Cooke
Rainbow trout Oncorhynchus mykiss (Walbaum) are usually cultured at high densities to maximize production, but little is known about the physiological and behavioural consequences of high-density fish culture. The purpose of this study was to develop quantitative correlates of activity for fish held under conditions of increasing density. Fifteen hatchery-reared rainbow trout (mean fork length = 432.3 ± 9.2 mm) were implanted with activity (electromyogram; EMGi) transmitters and randomly assigned to each of three replicate tanks. Original tank densities (15 kg m,3) were then increased to 30 and finally to 60 kg m,3 at weekly intervals by adding additional fish. Remote telemetry signals indicated that activity increased with increasing stocking density. Fish were relatively inactive during the middle of the day, with diel activity patterns not differing among treatments. Fish were more active during periods of darkness, with activity increasing with increasing stocking density. Relationships between swimming speed, EMGi activity and oxygen consumption were developed using a respirometer and used to estimate oxygen consumption of the fish in the density treatments. Average oxygen consumption estimates increased with increasing density treatments as follows: low density = 75.6 mg kg,1 h,1; medium density = 90.0 mg kg,1 h,1; and high density = 102.6 mg kg,1 h,1. Telemetry permits quantification of the effects of increasing density on fish activity. Physiological telemetry devices may provide a useful tool for remotely monitoring animal welfare correlates under controlled conditions for fish exposed to different husbandry conditions and may prove a valuable tool for the aquaculture industry. [source]


Brain distribution of myosin Va in rainbow trout Oncorhynchus mykiss

ACTA ZOOLOGICA, Issue 1 2008
Kátia Gisele Oliveira Rancura
Abstract This study presents data on myosin Va localization in the central nervous system of rainbow trout. We demonstrate, via immunoblots and immunocytochemistry, the expression of myosin Va in several neuronal populations of forebrain, midbrain, hindbrain and spinal cord. The neuronal populations that express myosin Va in trout constitute a very diverse group that do not seem to have many specific similarities such as neurotransmitters used, cellular size or length of their processes. The intensity of the immunoreactivity and the number of immunoreactive cells differ from region to region. Although there is a broad distribution of myosin Va, it is not present in all neuronal populations. This result is in agreement with a previous report, which indicated that myosin Va is approximately as abundant as conventional myosin II and kinesin, and it is broadly involved in neuronal motility events such as axoplasmatic transport. Furthermore, this distribution pattern is in accordance with what was shown in rats and mice; it indicates phylogenetic maintenance of the myosin Va main functions. [source]


The top 27 animal alien species introduced into Europe for aquaculture and related activities

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 2010
D. Savini
Summary The information extracted from IMPASSE, DAISIE, FishBase, and FAO-DIAS inventories of alien species were used to draw a list of the 27 most utilized animal alien species for aquaculture and related activities (e.g. stocking, sport fishing, ornamental purposes) in Europe. Three variables have been considered to assess their negative ecological impacts when these species escape from aquaculture facilities: (i) their distribution across Europe (including non-EU Member States); (ii) evidence of their environmental impact in the wild; and (iii) evidence of their being vectors of non-target alien species and other hitchhikers (e.g. pathogens). Drivers of use and mechanisms of dispersal in the wild have been also considered and reviewed. Twenty of the species are freshwater fishes: alien cyprinids and salmonids have been introduced into Europe mainly for food production, sport fishing and ornamental purposes. The most widespread species are the goldfish Carassius auratus and the rainbow trout Oncorhynchus mykiss, established in 29 and 28 European countries, respectively. Notwithstanding their successful distribution in Europe, only the Gibel carp Carassius gibelio and the peneid shrimp Marsupenaeus japonicus were found to have environmental impact in all the countries of establishment. Crayfish and predatory fishes (e.g. catfishes and salmonids) cause major environmental impacts in Europe by outcompeting native species and altering habitat structure. Alien crayfish, Procambarus clarkii and Pacifastacus leniusculus, are responsible for the largest range of impacts (i.e. crayfish plague dissemination, bioaccumulation of pollutants, community dominance, competition and predation on native species, habitat modifications, food web impairment, herbivory and macrophytes removal). Cyprinids (e.g. herbivorous carps) are vectors of diseases and parasites, while salmonids (e.g. Salvelinus fontinalis) often cause genetic impairment of native stocks by hybridization. The importation of alien farmed (target) species frequently leads to the introduction of associated non-target species. The cultures of the Pacific cupped oyster Crassostrea gigas and Manila clam Ruditapes philippinarum were responsible for the introduction of the largest number (60) of non-native invertebrates and algae, often attached to packaging material, fouling the shell or parasitizing bivalve tissues. [source]


A review of changes in the fish assemblages of Levantine inland and marine ecosystems following the introduction of non-native fishes

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2005
M. Goren
Summary The arrival of non-native fishes in the Levant Basin began in the late 19th century. Whereas the presence of most of the 40 non-native freshwater fishes stem from intentional introductions, either for aquaculture or pest control, the 62 species of non-native marine fishes arrived by natural dispersal via the Suez Canal. Of the non-native freshwater species, five have established successful breeding populations (mosquitofish Gambusia affinis, common carp Cyprinus carpio, crucian carp Carassius carassius, swordtail Xiphophorus hellerii and rainbow trout Oncorhynchus mykiss), and seven are regularly stocked in natural habitats (thinlip mullet Liza ramada, flathead mullet Mugil cephalus, European eel Anguilla anguilla, grass carp Ctenopharyngodon idella, Asian silver carp Hypophthalmichthys molitrix, bighead carp Aristichthys nobilis, black carp Mylopharyngodon piceus). Some non-native species appear to have out-competed native species. Gambusia affinis may have caused the extirpation of two native cyprinid fishes from the Qishon River basin (Levant silver carp Hemigrammocapoeta nana and common garra Garra rufa) and the southern Dead Sea (endemic Sodom's garra G. ghoerensis). The opening of the Suez Canal in 1869 allowed entry into the eastern Mediterranean of Indo-Pacific and Erythrean biota, with the latter now dominating the community structure (50,90% of fish biomass) and function (altered native food web) of the Levantine littoral and infra-littoral zones. The process has accelerated in recent years concurrent with a warming trend of the seawater. Record numbers of newly discovered non-native species is leading to the creation of a human-assisted Erythrean biotic province in the eastern Mediterranean. [source]


Predator-inspection behaviour in female three-spined sticklebacks Gasterosteus aculeatus is associated with status of gravidity

JOURNAL OF FISH BIOLOGY, Issue 8 2009
J. G. Frommen
Differences in predator-inspection behaviour between gravid and non-gravid female as well as between male and female three-spined sticklebacks Gasterosteus aculeatus were investigated. Gravid females confronted with a live rainbow trout Oncorhynchus mykiss showed bolder inspection behaviour than non-gravid ones. The behaviour of gravid females was comparable with that of males, maybe because both face a high risk of predation. The results indicate that antipredator behaviour in female G. aculeatus is not fixed but adjusted to their reproductive state. [source]


The hypoxic threshold for maximum cardiac performance in rainbow trout Oncorhynchus mykiss (Walbaum) during simulated exercise conditions at 18° C

JOURNAL OF FISH BIOLOGY, Issue 3 2007
L. M. Hanson
Perfused rainbow trout Oncorhynchus mykiss hearts exposed to simulated exercise conditions (hypoxia, hyperkalemia and acidosis) at 18° C experienced complete failure of maximum cardiac performance at oxygen tensions <5·6 kPa and partial failure at <6·7 kPa. This hypoxic threshold, which occurred in the presence of maximal adrenergic stimulation (500 nM adrenaline), is unusually high compared with previous results at a colder acclimation temperature. Cardiac failure was primarily due to significant decreases (P < 0·05) in heart rate rather than cardiac stroke volume at all hypoxia levels tested. [source]


In vitro interactions between Neoparamoeba spp. and salmonid leucocytes; the effect of parasite sonicate on anterior kidney leucocyte function

JOURNAL OF FISH BIOLOGY, Issue 2006
K. Gross
Sonicated Neoparamoeba spp. (Nspp) did not affect the in vitro respiratory burst response of leucocytes isolated from Atlantic salmon Salmo salar, rainbow trout Oncorhynchus mykiss and chinook salmon Oncorhynchus tshawytscha anterior kidneys (P > 0·05). Atlantic salmon and chinook salmon leucocytes pre-incubated with the parasites, however, responded to phorbol myristate acetate (PMA) stimulation with a greater response compared to cells incubated with PMA on its own (P < 0·05). Sonicated Nspp was not chemo-attractive for anterior kidney leucocytes isolated from all three fish species. [source]


In vitro analysis of intestinal absorption of cadmium and calcium in rainbow trout fed with calcium- and cadmium-supplemented diets

JOURNAL OF FISH BIOLOGY, Issue 3 2006
B. Baldisserotto
The protective effects of dietary Ca2+ supplementation against Cd accumulation in rainbow trout Oncorhynchus mykiss fed with Cd-contaminated food were evaluated in relation to chronic changes in intestinal absorption rates. The changes were measured ,in vitro'. The control diet contained c. 20 mg Ca2+ g,1 food and 0·25 ,g Cd g,1 food; the experimental diets were supplemented with CaCO3 and Cd(NO3)2·4H2O to levels of 50 mg Ca2+ g,1 food and 300 ,g Cd g,1 food, alone and in combination. The Ca2+ and Cd absorption rates were measured using radiotracers (45Ca, 109Cd) at total Ca2+ and Cd concentrations of 3·0 and 0·12 mmol l,1, respectively in the intestinal saline. Chronically elevated dietary Cd caused a significant increase in Cd absorption rate by up to 10-fold at 30 days in the mid-intestine. The high Ca2+ diet prevented this up-regulation of Cd transport rate. Conversely, intestinal Ca2+ absorption was significantly increased by two- to five-fold by the Ca2+ -supplemented diet at 30 days in both the mid- and posterior intestine, and this effect was eliminated when Cd was simultaneously elevated in the diet. Ca2+ and Cd probably interact at common pathways and transport mechanisms in the intestine, though independent pathways may also exist. [source]


Growth, carcass composition and plasma growth hormone levels in cyclically fed rainbow trout

JOURNAL OF FISH BIOLOGY, Issue 3 2006
R. W. Blake
Growth, body composition and plasma growth hormone levels were recorded weekly for 24 weeks in rainbow trout Oncorhynchus mykiss. Underyearling rainbow trout were individually identified using coded tags and placed on either a cyclic feeding regime of 3 weeks of deprivation followed by 3 weeks of feeding or a daily feeding regime. No significant difference was found in standard length and mass among the cyclically fed and daily fed fish at the end of the experiment. For cyclically fed fish, the absolute specific growth rate and condition factor reached a maximum during the last week of refeeding. Cyclically fed fish had a significantly higher moisture and protein content and lower lipid levels relative to fish fed daily. Absolute mass and fat loss in the deprivation phase of the feeding cycle decreased in intensity with subsequent feeding cycles, indicating that the fish were acclimatizing to the feeding regime. It was proposed that this response was an adaptation against possible adverse effects in the adults (e.g. locomotor performance, bone ossification rates, fat deposition rate, growth rate and age at sexual maturity). Plasma growth hormone concentrations were not affected by cyclic feeding indicating that variations in plasma growth hormone concentration are not the cause of compensatory growth in rainbow trout. [source]


Evaluation of in vitro endocytosis and antibody synthesis by rainbow trout head kidney cells treated with bovine lactoferrin

JOURNAL OF FISH BIOLOGY, Issue 3 2005
S. Cecchini
Bovine lactoferrin (LF) was evaluated for its capacity to modulate the in vitro endocytosis (phagocytosis and pinocytosis) and antibody synthesis by head kidney cells of rainbow trout Oncorhynchus mykiss. Phagocytic activity and phagocytic index of head kidney macrophages, determined by measurement of ingested yeast, were influenced by bovine LF starting from the LF concentration of 1 and 0·1 ,g ml,1, respectively. Endocytosis, determined by the evaluation of droplet uptake of neutral red dye solution, was significantly enhanced by 10 ,g ml,1 of LF. In contrast, antibody synthesis by head kidney cells, evaluated by immunoenzymatic assay, from fish immunized against human-,-globulins (HGG)in vivo was not affected by bovine LF. Although these results showed that bovine LF had no effect on specific immunoglobulin production in vitro, an enhancement of the acquired immune response may be assumed in LF-treated fish in vivo, as observed in higher vertebrates. [source]


About the oldest domesticates among fishes

JOURNAL OF FISH BIOLOGY, Issue 2004
E. K. Balon
Domestication of mammals such as cattle, dogs, pigs and horses preceded that of fishes by at least 10 000 years. The first domesticated fish was the common carp Cyprinus carpio. Initially it was held as an exploited captive and did not undergo major changes in body shape or colour variations. About 2000 years ago, wild common carp were most abundant in the inland delta of the Danube River. These fish were torpedo shaped, golden-yellow in colour and had two pairs of barbels and a mesh-like scale pattern. Large schools of them thrived and reproduced on the flood plains of the Danube. The Romans kept fishes in specially built ponds at that time. The common carp was an ideal candidate and its rearing became more popular in medieval times. Common carp culture gradually became the most profitable branch of agriculture in central Europe and many special ponds were built. Soon common carp were being produced in pond systems including spawning and growing ponds. Unintentional artificial selection had taken place between the 12th and mid-14th century, and deep bodied and variously scaled or scaleless domesticated forms appeared in nearly every pond system. Some colour aberrations appeared in the 1950s in Japan, which, as koi, became the most expensive of fish. Common carp were not originally domesticated in China but wild ,chi'Carassius auratus occasionally appeared as a xanthic form that, as the goldfish, has been known since 960 A.D. By the 1200s the fish were used as ornamental animals in the garden pools of rich landowners. Circa 1276 to 1546, the Chinese began keeping golden chi in aquarium-like vessels and soon rich and poor alike became breeders of the fancy domesticated goldfish. The variously shaped monstrosities and colour aberrants were freaks but they became very fashionable at that time and still are. Domesticated goldfish monstrosities were first exported from China to Japan and much later to Europe and around the world. More recently other species have been domesticated by aquarists, such as the guppy Poecilia reticulata or the neon tetra Paracheirodon innesi. Other fishes kept as ornamentals, like swordtails Xiphophorus hellerii and platies Xiphophorus maculatus, the discus and angelfishes (Cichlidae), as well as those cultured for food like the rainbow trout Oncorhynchus mykiss, channel catfish Ictalurus punctatus or sturgeons (Acipenseridae) are merely exploited captives. [source]


Influence of temperature on silver accumulation and depuration in rainbow trout

JOURNAL OF FISH BIOLOGY, Issue 6 2004
J. W. Nichols
To assess the influence of water temperature on silver uptake, rainbow trout Oncorhynchus mykiss(c. 50 g; held at 13° C) were exposed to 0·1 ,M AgNO3 in ion-poor water for 1 week at 4 and 16° C without previous temperature acclimation. To assess the influence of temperature on elimination of previously accumulated Ag, rainbow trout were exposed to 0·1 ,M AgNO3 in ion-poor water for 1 week at 12° C, then were randomly divided amongst two Ag-free water containers, differing only in temperature (3 and 16° C), for 2 months. In the uptake study greater accumulation of Ag was seen in the gills, plasma and especially the livers and bile of ,warm' rainbow trout (16° C) compared to ,cold' rainbow trout (4° C), which can be explained by the higher metabolic rates of the warmer fish. In the depuration study there was no net elimination of Ag from the livers and bile but there was biphasic elimination of Ag from the gills and plasma of ,warm' and ,cold' fish, but with few differences between them. This indicated that temperature-dependent processes were less important in Ag elimination than in Ag uptake. Toxicokinetic modelling of Ag uptake by livers indicated four-fold greater uptake of Ag by ,warm' rainbow trout compared to ,cold' rainbow trout (one compartment uptake model). Elimination of previously accumulated Ag from the plasma was best fitted by a two compartment rate-constant based model, with approximately half the plasma Ag load eliminated within 24 h, followed by slower elimination of Ag over 2 months. [source]


Biochemical, histological and behavioural aspects of visual function during early development of rainbow trout

JOURNAL OF FISH BIOLOGY, Issue 4 2004
P. S. M. Carvalho
Retinal structure and concentration of retinoids involved in phototransduction changed during early development of rainbow trout Oncorhynchus mykiss, correlating with improvements in visual function. A test chamber was used to evaluate the presence of optokinetic or optomotor responses and to assess the functionality of the integrated cellular, physiological and biochemical components of the visual system. The results indicated that in rainbow trout optomotor responses start at 10 days post-hatch, and demonstrated for the first time that increases in acuity, sensitivity to low light as well as in motion detection abilities occur from this stage until exogenous feeding starts. The structure of retinal cells such as cone ellipsoids increased in length as photopic visual acuity improved, and rod densities increased concurrently with improvements in scotopic thresholds (2·2 log10 units). An increase in the concentrations of the chromophore all-trans-retinal correlated with improvements of all behavioural measures of visual function during the same developmental phase. [source]


Characterization of a novel fibroblast-like cell line from rainbow trout and responses to sublethal anoxia

JOURNAL OF FISH BIOLOGY, Issue 4 2004
C. G. Ossum
A novel fibroblast-like cell line RTHDF was established from hypodermal connective tissue of rainbow trout Oncorhynchus mykiss and telomerase activity was demonstrated early and late in cell line development. When RTHDF cells were exposed to bioenergetic stress, i.e. anoxia, activation of the stress activated member of the mitogen-activated protein kinase family, p38MAPK and induction of heat shock protein (Hsp70) were evident. The time-course of the p38MAPK activation and the induction of Hsp70 expression in RTHDF were studied in response to chemically induced anoxia. p38MAPK was activated rapidly, with maximal activity after 10 min of anoxia. Hsp70 was induced after 30 min of anoxia, followed by overnight recovery in growth medium at 21° C. Using the p38MAPK -specific inhibitor SB203580, the enhanced expression of Hsp70 occurred independently of p38MAPK activation in RTHDF. These data suggests that RTHDF can be useful in studying biochemical responses of teleost cells to environmental stress. [source]


Plasma Ca2+ concentration limits melatonin night production in two fish species

JOURNAL OF FISH BIOLOGY, Issue 6 2003
M. Gozdowska
In freshwater (FW) rainbow trout Oncorhynchus mykiss of spontaneously low plasma calcium concentrations ([Ca2+]pl), plasma melatonin at night was significantly lower than that measured in FW fish with the highest [Ca2+]pl. In brackish water adapted rainbow trout with originally high [Ca2+]pl, plasma melatonin concentration at night was elevated. In cannulated flounder Platichthys flesus, night plasma melatonin increases (,Mel) corresponded to [Ca2+]pl. It is postulated that in physiological steady-state conditions, melatonin synthesis capacity is coupled to free calcium concentration in plasma of O. mykiss and P. flesus. [source]


Influence of plasma lipid changes in response to 17,-oestradiol stimulation on plasma growth hormone, somatostatin, and thyroid hormone levels in immature rainbow trout

JOURNAL OF FISH BIOLOGY, Issue 3 2001
F. Mercure
Plasma total lipids were significantly higher in 17,-oestradiol(E2)-treated immature rainbow trout Oncorhynchus mykiss at week 4 after implantation, due to increases in polar and neutral lipids. The lipid classes responding were phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine, sterols and sterol esters, in a proportion that approximately reflected the increase in plasma vitellogenin (VtG) levels as measured by a non-competitive enzyme-linked immunosorbent assay (ELISA). Plasma non-esterified fatty acids and triacylglycerol were not affected by E2 treatment. Plasma growth hormone GH levels were increased, and plasma somatostatin-14 (SRIF) levels decreased in E2 -treated fish, responses which could be secondary to elevated plasma lipid (VtG) content, although a direct E2 action on somatotroph function is possible. Plasma T4 concentrations were not affected by E2 treatment, but plasma T3 concentrations were significantly lower than in controls 1 week after implantation when plasma E2 concentrations were the highest; this is in support of the hypothesis that E2 has a suppressive action on T3 production. [source]


First record of Pomphorhynchus laevis (Acanthocephala) in fishes from Northern Ireland

JOURNAL OF FISH BIOLOGY, Issue 1 2001
D. W. Evans
During the spring and summer of 1999, Pomphorhynchus laevis was recovered from rainbow trout Oncorhynchus mykiss raised in a Northern Ireland fish farm and from a European eel Anguilla anguilla from the Erne catchment, Ireland. These records appear to be independent of each other. They are the first reports of P. laevis from fish in Northern Ireland. [source]


Biosynthesis of ascorbic acid by extant actinopterygians

JOURNAL OF FISH BIOLOGY, Issue 3 2000
R. Moreau
Polypterus senegalus, the longnose gar Lepisosteus osseus and the bowfin Amia calva had gulonolactone oxidase activity in the kidney and thus can synthesize ascorbic acid de novo. The enzyme activity was associated with the microsomal fraction. The common carp Cyprinus carpio and the goldfish Carassius auratus had no gulonolactone oxidase activity. Antibodies directed against white sturgeon gulonolactone oxidase showed cross-reactivity with lake sturgeon, bowfin and longnose gar kidney enzymes, but not with enzymes from Polypterus, sea lamprey, and tadpole kidney or pig liver. Given cross-reactivity, gulonolactone oxidase relatedness matched actinopterygian phylogeny, and suggested homology of the character throughout fishes. Modern teleosts may have lost the ability to synthesize ascorbic acid since the late Triassic as a result of a single reversal in the founding population. Wild bowfin and longnose gar exhibited high ascorbate concentrations in liver and spleen when compared with the teleosts rainbow trout Oncorhynchus mykiss and common carp fed vitamin C-supplemented diets. [source]


Lower fitness of hatchery and hybrid rainbow trout compared to naturalized populations in Lake Superior tributaries

MOLECULAR ECOLOGY, Issue 11 2004
L. M. MILLER
Abstract We have documented an early life survival advantage by naturalized populations of anadromous rainbow trout Oncorhynchus mykiss over a more recently introduced hatchery population and outbreeding depression resulting from interbreeding between the two strains. We tested the hypothesis that offspring of naturalized and hatchery trout, and reciprocal hybrid crosses, survive equally from fry to age 1+ in isolated reaches of Lake Superior tributary streams in Minnesota. Over the first summer, offspring of naturalized females had significantly greater survival than offspring of hatchery females in three of four comparisons (two streams and 2 years of stocking). Having an entire naturalized genome, not just a naturalized mother, was important for survival over the first winter. Naturalized offspring outperformed all others in survival to age 1+ and hybrids had reduced, but intermediate, survival relative to the two pure crosses. Averaging over years and streams, survival relative to naturalized offspring was 0.59 for hybrids with naturalized females, 0.37 for the reciprocal hybrids, and 0.21 for hatchery offspring. Our results indicate that naturalized rainbow trout are better adapted to the conditions of Minnesota's tributaries to Lake Superior so that they outperform the hatchery-propagated strain in the same manner that many native populations of salmonids outperform hatchery or transplanted fish. Continued stocking of the hatchery fish may conflict with a management goal of sustaining the naturalized populations. [source]


Apparent amino acid availability from feedstuffs in extruded diets for rainbow trout Oncorhynchus mykiss

AQUACULTURE NUTRITION, Issue 4 2010
T.G. GAYLORD
Abstract Apparent amino acid availability coefficients of several typical and novel feed ingredients were determined in rainbow trout using extruded diets and the faecal stripping technique. The ingredients were tested included five fish meals, three terrestrial animal by-products, five plant protein concentrates, four plant meals, and seven low-protein plant ingredients. Amino acid availability from the fish meals was relatively high ranging from 90 to 101%. Lower coefficients overall were observed for Menhaden fish meal FAQ when compared to the other fish meals. No differences in apparent amino acid availability were detected among the animal by-products. Within the plant concentrate group, rice protein concentrate and barley protein concentrate exhibited generally lower amino acid availabilities compared to other concentrates tested. Among the plant meals, only the availabilities of histidine, valine, isoleucine and lysine in flaxseed meal were lower than those of soybean meal. Apparent amino acid availabilities among the low-protein plant products were variable and significantly different. [source]


An evaluation of DVAqua®, a fully-fermented yeast culture, during long-term hatchery rearing of McConaughy strain rainbow trout

AQUACULTURE NUTRITION, Issue 3 2010
M.E. BARNES
Abstract The addition of a proprietary, fully-fermented yeast Saccahromyces cerevisiae culture supplement (DVAqua®, Diamond V Mills, Cedar Rapids, IA, USA) was evaluated during long-term feeding of McConaughy strain rainbow trout Oncorhynchus mykiss. Beginning at initial feeding and continuing for 408 days of hatchery rearing, the trout received either a commercially-manufactured feed or the same feed containing 0.125 g kg,1 DVAqua. This study was conducted at a production level as part of normal (real-world) hatchery operations, with the fish periodically inventoried and moved into different rearing units. Although no rearing-tank replication occurred during the first 54 days of feeding, multiple tanks and raceways were used thereafter. Fish in rearing units receiving DVAqua supplementation exhibited less mortality, particularly during the earlier rearing stages. During the final 177 days of rearing in six raceways, DVAqua-fed McConaughy strain trout were significantly larger and had a significantly improved feed conversion ratio. The overall feed conversion ratio for the entire duration of the study was 1.17 in the fish receiving DVAqua supplementation compared to 1.21 in the control group. Despite the limitations of this study, the use of DVAqua is recommended for McConaughy strain rainbow trout and other less-domesticated, more difficult-to-rear salmonids. [source]


Apparent digestibility of nutrients and energy in extruded diets from cultivars of barley and wheat selected for nutritional quality in rainbow trout Oncorhynchus mykiss

AQUACULTURE NUTRITION, Issue 3 2009
T.G. GAYLORD
Abstract A digestibility trial was conducted to elucidate potential differences in barley (Hordeum vulgare L.) lines and varieties as a first step in defining their potential for use in aquafeeds. A diverse group of six barley lines having six combinations of selected attributes, normal versus low phytic acid, normal versus waxy, and hulled versus hull-less, were chosen for evaluation along with a waxy wheat (Triticum aestivum L.) and soft white wheat. The experimental diets were manufactured by cooking extrusion and consisted of a 70% reference diet that was formulated to contain a minimal level of phosphorus and 30% test ingredient. Phosphorus availability ranged from 17 to 78% and was influenced by starch type in wheat. Apparent protein digestibility ranged from 53 to 125% and differences were observed between wheat varieties based on starch type. Apparent energy digestibility ranged from 32 to 63%, with waxy barley varieties having higher energy digestibility coefficients than normal starch varieties. Waxy starch varieties had higher starch digestibility in both barley and wheat because of the greater digestibility of amylopectin than amylose. In summary, the higher energy digestibility of waxy barley lines suggests that these varieties warrant further attention as feed ingredients for rainbow trout. [source]


Effects of extrusion processing of feed ingredients on apparent digestibility coefficients of nutrients for rainbow trout (Oncorhynchus mykiss)

AQUACULTURE NUTRITION, Issue 2 2003
Zongjia J. Cheng
Abstract An experiment was conducted to evaluate the effects of extrusion processing on apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude fat, energy and minerals in soya bean meal (SBM), barley, corn gluten meal and whole wheat, using rainbow trout Oncorhynchus mykiss as the test species. In addition, availabilities of amino acids were also determined in SBM. Feed ingredients were preconditioned at 89,93 °C and then extruded using a Wenger X-85 extruder. Nonextruded ingredients were used as is, meaning that they were not preconditioned. The extruded and nonextruded ingredients were mixed with a casein,gelatin reference diet at 3 : 7 ratio prior to determination of ADC values. A total of 135 trout (initial mean body weight 223.4 ± 12.7 g) were stocked into nine 140-L fibreglass digestibility tanks with 15 fish per tank. Individual tanks were assigned randomly to each of eight diets made from the four ingredients (extruded and nonextruded) plus the reference diet. After faeces were collected in the first week, the diets were switched among tanks, and faeces were collected again after 5-day acclimation period in the second week. Yttrium oxide was used as the inert marker. Results showed that extrusion processing significantly improved ADCs of dry matter, crude fat and gross energy, and reduced ADCs of crude protein, phosphorus, copper, iron and zinc. Results also showed that the effects of extrusion processing on chemical composition and ADCs of nutrients depended on the ingredients. It is recommended that trace minerals such as copper, iron and zinc be supplemented by an additional 10,20% when rainbow trout diets are extruded because of their reduced bioavailability in plant meal-based feed ingredients. [source]


Effect of GnRHa injection on milt volume in recently stripped rainbow trout Oncorhynchus mykiss

AQUACULTURE RESEARCH, Issue 10 2010
Fatemeh Paykan Heyrati
Abstract In this study, the effect of gonadotropin-releasing hormone agonist (GnRHa) injection on milt production in spent rainbow trout was investigated. On day 0, 25 newly matured male rainbow trout (Oncorhynchus mykiss) were stripped manually, and sperm quantity (vol: mL fish,1) and quality, spermatocrit (%), sperm count (cell mL,1), motile sperm percentage and motility duration (s) were evaluated. After stripping, fish were randomly divided into five groups: intact; sham (injected with propylene glycol as a hormone vehicle); and groups receiving 4, 8 or 16 ,g kg,1 BW of [d -Ala6 Des-Gly10] mGnRHa. On day 7, the fish were stripped again and the same sperm characteristics as on day 0 were measured. At the beginning of the experiment, there were no significant differences in any of the sperm quantity characteristics between groups. On day 7, expressible milt volume was significantly reduced compared with day 0 (P<0.05, t -test) in the intact and sham groups but milt quality remained the same (P>0.05, t -test). The present study shows that GnRHa injection with a concentration as low as 4 ,g kg,1 BW after first stripping could prevent a significant reduction in milt quantity collected 7 days later without any adverse effects on sperm quality. [source]


The patterns of plasma free amino acids after force-feeding in rainbow trout Oncorhynchus mykiss (Walbaum) with and without dorsal aorta cannulation

AQUACULTURE RESEARCH, Issue 2001
I-H Ok
Abstract Two experiments were conducted to compare the patterns of plasma free amino acid concentrations after force-feeding in rainbow trout Oncorhynchus mykiss (Walbaum) with and without dorsal aorta cannulation. In the first experiment, 35 rainbow trout averaging 504 ± 7.8 g (mean ± SD) were divided into seven groups of five fish each. After 48 h starvation, a group of fish was anaesthetized and blood samples were taken at one of the following time periods: 0, 4, 8, 12, 24, 36 and 48 h after feeding. In the second experiment, five dorsal aorta cannulated rainbow trout averaging 511 ± 6.2 g (mean ± SD) were kept in a cage. After 48 h starvation, the fish were anaesthetized and blood samples were taken from the same fish at 0, 4, 8, 12, 24, 36 and 48 h after feeding. In the first experiment, the concentration of all plasma free amino acids except histidine and glycine peaked at 4 h and returned to the basal level 24 h after feeding. In the second experiment, the concentration of all plasma free amino acids except isoleucine, leucine, phenylalanine and tryptophan also peaked at 4 h and returned to the basal level 24 h after feeding. These results showed that the pattern of plasma free amino acid concentrations from fish with and without dorsal aorta cannulation were similar. [source]


The acute effect of cortisol implant on self-feeding activity of rainbow trout Oncorhynchus mykiss (Walbaum)

AQUACULTURE RESEARCH, Issue 6 2001
T Lyytikäinen
No abstract is available for this article. [source]


Swimming activity and energetic expenditure of captive rainbow trout Oncorhynchus mykiss (Walbaum) estimated by electromyogram telemetry

AQUACULTURE RESEARCH, Issue 6 2000
S J Cooke
Rainbow trout Oncorhynchus mykiss (Walbaum) are usually cultured at high densities to maximize production, but little is known about the physiological and behavioural consequences of high-density fish culture. The purpose of this study was to develop quantitative correlates of activity for fish held under conditions of increasing density. Fifteen hatchery-reared rainbow trout (mean fork length = 432.3 ± 9.2 mm) were implanted with activity (electromyogram; EMGi) transmitters and randomly assigned to each of three replicate tanks. Original tank densities (15 kg m,3) were then increased to 30 and finally to 60 kg m,3 at weekly intervals by adding additional fish. Remote telemetry signals indicated that activity increased with increasing stocking density. Fish were relatively inactive during the middle of the day, with diel activity patterns not differing among treatments. Fish were more active during periods of darkness, with activity increasing with increasing stocking density. Relationships between swimming speed, EMGi activity and oxygen consumption were developed using a respirometer and used to estimate oxygen consumption of the fish in the density treatments. Average oxygen consumption estimates increased with increasing density treatments as follows: low density = 75.6 mg kg,1 h,1; medium density = 90.0 mg kg,1 h,1; and high density = 102.6 mg kg,1 h,1. Telemetry permits quantification of the effects of increasing density on fish activity. Physiological telemetry devices may provide a useful tool for remotely monitoring animal welfare correlates under controlled conditions for fish exposed to different husbandry conditions and may prove a valuable tool for the aquaculture industry. [source]


Survival, growth and dressing traits of triploid hybrids between rainbow trout and three charr species

AQUACULTURE RESEARCH, Issue 4 2000
J M. Blanc
Triploid hybrids between female rainbow trout Oncorhynchus mykiss and male brook charr Salvelinus fontinalis, Arctic charr S. alpinus and lake charr S. namaycush, together with diploid and triploid rainbow trout controls from the same dams, were tested in freshwater farming up to their fourth year of life. All hybrids displayed lower survival rates than the controls, the weakest genotype being the Arctic charr hybrid. Mortalities were mostly observed at the embryonic and larval stages and at the adult stage as a consequence of male sexual maturation. Growth of all hybrids was hindered (compared with controls) during the first year, but only moderate differences remained after 3 years. Sexual maturation resulted in a weight inferiority of males in all genotypes. As to carcass traits, female hybrids displayed a slightly higher dressing percentage than female triploid rainbow trout, as a result of lower visceral losses. These results are discussed with reference to hybrid resistance to rhabdoviruses from the viewpoint of fish farming improvement. [source]