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Atlantic Salmon Populations (atlantic + salmon_population)
Selected AbstractsHabitat selection by juvenile Atlantic salmon: the interaction between physical habitat and abundanceJOURNAL OF FISH BIOLOGY, Issue 4 2005R. D. Hedger The effect of physical river habitat variables on the distribution of juvenile Atlantic salmon Salmo salar L. in the Rivière de la Trinité, Québec, Canada, was examined using generalized additive modelling. A survey of Atlantic salmon fry and parr densities and habitat variables (flow velocity, water column depth and substratum size) was conducted in the summer months from 1984 to 1992. Clear patterns of habitat use existed: specific ranges of habitat variables were selected, with parr preferring greater velocities, depths and substratum sizes than fry. There was a large variation, however, in juvenile densities for given velocities, depths or substratum sizes, with this variation being greatest in optimal habitats. On examination of an individual year, interaction between the variables was found to explain some of the variation. On a year-to-year basis the juvenile Atlantic salmon population was found to exhibit an ,Ideal Free Distribution', which resulted in greatest variation in optimal habitats with year-to-year changes in population abundance. [source] Detection of QTL affecting harvest traits in a commercial Atlantic salmon populationANIMAL GENETICS, Issue 5 2009R. D. Houston Summary Genetic variation in performance and quality traits measured at harvest has previously been demonstrated in Atlantic salmon aquaculture populations. To map major loci underlying this variation, we utilized data from 10 families from a commercial breeding programme. Significant QTL were detected affecting harvest weight and length traits on linkage group 1, and affecting waste weight on linkage group 5. In total, 11 of the 29 linkage groups examined showed at least suggestive evidence for a QTL. These data suggest that major loci affecting economically important harvest characteristics are segregating in commercial salmon populations. [source] Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): a review of aspects of their life historiesECOLOGY OF FRESHWATER FISH, Issue 1 2003A. Klemetsen Abstract ,,,Among the species in the family Salmonidae, those represented by the genera Salmo, Salvelinus, and Oncorhynchus (subfamily Salmoninae) are the most studied. Here, various aspects of phenotypic and life-history variation of Atlantic salmon Salmo salar L., brown trout Salmo trutta L., and Arctic charr Salvelinus alpinus (L.) are reviewed. While many strategies and tactics are commonly used by these species, there are also differences in their ecology and population dynamics that result in a variety of interesting and diverse topics that are challenging for future research. Atlantic salmon display considerable phenotypic plasticity and variability in life-history characters ranging from fully freshwater resident forms, where females can mature at approximately 10 cm in length, to anadromous populations characterised by 3,5 sea-winter (5SW) salmon. Even within simple 1SW populations, 20 or more spawning life-history types can be identified. Juveniles in freshwater can use both fluvial and lacustrine habitats for rearing, and while most smolts migrate to sea during the spring, fall migrations occur in some populations. At sea, some salmon undertake extensive oceanic migrations while other populations stay within the geographical confines of areas such as the Baltic Sea. At the other extreme are those that reside in estuaries and return to freshwater to spawn after spending only a few months at sea. The review of information on the diversity of life-history forms is related to conservation aspects associated with Atlantic salmon populations and current trends in abundance and survival. Brown trout is indigenous to Europe, North Africa and western Asia, but was introduced into at least 24 countries outside Europe and now has a world-wide distribution. It exploits both fresh and salt waters for feeding and spawning (brackish), and populations are often partially migratory. One part of the population leaves and feeds elsewhere, while another part stays as residents. In large, complex systems, the species is polymorphic with different size morphs in the various parts of the habitat. Brown trout feed close to the surface and near shore, but large individuals may move far offshore. The species exhibits ontogenetic niche shifts partly related to size and partly to developmental rate. They switch when the amount of surplus energy available for growth becomes small with fast growers being younger and smaller fish than slow growers. Brown trout is an opportunistic carnivore, but individuals specialise at least temporarily on particular food items; insect larvae are important for the young in streams, while littoral epibenthos in lakes and fish are most important for large trout. The sexes differ in resource use and size. Females are more inclined than males to become migratory and feed in pelagic waters. Males exploit running water, near-shore and surface waters more than females. Therefore, females feed more on zooplankton and exhibit a more uniform phenotype than males. The Arctic charr is the northernmost freshwater fish on earth, with a circumpolar distribution in the Holarctic that matches the last glaciation. Recent mtDNA studies indicate that there are five phylogeographic lineages (Atlantic, Arctic, Bering, Siberian and Acadian) that may be of Pleistocene origin. Phenotypic expression and ecology are more variable in charr than in most fish. Weights at maturation range from 3 g to 12 kg. Population differences in morphology and coloration are large and can have some genetic basis. Charr live in streams, at sea and in all habitats of oligotrophic lakes, including very deep areas. Ontogenetic habitat shifts between lacustrine habitats are common. The charr feed on all major prey types of streams, lakes and near-shore marine habitats, but has high niche flexibility in competition. Cannibalism is expressed in several cases, and can be important for developing and maintaining bimodal size distributions. Anadromy is found in the northern part of its range and involves about 40, but sometimes more days in the sea. All charr overwinter in freshwater. Partial migration is common, but the degree of anadromy varies greatly among populations. The food at sea includes zooplankton and pelagic fish, but also epibenthos. Polymorphism and sympatric morphs are much studied. As a prominent fish of glaciated lakes, charr is an important species for studying ecological speciation by the combination of field studies and experiments, particularly in the fields of morphometric heterochrony and comparative behaviour. [source] Evaluation of the effects of catch-and-release angling on the Atlantic salmon (Salmo salar) of the Ponoi River, Kola Peninsula, Russian FederationECOLOGY OF FRESHWATER FISH, Issue 1-2 2000F. G. Whoriskey Abstract , We studied the effects of catch-and-release fishing upon the Ponoi River's Atlantic salmon populations. The Ponoi River is located on the Kola Peninsula of the Russian Federation, and has recently been developed for sports fishing. Angler exploitation rates are estimated to range from 10.4% to 19% of the river's salmon, thus the possibility of significant levels of post-release mortality is of concern. We radio-tracked fish caught and released by anglers in 1995 and 1996. Despite our simple equipment and the large size of the river, we were able to relocate most fish. These fish had high rates of survival, and anglers recaptured about 11% of them per year a second time. This is very similar to the recapture rates observed for Floy-tagged fish released in an angler-based mark-recapture assessment. We also held 62 angled fish for 24 hours in a live cage to evaluate rates of delayed mortality. Only one of the 62 fish died, and it was heavily scarred with gillnet marks. Most fish that are fatally stressed by angling die within 24 h (e.g., Booth et al. 1995). In 1996, up to 10% of our Floy-tagged fish were angled and released twice, and about 0.5% were angled and released three times. No significant biases were detected in the post-angling movement patterns of these fish. The multiple captures and lack of movement bias suggest that fish behavior was little altered by the angling experience. Nine fish Floy tagged prior to spawning have been recovered as typical emaciated kelts. Three were killed, and a post mortem exam showed all had spawned. Parr numbers at all monitored sites have been steadily increasing since the advent of catch-and-release fishing. By contrast, parr growth rates are generally unchanged or significantly better., [source] Stocking-related patterns of genetic variation at enzymatic loci in south European Atlantic salmon populationsJOURNAL OF FISH BIOLOGY, Issue 2005P. Morán Genetic variation at 24 enzymatic loci was investigated in eight south European Atlantic salmon populations from the rivers Nivelle, Cares, Sella, Narcea, Esva, Navia, Porcia and Eo. In these rivers, management based on supplementation of native populations with foreign stocks was carried out for more than one decade. Population genetic patterns expressed in terms of allele frequencies, mean heterozygosity and conformity to Hardy-Weinberg equilibrium, were significantly different between populations. Relevant temporal changes of genetic variability were reported. Evidence that foreign stocking has disturbed the genetic patterns of some of the studied populations is presented. [source] Competition for shelter among over-wintering signal crayfish and juvenile Atlantic salmonJOURNAL OF FISH BIOLOGY, Issue 2 2004S. W. Griffiths Three separate effects on refuge use by signal crayfish Pacifastacus leniusculus and Atlantic salmon Salmo salar were examined: (1) the effect on Atlantic salmon of an addition of signal crayfish (doubling the total number of animals), (2) the effect on signal crayfish of an addition of Atlantic salmon and (3) intraspecific compared with interspecific competition, compared by holding total density of animals constant and varying the proportion of signal crayfish and Atlantic salmon in trials. Observations were made during winter, when both species are nocturnal. The proportion of Atlantic salmon sheltering was significantly lower in the presence than in the absence of signal crayfish when the interspecific treatment (Atlantic salmon plus signal crayfish) effected a doubling in density compared to the intraspecific treatment (Atlantic salmon alone). The proportion of signal crayfish sheltering was independent of the presence of Atlantic salmon. When total density was constant, the proportion of Atlantic salmon sheltering was significantly higher in intraspecific (52·8%) than interspecific trials (27·3%). Atlantic salmon out of shelter during the day in winter are believed to be very vulnerable to predators and the capacity for fish to share shelters with one another is known to be very low. Therefore, competition from crayfish for winter shelters may lead to detrimental effects on Atlantic salmon populations. [source] Lacustrine spatial distribution of landlocked Atlantic salmon populations assessed across generations by multilocus individual assignment and mixed-stock analysesMOLECULAR ECOLOGY, Issue 10 2001C. Potvin Abstract The objective of this study was to assess the spatiotemporal distribution of four landlocked Atlantic salmon (Salmo salar) populations during their sympatric feeding phase in lake St-Jean (Québec, Canada). A total of 1100 fish captured over a period of 25 years was genotyped at six microsatellite loci in order to assess the temporal stability of the relative proportion of each population in different lake sectors using both individual-based assignment and mixed-stock analysis. Estimates of relative proportions obtained from both methods were highly correlated. A nonrandom spatial distribution of populations was observed for each period and, despite the fact that the overall proportion of each population varied over time, the pattern of differential distribution remained generally stable over time. Furthermore, there were indications that the extent of horizontal spatial overlap among populations was negatively correlated with that of their genetic differentiation at both microsatellites and a major histocompatibility complex locus, and independent of the geographical distance between the rivers of origin. We discuss the hypothesis that the temporal stability of spatial distribution, the lack of an association between spatial partitioning and geographical distance between rivers of origin, and the apparent negative correlation between spatial overlap and genetic differentiation, reflect the outcome of selective pressures driving behavioural differences for spatial niche partitioning among populations. [source] Population structure of Atlantic salmon (Salmo salar L.): a range-wide perspective from microsatellite DNA variationMOLECULAR ECOLOGY, Issue 4 2001T. L. King Abstract Atlantic salmon (n = 1682) from 27 anadromous river populations and two nonanadromous strains ranging from south-central Maine, USA to northern Spain were genotyped at 12 microsatellite DNA loci. This suite of moderate to highly polymorphic loci revealed 266 alleles (5,37/locus) range-wide. Statistically significant allelic and genotypic heterogeneity was observed across loci between all but one pairwise comparison. Significant isolation by distance was found within and between North American and European populations, indicating reduced gene flow at all geographical scales examined. North American Atlantic salmon populations had fewer alleles, fewer unique alleles (though at a higher frequency) and a shallower phylogenetic structure than European Atlantic salmon populations. We believe these characteristics result from the differing glacial histories of the two continents, as the North American range of Atlantic salmon was glaciated more recently and more uniformly than the European range. Genotypic assignment tests based on maximum-likelihood provided 100% correct classification to continent of origin and averaged nearly 83% correct classification to province of origin across continents. This multilocus method, which may be enhanced with additional polymorphic loci, provides fishery managers the highest degree of correct assignment to management unit of any technique currently available. 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