Genetic Changes in Hatchery Stocks of Brown Trout (Salmo trutta)

1980 ◽  
Vol 37 (1) ◽  
pp. 82-87 ◽  
Author(s):  
Nils Ryman ◽  
Gunnar Ståhl
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Natural Populations ◽  
Starch Gel Electrophoresis ◽  
Genetic Changes ◽  
Genetic Characteristics ◽  
Glycerophosphate Dehydrogenase ◽  
Field Samples ◽  
Brown Trout Salmo Trutta ◽  
Frequency Changes

Preservation of the genetic characteristics of a population is one of the primary objectives of many fish stocking programs. Using starch gel electrophoresis we have tested for temporal gene frequency stability at two polymorphic loci coding for α-glycerophosphate dehydrogenase and creatine phosphokinase. Three Swedish hatchery stocks of brown trout (Salmo trutta) and field samples from natural populations corresponding to two of these stocks were analyzed. Highly significant allele frequency changes at both loci indicated considerable lack of intra-stock genetic homogeneity. In the light of these findings we emphasize the importance of using large numbers of actual as well as effective parents to avoid inadvertent genetic changes and inbreeding. No stock should be founded or perpetuated using less than approximately 30 parents of the least numerous sex in any generation.Key words: inbreeding, genetic drift, gene bank, electrophoresis, stocking, trout

Genetic Perspectives of the Identification and Conservation of Scandinavian Stocks of Fish

1981 ◽  
Vol 38 (12) ◽  
pp. 1562-1575 ◽  
Author(s):  
Nils Ryman ◽  
Gunnar Ståhl
Keyword(s):  
Salmo Trutta ◽  
Fishery Management ◽  
Natural Populations ◽  
Morphological Characteristics ◽  
Genetic Changes ◽  
Genetic Characteristics ◽  
Hatchery Fish ◽  
Genetic Patterns ◽  
Brown Trout Salmo Trutta ◽  
Natural Situation

Intraspecific planting and introduction of new species of fish has been much more restricted in northern Scandinavia than in many other parts of the world. Further, the general geography, with a large number of independent drainages and numerous impassable waterfalls, often prevented extensive spread of planted freshwater fish. Therefore, the genetic patterns observed among Scandinavian populations, e.g. their structure and the amount of distribution of genetic variation, may more accurately picture a natural situation than that reflected by stocks which have been influenced by a variety of fishery management activities. Natural populations of Scandinavian salmonids seem to be characterized by a more apparent subdivision than is usually observed, and multiple cases of genetically distinct sympatric demes have been identified within many species. Detailed electrophoretic analyses of natural populations have revealed the existence of previously unrecognized reproductive units exhibiting quite different ecological and morphological characteristics. At least in the brown trout (Salmo trutta), these units seem to have evolved independently, and there are no indications that they reflect the existence of two or more widespread sub- or sibling-species. In several cases attempts to preserve, in hatcheries, the genetic characteristics of endangered or unique remnant natural populations have proven unsuccessful; genetic changes and loss of genetic variability have occurred during the stocking. There is also strong evidence that planted hatchery fish have hybridized and drastically altered the genetic composition of valuable remnant natural populations. We discuss the ecological and fishery management implications of these findings and indicate some of the problems which we consider important to be addressed in future research.Key words: genetic characteristics, Scandinavian salmonids, sympatric demes, identification, conservation

scholarly journals No additive genetic variance for tolerance to ethynylestradiol exposure in natural populations of brown trout ( Salmo trutta )

2019 ◽  
Vol 12 (5) ◽  
pp. 940-950 ◽  
Author(s):  
Lucas Marques da Cunha ◽  
Anshu Uppal ◽  
Emily Seddon ◽  
David Nusbaumer ◽  
Etienne L.M. Vermeirssen ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Brown Trout Salmo Trutta

scholarly journals Demographic Genetics of Brown Trout (Salmo trutta) and Estimation of Effective Population Size From Temporal Change of Allele Frequencies

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1369-1381 ◽  
Author(s):  
Per Erik Jorde ◽  
Nils Ryman
Keyword(s):  
Allele Frequency ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Natural Populations ◽  
Effective Size ◽  
Effective Population ◽  
Frequency Shifts ◽  
Brown Trout Salmo Trutta ◽  
Population Sizes ◽  
Allozyme Loci

Abstract We studied temporal allele frequency shifts over 15 years and estimated the genetically effective size of four natural populations of brown trout (Salmo trutta L.) on the basis of the variation at 14 polymorphic allozyme loci. The allele frequency differences between consecutive cohorts were significant in all four populations. There were no indications of natural selection, and we conclude that random genetic drift is the most likely cause of temporal allele frequency shifts at the loci examined. Effective population sizes were estimated from observed allele frequency shifts among cohorts, taking into consideration the demographic characteristics of each population. The estimated effective sizes of the four populations range from 52 to 480 individuals, and we conclude that the effective size of natural brown trout populations may differ considerably among lakes that are similar in size and other apparent characteristics. In spite of their different effective sizes all four populations have similar levels of genetic variation (average heterozygosity) indicating that excessive loss of genetic variability has been retarded, most likely because of gene flow among neighboring populations.

Sign in / Sign up

Export Citation Format

Share Document