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

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

scholarly journals Hybridisation of Malus sylvestris (L.) Mill. with Malus × domestica Borkh. and Implications for the Production of Forest Reproductive Material

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 367
Author(s):  
Mateja Kišek ◽  
Kristjan Jarni ◽  
Robert Brus
Keyword(s):  
Malus Domestica ◽  
Natural Populations ◽  
Morphological Characteristics ◽  
Apple Trees ◽  
Genetic Characteristics ◽  
Malus Domestica Borkh ◽  
Malus Sylvestris ◽  
Forest Reproductive Material ◽  
Reproductive Material ◽  
Crab Apple

This study focuses on the morphological and genetic characteristics of European crab apple (Malus sylvestris (L.) Mill.) and the occurrence of hybrids in its populations. We analyzed a total of 107 putative European crab apple trees in Slovenia: 92 from nine natural populations, five from a seed stand and 10 from a stand of unnatural origin. We also included 18 domesticated apple trees (Malus × domestica Borkh.) and two Japanese flowering crab apple trees (Malusfloribunda van Houtte) as outliers. The trees were classified into groups of European crab apples, hybrids and domesticated apples according to their morphological and genetic characteristics. Classification based on morphological traits produced different results (58.75% European crab apple, 37.11% hybrids and 4.14% domesticated apple) compared to those based on genetic analysis (70.10% European crab apple, 21.64% hybrids and 8.26% domesticated apple). When genetic and morphological characteristics were combined, only 40.20% of the trees were classified as European crab apple, and an additional group of feral cultivars of domesticated apples (6.18%) was identified. The analysis revealed that hybridization with domesticated apple is taking place in all studied natural European crab apple populations; however, hybrids and feral cultivars only occur to a limited extent. When introducing European crab apple into forests in the future, only genetically verified forest reproductive material obtained exclusively from suitable seed stands should be used.

Migration barriers protect indigenous brown trout (Salmo trutta) populations from introgression with stocked hatchery fish

2005 ◽  
Vol 6 (2) ◽  
pp. 175-191 ◽  
Author(s):  
J. K. J Van. Houdt ◽  
J. Pinceel ◽  
M. -C. Flamand ◽  
M. Briquet ◽  
E. Dupont ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Hatchery Fish ◽  
Migration Barriers ◽  
Brown Trout Salmo Trutta

Reduced hatchery rearing density increases social dominance, postrelease growth, and survival in brown trout (Salmo trutta)

2010 ◽  
Vol 67 (2) ◽  
pp. 288-295 ◽  
Author(s):  
Sofia Brockmark ◽  
Jörgen I. Johnsson
Keyword(s):  
Brown Trout ◽  
Social Dominance ◽  
Salmo Trutta ◽  
Adaptive Behaviour ◽  
Dominance Status ◽  
Growth And Survival ◽  
Hatchery Fish ◽  
Brown Trout Salmo Trutta ◽  
Rearing Density ◽  
Natural Density

Hatchery fish reared for conservation or supplementation often have difficulties adapting to natural conditions, resulting in poor performance in the wild. In a standard hatchery, fish are confined at high densities, which creates a social environment different from that experienced after release. Here we investigated how rearing density influences social dominance, postrelease growth, and survival in brown trout ( Salmo trutta ). Fish were reared at three density treatments: conventional hatchery density, half of conventional hatchery density, and natural density. Four months after hatching, dominance status was determined, and 36 fish from each treatment were released into an enclosed stream and recaptured after 36 days. Trout reared at natural density had higher dominance status and grew faster, both in the hatchery and in the natural stream, than trout from higher densities. Moreover, trout reared at natural density were twice as likely to survive in the stream as trout from higher densities. These novel results suggest that more natural rearing densities would facilitate the development of adaptive behaviour in hatchery salmonids and, thereby, their contribution to natural production.

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 Genetic risks of supplementing trout populations with native stocks: a simulation case study from current Pyrenean populations

2014 ◽  
Vol 71 (8) ◽  
pp. 1243-1255 ◽  
Author(s):  
Raquel Fernández-Cebrián ◽  
Rosa Maria Araguas ◽  
Nuria Sanz ◽  
Jose Luis García-Marín
Keyword(s):  
Salmo Trutta ◽  
Captive Breeding ◽  
Gene Diversity ◽  
Genetic Changes ◽  
Study Region ◽  
Local Diversity ◽  
Genetic Risks ◽  
Complex Population ◽  
Brown Trout Salmo Trutta

The risks of supplementation must be examined to assess the genetic effects to native wild populations before full implementation or exclusion of programs that involve captive breeding and release. Real genetic data can be applied to simulations of genetic changes in populations of interest and subsequently used in risk assessment. Ancestral Mediterranean brown trout (Salmo trutta) lineages exhibit complex population structure among native populations. Genetically divergent Atlantic stocks were maintained and released in the Mediterranean rivers as recreational fish, which resulted in hybridization and introgression with local populations. Therefore, we designed a new supplementation program based on native stocks and evaluated the genetic risks associated with releasing native fish in recreational fisheries. Our simulation was delimited by the observed population genetic structure and available hatchery facilities in the study region. Supplementation with native stocks maintained estimates of gene diversity indexes (total diversity (HT), local diversity (HS), and population differentiation (GST)). However, simulations indicated that long-term supplementation significantly reduced genetic diversity among locations because of a homogenizing effect of populations along each management unit. Therefore, such reinforcements compromised the conservation of local genetic variation. Nevertheless, replacement of current foreign stocks with native stocks can be an important step towards promoting the value of preserving local diversity among anglers.

Fine-spotted Brown Trout (Salmo trutta): Its Phenotypic Description and Biochemical Genetic Variation

1987 ◽  
Vol 44 (10) ◽  
pp. 1775-1780 ◽  
Author(s):  
Øystein Skaala ◽  
Knut E. Jørstad
Keyword(s):  
Genetic Variation ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Morphological Characteristics ◽  
Genetic Data ◽  
Small Population ◽  
The Body ◽  
Black Spots ◽  
Brown Trout Salmo Trutta ◽  
Biochemical Genetic

Initial studies on a small population of brown trout (Salmo trutta) in the Hardangervidda area in Norway revealed specimens with remarkable morphological characteristics. About one third of the population was classified as "fine-spotted trout" due to the occurrence of small black spots on the body and fins. These individuals also have from four to seven black spots located around the pupil of the eye. Genetic data, obtained by electrophoresis of tissue enzymes, demonstrated large differences compared with other brown trout populations. According to the information available, the abundance of fine-spotted trout has decreased during the last eight decades, which focuses on the need for preservation of the population and its habitat.

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.

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