Genetic monitoring of supportive breeding in brown trout (Salmo trutta L.), using microsatellite DNA markers

2000 ◽  
Vol 57 (10) ◽  
pp. 2130-2139 ◽  
Author(s):  
Michael M Hansen ◽  
Einar E Nielsen ◽  
Daniel E Ruzzante ◽  
Carmen Bouza ◽  
Karen-Lise D Mensberg
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Allelic Diversity ◽  
Reference Population ◽  
Randomization Test ◽  
Population Bottlenecks ◽  
Effective Population ◽  
Supportive Breeding ◽  
Statistical Procedures ◽  
Brown Trout Salmo Trutta

Stocking with offspring of local wild fish, so-called supportive breeding, is often advocated as an alternative to stocking domesticated fish. However, it is important to ensure that supportive breeding does not result in inbreeding and loss of genetic variability. We analysed eight microsatellite loci in samples of wild and hatchery-reared brown trout (Salmo trutta) from three populations subject to supportive breeding. For calibrating statistical procedures, we included two test samples of reared offspring for which the precise number of parent fish was known and a sample from a further wild reference population. Three different statistical procedures were used to detect population bottlenecks and loss of variability: (i) a randomization test for comparing allelic diversity between samples; (ii) estimates of effective number of breeders from gametic-phase disequilibrium; and (iii) a test for assessing population bottlenecks based on detecting deviations from mutation-drift equilibrium. All three procedures were useful but they also exhibited different strengths and limitations, with the test for population bottlenecks probably being the single most useful procedure for routine monitoring. In two populations subject to supportive breeding, there were strong indications of reduced effective population sizes, and significant genetic differentiation was observed between different samples from the same population.

Spatial and temporal genetic differentiation and effective population size of brown trout (Salmo trutta, L.) in small Danish rivers

2005 ◽  
Vol 6 (4) ◽  
pp. 615-621 ◽  
Author(s):  
Lasse F. Jensen ◽  
Michael M. Hansen ◽  
Jens Carlsson ◽  
Volker Loeschcke ◽  
Karen-Lise D. Mensberg
Keyword(s):  
Genetic Differentiation ◽  
Population Size ◽  
Effective Population Size ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Effective Population ◽  
Brown Trout Salmo Trutta

scholarly journals Long-term monitoring of a brown trout (Salmo trutta) population reveals kin-associated migration patterns and contributions by resident trout to the anadromous run

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Eloïse Duval ◽  
Øystein Skaala ◽  
María Quintela ◽  
Geir Dahle ◽  
Aurélien Delaval ◽  
...  
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Anthropogenic Pressure ◽  
Parentage Assignment ◽  
Effective Population ◽  
Migration Timing ◽  
Brown Trout Salmo Trutta ◽  
And Migration

Abstract Background In species showing partial migration, as is the case for many salmonid fishes, it is important to assess how anthropogenic pressure experienced by migrating individuals affects the total population. We focused on brown trout (Salmo trutta) from the Guddal River in the Norwegian Hardanger Fjord system, which encompasses both resident and anadromous individuals. Aquaculture has led to increased anthropogenic pressure on brown trout during the marine phase in this region. Fish traps in the Guddal River allow for sampling all ascending anadromous spawners and descending smolts. We analyzed microsatellite DNA markers from all individuals ascending in 2006–2016, along with all emigrating smolts in 2017. We investigated (1) if there was evidence for declines in census numbers and effective population size during that period, (2) if there was association between kinship and migration timing in smolts and anadromous adults, and (3) to what extent resident trout were parents of outmigrating smolts. Results Census counts of anadromous spawners showed no evidence for a decline from 2006 to 2016, but were lower than in 2000–2005. Estimates of effective population size also showed no trends of declines during the study period. Sibship reconstruction of the 2017 smolt run showed significant association between kinship and migration timing, and a similar association was indicated in anadromous spawners. Parentage assignment of 2017 smolts with ascending anadromous trout as candidate parents, and assuming that unknown parents represented resident trout, showed that 70% of smolts had at least one resident parent and 24% had two resident parents. Conclusions The results bear evidence of a population that after an initial decline has stabilized at a lower number of anadromous spawners. The significant association between kinship and migration timing in smolts suggests that specific episodes of elevated mortality in the sea could disproportionally affect some families and reduce overall effective population size. Finally, the results based on parentage assignment demonstrate a strong buffering effect of resident trout in case of elevated marine mortality affecting anadromous trout, but also highlight that increased mortality of anadromous trout, most of which are females, may lower overall production in the system.

scholarly journals Genetic Diversity of Hatchery-Bred Brown Trout (Salmo trutta) Compared with the Wild Population: Potential Effects of Stocking on the Indigenous Gene Pool of a Norwegian Reservoir

Diversity ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 414
Author(s):  
Arne N. Linløkken ◽  
Stein I. Johnsen ◽  
Wenche Johansen
Keyword(s):  
Genetic Diversity ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Balancing Selection ◽  
Wild Fish ◽  
Effective Population ◽  
Population Potential ◽  
Brown Trout Salmo Trutta ◽  
Age Structured ◽  
Simple Sequence

This study was conducted in Lake Savalen in southeastern Norway, focusing on genetic diversity and the structure of hatchery-reared brown trout (Salmo trutta) as compared with wild fish in the lake and in two tributaries. The genetic analysis, based on eight simple sequence repeat (SSR) markers, showed that hatchery bred single cohorts and an age structured sample of stocked and recaptured fish were genetically distinctly different from each other and from the wild fish groups. The sample of recaptured fish showed the lowest estimated effective population size Ne = 8.4, and the highest proportion of siblings, despite its origin from five different cohorts of hatchery fish, counting in total 84 parent fish. Single hatchery cohorts, originating from 13–24 parental fish, showed Ne = 10.5–19.9, suggesting that the recaptured fish descended from a narrow group of parents. BayeScan analysis indicated balancing selection at several loci. Genetic indices of wild brown trout collected in the lake in 1991 and 2010 suggested temporal genetic stability, i.e., the genetic differentiation (FST) was non-significant, although the Ne, the number of alleles per locus and the number of private alleles were lower in the 2010 sample.

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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