Research Activities                              Go Back!

Laboratory:
Danish Institute for Fisheries Research, Department of Inland Fisheries, Denmark.
Contact person (name and e-mail):
Michael M. Hansen, mmh@dfu.min.dk
Persons working on brown trout population genetics:
Hanne Jørgensen, Siri Østergaard (M.Sc. students), Karen-Lise Mensberg, Dorte Meldrup (technicians), NN, Einar Eg Nielsen, Michael M. Hansen (scientists).
General research topics of the laboratory:
Conservation and management, genetic population structure, phylogeography, reproduction biology.
General description of research on brown trout population genetics:
A large part of the research at the laboratory is aimed at brown trout. The most important topic is conservation and management, in particular in relation to stocking activity and genetic interactions between wild and hatchery trout. Studies of genetic population structure and, to some extend phylogeography, are also important. Recently, we have initiated studies aimed at assessing the parentage of offspring and relatedness among individuals in trout populations, and we plan to do further work at the interphase between behavioral ecology and population genetics.

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List of projects (brown trout) for the past 3 years:

 

Study #1
Researcher: Siri Østergaard (M.Sc. student), Michael M. Hansen (co-supervisor).
Collaborators: Volker Loeschcke, Dept. of Ecology and Genetics, University of Aarhus (supervisor).
Source of project funding: In house.
Topic: Genetic population structure, temporal variation, gene flow, isolation by distance, metapopulation structure.
Objective: To study patterns of extinction and recolonisation in brown trout in a very unstable environment (rivers suffering from frequent dessiccations).
Design: Genetic structure and composition of populations is studied over time. This involves analysis of DNA from old scale samples, as well as from recent samples. The consequences of different metapopulation models are studied by computer simulations.
Methodology: Microsatellites, computer simulations.
Trout population: Anadromous populations.
Origin of samples: Bornholm Island, Denmark, Baltic Sea Basin.
Status: Started 1997, going to be finished in 1999.

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Study #2
Researcher: Hanne Jørgensen (M.Sc. student), Michael M. Hansen (co-supervisor).
Collaborators: Volker Loeschcke, Dept. of Ecology and Genetics, University of Aarhus (supervisor).
Source of project funding: In house.
Topic: Conservation and management, fluctuating assymmetry.
Objective: To study relationship between fluctuating assymmetry and population sizes and homozygosity (as detected by microsatellite analysis).
Design: Fluctuating assymmetry in metric and meristic traits and genetic variation at microsatellite loci is studied in three different trout populations, a small, dammed population, a large population accessible to gene flow and offspring of wild trout, reared in a hatchery.
Methodology: Microsatellites, measurement of meristic and metric traits.
Trout population: Resident and anadromous populations.
Origin of samples: Denmark, Karup River system, North Sea Basin.
Status: Started 1997, going to be finished in 1998.

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Study #3
Researcher: Einar Eg Nielsen, Michael M. Hansen
Source of project funding: In house.
Topic: Conservation and management, reproduction biology, estimation of mating structure, mating preferences etc.
Objective: To estimate mating preferences, variance in reproductive success among individuals and effective population size in a trout population (in one spawning season).
Design: All ascending spawners are caught in a trap, tissue samples are taken and the spawners are released to spawn. Later on samples are taken from all spawning redds. Offspring are assigned to parent fish based on analysis of microsatellites and mtDNA.
Methodology: MtDNA RFLP, microsatellites.
Trout population: Anadromous population.
Origin of samples: Denmark, the Skibelund River, North Sea Basin.
Status: Started 1996, going to be finished in 1998.

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Study #4
Researcher: Michael M. Hansen, Einar Eg Nielsen
Source of project funding: In house.
Topic: Conservation and management, stocking effects and efficiency, genetic monitoring, genetic population structure, gene flow, isolation by distance, temporal variation, phylogeography.
Objective: To study genetic differentiation and variation in Danish wild brown trout populations and hatchery strains and to estimate the stocked or wild origin of populations.
Design: Various wild and hatchery populations are screened using relevant molecular techniques.
Methodology: Microsatellites, mtDNA RFLP.
Trout population: Hatchery stocks, anadromous and resident populations.
Origin of samples: Various rivers and hatcheries in Denmark, North Sea and Baltic Sea Basin.
Status: Started 1992, ongoing.

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Study #5
Researcher: NN, Michael M. Hansen
Source of project funding: The Danish Rod License Funds.
Topic: Mixed-stock analysis, conservation and management, stocking efficiency, temporal variation.
Objective: To study the contribution of different wild and hatchery populations to the fisheries in a marine environment (the Limfjord, Denmark).
Design: Populations in rivers of the study area and hatchery strains are sampled (baseline data). Samples are collected from angler- and net-caught trout from the Limfjord (mixed-stock samples).
Methodology: Microsatellites, mixed-stock analysis.
Trout population: Hatchery stocks, anadromous populations.
Origin of samples: Denmark, tributaries to the Limfjord, Denmark, relevant hatchery strains, North Sea Basin.
Status: Project period September 1998 – August 2000.

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Study #6
Researcher: Michael M. Hansen, Einar Eg Nielsen.
Source of project funding: In house.
Topic: Conservation and management, stocking effects and efficiency.
Objective: To study the impact of stocking hatchery trout into a wild population, with special regard to founder effects of stocked trout, differential survival and reproductive success of different families of hatchery trout, and mating preferences of adult wild and hatchery trout.
Design: A limited number of full-sib families of hatchery trout (coded wire tagged) have been stocked into a wild populations. Differential survival of families is studied by taking tissue samples from hatchery trout caught in the experimental river. Using microsatellite analysis individual trout can be assigned to family. When/if adult hatchery trout return to spawn, all ascending spawners will be caught in a trap, a tissue sample will be taken and later on the spawning redds will be sampled. Offspring will be assigned to parent fish based on analysis of microsatellites and mtDNA.
Methodology: Microsatellites, mtDNA RFLP.
Trout population: Hatchery stocks, anadromous populations.
Origin of samples: The Skibelund River, Denmark, North Sea Basin.
Status: Started 1996, ongoing. Hatchery trout were stocked in autumn 1997 at an age of 0.5 year.

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Publications (brown trout genetics)

Journal papers:

  • Hansen, M.M. & Loeschcke, V. (1994). Effects of releasing hatchery-reared brown trout to wild trout populations. In: (Loeschcke, V., Tomiuk, J. & Jain, S.K., eds.) Conservation Genetics, pp. 273-289. Birkhäuser Verlag, Basel.
  • Hansen, M.M. & Loeschcke, V. (1996). Genetic differentiation among Danish brown trout (Salmo trutta L.) populations, as detected by RFLP analysis of PCR amplified mitochondrial DNA segments. J. Fish Biol., 48, 422-436.
  • Hansen, M.M. & Loeschcke, V. (1996). Temporal variation in mitochondrial DNA haplotype frequencies in a brown trout (Salmo trutta L.) population that shows stability in nuclear allele frequencies. Evolution, 50, 454-457.
  • Hansen, M.M. & Mensberg, K.-L. D. (1996). Founder effects and genetic population structure of brown trout (Salmo trutta) in a Danish river system. Can. J. Fish. Aquat. Sci., 53, 2229-2237.
  • Hansen, M.M. & Mensberg, K.-L.D. (1998). Genetic differentiation and relationship between genetic and geographical distance in Danish sea trout (Salmo trutta L.) populations. Heredity, in press.
  • Hansen, M.M., Nielsen, E.E. & Mensberg, K.-L.D (1997). The problem of sampling families rather than populations: Relatedness among individuals in samples of juvenile brown trout (Salmo trutta L.). Mol. Ecol., 6, 469-474.
  • Hansen, M.M., Hynes, R.A., Loeschcke, V. & Rasmussen, G. (1995). Assessment of the stocked or wild origin of anadromous brown trout (Salmo trutta L.) in a Danish river system, using mitochondrial DNA RFLP analysis. Mol. Ecol., 4, 189-198.
  • Hansen, M.M., Loeschcke, V., Rasmussen, G. & Simonsen, V. (1993). Genetic differentiation among Danish brown trout (Salmo trutta L.) populations. Hereditas 118, 177-185.
  • Hansen, M.M., Mensberg, K.-L. D., Rasmussen, G. & Simonsen, V. (1997). Genetic variation within and among Danish brown trout (Salmo trutta L.) hatchery strains, assessed by PCR-RFLP analysis of mitochondrial DNA segments. Aquaculture, 153, 15-29.
  • Nielsen, E.E., Hansen, M.M. & Mensberg, K.-L.D. (1998) Improved primer sequences for the mitochondrial ND1, ND3/4 and ND5/6 segments in salmonid fishes. Application to RFLP analysis of Atlantic salmon. J. Fish Biol., in press.

Technical Reports:

  • Berg, S. & Hansen, M.M. (1997). Genetiske og økologiske anbefalinger for fiskeudsætninger i Danmark. (Genetical and ecological guidelines for fish stocking activity in Denmark). Publication from the Danish Ministry for Food, Agriculture and Fisheries. (In Danish).
  • Hansen, M.M. (1996). Grundlaget for fiskeudsætninger i Danmark. (The scientific basis for fish stocking activity in Denmark). DFU Rapport no. 28. (In Danish). Report from the Danish Institute for Fisheries Research.
  • Simonsen, V. & Rasmussen, G. (1989). Undersøgelse af genetisk variation hos ørred (Salmo trutta) som funktion af tid og dambrug. (Allozyme variation in Danish brown trout hatchery strains). DFH Rapport no. 367. (In Danish). Report from the Danish Institute for Fisheries Research.

Theses (eg, PhD and MSc theses):

  • Hansen, M.M. (1994). Genetic differentiation among Danish brown trout (Salmo trutta) populations and interactions between wild and hatchery-reared trout. Ph.D. thesis. University of Aarhus, Dept. of Ecology and Genetics.
  • Landbo, L. & Persson, B. (1987). Genetisk variation hos ørreden (Salmo trutta) i Limfjordsområdet. (Genetic variation in brown trout in the Limfjord area). M.Sc. thesis. University of Copenhagen, Institute of Population Biology. (In Danish).
  • Nielsen, E.E. (1997). Genetic structure of salmonid fish populations. Ph.D. thesis. University of Aarhus, Dept. of Ecology and Genetics.

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