Lake spawning of brown trout related to groundwater influx

Authors

  • Å. Brabrand,

    Corresponding author
    1. Freshwater Ecology and Inland Fisheries Laboratory (LFI), Natural History Museums and Botanical Garden, University of Oslo, Box 1172 Blindern, 0318 Oslo, Norway
      Author to whom correspondence should be addressed. Tel.: + 47 22 85 17 29; fax: +47 22 85 18 37; email: age.brabrand@nhm.uio.no
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  • A. G. Koestler,

    1. Geo-Recon A.S., Munkedamsveien 67, 0270 Oslo, Norway
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  • R. Borgstrøm

    1. Department of Biology and Nature Conservation, Agricultural University of Norway, Box 5014, N-1432-Ås, Norway
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Author to whom correspondence should be addressed. Tel.: + 47 22 85 17 29; fax: +47 22 85 18 37; email: age.brabrand@nhm.uio.no

Abstract

Seepage water through a lake bottom and the layering of tight and high-permeable layers in the aquifer produce groundwater under greater pressure than the water column of the lake. This results in under-water springs and seepages. When spawning substrata were available, there was a spatial correlation between the degree of groundwater influx and the redd density of brown trout Salmo trutta. In high density spawning areas with > 100 observed redds ha−1, the mean seepage water influx during spring was c. 1200 ml m−2 min−1 compared to a mean flux of 113 ml m−2 min−1 in low density spawning areas with 5–10 redds ha−1.

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