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Influence of environmental factors on the density and biomass of stocked brown trout, Salmo trutta L., parr in brooks affected by intensive forestry
Author(s) -
JUTILA E.,
AHVONEN A.,
LAAMANEN M.
Publication year - 1999
Publication title -
fisheries management and ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 55
eISSN - 1365-2400
pISSN - 0969-997X
DOI - 10.1046/j.1365-2400.1999.00149.x
Subject(s) - brown trout , salmo , stocking , biomass (ecology) , trout , benthic zone , fishery , forestry , habitat , abundance (ecology) , standing crop , environmental science , population density , population , ecology , biology , geography , fish <actinopterygii> , demography , sociology
The influence of environmental factors on the density and biomass of stocked brown trout, Salmo trutta L., parr was studied in brooks subjected to intensive forestry in the Isojoki river basin, western Finland. Multivariate regression analysis showed that 69% of the variation in the population density of parr was determined by five variables: (1) mean water depth; (2) the abundance of pools; (3) stony bottom substrates with stones sized between 2 and < 10 cm in diameter; (4) undercut banks; and (5) the percentage of shading by trees. Correspondingly, 57% of the variation in the biomass of parr was determined by three variables: (1) mean water depth; (2) the abundance of pools; and (3) benthic vegetation. Dredging of the brooks and forest ditching had the most harmful consequences for the nursery habitats of brown trout parr. Measures for the rehabilitation of brown trout production in these brooks are discussed.