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Variability of Mesohabitat Used by Brown Trout Populations in the French Central Pyrenees
Author(s) -
Baran P.,
Delacoste M.,
Lascaux J. M.
Publication year - 1997
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1997)126<0747:vomubb>2.3.co;2
Subject(s) - brown trout , salmo , intraspecific competition , trout , habitat , biology , ecology , fishery , geography , fish <actinopterygii>
The variability of mesohabitat used by populations of brown trout Salmo trutta was studied in seven rivers of the central Pyrenees, France. Physical habitat preferences of individuals, intraspecific competition, season, and diversity of adjacent channel unit segments explained the trout density variation among different types of mesohabitat. Total trout density, size‐class densities, and redd densities differed significantly among mesohabitats and 18 subgroups of a hierarchical classification. The total density followed a gradient from deep channel morphodynamic units to shallow rapids including step channel, glides, riffles, and cascades. The different size‐classes of trout expressed a strong spatial segregation between fry and adult stages. Fry were more often found in riffles and glides, whereas adults concentrated in deep habitats. During the reproduction period, the highest redd densities were observed in glides and riffles. The density of trout in deep mesohabitat increased in relation to the diversity of mesohabitat type and the percentage of riffles in the adjacent segment. These results clearly showed the importance of the diversity of hydrodynamic conditions for the life cycle of brown trout in mountain streams.