Microrépartition des populations de truite commune (Salmo truttaL.) de juvenile de saumon atlantique (Salmo salarL.) et des autres espès préntes dans la partie haute du Scorff (Bretagne)
✍ Scribed by J. L. Bagliniere; D. Arribe-Moutounet
- Book ID
- 104621443
- Publisher
- Springer
- Year
- 1985
- Tongue
- English
- Weight
- 856 KB
- Volume
- 120
- Category
- Article
- ISSN
- 1573-5141
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✦ Synopsis
We describe the microdistribution of populations of Brown Trout (Salmo trutta L.) and ofjuvenile atlantic Salmon (Salmo salar L.) in the upstream part of the Scorff river (Brittany) at the end of summer.
The Salmon population was composed of one age classe (O+) only while Trout age varied from O+ to 3+ years, with a majority in age class I +. Salmon density increased with current velocity(r = 0.99) and the nature of the substratum. A very favorable habitat for this species was characterized by reduced depth (< 23 cm), a high current velocity(61 cm s r) and a stony substrate. The largest part ofthe population(74%) was localized in the centre of the running open water.
A bank effect was particularly important for brown trout, irrespective of age (80.1%). The trout O+ is absent from shallow rifles and its presence in the few deep running water areas (41 cm s-r) along the banks involved a spatial segregation with salmon Of. The trout of one year and older were localized in deeper habitats (27 cm) with zero to medium current velocity (< 28 cm s-1). The bank effect was intensified by the presence of many overhangs along the bank.
Among the secondary species, sculpin had the widest distribution, but Stone-loach and brook lamprey were the most abundant species and reached high densities in characteristic areas.
tous les types d'habitat pourvu que ceux-ci comportent un certain nombre de caches et d'abris.
Cependant, ces resultats sont obtenus sur des secteurs isolts representatifs d'un type d'habitat. Bagliniere& Champigneulle( 1982) considtrent que la distribution de la truite commune et du juvenile de saumon atlantique doit &tre ttudiee sur un secteur oti tous les types d'habitat peuvent Ctre rencontres.
Ainsi une telle etude est rtaliste avec par ailleurs une analyse plus fine des caracteristiques du milieu permettant de dtfinir une microrepartition automnale de la population de salmonides associte a celle des autres especes prtsentes sur la partie haute du Scorff. Hydrobiologia 120, 229-239 (1985).