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Title: Habitat use by native and stocked trout (Salmo trutta L.) in two northeast streams, Portugal
Authors: Teixeira, Amílcar
Cortes, R.
Oliveira, Daniel
Keywords: Salmo trutta
Preference curves
Issue Date: 2006
Publisher: ONEMA - Office National de L’eau et des Milieux Aquatiques
Citation: Teixeira, Amílcar; Cortes, Rui; Oliveira, Daniel (2006) - Habitat use by native and stocked trout (Salmo trutta L.) in two northeast streams, Portugal. Bulletin Français de la Pêche et de la Pisciculture. ISSN 1297-6318. 382 (2006) p. 1-18
Abstract: Habitat use by stocked and native brown trout (Salmo trutta L.) was assessed in two headwater streams of northeastern Portugal. Underwater observations were made during the summer season in three successive years to evaluate the effect of supplemental trout stocking. Multivariate analysis techniques applied to microhabitat use data sets were used to identify the focal elevation (distance of fish from the bottom), total depth and cover as the variables that contribute most to the discrimination between stocked and native trout. Preference curves computed for native and stocked trout of the same age (1+), showed a distinct pattern in their ability to explore the available microhabitat resources. Stocked trout tended to occupy deeper pools (total depth > 100 cm vs. 60-100 cm for native trout), holding higher focal elevations (140-160 cm vs. < 20 cm for native) with lower water column velocities (< 10 cm.s-1 vs. 10-20 cm.s-1 for native) and no specific preference for cover. In contrast, native trout displayed a clear preference for microhabitats with coarse substrate (particle size > 22.5 cm) and cover (combination of boulders and overhanging vegetation or undercut banks). Furthermore, a high post-stocking movement of 80 % hatchery-reared fish was verified just one month after their release, suggesting that stocking did not contribute to the sustainable populations in either stream, and is far from being an adequate management technique.
ISSN: 1297-6318
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Appears in Collections:ARN - Artigos em Revistas Indexados ao ISI/Scopus

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