A comparative study of juvenile salmon density in 20 streams throughout a very large river system in northern Norway

Authors: Johansen, M.¹; Elliott, J. M.²; Klemetsen, A.¹

Source: Ecology of Freshwater Fish, Volume 14, Number 1, March 2005 , pp. 96-110(15)

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Abstract:

Johansen M, Elliott JM, Klemetsen A. A comparative study of juvenile salmon density in 20 streams throughout a very large river system in northern Norway.

Ecology of Freshwater Fish 2005. © Blackwell Munksgaard, 2005 Abstract –

The objective was to compare juvenile salmon density in 20 streams throughout the very large River Tana, northern Norway, and to relate variation in density to a suite of environmental factors. Four sampling sites were electrofished in each stream (one at the mouth of the stream and three within the stream) in August and October 2000, 2001, 2002. 0+ salmon parr were absent from seven streams, present at the mouth of 11 streams, and present within only two streams, both of which were probably spawning streams. Older parr migrated upstream into most streams and their highest densities were usually found in streams flowing directly into the spawning habitat in the three largest tributaries of the Tana or the river itself. Juvenile salmon were sparse or absent in streams flowing into smaller tributaries. Most streams with high parr densities were those of dense riparian vegetation that provided terrestrial invertebrates as drift food for the salmon parr, cover for fish, cooler stream temperatures in summer, and food for benthic stream invertebrates that were also a source of food for the parr.

Keywords: fish density; habitat; juvenile fish; Salmo salar; streams

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1600-0633.2004.00082.x

Affiliations: 1: Norwegian College of Fishery Science, University of Tromsø, Tromsø, Norway 2: Freshwater Biological Association, Far Sawrey, Ambleside, Cumbria, UK

Publication date: 2005-03-01