Visual isolation, habitat complexity, and the density of stream salmonids
The effect of visual isolation on the density of territorial fish such as Atlantic salmon ( Salmo salar ) was examined. Kalleberg's (1958) hypothesis that the density of salmon can be increased by adding boulders was tested for the first time in a natural stream. Eight study reaches were establ...
Main Author: | |
---|---|
Format: | Thesis |
Language: | English |
Published: |
2004
|
Subjects: | |
Online Access: | https://spectrum.library.concordia.ca/id/eprint/8339/ https://spectrum.library.concordia.ca/id/eprint/8339/1/MR04339.pdf |
id |
ftconcordiauniv:oai:https://spectrum.library.concordia.ca:8339 |
---|---|
record_format |
openpolar |
spelling |
ftconcordiauniv:oai:https://spectrum.library.concordia.ca:8339 2023-05-15T15:32:43+02:00 Visual isolation, habitat complexity, and the density of stream salmonids Dolinsek, Ivan J 2004 text https://spectrum.library.concordia.ca/id/eprint/8339/ https://spectrum.library.concordia.ca/id/eprint/8339/1/MR04339.pdf en eng https://spectrum.library.concordia.ca/id/eprint/8339/1/MR04339.pdf Dolinsek, Ivan J (2004) Visual isolation, habitat complexity, and the density of stream salmonids. Masters thesis, Concordia University. Thesis NonPeerReviewed 2004 ftconcordiauniv 2022-05-28T18:57:58Z The effect of visual isolation on the density of territorial fish such as Atlantic salmon ( Salmo salar ) was examined. Kalleberg's (1958) hypothesis that the density of salmon can be increased by adding boulders was tested for the first time in a natural stream. Eight study reaches were established in Catamaran Brook and the Little Southwest Miramichi River (New Brunswick). Each reach was divided into three sites of 3 x 2 m, and received one of three treatments: boulder-added, 36 boulders (median diameter = 0.21 m) were added to increase visual isolation; boulder-removed, where all boulders were removed; and a control, where the reach was left unchanged. A three-fold increase in the density of salmon was observed in the boulder-added treatment compared to the boulder-removed and control sites. The impact of adding boulders was more important for the young-of-the-year than for the 1+ and 2+ salmon. However, for non-salmonid fishes, no effect was found. A Geographic Information System (GIS) viewshed analysis showed that the visible area and the distance to nearest neighbour were significantly smaller in the boulder-added treatment than in the other two treatments. Although mean water velocity was reduced in the boulder-added treatments, the snout velocity of individual salmon did not differ among treatments, suggesting that the boulders were not used as a velocity refuge. The results support Kalleberg's hypothesis that visual isolation is a key factor controlling salmon density, and that it might be used as a low-cost method for increasing the density of territorial fish. Thesis Atlantic salmon Salmo salar Spectrum: Concordia University Research Repository (Montreal) |
institution |
Open Polar |
collection |
Spectrum: Concordia University Research Repository (Montreal) |
op_collection_id |
ftconcordiauniv |
language |
English |
description |
The effect of visual isolation on the density of territorial fish such as Atlantic salmon ( Salmo salar ) was examined. Kalleberg's (1958) hypothesis that the density of salmon can be increased by adding boulders was tested for the first time in a natural stream. Eight study reaches were established in Catamaran Brook and the Little Southwest Miramichi River (New Brunswick). Each reach was divided into three sites of 3 x 2 m, and received one of three treatments: boulder-added, 36 boulders (median diameter = 0.21 m) were added to increase visual isolation; boulder-removed, where all boulders were removed; and a control, where the reach was left unchanged. A three-fold increase in the density of salmon was observed in the boulder-added treatment compared to the boulder-removed and control sites. The impact of adding boulders was more important for the young-of-the-year than for the 1+ and 2+ salmon. However, for non-salmonid fishes, no effect was found. A Geographic Information System (GIS) viewshed analysis showed that the visible area and the distance to nearest neighbour were significantly smaller in the boulder-added treatment than in the other two treatments. Although mean water velocity was reduced in the boulder-added treatments, the snout velocity of individual salmon did not differ among treatments, suggesting that the boulders were not used as a velocity refuge. The results support Kalleberg's hypothesis that visual isolation is a key factor controlling salmon density, and that it might be used as a low-cost method for increasing the density of territorial fish. |
format |
Thesis |
author |
Dolinsek, Ivan J |
spellingShingle |
Dolinsek, Ivan J Visual isolation, habitat complexity, and the density of stream salmonids |
author_facet |
Dolinsek, Ivan J |
author_sort |
Dolinsek, Ivan J |
title |
Visual isolation, habitat complexity, and the density of stream salmonids |
title_short |
Visual isolation, habitat complexity, and the density of stream salmonids |
title_full |
Visual isolation, habitat complexity, and the density of stream salmonids |
title_fullStr |
Visual isolation, habitat complexity, and the density of stream salmonids |
title_full_unstemmed |
Visual isolation, habitat complexity, and the density of stream salmonids |
title_sort |
visual isolation, habitat complexity, and the density of stream salmonids |
publishDate |
2004 |
url |
https://spectrum.library.concordia.ca/id/eprint/8339/ https://spectrum.library.concordia.ca/id/eprint/8339/1/MR04339.pdf |
genre |
Atlantic salmon Salmo salar |
genre_facet |
Atlantic salmon Salmo salar |
op_relation |
https://spectrum.library.concordia.ca/id/eprint/8339/1/MR04339.pdf Dolinsek, Ivan J (2004) Visual isolation, habitat complexity, and the density of stream salmonids. Masters thesis, Concordia University. |
_version_ |
1766363207820115968 |