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Restoration of streams used for timber floating

egg to fry survival, fry displacement, over-wintering and population density of juvenile brown trout (Salmo trutta L.)

Palm, Daniel (2007). Restoration of streams used for timber floating. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., ; 120
ISBN 1652-6880
[Doctoral thesis]

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Abstract

The construction of floatways during the 19th and 20th century profoundly changed the habitat conditions for fish and other aquatic organisms in lotic environments. Increased mortality during early life stages, reduced habitat quality and availability probably had large negative consequences for populations of salmonids. As timber floating ended during the 1970’s, restoration programs were initiated that aimed to reverse the damage caused by floatway activities and to increase the production of salmonids. We predicted that restoration would have positive effects on egg to fry survival, fry displacement, over-wintering and population density of juvenile brown trout and on fish species diversity. To test these predictions, I conducted studies in restored (treatment) and unrestored (control) reaches in tributaries to the rivers Ume-, Vindel, Pite- and Kalixälven in northern Sweden. Egg-to-fry survival was approximately six times higher in restored (10.3%) compared to unrestored (1.7%) gravel beds. Displacement of newly emerged fry was reduced from 10.1% to 2.3% and first summer recruitment increased approximately three fold (from 0.2‰ to 0.6‰) following habitat restoration. Trout density increased significantly (>360%) in restored stream reaches whereas no change was evident in unrestored control reaches during a period of eleven years. Tracking of PIT-tagged individuals revealed that brown trout managed to over-winter within a restored stream. Minimum habitat suitability index explained a large portion (66.8 %) of the variation in the proportion of individuals that over wintered within different stream reaches. Although more fish species were caught in restored reaches, restoration did not result in significantly higher fish species diversity. These results show that restoration of streams utilized for timber floating can be an efficient method to enhance and conserve populations of trout and salmon. However, success of restoration relies on good knowledge about other species occurring in the system and their ecology. For instance, using wrong substrate sizes during restoration of spawning habitat can result in increased rates of egg predation by benthic predators. As brown trout utilize a variety of different environments during their lifecycle, including streams, lakes and sea, maximal response to habitat restoration will not be achieved as long as other factors, i.e. migration barriers and over exploitation, also constrain populations.

Authors/Creators:Palm, Daniel
Title:Restoration of streams used for timber floating
Subtitle:egg to fry survival, fry displacement, over-wintering and population density of juvenile brown trout (Salmo trutta L.)
Year of publishing :2007
Volume:120
Number of Pages:33
Papers/manuscripts:
NumberReferences
ALLI. Nilsson, C., Lepori, F., Malmqvist, B., Törnlund, E., Helfield, J.M., Palm, D., Östergren, J., Jansson, R., Brännäs, E., and Lundqvist, H. 2005. Forecasting environmental responses to restoration of rivers used as log floatways: an interdisciplinary challenge. Ecosystems 8, 779-800. II. Palm, D., Brännäs, E., Lepori, F., Nilsson, K., and Stridsman, S. 2007. The influence of spawning habitat restoration on the density of juvenile brown trout (Salmo trutta L.). Canadian Journal of Fisheries and Aquatic Sciences 64: 509-515. III. Palm, D., Brännäs, E. Östergren, J., Lindberg, M., and Lundqvist, H. The influence of bullhead (Cottus gobio L.) on Atlantic salmon (Salmo salar L.) recruitment – implications for spawning habitat restoration. Manuscript. IV. Palm, D., Lepori, F., and Brännäs, E. Post-emergence displacement of brown trout Salmo trutta L., fry in a northern Swedish stream: influence of habitat restoration. Manuscript. V. Palm, D., Brännäs, E. and Nilsson, K. Over-winter migration strategies of juvenile brown trout (Salmo trutta L.) in a restored ice-covered stream: influence of habitat suitability. Manuscript. VI. Lepori, F., Palm, D., Brännäs, E., and Malmqvist, B. 2005. Does restoration of structural heterogeneity enhance the diversity of fish and macroinvertebrates? Ecological Applications 15, 2060-2071.
Place of Publication:Umeå
ISBN for printed version:1652-6880
ISSN:978-91-85913-19-0
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:salmo trutta, trout, rivers, timber floating, habitat improvement, population density, survival, sweden
Keywords:channelization, log driving, salmonids, substrate, incubation, ice, habitat enhancement, migration, PIT-tag, spawning, habitat suitability, electrofishing, predation, recruitment, species diversity, habitat heterogeneity
URN:NBN:urn:nbn:se:slu:epsilon-1939
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-1939
ID Code:1649
Department:(S) > Dept. of Wildlife, Fish and Environmental Studies
Deposited By: Daniel Palm
Deposited On:04 Dec 2007 00:00
Metadata Last Modified:02 Dec 2014 10:13

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