The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification

Needham, R. J., Gaywood, M., Tree, A., Sotherton, N., Roberts, D., Bean, C. W. and Kemp, P. S. (2021) The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification. Canadian Journal of Fisheries and Aquatic Sciences, 78(11), pp. 1650-1660. (doi: 10.1139/cjfas-2021-0023)

Abstract

Globally, freshwaters are the most degraded and threatened of all ecosystems. In northern temperate regions, beaver (Castor spp.) reintroductions are increasingly used as a low-cost and self-sustaining means to restore river corridors. River modifications by beavers can increase availability of suitable habitat for fish, including salmonids. This study investigated the response of a population of brown trout (Salmo trutta) to reintroduced Eurasian beaver (Castor fiber) habitat modifications in northern Scotland. The field site comprised two streams entering a common loch; one modified by beavers, the other unaltered. Electrofishing and PIT telemetry surveys indicated abundance of post-young-of-the-year (post-YOY) trout was higher in the modified stream. Considering juvenile year groups (YOY and post-YOY) combined, abundance and density varied with year and season. In the modified stream, fork length and mass were greater, there was a greater variety of age classes, and mean growth was positive during all seasons. Beavers had profound effects on the local brown trout population that promoted higher abundances of larger size classes. This study provides important insight into the possible future effect of beavers on freshwater ecosystems.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Bean, Professor Colin
• Authors: Needham, R. J., Gaywood, M., Tree, A., Sotherton, N., Roberts, D., Bean, C. W., and Kemp, P. S.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Canadian Journal of Fisheries and Aquatic Sciences
• Publisher: NRC Research Press
• ISSN: 0706-652X
• ISSN (Online): 1205-7533
• Published Online: 06 October 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Canadian Journal of Fisheries and Aquatic Sciences 78(11): 1650-1660
• Publisher Policy: Reproduced under a Creative Commons licence