Mapping floodplain fish habitat in the heart of the Fraser River and restoration options for impacted attributes on selected large mid-channel islands

Bartsch, Lori Susan (author)
Ashley, Ken (thesis advisor)
Ransome, Douglas
Owen, Susan
Simon Fraser University Faculty of Environment (Degree granting institution)

Dissertation/thesis

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© Lori Susan Bartsch, 2019. All rights reserved. No part of this work covered by the copyright heron may be reproduced or used in any form or by any means - graphics, electronic, or mechanical including photocopying, taping, or information storage and retrieval systems - without written permission of the author.

British Columbia Institute of Technology

2019-04-12

96 pages

The purpose of this project is to develop an ecological restoration plan for degraded habitats on mid-channel islands in the lower Fraser River. The study focuses on Herrling, Carey, and Strawberry islands, large mid-channel islands located in the gravel reach between Mission and Hope, British Columbia. These islands are known to be critical off-channel rearing habitat for many fish species including the threatened White Sturgeon (Acipenser transmontanus) and interior and lower Fraser watershed Chinook Salmon (Oncorhynchus tshawytscha) populations. These islands are also home to many riparian plant and animal species. The flood-pulse concept (FPC) states that seasonal fluctuations in water levels for streams such as the Fraser River contribute substantially to the ecological function of the floodplain ecosystem where this phenomenon occurs. This often results in improved growth and survival rates for fish species that rely on a laterally-moving littoral zone of inundation. This phenomenon is thought by many to be the key to a properly functioning ecosystem in the lower Fraser River. Using a Digital Elevation Model (DEM) for the Fraser River between Hope and Mission, British Columbia, freshet flows (high water elevations) are presented to define the spatial extent of over-bank watering of Strawberry, Carey and Herrling islands. This over-bank watering provides lateral connectivity to floodplain islands. Based on extensive sampling in other studies, this lateral movement results in the creation of high-quality juvenile fish rearing habitat. A restoration plan is presented for those areas of Strawberry, Carey and Herrling islands degraded by recent land clearing for agriculture where they overlap sections defined as fish habitat from the spatial analysis.

gravel reach
mid-channel islands
floodplain fish habitat
flood pulse concept
juvenile Chinook Salmon
lower Fraser River
White Sturgeon

Fish habitat
Chinook salmon
Fraser River (B.C.)
White sturgeon

electronic

Master of Science