Fish Use of Estuarine Tidal Channels Enhanced with Large Woody Debris

Identification Information

Citation

Originator: South Slough National Estuarine Research Reserve and ABR, Inc.

Publish Date: October 2006

Online Link: None

BPA Project #:

Contact Information

Agency: Watershed Councils

Name: Jena L. Lemke

Job Position: Consultant

Telephone: 503.359.7525

E-Mail Address: jlemke@abrinc.com

Description

Abstract: In 2005 and 2006, fish use of tidal channel habitat enhanced with artificially placed large woody debris was investigated in the Winchester Creek Tidelands Restoration Area of South Slough National Estuarine Research Reserve. Large woody debris (LWD) in the form of mature Sitka spruce trees was intentionally placed in the study area to enhance rearing and foraging habitat for juvenile salmonids and other fish species in 2005. Soon after the placement of LWD in the estuary, a study was initiated to compare fish abundance and species composition in tidal channels enhanced with LWD to those without LWD using electrofishing techniques. Two tidal channels, which are tributaries to Winchester Creek, were chosen for the study. A control reach was established on Tom’s Creek with no LWD present in the reach, while a treatment reach was established on Dalton Creek containing two intentionally placed Sitka spruce trees. In 2006, sampling was conducted to monitor the control and treatment reaches over a longer time period in an effort to ensure juvenile salmonids were sampled if present in the study area. Additionally, sampling was conducted on the mainstem of Winchester Creek to determine if juvenile salmonids were utilizing habitat in the main channel exclusive of the tidal channels. Within the Winchester Creek study area, electrofishing passes were performed within a single reach of Dalton and Tom’s Creeks, while beach seining was performed within two adjacent reaches of Winchester Creek. Beach-seined reaches were located between the confluences of Dalton and Tom’s Creeks with Winchester Creek. Electrofishing and beach seine sampling occurred on two consecutive days in each of five sampling periods. While only a small number of salmonids were observed in the Winchester Creek study area, all of the salmonids observed in the tidal tributaries were found in the Dalton treatment reach which has been enhanced with the placement of large wood debris. No salmonids were observed in the Tom’s Creek control reach. All of the coho sampled in Dalton Creek were found under an old wood weir structure, not associated with the placed LWD. This may be due in part to the difficulty of sampling under the placed LWD, where branches and deep water limit the effectiveness of electrofishing techniques.

Purpose: The objective of this investigation was to determine fish use, abundance and species composition in locations around LWD placed in the Winchester Creek study area.

Time Period of Content: February - June 2006

Geographic Extent: Dalton Creek, Tom's Creek, Winchester Creek - Coos Watershed

Status: Final

Use Constraints:

Format: PDF

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