Effects of Dredging and In-water Disposal of Dredged Materials on Sturgeon Movements and Behavior

The Problem

The navigation channel in the lower Columbia River must be maintained through periodic dredging. This study will provide information to determine if these dredging activities influence the behavior of sturgeon and if the disposal of dredged materials will affect available habitat for sturgeon. In performing this research, the USGS will improve existing methodologies for analyzing fish movements in riverine environments.

Objectives

A white sturgeon from the Columbia River.

The goal of this research is to determine the effects of in-water disposal of dredged materials on behavior related to habitat and resource use by white sturgeon (Acipenser transmontanus) and green sturgeon (A. medirostris). Studies will be done to 1) describe how juvenile and adult sturgeon use the aquatic habitat within proposed deepwater disposal areas, 2) describe how sturgeon movement patterns are affected by dredging operations, and 3) assess how continued use of a deepwater disposal site may affect lower Columbia River sturgeon populations.

Methodology

Acoustic telemetry is used to monitor fish movements. The analysis of individual fish positions over time will show if site fidelity or home ranges of juvenile and adult sturgeon include or are restricted to deepwater areas that may be affected by dredge material disposal. To obtain this information, individual fish are captured, fitted with an acoustic transmitter, and released back into the river. A stationary array

Conceptualization of a radio-acoustic position system.

of buoyed hydrophones enables the determination of fish positions in three dimensions at very short time intervals. The acoustic information received by each buoy is relayed via radio modem to a receiver station located on shore. Here, individual fish positions are derived from the acoustic signals and automatically plotted on a base map. Information on fish movements within the hydrophone array is recorded continuously, and a series of data-logging receivers placed outside the array record fish egress from the study area. Sturgeon movements are analyzed and displayed within a geographic information system.

Highlights and Key Findings

The U.S. Army Corps of Engineers began funding this project in 2001. After a series of range tests were conducted, a wireless acoustic-radio positioning system was purchased and deployed in August 2002 along with seven acoustic data logging receivers that function as gates to monitor egress from the study area. Nineteen white sturgeon were fitted with acoustic transmitters in August 2002. The system has been recording fish positions which will be used to describe their movements and behavior.

Where Are We Headed In 2003

Approaching a radio-acoustic buoy. A dredge is operating in the background.

We will continue to operate and maintain the acoustic positioning system and the data loggers. Fish movements within the hydrophone array will be logged continuously throughout the year. Additional fish will be captured and outfitted with acoustic transmitters throughout the year. To determine how sturgeon react to dredging operations, the U.S. Army Corps of Engineers will direct a loaded hopper dredge to offload its cargo of dredged material within the hydrophone array. Continuous monitoring of fish movements will enable us to determine how fish react to this activity.

Project Contact

Michael J. Parsley
U.S. Geological Survey
Western Fisheries Research Center
Columbia River Research Laboratory
5501-A Cook-Underwood Rd.
Cook, WA 98605-9717

Email: mike_parsley@usgs.gov
Phone: 509-538-2299
Fax: 509-538-2843

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