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Project Overview

Background
Objectives
Cooperators
Associated Projects

Adult Salmon Research

Spawning Distribution
Redd Characteristics
Creel survey
Carcass Counts
Hatchery Counts

Juvenile Salmon Research

Distribution
Habitat Preference

Migration Research

Hydroacoustics
Migration Timing
Abundance

 


This project is providing important information about the wild production of Chinook salmon in the Salmon River.

Other projects conducted around the Basin by agencies, universites and other partners are documenting wild reproduction of salmon and trout, and providing managers with other scientific knowledge needed to effectively manage this highly-valued diverse fishery.

 

Natural Reproduction of Chinook Salmon in the Salmon River, NY


Research Activities and Results of 2004

Hydroacoustics uses sound to detect objects in water. Basically, it is like using a sophisticated fish finder. In a River situation,however, we turn the transducer sideways to look across the river, and track fish travelling through the sound pulse. Every second, at least 3 pings of sound are produced by the transducer. Objects in the water will reflect some of that sound back and the charactistics of the sound received is used to determine an objects size, direction and speed of travel.

Sound is measured in decibels. Scientists use the "target strength" of an object to estimate its size. Large objects will have a greater target strength than smaller objects. For example, Chinook salmon-sized fish have a target strength between -35 decibels (dB) and -15 dB. Small fish like a bass or perch may have target strengths between -45 and -35 dB.

 


To monitor adult migration, distribution, and timing in the Salmon River,

we installed a Simrad EY500 120 kHz split-beam hydroacoustic system at the Lighthouse Marina site, and recorded data continuously from September 6 until November 1, 2004. A 7-degree conical transducer was mounted on an aluminum pole, aimed horizontally across the river, and placed at a depth of 0.6 m. from the bottom. Data were downloaded daily from the site.

The Salmon River outlet

Preliminary analyses and results
We used Sonar5 software for post-processing and analysis of data (Balk and Lindem 2002). To determine diel and water column distribution of adult salmon, we originally planned to conduct snorkeling observations, but the turbidity of the river precluded this method. Instead, we used our sonar data to determine these distribution patterns. We selected data from September 15, 2004, in which 384 adult salmon-sized targets passed through the beam. Only targets with a mean target-strength (TSc) greater than –35 dB and a mean upstream velocity (mean Vx) greater than 0.1 m s-1 were counted (Figures 2a and 4). Data were stratified into six 4-hour periods, and three 1/2-hour samples were randomly selected and analyzed from each period. We are currently analyzing hydroacoustic data to estimate total adult salmon migration and timing to compare with data obtained by other methods.

 

 

Preliminary results show that average length of migrating salmon on September 15th was 63 cm, with fish ranging from 31 to 121 cm (Figure 2b)

 

Fish migrated significantly more at night (Figure 3), with migrating salmon totaling 368 at night compared to 16 fish during the day (t-test, p=0.009). .

Figure 3. Diel distribution of tracked migrating adult Chinook salmon in the Salmon River, New York, September 15, 2004


Fish tended to swim in the mid-water column, slightly below the transducer’s x-axis (mean Alo=-0.83o), equivalent to a mean depth of 2.3 meters (Figure 4).

Figure 4. Distribution of tracked migrating adult Chinook salmon relative the transducer in the Salmon River, New York, September 15, 2004.

Page last modified May 12, 2005

Project Cooperators

New York
Department of Environmental Conservation



Project funded by New York Sea Grant