Adult Chinook Migration Monitoring Using Dual Frequency Identification Sonar (DIDSON) 2016

This study used a mobile application of the ARIS 1200 sonar camera to observe and enumerate fish congregating in pools and thermal refugia areas in the Lower Klamath River from 25-Aug-2016 to 28-Sep-2016. The study objectives were to: 1) use a fish per area (ha) metric as an index for fish density and crowding, and 2) determine if fish were actively migrating through the lower river, or were being delayed and crowded into areas of the Lower Klamath River. Reconnaissance surveys conducted in August 2016 were used to identify 17 survey locations in the Lower Klamath River from Tectah Creek (river mile 18) to the mouth of the Klamath River. Initial criteria for selecting survey sites or transects were based on traditional and recreational fishing locations and known thermal refugia. The Sound Metrics Corporation ARISfish software was used to analyze ARIS data and count and measure fish. The total length (TL) of fish was measured to the nearest cm using the echogram and manual processing software functions. Six hundred forty-six fish were measured for length frequency calculations. Fish greater than 45cm TL were counted as adults. Data was exported into Excel spreadsheets for length frequency analyses and fish count summaries.
An index for the density of fish per site was the desired metric for the study. This was calculated as the ratio of fish counted in transects to the approximate transect areas (ha).

The main task of this project is to monitor fall Chinook salmon densities in the Lower Klamath River during the fall migration period. This part of the study is closely related to, and will be done in conjunction with ongoing Adult Chinook Pathology monitoring that the YTFP has been conducting since the 2002 fish die off. We will use a mobile boat mounted DIDSON to monitor fall Chinook densities in large pools on the Lower Klamath River (downstream of river kilometer 85). This will allow us to examine whether fish are migrating normally, or are being delayed and crowding into the large pools of the Lower Klamath River (overcrowding is thought to be a key factor in the 2002 die off). Data from this study could be used in near real-time to inform managers of deteriorating river conditions so that appropriate emergency actions could be taken if necessary. Operating costs, supporting supplies, maintenance, and data processing are included in the budget.

PCSRF Goals, Objectives addressed:
This project addresses the need to acquire detailed information on the migration of adult salmonids in the lower Klamath River. The fish kill of 2002 was thought to be due in part to migration delays.

Outcomes & Benefits
Provide information on fish numbers, densities, residence times and related information to fisheries and water managers so that water and/or fisheries can be managed more effectively.

Other measurable outcomes and benefits include:
Monitoring Salmonid Smolts and/or Fry (E.1.c.2)