GLERL 2004 Milestone Reports

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NOAA Performance Measure: Increased number of fish species with adequate information to assess their condition.

Scientist: Dr. Doran Mason (GLERL)

OAR PM: Baseline: 0 fish species; Target: 1 fish species.

Milestone: Complete an evaluation of hydroacoustics technology to quantify natural production of Chinook smolts in Great Lake tributaries.

Purpose: Annual production of wild chinook smolts (recruits) in the Great Lakes is highly variable and unpredictable. We currently know little about which river(s) contribute the majority of natural recruitment to the fishery, the magnitude of the adult spawning runs and corresponding recruitment, and the corresponding rates of river exploitation. Here, we proposed to use fixed-location, split-beam hydroacoustics technology in the Muskegon River (tributary to Lake Michigan) to estimate absolute abundance and production of out-migrating chinook smolts. Fixed-location hydroacoustic technology is a cost-effective approach that has been used effectively to estimate adult salmon escapement in nearly 50 rivers in both North America and Europe. Our specific objectives were:

To evaluate the feasibility of using fixed-location riverine hydroacoustics technology to measure smolt abundance
To quantify smolt behavior during migration
To estimate abundance of out-migrating smolts

Efforts and Results (to date): The application of side-looking fixed river acoustics holds promise for quantifying the out-migration of salmon smolts in the Great Lakes. Despite difficulties in deploying the acoustic system, mechanical issues, and river flooding we were able to provide some hydroacoustic estimates of smolt passage. Acoustic estimates of the number of out-migrating chinook smolts was always greater than estimates using standard, but more intensive, direct field sampling techniques. This was likely do to the greater volume of water sampled by the acoustics relative to standard sampling techniques, or mistakenly identifying noise (e.g., drifting branches and bubbles) in the river as chinook smolts. Further development of the methods used in this project will be necessary before accurate estimates of smolt production can be attained using hydroacoustics. Improvements must be made in the quality and volumes of usable data collected for analysis. Improved data quality should result in enhanced performance and increased detection probabilities of out-migrating smolts at extended ranges. Larger numbers of daily estimates will translate to enhanced analytical abilities and clearer explanations of the results obtained. Although hydroacoustics can never completely replace other sampling methods due to the need for ground-truthing data (i.e., direct identification of acoustic targets), the method still is worthy of further investigation and development for use enumerating out-migrant salmonids smolt.

For project details see: http://www.glerl.noaa.gov/res/Task_rpts/Resources/glft_201999_9.pdf

Customer(s): Customers for this project are primarily fisheries managers in the Great Lakes who are tasked with the job of managing the salmon sports fishery and maintaining a balance between native fish populations (e.g., yellow perch) and the highly prized salmon fishery. The public, e.g., recreational anglers, are expected to benefit in the long term through management with the best available scientific information.

Cause Factors (if milestone not met): NA

Revised Completion Date (if milestone not met): NA

Last updated: 2004-09-23 js