Feasibility of Split-beam Hydroacoustic Gear to Provide Estimates of Coho Salmon Abundance in the Kenai River
Feasibility of Split-beam Hydroacoustic Gear to Provide Estimates of Coho Salmon Abundance in the Kenai River

Author: Kyle D. Vaught

Publisher:

Published: 1993

Total Pages: 22

ISBN-13:

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Reports on the feasibility of using split-beam sonar to facilitate data collection for estimating riverine abundance estimates of coho salmon (Oncorhynchus kisutch) in the Kenai River. Drift gill nets and fish wheels were also used to collect length frequency data; diurnal patterns in fish passage were also documented.

Estimating Salmon Abundance in the Kuskokwim River Using Sonar, 2017
Estimating Salmon Abundance in the Kuskokwim River Using Sonar, 2017

Author: Keegan O. Birchfield

Publisher:

Published: 2019

Total Pages: 40

ISBN-13:

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In 2017, sonars were operated on the Kuskokwim River to estimate the abundance and run timing of Pacific salmon Oncorhynchus spp. following recommendations from a 2014–2016 feasibility study. After identifying a location with a suitable bottom profile, split-beam and imaging sonar were deployed on the gentle sloping left bank and an imaging sonar was deployed on the steep right bank. Species-specific fish passage abundance estimates were generated using a 3-step process. First, all fish passing the site were estimated, without regard to species. Second, species compositions were estimated and adjusted using selectivity parameters. Finally, species composition estimates were applied to total passage estimates to create species-specific abundance estimates. An unadjusted estimate of 2,531,397 fish passed the sonar site between June 1 and July 26. However, right bank vertical sonar coverage was incomplete in 2017 due to late installation of a spreader lens. An expansion based on 2016 and 2017 left bank counts was used to produce estimates of right bank missed passage by species. Despite adjustments, there were still substantial differences between sonar estimates and Kuskokwim River run reconstruction and mark–recapture projects estimates of Chinook salmon Oncorhynchus tshawytscha that may be due to abnormal river conditions in 2017 (i.e., low water levels).

Estimating Salmon Abundance in the Kuskokwim River Using Sonar, 2016
Estimating Salmon Abundance in the Kuskokwim River Using Sonar, 2016

Author: Keegan O. Birchfield

Publisher:

Published: 2019

Total Pages: 72

ISBN-13:

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A 3-year study was initiated in 2014 to assess the feasibility of using sonar, in combination with drift gillnetting, to estimate salmon abundance in the Kuskokwim River. This report presents the results of the final year of feasibility assessment in 2016. After identifying a location with a suitable bottom profile, split-beam and imaging sonars were deployed on the gentle sloping left bank and an imaging sonar was deployed on the steep right bank. A range of drift gillnet mesh sizes were deployed along both banks to apportion sonar counts to species. Following a late project start, there were few interruptions in apportionment and sonar counts. Consistent fishing and sonar operation allowed estimation of daily and total passage of most salmon and whitefish species. A general comparison was made between the 2016 sonar, Bethel test fishery, Kuskokwim River Chinook salmon mark-recapture, and weir escapement projects. Run timing tracked well between Bethel test fishery and the Kuskokwim River sonar with small discrepancies between chum to sockeye salmon ratios that may be due to the differing mesh sizes employed by each project. Chinook salmon was the only species assessed by other projects for drainagewide estimates; a comparison was made between sonar passage estimates (with annotations concerning harvest) and run size estimates from the mark-recapture project and escapement estimates from the run reconstruction model. When considering the shorter sonar sampling season, preliminary total passage estimates of Chinook salmon were within 90% CI across all projects. When including the modifications recommended by the feasibility study, sonar has the potential to accurately estimate salmon and whitefish abundance, in real time, on the Kuskokwim River for future management purposes.

Feasibility of Estimating Salmon Abundance in the Tanana River Using Sonar, 2012-2014
Feasibility of Estimating Salmon Abundance in the Tanana River Using Sonar, 2012-2014

Author: Naomi B. Brodersen

Publisher:

Published: 2016

Total Pages: 111

ISBN-13:

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A study was conducted from 2012 to 2014 to assess the feasibility of using sonar, in combination with gillnetting and a fish wheel, to estimate salmon abundance in the Tanana River. Eight sites between Cosna Bluff and the confluence of the Kantishna and Tanana rivers were surveyed, bottom profiles were analyzed for suitability of sonar operation, and a site near Manley Hot Springs was selected. Split-beam sonar was operated on the left bank, and imaging sonar on the right bank. Drift and set gillnets were used to apportion the left bank sonar estimates, and drift gillnets and a fish wheel were used to apportion the right bank sonar estimates. Both sonar and test fishing methods were modified and assessed for effectiveness throughout both seasons. The sonars were found to provide effective coverage with 95% of fish passing within 80 m of the transducer on the left bank, and within 16 m on the right bank. The drift gillnets and fish wheel proved to be effective fishing methods, though refinement of these methods should be a goal in future seasons. Based on the information obtained, estimating salmon abundance in the Tanana River using sonar, with drift gillnets and a fish wheel used for species apportionment is feasible.