Michael M. Bailey
Joseph D. Zydlewski
Joseph E. Hightower
Ann B. Grote
2014
<p><span>We investigated the fish community approaching the Veazie Dam on the Penobscot River, Maine, prior to implementation of a major dam removal and river restoration project. Multibeam sonar (dual-frequency identification sonar, DIDSON) surveys were conducted continuously at the fishway entrance from May to July in 2011. A 5% subsample of DIDSON data contained 43 793 fish targets, the majority of which were of Excellent (15.7%) or Good (73.01%) observation quality. Excellent quality DIDSON targets (</span><i>n</i><span> = 6876) were apportioned by species using a Bayesian mixture model based on four known fork length distributions (river herring (alewife,</span><i>Alosa psuedoharengus</i><span>, and blueback herring, </span><i>Alosa aestivalis</i><span>), American shad, </span><i>Alosa sapidissima</i><span>) and two size classes (one sea-winter and multi-sea-winter) of Atlantic salmon (</span><i>Salmo salar</i><span>). 76.2% of targets were assigned to the American shad distribution; Atlantic salmon accounted for 15.64%, and river herring 8.16% of observed targets. Shad-sized (99.0%) and salmon-sized (99.3%) targets approached the fishway almost exclusively during the day, whereas river herring-sized targets were observed both during the day (51.1%) and at night (48.9%). This approach demonstrates how multibeam sonar imaging can be used to evaluate community composition and species-specific movement patterns in systems where there is little overlap in the length distributions of target species.</span></p>
application/pdf
10.1139/cjfas-2013-0308
en
Canadian Science Publishing
Multibeam sonar (DIDSON) assessment of American shad (<i>Alosa sapidissima</i>) approaching a hydroelectric dam
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