Salmon enumeration in the Fraser River with the dual-frequency identification sonar (DIDSON) acoustic imaging system

Abstract

Reliable data on the number of salmon entering tributaries of the Fraser River to spawn (escapement) is needed for Pacific salmon management. Existing escapement techniques are costly and the number of populations requiring assessments has risen because of stock rebuilding efforts. The efficacy of a DIDSON acoustic imaging system for salmon stock assessment was investigated. Sixteen potential sites within the Fraser watershed were surveyed and based on channel morphology, bottom morphology, flow pattern, fish behavior and location relative to spawning grounds, ten sites in six rivers meet the needs of fisheries managers and the DIDSON system for escapement estimates. Fish count data from the DIDSON were compared to data from a counting fence (used as a standard) using regression techniques, resulting in relationships with slopes ranging from 0.98 to 1.02. The precison of DIDSON counts >50 (measured by CV) among three readers was 1.7%. This work supports the conclusion that the DIDSON system can deliver escapement estimates whose accuracy, precision and scientific defensibility is consistent with or better than existing escapment techniques and at a lower operating cost to assessment programs. [Work supported by the Southern Boundary Restoration and Enhancement Fund of the Pacific Salmon Commission.]

Multibeam sonar (DIDSON) assessment of American shad (Alosa sapidissima) approaching a hydroelectric dam

“…The majority of enumerative DIDSON fisheries research has focused on systems where individuals were surveyed once, either because they were migrating upstream (Holmes et al 2005;Burwen et al 2007;Pipal et al 2012) or because they were sedentary relative to mobile survey vessels (Han and Uye 2009;Lachapelle et al 2013). This study is part of a growing body of work using DIDSON to identify and quantify fish interacting with anthropogenic barriers, such as dams (Baumgartner et al 2006) and flood gates (Doehring et al 2011).…”

“…This study used dual-frequency identification sonar (DIDSON) to collect baseline data on migration dynamics and species composition of the fish community at the base of the Veazie Dam during spring 2011. The DIDSON records near-video quality sonar images (Moursund et al 2003) and can be used for a wide range of fisheries applications, including generating escapement (Holmes et al 2005) or abundance (Han and Uye 2009) estimates and monitoring fish presence (Crossman et al 2011), behavior (Boswell et al 2008), and community dynamics (Becker et al 2011). DIDSON surveys are Fig.…”