Accuracy and Precision of Salmon Length Estimates Taken from DIDSON Sonar Images

Abstract

Experiments were conducted with a multibeam dual‐frequency identification sonar (DIDSON) to evaluate the accuracy and precision of estimating lengths from images of tethered fish insonified at side aspect in an Alaskan river. Live tethered Chinook salmon Oncorhynchus tshawytscha and sockeye salmon O. nerka were suspended in front of a long‐range DIDSON (1.2 MHz, 48 beams) equipped with an ultra‐high‐resolution lens. Lengths measured manually from DIDSON images were highly correlated with the actual lengths (R2 = 0.90, RMSE = 5.76 cm). No range dependency in the accuracy of the range estimates was documented. We conclude that relatively accurate and precise estimates of fish length are now possible with certain DIDSON system configurations at up to 21 m.

Use of high-frequency imaging sonar (DIDSON) to observe fish behaviour towards a surface trawl

“…Recent development of hydroacoustic methods (Belcher et al, 2001;Holmes et al, 2006;Burwen et al, 2007Burwen et al, , 2010 opens new possibilities to investigate this issue. Split-beam echo-sounders have been successfully used in several occasions to monitor the movements of individual fish (Handegard et al, 2003;Hjellvik et al, 2003;McQuinn and Winger, 2003;Jorgensen et al, 2004;Handegard and Tjostheim, 2005;Rakowitz et al, 2008).…”

Fish Movement Through an Estuary Mouth Is Related to Tidal Flow

“…This makes moving objects, like fish, easier to identify and measure. Every fish passing through the DIDSON field of view was counted, measured (total length) using the software measurement tool (Burwen, Fleischman, & Miller 2010;Becker & Suthers 2014), and its swimming direction recorded (into the estuary, Bincoming,^or leaving the estuary, Boutgoing^). Most fish passed from one side of the field of view to the other, in an obvious and deliberate swimming direction within a matter of seconds.…”

Detecting a nearshore fish parade using the adaptive resolution imaging sonar (ARIS): An automated procedure for data analysis

“…Single point fish recordings of fish transit through water control structures in salt marshes have also shown interesting patterns of fish behavior contrasting with fish size (Kimball et al, 2010). Collecting data on anadromous species from a single point as they make their way through a fish passage is becoming popularized (Burwen et al, 2011;Maxwell and Gove, 2007). Sonar cameras are not limited to single point deployment and are configurable for mobile application.…”