Chapter 13: Fisheries Acoustics
Lars G. Rudstam, J. Michael Jech, Sandra L. Parker-Stetter, John K. Horne, Patrick J. Sullivan, and Doran M. Mason
Fisheries acoustics is the use of sound to measure the distribution and abundance of fish and other aquatic organisms. Passive listening to sound produced by aquatic organisms can be informative (Rountree et al. 2006) but will not be dealt with here. This chapter focuses on the process of actively transmitting sound pulses (pings) and analyzing the returning echoes. Sound has been used to detect fish schools since the late 1930s, and improvements to technology during World War II made echo sounders more readily available for fisheries applications. Subsequent hardware innovations include the development of high-frequency acoustic “cameras,” multibeam sonars, and multifrequency instruments. Software can identify and track single fish, detect and classify fish schools, and visualize acoustic data in three dimensions. Because all fisheries professionals will probably encounter, use, or evaluate results from acoustic surveys at some point in their careers, some familiarity with the technique is important. This chapter builds on those in earlier editions of Fisheries Techniques (Thorne 1983; Brandt 1996) and on a standard operating procedure developed for the Great Lakes (Parker-Stetter et al. 2009). Additional details, including equations and example calculations, are available on the Acoustics Unpacked Web site (www. acousticsunpacked.org). Simmonds and MacLennan (2005) provide excellent in-depth coverage of fisheries acoustics.
The primary advantage of fisheries acoustics is the ability to measure the distribution and abundance of organisms with high resolution during both day and night in nearly the entire water column (Figure 13.1), at depths ranging from hundreds to thousands of meters. Large areas can be surveyed efficiently, thereby reducing the amount of resources needed to generate abundance estimates. Acoustics surveys are therefore part of the routine assessment of many important marine fish stocks. Fish passage in rivers and at dams is monitored with fixed deployment, and acoustic data are used to open or close fisheries on many Pacific salmon spawning runs (Miller et al. 2007). Applications of acoustics in fisheries science are many (MacLennan et al. 2003; Massé et al. 2003; Kubecka et al. 2008; Demer et al. 2009).