Tail‐Beat Patterns in Dual‐Frequency Identification Sonar Echograms and their Potential Use for Species Identification and Bioenergetics Studies

Abstract

We observed patterns in echograms of data collected with a dual-frequency identification sonar (DIDSON) that were related to the tail beats of fish. These patterns reflect the size, shape, and swimming motion of the fish and also depend on the fish's angle relative to the axis of the beam. When the tail is large enough to reflect sound of sufficient intensity and the body is angled such that the tail beat produces periodic changes in the range extent covered by the fish image, then the tail beat becomes clearly visible on echograms that plot the intensity maximum of all beams. The analysis of DIDSON echograms of a mix of upstreammigrating Chinook salmon Oncorhynchus tshawytscha and sockeye salmon O. nerka resulted in the separation of two groups: (1) fish of sockeye salmon size that swam with a tail-beat frequency (TBF) between 2.0 and 3.5 beats/s and (2) fish of Chinook salmon size with a TBF between 1.0 and 2.0 beats/s. There was no correlation between TBF and fish size within each group, which suggests that the observed difference in TBF between the two groups was species-specific rather than an indirect effect of the groups' difference in size. The technique of extracting TBF from DIDSON echograms may also be useful for bioenergetics studies. Compared with electromyogram telemetry, it offers the advantages of being nonintrusive and faster to set up and analyze and therefore is suitable for analyzing larger sample sizes. The disadvantages are that the technique's potential is limited to relatively large fish, it can cover only relatively small areas, it cannot be used to follow individual fish over long distances, and some environments are too noisy to produce DIDSON images of sufficient quality.

Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length: a myth revisited

“…A species-specific stride length was obtained either from our own measurements or from published values: sailfish, L s =0.76 L f observed in steady swimming during predator-prey interactions in the wild (Marras et al, 2015); barracuda, L s =0.63 L f obtained using DIDSON echograms (see below), and Boswell et al (2008) and Mueller et al (2010); little tunny, L s =0.65 L f based on published values of a similar species, skipjack tuna ( Euthynnus affinis ), from a swim tunnel at constant speed (Donley and Dickson, 2000); and dorado, L s =0.65 L f based on observations in a 7.3 m diameter tank for most commonly observed swim speeds (Murchison and Magnuson, 1966). …”

Semiautomated Analysis of Data from an Imaging Sonar for Fish Counting, Sizing, and Tracking in a Post-Processing Application

“…Mueller et al (2010) found that the tail-beat frequency was 2.0-3.5 beats/s in sockeye salmon and 1.0-2.0 beats/s in chinook salmon. This technique was implemented in Echoview.…”

“…Plotting the maximum intensity of all beams provides a fish tail-beat pattern, reflecting the size, shape, and swimming motion of the fish (Mueller et al, 2010). Mueller et al (2010) found that the tail-beat frequency was 2.0-3.5 beats/s in sockeye salmon and 1.0-2.0 beats/s in chinook salmon.…”

“…Data were collected from 00:00:38 on May 11, 2009, to 23:51:33 on the same day. The DIDSON system is a type of sonar, consisting of multiple pings, which are also called frames in some studies (Moursund et al, 2003;Burwen et al, 2007;Mueller et al, 2010). The total number of beams per ping was 48, and the angle of the beams was between -14.13° and 14.13°.…”

Use of High-Resolution DIDSON Sonar to Quantify Attributes of Predation at Ecologically Relevant Space and Time Scales

“…For example, Boswell et al (2008) developed methods for autonomous analysis of large data sets from DIDSON records in order to measure fish size, biomass, swimming speed and direction. Mueller et al (2010) used Echoview software (Myriax Echoview and Eonfusion, Hobart, Tasmania, Australia) to quantify species-specific tailbeat frequencies of two salmonids in a river in Alaska. Such approaches can then be used in sonar studies of migration behaviors addressing issues such as timing of upstream movements and patterns of habitat use.…”