Observation and extraction of three-dimensional information on fish schools

Abstract

The paper describes the performance calibration and use of a 90-deg sector scanning sonar for the collection and extraction of information on the 3D structure of fish schools. The equipment, which consists of a 455-kHz 60-beam sector scanning sonar linked to a PC is described briefly. The specific calibration problems of a high-frequency instrument with multiple beams is discussed and calibration data from on-axis and beam shape measurements are presented. The deployment of the instrument for data collection at sea and the data collection methods are described. Examples of the data collected are given. A three-dimensional data processing algorithm is presented along with results of reconstruction from selected schools. The statistical properties of within school data are discussed along with indications of the precision of internal structures that can be evaluated using the sonar. The development of this system is supported by the European research program, AIR.

The three-dimensional morphology and internal structure of clupeid schools as observed using vertical scanning multibeam sonar

“…Some correction must be applied to the data, especially the length, using the classical correction related to the distance of the target (Johannesson and Losse, 1977). Simmonds et al (1999) developed a calibration procedure for this MBS, which gives a beam angle of 22 × 1.5°for our sonar (instead of the nominal 15 × 1.5°), that we applied for correcting the length.…”

Waves of agitation inside anchovy schools observed with multibeam sonar: a way to transmit information in response to predation

“…Calibration of multibeam sonar is not easy (Simmonds and MacLennan, 2005), and this particular one has only been calibrated once, in 1999 (Simmonds et al, 1999), essentially to evaluate the beam angle. (The calibration appeared to be different from the manufacturer's specification: 22( instead of 15(.)…”

Omnidirectional multibeam sonar monitoring: applications in fisheries science

“…From these reviews and our own sea-based observations, we have determined the main advantages and limitations of two different omnidirectional fisheries sonar systems. The literature on sonar data analysis is mainly directed towards scientific scanning sonar (Misund 1990;Misund et al 1994;Godø 1998;Farmer et al 1999;Gerlotto et al 1999;Pedersen and Trevorrow 1999;Simmonds et al 1999;Dalen et al 2000;Axelsen et al 2001;Hamano et al 2002;Mayer et al 2002;Melvin et al 2002). This paper presents the methodologies for continuous data acquisition, extraction and analysis from standard omnidirectional sonar systems, a review of their use and a proposal for new sampling schemes and applications in fisheries sciences.…”