Species identification in deep water using multiple acoustic frequencies

• DOI: 10.1139/f02-076
• Publication Date: 2002-10-01T16:05:45Z
• Authors: R J Kloser; T Ryan; P Sakov; A Williams; J A Koslow
• Keywords: Demersal zone; Demersal fish; Seamount; Target strength

Multifrequency 12, 38, and 120 kHz acoustics were used to identify the dominant fish groups around a deepwater (>600 m) seamount (a known spawning site for orange roughy, Hoplostethus atlanticus) by amplitude mixing of frequencies. This method showed three distinct acoustic groupings that corresponded fishes based on size swimbladder type: myctophids total length less than 10 cm, morids macrourids with lengths >30 roughy mean standard 36 cm. These caught in demersal pelagic trawls study area. A simple model resonance at depth large small gas-filled bladder is agreement our experimental observations. Traditionally, trawling species records. However, are rarely mid-water owing net avoidance. Using frequencies, these could be distinguished directly over their entire vertical extent from reduces major source positive bias uncertainty (factor range 2.0–6.4) biomass estimates.