The objective of the IMR-2009615 cruise was to study the distribution of fish and plankton in relation to the occurrence of Lophelia cold-water coral reefs and the general topography in the Traena Deep coral reef field. The acoustic data were collected using the Simrad ER60 scientific echosounder at a cruising speed of 10 knots. Abundance estimations of fish were generated for the 38 kHz data. Three other operating frequencies were used during the survey (18, 120 and 200 kHz) for trace recognition purposes. Echograms were scrutinized using Large Scale Survey System-software. The allocation of area backscattering strengths to species was made by comparison of the appearance of the echo recordings to trawl catches and video recordings. This dataset contains three hundred and sixty (360) vertical profiles of plankton and fish abundance expressed as Nautical Area Scattering Coefficient (NASC) determined from acoustics measurements at 38 kHz.
Abundances expressed as NASC (meter square per nautical mile square) can be converted to numbers of individuals using "target strength to length" relationships for the targeted species/group. For single species these relationships can be determined through in situ measurements of target strength during the survey and the size distribution of the insonified fish. The number of fish (N) in a particular area can be calculated using standard equations, e.g. Foote et al. (1987), Toresen et al. (1998), Roa-Ureta and Nikilitschek (2007).