New Zealand Journal of Marine and Freshwater Research abstracts

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DEEP SCATTERING LAYERS RESOLVED BY NARROW-BEAM ECHO SOUNDER ALONG 35° S IN THE SOUTH PACIFIC

Dale C. Krause

Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode Island 02881

Atlantic Oceanographic and Meteorological Laboratories, National Oceanic and Atmospheric Administration, 901 South Miami Avenue, Miami, Florida 33130, United States of America

Abstract The narrow-beam echo sounder (3.5° half angle, 20 kHz) is capable of resolving the configuration of deep scattering layers to 750 m and was used to study the ecology and population density of organisms that make up the layers. Several layers to 1,000 m depth were identified in the South Pacific Ocean, and the population densities calculated. Swimming speeds of possible predators are estimated at 0.2-0.3 m.sec-¹. Among organisms calculated to range in length from 0.01 m to 0.07 m, the larger were interpreted as grazing on smallei organisms, after comparing results from two echo sounders of 12 kHz and 20 kHz frequencies respectively.

N.Z. Journal of Marine and Freshwater Research 5 (2): 219-32
Received for publication 11 March 1969; revisions received 12 October 1970,

PDF file of entire paper: medium quality (2277K); (scanned from paper original: notes about this process)

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