Accession Number : AD0709312

Title :   ON THE PROSPECTS OF QUANTITATIVE EVALUATION OF THE DENSITY OF FISH ACCUMULATION ACCORDING TO DATA OBTAINED BY HYDROACOUSTIC INSTRUMENTS (O Vozmozhnosti Kolichestvennoi Otsenki Plotnosti Skoplenii Ryb po Dannym Gidroakusticheskikh Priborov),

Corporate Author : NAVAL OCEANOGRAPHIC OFFICE WASHINGTON D C

Personal Author(s) : Yudanov,K. I.

Report Date : 1970

Pagination or Media Count : 17

Abstract : The finding of fish schools and the appraisal of their density depends upon (1) the sensitivity of hydroacoustic equipment, (2) the nature of reflections from fishes and (3) the accuracy of echo measurements. Thus, the structure of transducers, the electrical intensity of the oscillators, amplification factors, frequency of ultrasonic oscillations, and other parameters of instruments are discussed in detail. The Soviet echosounder NEL-4cy and its practical application in reconnaissance of fish schools is outlined. The effects of acoustic resistance of sea water and various species of fishes, including individual parts of their body, such as head, swim bladder, etc., are analyzed and compared. In addition, the reflected impulses, their amplitudes and statistical characteristics are defined and their significance in the evaluation of density and size of fish schools is pointed out. (Author)

Descriptors :   (*FISHES, QUANTITATIVE ANALYSIS), (*UNDERWATER SOUND EQUIPMENT, FISHES), DENSITY, DETECTORS, ECHO RANGING, ACOUSTIC EQUIPMENT, HYDROPHONES, MEASUREMENT, UNDERWATER SOUND, USSR

Subject Categories : Biological Oceanography
      Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE