Feasibility of Ocean Acoustic Waveguide Remote Sensing (OAWRS) of Atlantic Cod with Seafloor Scattering Limitations

Remote Sensing

Ankita D. Jain¹  Anamaria Ignisca¹  Dong Hoon Yi¹  Purnima Ratilal² 

[1] Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; E-Mails:;Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115, USA; E-Mail:

关键词: acoustic remote sensing;    wide-area fish detection;    OAWRS;    waveguide propagation;    Atlantic cod;    fisheries;    seafloor scattering;   

DOI  :  10.3390/rs6010180

来源: mdpi

【 摘 要 】

Recently reported declines in the population of Atlantic cod have led to calls for additional survey methods for stock assessments. In combination with conventional line-transect methods that may have ambiguities in sampling fish populations, Ocean Acoustic Waveguide Remote Sensing (OAWRS) has been shown to have a potential for providing accurate stock assessments (Makris N.C., et al. Science 2009, 323, 1,734–1,737; 54th Northeast Regional Stock Assessment Workshop (54th SAW) US Department of Commerce, Northeast Fisheries Science Center, 2012). The use of OAWRS technology enables instantaneous wide-area sensing of fish aggregations over thousands of square kilometers. The ratio of the intensity of scattered returns from fish versus the seafloor in any resolution cell typically determines the maximum fish detection range of OAWRS, which then is a function of fish population density, scattering amplitude and depth distribution, as well as the level of seafloor scattering. With the knowledge of oceanographic parameters, such as bathymetry, sound speed structure and attenuation, we find that a Rayleigh–Born volume scattering approach can be used to efficiently and accurately estimate seafloor scattering over wide areas. From hundreds of OAWRS measurements of seafloor scattering, we determine the Rayleigh–Born scattering amplitude of the seafloor, which we find has a f^2.4 frequency dependence below roughly 2 kHz in typical continental shelf environments along the US northeast coast. We then find that it is possible to robustly detect cod aggregations across frequencies at and near swim bladder resonance for observed spawning configurations along the U.S. northeast coast, roughly the two octave range 150–600 Hz for water depths up to roughly 100 m. This frequency range is also optimal for long-range ocean acoustic waveguide propagation, because it enables multimodal acoustic waveguide propagation with minimal acoustic absorption and forward scattering losses. As the sensing frequency moves away from the resonance peak, OAWRS detection of cod becomes increasingly less optimal, due to a rapid decrease in cod scattering amplitude. In other environments where cod depth may be greater, the optimal frequencies for cod detection are expected to increase with swim bladder resonance frequency.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland