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Acoustic detection of mesoscale biophysical features in the Shelikof sea valley, and their relevance to pollock larvae in the Gulf of Alaska
Author(s) -
BRODEUR RICHARD D.,
NAPP JEFFREY M.,
WILSON MATTHEW T.,
BOGRAD STEVEN J.,
COKELET EDWARD D.,
SCHUMACHER JAMES D.
Publication year - 1996
Publication title -
fisheries oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 80
eISSN - 1365-2419
pISSN - 1054-6006
DOI - 10.1111/j.1365-2419.1996.tb00083.x
Subject(s) - mesoscale meteorology , pollock , oceanography , geology , marine snow , backscatter (email) , eddy , transect , water column , zooplankton , echo sounding , bathythermograph , entrainment (biomusicology) , acoustic doppler current profiler , remote sensing , current (fluid) , meteorology , geography , turbulence , acoustics , telecommunications , physics , computer science , rhythm , wireless
Mesoscale features such as fronts and eddies can act to retain larval walleye pollock ( Theragra chalcogramma ) within the continental shelf zone in the western Gulf of Alaska. During two May cruises, we observed unusual patterns of backscattering with a 38 kHz acoustic system. Characteristics of this signal were a strong scattering layer at the surface and in midwater, with the water column between nearly void of sound scattering organisms. This signal appeared in several transects where satellite remote sensing indicated the presence of an eddy. Analysis of concomitant water properties and ADCP (153 kHz) data confirmed the existence of an anomalous physical feature at this location. Biological properties (chlorophyll and zooplankton) showed marked changes across the edge of the feature. Larval pollock densities were estimated to be an order of magnitude higher within this feature compared to those outside. Acoustic backscatter signals can be used to identify and characterize mesoscale biophysical features in the ocean, thereby enabling real‐time studies of these features.