Acoustic scattering characteristics of pelagic and coastal nekton

Abstract

Measurements of several acoustic scattering characteristics were made for a variety of different nekton. At-sea broadband high-frequency (100s to 1000s kHz) backscatter measurements were made on several species of myctophids and other types of pelagic nekton (e.g. fish, shrimp). Animals were caught in mid-water trawls off the coast of Oregon during the summer of 2012, and measurements were made on fresh specimens from multiple species. Both broadside (dorsal) and end-on (head/tail) measurements were recorded. There was strong variability among and within species as well as with animal orientation. We also report measurements of swim-bladder size, shape, and fullness for the pelagic myctophids. Additionally, high-resolution computerized tomography (CT) scans were made for several coastal nekton (including squid, silverside, and sea bass) species from New York. These scans provide information on the density contrast of the various organs and other structures in the animal. These data provide useful information for acoustic scattering models of these and other similar animals.