caa a22 4500 397550839 CHVBK 20180308164749.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0024 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0024 Use of a two-frequency algorithm to determine size and abundance of plankton in three widely spaced locations [Elektronische Daten] [R. B. Mitson, Y. Simard, C. Goss] The application of a two-frequency algorithm to the in situ estimation of large zooplankton is explored in an effort to use information from more than one acoustic frequency. To accomplish this, 38 and 120 kHz echo-sounders, found on most fisheries research vessels, were utilized. A two-frequency method using a highpass fluid sphere scattering model was employed to estimate the mean size (length) and the density per m3 of the dominant acoustic scatterers (mainly euphausiids and shrimps), by selected depth layer. Three locations were surveyed: the Gulf of St Lawrence, the Antarctic, and the Irish Sea. Ground-truth samples were collected from various plankton net systems, the catches being compared to the acoustic estimates. Results are discussed with regard to conditions that apply to the method, the ground-truth performance and the relative complexity of the zooplankton composition at the different study sites. The conclusion is that this method has provided satisfactory results but still has a capacity for refinement. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence euphausiids nationallicence plankton acoustics nationallicence two-frequency abundance estimates nationallicence Mitson R. B. ACOUSTEC Swiss Cottage, 5 Gunton Ave, Lowestoft, Suffolk, NR32 5DA, England aut Simard Y. Department of Fisheries and Oceans, Maurice Lamontagne Institute PO Box 1000, Mont-Joli, Quebec, Canada, G5H 3Z4 aut Goss C. British Antarctic Survey High Cross, Madingley Road, Cambridge, CB3 0ET, England aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 209-215 1054-3139 53:2<209 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0024 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0024 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mitson R. B. ACOUSTEC Swiss Cottage, 5 Gunton Ave, Lowestoft, Suffolk, NR32 5DA, England aut NATIONALLICENCE 700 1- Simard Y. Department of Fisheries and Oceans, Maurice Lamontagne Institute PO Box 1000, Mont-Joli, Quebec, Canada, G5H 3Z4 aut NATIONALLICENCE 700 1- Goss C. British Antarctic Survey High Cross, Madingley Road, Cambridge, CB3 0ET, England aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 209-215 1054-3139 53:2<209 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford