© 2003 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
The influence of ontogeny, physiology, and behaviour on the target strength of walleye pollock (Theragra chalcogramma)
University of Washington, School of Aquatic and Fishery Sciences Box 35520, Seattle, WA 98355, USA
*tel: +1 206 221 6890; fax: +1 206 221 6939. e-mail: jhorne{at}u.washington.edu.
Variability in echo intensities from aquatic organisms is caused by physical factors associated with the transmission of sound through water, and by biological factors associated with the ontogeny, physiology, and behaviour of targets. Acoustic-based density estimates depend on accurately characterizing reflected or backscattered sound from any species of interest. Digitized lateral and dorsal radiographs of walleye pollock (Theragra chalcogramma) were used to characterize intra-specific variability among young-of-the-year, juvenile, and adult life-history stages. Kirchhoff-ray mode (KRM) models were used to quantify variability in backscatter intensities at 38 and 120 kHz. At these geometric scattering frequencies, swimbladder surface areas influence echo intensities. Dorsal swimbladder surface areas were proportionate to fish lengths and decreased after fish were fed. Corresponding changes in backscatter were not proportionate to the reduction in dorsal surface area. The ratio of dorsal to lateral swimbladder surface areas was consistent among gravid and non-gravid fish. Walleye pollock tilt angles were centred at 90° and did not differ among densities or between light and dark cycles. Target strength–length regressions and KRM-predicted backscatter models closely matched in situ target-strength measurements for walleye pollock in the Bering Sea. Backscatter variability can be minimized through judicious deployment of equipment and equipment-parameter settings, but the relative influence of biological factors on backscatter amplitude has not been determined.
Keywords: acoustics, behaviour, ontogeny, physiology, target strength, walleye pollock
Received 16 October 2002; accepted 3 March 2003.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  H. Pena and K. G. Foote Modelling the target strength of Trachurus symmetricus murphyi based on high-resolution swimbladder morphometry using an MRI scanner ICES J. Mar. Sci., December 1, 2008; 65(9): 1751 - 1761. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Henderson, J. K. Horne, and R. H. Towler The influence of beam position and swimming direction on fish target strength ICES J. Mar. Sci., March 1, 2008; 65(2): 226 - 237. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. G. Winter and G. L. Swartzman Interannual changes in distribution of age-0 walleye pollock near the Pribilof Islands, Alaska, with reference to the prediction of pollock year-class strength ICES J. Mar. Sci., January 1, 2006; 63(6): 1118 - 1135. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Kang, T. Mukai, K. Iida, D. Hwang, and J.-G. Myoung The influence of tilt angle on the acoustic target strength of the Japanese common squid (Todarodes pacificus) ICES J. Mar. Sci., January 1, 2005; 62(4): 779 - 789. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Gorska, E. Ona, and R. Korneliussen Acoustic backscattering by Atlantic mackerel as being representative of fish that lack a swimbladder. Backscattering by individual fish ICES J. Mar. Sci., January 1, 2005; 62(5): 984 - 995. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. L. Hazen and J. K. Horne Comparing the modelled and measured target-strength variability of walleye pollock, Theragra chalcogramma ICES J. Mar. Sci., January 1, 2004; 61(3): 363 - 377. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Gauthier and J. K. Horne Potential acoustic discrimination within boreal fish assemblages ICES J. Mar. Sci., January 1, 2004; 61(5): 836 - 845. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. A. Logerwell and C. D. Wilson Species discrimination of fish using frequency-dependent acoustic backscatter ICES J. Mar. Sci., January 1, 2004; 61(6): 1004 - 1013. [Abstract] [Full Text] [PDF]
|
|