Laboratory target strength measurements of free-swimming Antarctic krill (<i>Euphausia superba</i>)

Pauly, Tim; Penrose, John D.

doi:10.1121/1.423077

Cited by 19 publications

(7 citation statements)

References 21 publications

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“…The same target strengths compute to 79.2 to 82.7 dB using the Foote (1990) physical parameters and the common volume to length relationship advanced by Kils (1979) for E. superba and M. norvegica. The latter target strengths for small average inclinations appear comparable to both the E. superba laboratory target strength measurements of Pauly and Penrose (1998) and target strengths predicted by the 1991 Scientific Committee for CCAMLR regression (Pauly and Penrose, 1998). Both indicate about 78 dB for 2.8-cm euphausiids with an apparent uncertainty of 1-2 dB.…”

Section: Acoustic Modellingsupporting

confidence: 64%

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Scotian Shelf euphausiid and silver hake population changes during 1984–1996 measured by multi-frequency acoustics

Cochrane

Sameoto

Herman

2000

ICES Journal of Marine Science

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A 13-year time series of integrated acoustic volume backscattering strengths from Emerald Basin on the Scotian Shelf at 12, 50, 122, and 200 kHz are examined here, together with zooplankton data from net sampling. The three highest acoustic frequencies delineate relative abundances of the euphausiid Meganyctiphanes norvegica while the 12-kHz frequency primarily reflects abundances of pelagic silver hake. Euphausiid populations derived from acoustics fluctuate by a factor of 20 combining both seasonal and inter-annual variation components. Acoustically derived euphausiid populations correlate significantly with both net-sampled euphausiid populations and acoustically derived silver hake abundances, but show no clear long-term (multi-year) trends. The correlation between Emerald Basin euphausiid and migratory pelagic fish abundances suggests the ecological influence of the Shelf Basin euphausiid stocks extends to the surrounding shelf areas. International Council for the Exploration of the Sea

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Section: Acoustic Modellingsupporting

confidence: 64%

“…For example, Chu et al (1993) have achieved insights into orientational dependencies using advanced theoretical models combined with acoustic observation. Of special note are the precise E. superba laboratory target strength measurements of Pauly and Penrose (1998). Miyashita et al (1996) have reported work on E. pacifica using photographic techniques.…”

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confidence: 98%

Scotian Shelf euphausiid and silver hake population changes during 1984–1996 measured by multi-frequency acoustics

Cochrane

Sameoto

Herman

2000

ICES Journal of Marine Science

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“…(1992) review, Hewitt and Demer (1991) and Pauly and Penrose (1998) have also reported observations of krill target strength. Most of these earlier observations lie above our newly-parameterized scattering model (Figure 3.8).…”

Section: Discussionmentioning

confidence: 99%

Distribution, patchiness, and behavior of Antarctic zooplankton, assessed using multi-frequency acoustic techniques

Lawson¹

2006

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The physical and biological forces that drive zooplankton distribution and patchiness in an antarctic continental shelf region were examined, with particular emphasis on the Antarctic krill, Euphausia superba. This was accomplished by the application of acoustic, video, and environmental sensors during surveys of the region in and around Marguerite Bay, west of the Antarctic Peninsula, in the falls and winters of 2001 and 2002. An important component of the research involved the development and verification of methods for extracting estimates of ecologically-meaningful quantities from measurements of scattered sound. The distribution of acoustic volume backscattering at the single frequency of 120 kHz was first examined as an index of the overall biomass of zooplankton. Distinct spatial and seasonal patterns were observed that coincided with advective features. Improved parameterization was then achieved for a theoretical model of Antarctic krill target strength, the quantity necessary in scaling measurements of scattered sound to estimates of abundance, through direct measurement of all necessary model parameters for krill sampled in the study region and survey period. Methods were developed for identifying and delineating krill aggregations, allowing the distribution of krill to be distinguished from that of the overall zooplankton community. Additional methods were developed and verified for estimating the length, abundance, and biomass of krill in each acoustically-identified aggregation. These methods were applied to multifrequency acoustic survey data, demonstrating strong seasonal, inter-annual, and spatial variability in the distribution of krill biomass. Highest biomass was consistently associated with regions close to land where temperatures at depth were cool. Finally, the morphology, internal structure, and vertical position of individual krill aggregations were examined. The observed patterns of variability in aggregation characteristics between day and night, regions of high versus low food availability, and in the presence or absence of predators, together reinforced the conclusion that aggregation and diel vertical migration represent strategies to avoid visual predators, while also allowing the krill access to shallowly-distributed food resources. The various findings of this work have important implications to the fields of zooplankton acoustics and Antarctic krill ecology, especially in relation to the interactions of the krill with its predators.

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“…Although, the TS of Antarctic krill at 120 kHz has been measured already Hewitt and Demer, 1991;Pauly and Penrose, 1998), the TS-pattern itself was not obtained experimentally. McGehee et al (1998) conducted TS-pattern measurements for Antarctic krill, which were tied on the beam axis with a monofilament line, using a single-beam transducer at 120 kHz.…”

Section: Introductionmentioning

confidence: 95%

The target strength of Antarctic krill (Euphausia superba) measured by the split-beam method in a small tank at 70 kHz

Amakasu

Furusawa

2006

ICES Journal of Marine Science

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The target strength of Antarctic krill (Euphausia superba) measured by the split-beam method in a small tank at 70 kHz Kazuo Amakasu and Masahiko Furusawa Amakasu, K., and Furusawa, M. 2006. The target strength of Antarctic krill (Euphausia superba) measured by the split-beam method in a small tank at 70 kHz. e ICES Journal of Marine Science, 63: 36e45.The target strengths (TS) of Antarctic krill (Euphausia superba) were measured at 70 kHz aboard the research and training vessel ''Umitaka-maru'' of Tokyo University of Marine Science and Technology in February 2003 during a Southern Ocean survey. The systematic variations of TS vs. the incident angle of the ensonified wave, henceforth called TS-patterns, were successfully measured for 12 live Antarctic krill. These measurements were compared with the theoretical TS-patterns predicted by the Distorted-Wave Born Approximation-based deformed-cylinder model (DWBA model). While there was good agreement near the main lobe, the measurements were higher than the model predictions in the sidelobe regions; this is consistent with the observations of others. Several possible causes of this discrepancy such as the bending of abdomen and scattering from pleopods were examined, but no single factor was identified as the cause. Rather, it is likely that the discrepancy is a result of a combination of several factors.

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Laboratory target strength measurements of free-swimming Antarctic krill (Euphausia superba)

Cited by 19 publications

References 21 publications

Scotian Shelf euphausiid and silver hake population changes during 1984–1996 measured by multi-frequency acoustics

Scotian Shelf euphausiid and silver hake population changes during 1984–1996 measured by multi-frequency acoustics

Distribution, patchiness, and behavior of Antarctic zooplankton, assessed using multi-frequency acoustic techniques

The target strength of Antarctic krill (Euphausia superba) measured by the split-beam method in a small tank at 70 kHz

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