Can Acoustic Methods Be Used to Monitor Grenadier
(Macrouridae) Abundance in the Ross Sea Region?¹

R. L. O’Driscoll^a, S. M. Hanchet^b, and B. S. Miller^{a, c}

^a National Institute of Water and Atmospheric Research Limited, Wellington, New Zealand

^b National Institute of Water and Atmospheric Research Limited, Nelson, New Zealand

^c Australian Antarctic Division, Kingston, Tasmania, Australia

e-mail: richard.odriscoll@niwa.co.nz

Received April 12, 2012

Abstract—Grenadiers Macrourus spp. are the main bycatch species in the exploratory longline fishery for
toothfish Dissostichus spp. in the Ross Sea, Antarctica. Ongoing monitoring tools are needed to assess stock
status of grenadiers in the Ross Sea and to ensure ecological relationships are maintained. There may be poten-
tial to use fisheries acoustic methods to obtain estimates of grenadier abundance. Acoustic data collected during
New Zealand’s International Polar Year Census of Marine Life survey in February–March 2008 provide evi-
dence that single targets close to the bottom over the Ross Sea slope are grenadiers. The acoustic target strength
distribution of single targets was very similar to that predicted based on the measured size range of grenadiers.
There are also positive correlations between acoustic backscatter and trawl and longline catches of grenadiers.
Key uncertainties of the acoustic method are mark identification away from the bottom, and technical issues
with low signal-to-noise ratio at depths greater than 1000 m and the acoustic dead-zone close to the bottom.

Keywords: acoustics, grenadiers, Macrourus whitsoni, target strength, Antarctica

DOI: 10.1134/S0032945212100098

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