Fisheries Research 60 (2003) 569–576 Short communication An investigation of avoidance by Antarctic krill of RRS James Clark Ross using the Autosub-2 autonomous underwater vehicle Andrew S. Brierley a,∗ , Paul G. Fernandes b , Mark A. Brandon c , Frederick Armstrong b , Nicholas W. Millard d , Steven D. McPhail d , Peter Stevenson d , Miles Pebody d , James Perrett d , Mark Squires d , Douglas G. Bone a , Gwyn Griffiths d a British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK b FRS Marine Laboratory Aberdeen, P.O. Box 101, Victoria Road, Aberdeen AB11 9DB, UK c Department of Earth Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK d Southampton Oceanography Centre, Empress Dock, Southampton SO14 3ZH, UK Received 5 September 2001; received in revised form 31 May 2002; accepted 15 June 2002 Abstract The autonomous underwater vehicle (AUV) Autosub-2 was deployed on eight missions ahead of RRS James Clark Ross in the northern Weddell Sea and in the Bransfield Strait, Southern Ocean, to assess avoidance of the research vessel by Antarctic krill Euphausia superba. The AUV was equipped with the same type of scientific echosounder as the research vessel (Simrad EK500 operating at 38 and 120 kHz) and measured the density of krill along transect acoustically (g m -2 wet mass) prior to the ship’s arrival. We hypothesised that if krill avoided the ship, perhaps in response to radiated noise, then the ship should detect less krill than the AUV which is known to have much lower noise levels than the ship. We were unable to detect any significant difference between the density of krill detected by the ship or the AUV, either at the transect level or at finer scales within transects. We conclude, therefore, that avoidance by krill of RRS James Clark Ross will not significantly bias acoustic estimates of krill abundance by this vessel. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Acoustic survey; Avoidance; Autosub; Antarctic krill; Biomass estimate; Euphausia superba; Vessel noise 1. Introduction The acoustic survey is the principal method by which the abundance of Antarctic krill (Euphausia su- perba) is assessed. For example, in January and Febru- ary 2000 a multi-national, multi-ship acoustic survey was conducted to estimate the abundance of krill ∗ Corresponding author. Present address: Gatty Marine Labora- tory, University of St. Andrews, Fife KY16 8LB, UK. Tel.: +44-1334-463458; fax: +44-1334-463443. E-mail address: andrew.brierley@st-andrews.ac.uk (A.S. Brierley). throughout the south-west Atlantic Ocean (Trathan et al., 2001). This survey was conducted under the auspices of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Fur- thermore, individual nations conduct routine acoustic surveys to monitor variability in krill abundance proximate to their CCAMLR Ecosystem Monitoring Programme (CEMP) study sites (e.g. Brierley et al., 1999, 2001). Results from the CCAMLR 2000 acous- tic survey have already been used to reappraise the precautionary catch limit for krill. Elsewhere in the world acoustic surveys are conducted to assess stock 0165-7836/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0165-7836(02)00144-3