These data were collected on the sixth Nella Dan voyage of a long term field survey project being conducted by the Australian Antarctic Division, to collect distribution, abundance and population structure data for the krill Euphausia superba in the Prydz Bay region, Antarctica. This voyage, the Australian Antarctic Marine Biological Ecosystem Research 1986/1987 (AAMBER 86/87) cruise, operated between February and April 1987. The dataset includes two scanned copies of the Hyrdoacoustic logs of the voyage.

This is data describing acoustically observed krill swarms that was used in the Bestley et al. (2017) paper 'Predicting krill swarm characteristics important for marine predators foraging off East Antarctica' (http://onlinelibrary.wiley.com/doi/10.1111/ecog.03080/full). Abstract of the paper presented here: Open ocean predator-prey interactions are often difficult to interpret because of a lack of information on prey fields at scales relevant to predator behaviour. Hence, there is strong interest in identifying the biological and physical factors influencing the distribution and abundance of prey species, which may be of broad predictive use for conservation planning and evaluating effects of environmental change. This study focuses on a key Southern Ocean prey species, Antarctic krill Euphausia superba, using acoustic observations of individual swarms (aggregations) from a large-scale survey off East Antarctica. We developed two sets of statistical models describing swarm characteristics, one set using underway survey data for the explanatory variables, and the other using their satellite remotely sensed analogues. While survey data are in situ and contemporaneous with the swarm data, remotely sensed data are all that is available for prediction and inference about prey distribution in other areas or at other times. The fitted models showed that the primary biophysical influences on krill swarm characteristics included daylight (solar elevation/radiation) and proximity to the Antarctic continental slope, but there were also complex relationships with current velocities and gradients. Overall model performance was similar regardless of whether underway or remotely sensed predictors were used. We applied the latter models to generate regional-scale spatial predictions using a 10-yr remotely-sensed time series. This retrospective modelling identified areas off east Antarctica where relatively dense krill swarms were consistently predicted during austral mid-summers, which may underpin key foraging areas for marine predators. Spatiotemporal predictions along Antarctic predator satellite tracks, from independent studies, illustrate the potential for uptake into further quantitative modelling of predator movements and foraging. The approach is widely applicable to other krill-dependent ecosystems, and our findings are relevant to similar efforts examining biophysical linkages elsewhere in the Southern Ocean and beyond. This comma separated variable (CSV) file contains the krill swarm data used in: Bestley, S., Raymond, B., Gales, N.J., Harcourt, R.G., Hindell, M.A., Jonsen, I.D., Nicol, S., Peron, C., Sumner, M.D., Weimerskirch, H. and Wotherspoon, S.J., Cox, M.J. (2017). Predicting krill swarm characteristics important for marine predators foraging off East Antarctica. Ecography. The column descriptions are: Depth_mean_m = (units m) mean depth of a krill swarm Date = (YYYYMMDD) observation date (UTC) Time = (HH:mm:ss.ss) observation time (UTC) Lat = (dd.ddddd) latitude Lon = (ddd.ddddd) longitude transect = BROKE West transect number 7 to 11 (see Fig. 1, Bestley et al. 2017) denVolgm3 = (units g wet mass m-3) internal krill swarm density in gram wet mass per cubic metre.

The attached file details the workflow for the processing and analysis of active acoustic data (Simrad EK60; 12, 38, 120 and 200 kHz) collected from RSV Aurora Australis during the 2006 BROKE-West voyage. The attached file is in Echoview(R) (https://www.echoview.com/) version 8 format. The Echoview file is suitable for working with fisheries acoustics, i.e. water column backscatter, data collected using a Simrad EK60 and the file is set-up to read 38, 120 and 200 kHz split-beam data. The file has operators to remove acoustic noise, e.g. spikes and dropped pings, and operators for removing surface noise and seabed echoes. Echoes arising from krill are isolated using the ‘dB-difference’ method recommended by CCAMLR. The Echoview file is set-up to export the results of krill echo integration as both intervals and swarms. Full details of the method are available in Jarvis et al. (2010) and the krill swarms methods are described in Bestley et al. (2017).

Hydroacoustics data obtained from Australian Antarctic Division voyages from 1993 to 2004. Voyages were made to various locations within the Southern Ocean. Data are stored on 14 hard disks, 1 CD-R and 1 DVD-R for archiving in a secure storage area. A catalogue describing what data are held on each media is available for download from the provided URL. The hard disks in the archive box are labelled as 'Status 1'. These data were collected under several ASAC projects - ASAC 357 (Hydroacoustic Determination of the Abundance and Distribution of Krill in the Region of Prydz Bay, Antarctica) and ASAC 1250 (Krill flux, acoustic methodology and penguin foraging - an integrated study) - ASAC_357 and ASAC_1250. 2008-11-07 Note - all Australian Antarctic Division hydroacoustic data have now been collated on the AAD Storage Area Network (SAN). This digital collection supersedes the collection of hard disks, and comprises (as of now) the sum total of all AAD hydroacoustic data. Ideally as more hydroacoustic data are collected by AAD vessels, they will be added to the SAN. See the metadata record entitled "Hydroacoustic data collected from Southern Ocean Cruises by the Australian Antarctic Division" for more information.