Members of the NERC British Antarctic Survey, MESOPP partners, were back in the Southern Ocean onboard the RRS James Clark Ross (Cruise JR17002) investigating the marine polar ecosystem in the Atlantic sector of the Southern Ocean. Setting off from the Falkland Islands, they travelled to South Georgia to undertake the annual survey of the distribution of Antarctic krill within the Western Core Box [Fielding et al. 2014].

Like last year acoustic measurements, using an EK60, have been made as the ship has transited from the Falkland Islands to South Georgia adding to the 10 years of acoustic data collected across long transits in this region (see MESOPP catalogue).

Near South Georgia we observed an eight kilometre Antarctic krill swarm located on-shelf just north of South Georgia. Many penguins, seals and whales were seen in the area feeding upon it.

38 kHz echogram of acoustic target observed to the north of South Georgia

38 kHz echogram of acoustic target observed to the north of South Georgia

In addition to the hull mounted measurements, a glider equipped with a 120 kHz echosounder was deployed at an open-ocean deep water site to the north west of South Georgia. It carried out a 7 day mission, undertaking 99 dives. The glider, undulating from surface to 500 m depth and, covering areas beyond the ship’s track, is expected to provide new insights on the distribution of krill. Acoustic datasets collected from vehicles other than ships are an area that MESOPP has identified for future work, both in terms of inclusion in standard terminology and processing, as well as validation and potential applications.

Deployment of the BAS seaglider equipped with a 120 kHz echosounder

Deployment of the BAS seaglider equipped with a 120 kHz echosounder

The RRS James Clark Ross

The RRS James Clark Ros

Reference

Fielding S, JL Watkins, P Trathan, P Enderlein, C Waluda, G Stowasser, G Tarling, EJ Murphy (2014) Inter-annual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997 – 2013. ICES Journal of Marine Science, 71(9): 2578-2588