Assessing the performance of seaglider based acoustics in detecting krill swarms
The distribution of Antarctic krill (Euphausia superba) in the Weddell Sea is poorly understood, in large part due to the difficulty and expense of accessing this remote and often ice-covered region. The Weddell Sea is believed to be an important spawning site for Antarctic krill, seeding, among others, the population of the important fishing grounds of South Georgia. In an effort to gain further insight into the distribution and transport of krill out of the Weddell Sea and north into the Scotia Sea, a sea glider with an integrated echo sounder was deployed on the continental shelf, east of the Antarctic Peninsula. The glider sampled continuously for a period of almost two months, undertaking several dives a day to depths of up to 1000 m before being collected later in the season.
The echo sounder glider deployment is one aspect of the GENTOO project (Gliders: Excellent New Tool for Observing the Ocean), which saw three gliders in total deployed in the north-western Weddell Sea in late January and early February, 2012. The two other gliders housed conductivity and temperature cells as well as flourometers and oxygen optodes. In addition to the gliders, forty drifter were deployed and CTD, net and acoustic transects were undertaken.
Here we discuss the early results of the echo sounder deployment, including the success of the platform in detecting and measuring krill biomass. The advantages and disadvantages of using glider-based sensing platforms for krill detection, versus more traditional ship-based systems will be examined. The potential for accessing remote regions or gaining season-long data sets using sea gliders will also be considered, along with the cost effectiveness and coverage of glider fleets versus ship-based surveys.