Sub-Antarctic South Georgia (SG) is a marine biodiversity hotspot and was historically a very important feeding ground for whales, with >170,000 whales killed in local waters during 20th century whaling. A century later, regional whale populations are recovering and SG is becoming an important feeding ground again. The island’s waters are also a hotspot and key fishery area for Antarctic krill, characteristics of which are annually monitored by BAS (https://www.bas.ac.uk/project/poets-wcb/). Recovering whale populations are likely to target higher-density krill swarms and may have a significant impact on local krill densities and swarm behaviours, but whale foraging preferences are poorly known at SG. Antarctic krill at SG also have some unique characteristics compared to other Southern Ocean areas, including a predominance of larger-sized animals.
Using active acoustics and whale sightings, this project will study the interaction of whales and krill in a key hotspot for both, identifying krill density and swarm characteristics that are most closely associated with whale aggregations in the northern Scotia Arc, to understand (i) the foraging niches of whales on this important feeding ground, (ii) potential areas of competition with the fishery, (iii) influence of increasing whale density on prey foraging preference, as whale populations recover.
The project will use whale sighting datasets, collected alongside active acoustic zooplankton surveys, to determine: (1) which prey-swarm aspects best predict whale presence, and (2) primary prey-based drivers of whale habitat use in the northern Scotia Arc.
We will address the research question through linked activities, including:
(1) Acoustic analysis for krill-swarm identification and classification (including machine-learning tools) to determine swarm depth, size, density, etc.;
(2) Investigating associations between krill-swarm characteristics and whale occurrence (at a range of temporal and spatial scales) using whale sightings datasets associated with krill surveys and swarm characterizations (above);
(3) Comparing association patterns of krill and whales with earlier surveys, to identify any significant shifts in association over time.
For krill-swarm identification, we will develop custom-built machine-learning algorithms (R and Python), providing a resource for exploring similar questions elsewhere in the Southern Ocean. Whale sightings patterns will be investigated using DISTANCE software, with R-based tools used to investigate habitat use patterns and multiway associations among datasets.
Results will assist management bodies such as the Commission for the Conservation of Marine Living Resources in factoring whale habitat-use preferences into fishery management and ecosystem-based models of the Southern Ocean, through reports authored and presented by the student.
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the British Antarctic Survey. Specific training (by supervisors and by attendance at UK-based training courses) will include:
- Training in computer programming, particularly in R and Python
- Analysis of active acoustic data and whale sightings (line-transect distance-sampling)
- Habitat and species distribution modelling
- Application of machine-learning tools to large datasets
- Ecological statistics
The work may also include one Antarctic field-trip, to gain experience in collection of active acoustic and whale sightings data.
Tarling GA, Klevjer T, Fielding S, Watkins J, Atkinson A, Murphy EJ, et al. (2009) Variability and predictability of Antarctic krill swarm structure. Deep Sea Research Part I: Oceanographic Research Papers. 56:1994-2012. doi: 10.1016/j.dsr.2009.07.004
Fielding S, Watkins JL, Trathan PN, Enderlein P, Waluda CM, Stowasser G, et al. (2014) Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013. ICES Journal of Marine Science 71: 2578-2588. doi: 10.1093/icesjms/fsu104.
Reid K, Brierley AS, & Nevitt GA (2000) An initial examination of relationships between the distribution of whales and Antarctic krill Euphausia superba at South Georgia. Journal of Cetacean Research and Management 2:143-149. (www.iwc.int/jcrm)