The right sentinel for climate change: linking foraging ground variability to population recovery in the southern right whale
This IWC-SORP theme provides an over-arching research programme linking southern right whale population dynamics and health with foraging ecology. It aims to leverage the existing long-term datasets from the primary wintering grounds with new knowledge on foraging areas and linkages between migratory habitats, with the ultimate goal to investigate the impact of past and future climate variation on right whale recovery.
Background
Southern right whales underwent a dramatic and prolonged demographic bottleneck due to whaling, which caused a hemispheric population size decline from ~100,000 whales to possibly fewer than 400 whales by 1920. Today, due to the international protection from whaling, the species has recovered in some parts of its former range. Currently, sightings vary from large aggregations, seen in key winter calving/nursery areas (South Africa, Australia, Argentina, Brazil, sub-Antarctic New Zealand), to regular sightings of small numbers of SRWs in other parts of the historical range (e.g., southeast Australia, mainland New Zealand).
The species moves from these coastal, well-studied areas to higher latitude, typically off-shore feeding grounds. However, the latter tend to be poorly understood. Nonetheless, reproductive success, and thus population dynamics, is known to be mediated through body condition and thus foraging success. Certainly, recent research revealed a link between climate variations in foraging grounds with reproductive success of the species in South America.
In recent years, calving success has fluctuated enormously in the main calving grounds, with very low numbers of calves in 2014/2015 (for Australia) and 2015/2016 (for South America and South Africa) and generally very high numbers of calves in 2017/2018. It is believed that a greater understanding of the links between foraging ecology and population dynamics will provide insight into the recovery and persistence of southern right whales, now and into the future.
Objectives
This initiative will develop research projects to better understand how southern right whales use their foraging grounds by employing a diverse set of tools, including geochemical markers, genetics, oceanographic modelling and satellite telemetry. Foraging ground quality and variability will be linked to southern right whale health and population dynamics by leveraging existing long-term datasets. Individual whales have been identified using natural markings since the 1970s in South Africa (~2000 whales identified) and Argentina (~3200 whales identified), since the 1980s in Brazil (~800 whales identified) and since the 1990s in southwest Australia (~2000 whales identified); DNA profiles have been used in New Zealand since the 1990s (~800 whales identified). Statistical models will be used to understand important correlations between foraging and population dynamics, and potentially provide insight on a global and local scale.
Specific objectives
- Increase our understanding of southern right whale foraging ecology
- Update our knowledge on southern right whale population dynamics in a comparative framework
- Pursue integration of health assessment indicators with long-term monitoring data
- Investigate the impact of climate variation at foraging grounds on population recovery
Collaboration
The project leaders, Dr Emma Carroll and Dr Els Vermeulen, are working with a long list of researchers from these collaborating nations: Argentina, Australia, Brazil, New Zealand, South Africa, and USA.
Associated projects
Circumpolar foraging ecology of southern right whales: past and present – Alex Zerbini’s work
