Knowledge of Antarctic blue whales (Balaenoptera musculus intermedia) remains severely lacking, despite being true “ocean giants” (the largest animals on the planet). This charismatic sub-species was heavily exploited by 20th century whaling and is currently classified as “Critically Endangered” by the IUCN, with less than 3,000 individuals estimated alive in the 1990s. This species seasonally migrates to low-latitude oceanic breeding grounds which are also poorly understood and may span vast oceanic areas. The breeding areas and population abundance of historically abundant Southern Hemisphere fin whales (Balaenoptera physalus quoyi), are also poorly understood despite recent observations of large aggregations in the Scotia Arc and northern Antarctic Peninsula.
Obtaining information on the population biology, distribution and seasonal abundance of these rare and wide-ranging pelagic species is extremely difficult and costly; the International Whaling Commission undertook circumpolar summer surveys of the Southern Ocean between 1979 and 2010, but there have been no circumpolar-scale surveys since. Consequently, the last Antarctic blue whale abundance estimate is now ~30 years old.
Antarctic blue whales are important indicators of oceanic productivity, preferentially targeting productive feeding areas. Available data suggest Antarctic blue whales may aggregate close to the Southern Boundary of the Antarctic Circumpolar Current, Antarctic coast, and sub Antarctic waters in the SW Atlantic, likely associated with dense Antarctic krill aggregations. Fin and blue whales co-occur in some areas, including Ross Sea and southern Scotia Arc, potentially foraging on dense krill aggregations near the ice edge.
From a conservation perspective, the return of Antarctic blue whales to previously frequented areas presents a critical opportunity to understand the habitats that support this globally rare and poorly understood giant. Surveys in the Southern Ocean and at lower latitudes, combined with oceanographic assessments of their habitats and prey, are essential to underpin management recommendations for protection of their population and migratory ranges, particularly given the increasingly concentrated fishery for Antarctic krill. Additionally, Antarctic blue whale surveys often result in encounters with fin whales, providing valuable opportunities to compare the distributions, oceanographic and prey-related drivers of these krill-feeding species.
Passive acoustic tracking, following low-frequency underwater sounds produced by Antarctic blue whales, is a highly reliable means of finding and studying this rarely encountered species. Photo-identification of individual animals provide a pragmatic approach to obtain a new abundance estimate of blue whales using mark-recapture methods (e.g. Olson et al., 2025).
Antarctica InSync provides a very timely opportunity for the international community to collect sightings and photo-identification data while conducting coordinated research across the Southern Ocean using standard protocols. This initiative aims to estimate circumpolar blue whale abundance, habitat use, migratory routes, and prey consumption rates. The work proposed here aligns closely with the objectives of the Theme 4 ‘Improving knowledge and protection of the unique Antarctic life’, which aims to capture biodiversity through a comprehensive assessment of Antarctic life, combining traditional surveys with new technologies, providing the foundation for conservation and management strategies.
The aims of this project are to address knowledge gaps that are critical to conservation of Antarctic blue whales, and understanding their role in Southern Ocean trophic systems.
Our primary project aim is to estimate Antarctic blue whale abundance at the circumpolar scale, providing an up-to-date measure of the recovery of this iconic sub-species from whaling.
Our secondary aims are:
Integrating these datasets will substantially improve our understanding of Antarctic blue whale migration, behaviour, and health, thereby supporting the development of more effective conservation and management strategies. These outcomes will be advanced through our strong linkages with the International Whaling Commission (IWC), Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and the Scientific Committee for Antarctic Research (SCAR) as well as national governments.
We will contribute estimates of area-specific krill consumption rates for Antarctic blue (and possibly fin) whales for inclusion in CCAMLR’s Spatial Overlap Analysis, as part of its Krill Fishery Management Approach to set krill catch limits (SC-CAMLR 2025). We will advise the IWC Scientific Committee on new estimates of blue whale abundance and population structure for assessment of Antarctic blue whale recovery. We will also inform Marine Protected Area (MPA) proposals and reviews, including the Ross Sea regional MPA, and the developing nexus between CCAMLR, IWC and the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement).
Antarctic blue whale, opportunistically also Southern Hemisphere fin whale. To help guide targeted work during the 2028 focal survey period, the Australian Antarctic Division are conducting some exploratory analysis in Jan-Feb 2026, using available cetacean survey and sightings data from the last three decades in the Southern Ocean, to identify potential hotspots where dedicated survey effort would be most valuable.
Work to be conducted from survey vessels or platforms of opportunity:
Where researchers have access to small boats for working close to whales:
Expedition vessels and other platforms of opportunity:
We will engage closely with the International Association of Antarctic Tour Operators (IAATO) to identify opportunities for on-board vessel surveys and (where possible) small-boat work, allowing cruise companies and their staff to introduce and engage Antarctic visitors to whale science. In particular, outreach material and citizen science engagement underpins this initiative. Photo-ID images will be submitted to the project through online photo repositories Happywhale and the IWC’s Southern Hemisphere blue whale catalogue (SHBWC), who are closely engaged with the development of this project.
This working group has close links with a number of existing initiatives, as members of this group are also part of the SCAR Expert Group on Birds and Marine Mammals (EGBAMM), International Whaling Commission (IWC) Scientific Committee and CCAMLR Scientific Committee. The aims of this project closely align with the objectives of the new EGBAMM Working Group on Cetaceans at SCAR, and the photo-ID based abundance estimate will deliver an important outcome for updating the global assessment of Antarctic blue whale recovery from whaling for the IWC.
We anticipate generating the following project deliverables:
| Timeframe | Task |
|---|---|
| Regular meetings | We hold update meetings via Zoom every two months, with minutes recorded and circulated to participants and stakeholders. Once the project has been launched as an Insync WG, we will publish quarterly progress updates on our project website and provide regular updates to SCAR and IWC (see Section 9). |
| 2026 | We will be seeking funding for this project throughout 2026, with a website launch planned early in 2026, followed by media campaigns by our member institutes across multiple countries, to build community and funder interest in supporting and participating in this project. Scientifically, exploratory data analysis will be conducted by the Australian Antarctic Division in the first quarter of 2026 to identify potential blue whale hotspots where we can dedicate particular fundraising effort. Throughout 2026 we will engage closely with vessel operators to identify vessels available to participate in this project (both dedicated vessels, IAATO expedition ships and participating Insync vessels), and raise funds for dedicated charter vessels for small boat work. We will conduct exploratory cruises with IAATO cruise operators to develop common and achievable protocols |
| 2027 | During this year, we will conduct dedicated voyage planning for the 2027/28 Antarctic summer season: purchasing, sharing and shipping equipment, contracting personnel and finalising survey protocols. There will be regular engagement with IAATO leadership throughout this year, preparing outreach materials to support expedition vessels in contributing to the project with photo-ID of blue whales. These outreach materials will also be circulated to all vessels travelling to the Southern Ocean in the 2027/28 summer season that agree to participate in this study. We will also support related, lower-latitude studies of Antarctic blue whales on migration towards the Southern Ocean (e.g. from September to October 2027), including satellite tracking of whales migrating into Southern Ocean waters to measure habitat use, skin biopsy to identify sex and genetic identity of animals and UAV photogrammetry to measure body condition prior to the feeding season. |
| 2028 | Coordinated research voyages will take place around the Southern Ocean, with support (and in some cases expert personnel and equipment) also provided to participating IAATO expedition vessels from Nov 2027 to March 2028. Work will include: passive acoustics to detect and locate whales, photo-ID and quantitative observations of blue whale occurrence and respiration rates, satellite tagging individuals, collecting skin biopsies to identify sex, genetic identity, pregnancy status, and diet, UAV overflights to collect photogrammetry data on body mass and condition, surveys of the prey field (prey type, swarm density and size) in the vicinity of feeding blue (and potentially also fin) whales, deploying suction cup tags where feasible to investigate fine-scale feeding behaviour. We will also support related, lower-latitude studies of Antarctic blue whales on migration towards their breeding grounds during May to October 2028, to better understand wintering habitat, identify sex and genetic identity of animals at lower latitude sites and collect UAV photogrammetry data on body condition after the feeding season. For the remainder of 2028, equipment will be shipped back to countries of origin, samples will be processed and datasets compiled. Sightings, passive acoustic, and photo-ID data will be made open access via GBIF, Happywhale and the Southern Hemisphere blue whale catalogue, respectively. Data analysis will begin in October 2028. |
| 2029 | Data analysis will be conducted to measure Antarctic blue whale habitat use, identify individuals, their pregnancy status and sex, body mass gain and krill consumption rates, and estimate abundance using mark recapture. Research results from this work will be provided to the CCAMLR and IWC Scientific Committees in 2029 and 2030. |
