Content uploaded by Emma Carroll
Author content
All content in this area was uploaded by Emma Carroll on Jun 01, 2018
Content may be subject to copyright.
A preview of the PDF is not available
SIGHTINGS AND ACOUSTIC RECORDS OF RIGHT WHALES COLLECTED IN SOUTH GEORGIA (ISLAS GEORGIAS DEL SUR) WATERS JANUARY-FEBRUARY 2018
Figures
Figures - uploaded by Emma Carroll
Author content
All figure content in this area was uploaded by Emma Carroll
Content may be subject to copyright.
... The 2018 survey used visual and acoustic survey techniques to locate southern right whales. Poor weather conditions limited survey effort, but southern right whales were regularly sighted in the predominantly coastal survey area to the north of the island (Jackson et al., 2018). In 2019, BAS took part in a CCAMLR synoptic krill survey of the Scotia Arc and Antarctic Peninsula region. ...
... On previous expeditions to SG, southern right whales were observed frequently performing long dives (>10mins), perhaps associated with foraging (Jackson et al., 2018). Therefore, as part of the 2020 expedition, a pole-mounted 200kHZ EK80 echosounder was deployed in the vicinity of southern right whales performing long dives to characterise the local prey field. ...
... Signals were then digitized using a Fireface UFX sound board (RME Inc.) with digital gain control set to 20 dB which equated to a maximum input level of 8.4 V peak-peak. Digitized signals were recorded and processed using PAMGuard (Gillespie et al., 2008), and the DIFAR bearings to calls resolved as described by Miller et al., (2015;, and following the same methodology as Jackson et al., (2018). Calibrated received level measurements of calls were obtained in PAMGuard by following the calibration methods described by Rankin et al., (2019). ...
Over 170,000 whales were killed in the sub-Antarctic waters of South Georgia (Islas Georgias del Sur, SG, South Atlantic) from 1904 to 1965. In recent decades, whales are regular summer visitors, with the southern right whale (Eubalaena australis) and humpback whale (Megaptera novaeangliea) most commonly reported. A 23-day cetacean survey was conducted in SG waters during January/February 2020, using directional acoustics and visual surveys to localise whales, and collecting skin biopsies, faecal samples, photo-identifications, and blow samples for microbiome analysis. The survey focussed on southern right whales (SRW) and also collected sightings, photo-identifications and skin biopsies from other species. A total of 1,147 nautical miles of visual survey effort was conducted, and 4 prey-field surveys (totalling 34 nm) 2 using active acoustics. In total, cetaceans were encountered 540 times (521 encounters in SG waters), including southern right whales (SRW, 10 encounters of 11 individuals), humpback whales (409 encounters, ~790 individuals) and blue whales (Balaenoptera musculus, 38 encounters, ~58 individuals). Two SRW were satellite tagged and their movements subsequently tracked. Photo-identifications and biopsies were collected from southern right (11 and 7 respectively), humpback (48 and 17 respectively) and blue whales (25 and 9 respectively). Aerial imagery was collected via Unmanned Aerial Vehicles (UAVs) during four SRW, with three blow samples also collected. Additionally, one faecal sample was collected from one SRW. Overall, this expedition yielded an unprecedented number of sightings of both blue and humpback whales, suggesting that the waters of SG are once again becoming an important summer feeding ground for both species.
... The Workshop further discussed that while some telemetry studies with an excellent scientific basis can be successful and provide valuable information, the work is often not feasible to carry out due to logistical or geographical constraints. Recent work in South Georgia (Islas Georgias del Sur) provides an example of the difficulties due to the logistical, operational and environmental complexity of the prevailing field area (Jackson et al. 2018). ...
Report of the Workshop. Please use the following citation:
Carroll EL, Charlton C, Vermeulen E, Clarke P and J. A. Jackson (Eds). 2020. Roadmap to success for the International Whaling Commission - Southern Ocean Research Partnership (IWC-SORP) Theme 6 - the Right Sentinel for Climate Change: linking southern right whale foraging ecology to demographics, health and climate: Report of the Workshop. Report SC68B/SH/07 presented to the Scientific Committee of the International Whaling Commission, Cambridge, UK
As species recover from exploitation, continued assessments of connectivity and population structure are warranted to provide information for conservation and management. This is particularly true in species with high dispersal capacity, such as migratory whales, where patterns of connectivity could change rapidly. Here we build on a previous long-term, large-scale collaboration on southern right whales (Eubalaena australis) to combine new (nnew) and published (npub) mitochondrial (mtDNA) and microsatellite genetic data from all major wintering grounds and, uniquely, the South Georgia (Islas Georgias del Sur: SG) feeding grounds. Specifically, we include data from Argentina (npub mtDNA/microsatellite=208/46), Brazil (nnew mtDNA/microsatellite=50/50), South Africa (nnew mtDNA/microsatellite=66/77, npub mtDNA/microsatellite=350/47), Chile-Peru (nnew mtDNA/microsatellite=1/1), the Indo-Pacific (npub mtDNA/microsatellite=769/126), and SG (npub mtDNA/microsatellite=8/0, nnew mtDNA/microsatellite=3/11) to investigate the position of previously unstudied habitats in the migratory network: Brazil, SG and Chile-Peru. These new genetic data show connectivity between Brazil and Argentina, exemplified by weak genetic differentiation and the movement of one genetically identified individual between the South American grounds. The single sample from Chile-Peru had a mtDNA haplotype previously only observed in the Indo-Pacific and had a nuclear genotype that appeared admixed between the Indo-Pacific and South Atlantic, based on genetic clustering and assignment algorithms. The SG samples were clearly South Atlantic, and were more similar to the South American than the South African wintering grounds. This study highlights how international collaborations are critical to provide context for emerging or recovering regions, like the SG feeding ground, as well as those that remain critically endangered, such as Chile-Peru.
During dedicated surveys for the Critically Endangered eastern stock of North Pacific right whales Eubalaena japonica (NPRW) in the Bering Sea, focal follows (FFs) were combined with passive acoustic monitoring to correlate vocal activity with dive behavior. During FFs, impulsive gunshot calls (hereafter 'gunshots'), similar to those produced by other right whale populations, were localized to male and female NPRWs. The timing of gunshots correlated strongly with diving behavior observed during the FFs. Log survivorship analysis of inter-blow intervals showed a bout criterion interval of 40 s, separating the data into shorter surfacings and longer dives. For both, gunshots were skewed closer to the end of the sequence (modal gunshot to blow times: 5 s for dives, 7 s for surfacings) than the beginning (modal blow to gunshot times: 22 s for dives, 13 s for surfacings). Gunshots were more commonly produced during dives than surfacings. Mean gunshot calling rate during FFs was 133.0 calls h⁻¹ (range: 38.9-425.0). Other NPRW calls, including upcalls, the predominant call used to identify right whales acoustically, were not detected during the FFs. To determine comparative call detection rates, an additional 180 h of non-FF recordings were analyzed. Gunshots were detected ~50 times more frequently than upcalls (mean: 228.3 vs. 4.3 calls h⁻¹, respectively), with a maximum gunshot calling rate of 835.7 calls h⁻¹. This is the first study to definitively attribute gunshots to NPRW, and demonstrates the importance of including gunshots in passive acoustic studies, which will greatly increase NPRW detectability while supporting more accurate determinations of their spatio-temporal distribution.
Satellite transmitters were attached to seven southern right whales (Eubalaena australis) in their breeding grounds in Golfo Nuevo, Península Valdés, Argentina, to monitor their movements and migration towards feeding destinations. Fifteen integrated transdermal implanted tags were deployed in juvenile and adult whales. Tag duration varied between 10 and 237 days (average of 90 days). Movement patterns showed substantial individual and yearly variation. Tagged whales visited the outer Patagonian shelf east of Península Valdés and north of the Falkland/Malvinas Islands, the Scotia Sea near South Georgia/Islas Georgia del Sur and the South Sandwich Islands/Islas Sandwich del Sur, and the South Atlantic basin between 38 and 58 o S. State-space models were used to estimate behavioral states and suggested areas of potential foraging importance in the Patagonian shelf, the subtropical convergence and the continental shelf break east of South Georgia/Islas Georgia del Sur. A preliminary investigation of movement patterns relative to oceanographic features indicated that SRWs may be using anti-cyclonic cold eddies in the Subtropical Convergence for foraging. In addition, dive profiles suggest potential differences in how juvenile and adult whales explore the water column.
Quantitatively describing the acoustic repertoire of a species is important for establishing effective passive acoustic monitoring programs and developing automated call detectors. This process is particularly important when the study site is remote and visual surveys are not cost effective. Little is known about the vocal behavior of southern right whales (Eubalaena australis) in New Zealand. The aim of this study was to describe and quantify their entire vocal repertoire on calving grounds in the sub-Antarctic Auckland Islands. Over three austral winters (2010–2012), 4349 calls were recorded, measured, and classified into 10 call types. The most frequently observed types were pulsive, upcall, and tonal low vocalizations. A long tonal low call (≤15.5 s duration) and a very high call (peak frequency ∼750 Hz) were described for the first time. Random Forest multivariate analysis of 28 measured variables was used to classify calls with a high degree of accuracy (82%). The most important variables for classification were maximum ceiling frequency, number of inflection points, duration, and the difference between the start and end frequency. This classification system proved to be a repeatable, fast, and objective method for categorising right whale calls and shows promise for other vocal taxa.
The reproductive success of southern right whale (Eubalaena australis) depends on body condition and, therefore, on foraging success. This, in turn, might be affected by climatically driven change in the abundance of the species main prey, krill (Euphausia superba), on the feeding grounds. Annual data on southern right whale number of calves were obtained from aerial surveys carried out between 1997 and 2013 in southern Brazil, where the species concentrate during their breeding season. The number of calves recorded each year varied from 7 to 43 (x = 21.11 ± 11.88). Using cross-correlation analysis we examined the response of the species to climate anomalies and krill densities. Significant correlations were found with krill densities (r = 0.69, p = 0.002, lag 0 years), Oceanic Niño Index (r = −0.65, p = 0.03, lag 6 years), Antarctic Oscillation (r = 0.76, p = 0.01, lag 7 years) and Antarctic sea ice area (r = −0.68, p = 0.002, lag 0 years). Our results suggest that global climate indices influence southern right whale breeding success in southern Brazil by determining variation in food (krill) availability for the species. Therefore, increased frequency of years with reduced krill abundance, due to global warming, is likely to reduce the current rate of recovery of southern right whales from historical overexploitation.
Directional frequency analysis and recording (DIFAR) sonobuoys can allow real-time acoustic localization of baleen whales for underwater tracking and remote sensing, but limited availability of hardware and software has prevented wider usage. These software limitations were addressed by developing a module in the open-source software PAMGuard. A case study is presented demonstrating that this software provides greater efficiency and accessibility than previous methods for detecting, localizing, and tracking Antarctic blue whales in real time. Additionally, this software can easily be extended to track other low and mid frequency sounds including those from other cetaceans, pinnipeds, icebergs, shipping, and seismic airguns.
To examine the general population trends of large whales in South Georgia waters, 2 opportunistic data sets of sightings of large whales from 1991 to 2010 around South Georgia were analyzed: the South Georgia Museum log of whale sightings and the British Antarctic Survey whale sighting reports from the Bird Island research station. Bird Island abuts the northwest tip of South Georgia. The 4 most reported species in both data sets were southern right whale Eubalaena australis, humpback whale Megaptera novaeangliae, minke whale Balaenoptera bonaerensis, and killer whale Orcinus orca. These totally independent data sets showed comparable changes in abundance through time; thus, despite a lack of sighting effort records, inferences could be drawn about changes in relative abundance. The number of reported sightings per 5 yr period from both data sets increased from the 1991 to 1995 period through the 2001 to 2005 period and has since decreased. Species composition of reported sightings has changed over time; southern right whales have become the most sighted species in both data sets, with a peak of reported sightings in the 2001 to 2005 period. Sightings were concentrated around Shag Rocks, at the northwest tip of South Georgia, and along the north/east coastlines of South Georgia; sightings in the bays around South Georgia have increased over time. In an area such as the Antarctic, which poses many difficulties when conducting research, opportunistic data sources such as these, although not ideal, can become invaluable, since such information would otherwise be unattainable.
In the winters of 1995, 1996 and 1997, research was conducted in the Auckland Islands to evaluate the status of southern right whales inthe New Zealand sub-Antarctic. Whales were present in high concentrations each year (maximum count of 146 whales) in a small area onthe northeast side of the main island. Cow-calf pairs averaged 12% (range 9% to 14%) of the total population. Most cow-calf pairs weresighted resting at the surface (60%) or travelling (36%) and showed a strong preference for shallow ( < 20m depth) nearshore waters. Theratio of females to males, as determined by molecular sexing using biopsy samples, varied from 54% to 39% over the three years but didnot differ significantly from 1:1 in any year. Both males and females were found in varying group sizes, with the occurrence of social/sexualactivity predominant (85%) in groups of three or more whales. Most single whales were found resting (59%) and occasionally approachedthe research vessel (19%). A total of 217 individual whales have been photo-identified over the three years of this study, 24% of which wereresighted more than once in a season and approximately 15% of which were resighted in more than one year. The high density of whalesin Port Ross during winter months, the presence of cow-calf pairs, including newborns, and the frequency of social and sexual activityindicates that the Auckland Islands are a primary wintering habitat for southern right whales in New Zealand waters. However, the lowresighting rates within season and documented movement to nearby Campbell Island (290km) suggest that some whales are not residentin the Auckland Islands throughout the season. The rarity of right whales along the main islands of New Zealand and their apparent increasein numbers in the Auckland Islands suggests a major shift in habitat use from pre-exploitation times or the loss of a component of ahistorically sub-divided stock.
In its current stage of development PAMGUARD provides a powerful, flexible and easy to use program for real time acoustic detection and localisation of cetacean vocalisations that combines the functionality of several previous software products and, in many cases, extends them. Thus PAMGUARD is well positioned to provide the standard tool for PAM during mitigation operations and towed hydrophone surveys. The emphasis of development so far has been mainly on cetacean detection but the software is sufficiently flexible to be used for many other acoustic detection and localisation tasks. Perhaps of most fundamental importance is the programming environment that PAMGUARD offers to developers of new algorithms. The PAMGUARD API largely insulates algorithm developers from data handling tasks, making PAMGUARD an efficient development platform. It is this that promises to ensure PAMGUARD's future as a viable and evolving product as programmers choose it as an efficient environment in which to develop new PAM functionality. To date, PAMGUARD has primarily been developed to handle acoustic data. Many mitigation and survey applications combine both visual and acoustic data. The PAMGUARD API has been designed in such a way that it can be easily extended to handle visual data in the future. Clearly having both visual and acoustic data together within the same piece of software should greatly assist in the smooth running of both mitigation and survey applications. Results from field trials indicate that PAMGUARD can provide useful real time information on the locations of whales in the vicinity of a moving vessel. However, not all whales vocalise all of the time, so PAM cannot be considered as a 100% effective method for detecting cetaceans.