East Australian Humpback Whales Research Articles

Australia's east coast humpback whales: Satellite tag-derived movements on breeding grounds, feeding grounds and along the northern and southern migration.

Satellite tags were deployed on 50 east Australian humpback whales (breeding stock E1) between 2008 and 2010 on their southward migration, northward migration and feeding grounds in order to identify and describe migratory pathways, feeding grounds and possible calving areas. At the time, these movements were not well understood and calving grounds were not clearly identified. To the best of our knowledge, this dataset details all long-term, implantable tag deployments that have occurred to date on breeding stock E1. As such, these data provide researchers, regulators and industry with clear and valuable insights into the spatial and temporal nature of humpback whale movements along the eastern coastline of Australia and into the Southern Ocean. As this population of humpback whales navigates an increasingly complex habitat undergoing various development pressures and anthropogenic disturbances, in addition to climate-mediated changes in their marine environment, this dataset may also provide a valuable baseline. At the time these tracks were generated, these were the first satellite tag deployments intended to deliver long-term, detailed movement information on east Australian (breeding stock E1) humpback whales. The tracking data revealed previously unknown migratory pathways into the Southern Ocean, with 11 individuals tracked to their Antarctic feeding grounds. Once assumed to head directly south on their southern migration, five individuals initially travelled west towards New Zealand. Six tracks detailed the coastal movement of humpback whales migrating south. One tag transmitted a partial southern migration, then ceased transmissions only to begin transmitting eight months later as the animal was migrating north. Northern migration to breeding grounds was detailed for 13 individuals, with four tracks including turning points and partial southern migrations. Another 14 humpback whales were tagged in Antarctica, providing detailed Antarctic feeding ground movements.Broadly speaking, the tracking data revealed a pattern of movement where whales were at their northern limit in July and their southern limit in March. Migration north was most rapid across the months of May and June, whilst migration south was most rapid between November and December. Tagged humpback whales were located on their Antarctic feeding grounds predominantly between January and May and approached their breeding grounds between July and August. Tracking distances ranged from 68 km to 8580 km and 1 to 286 days. To the best of our knowledge, this dataset compiles all of the long-term tag deployments that have occurred to date on breeding stock E1.

Humpback Whales Have Super Feeding Events in Australian Waters

Each year, the east Australian humpback whale population migrates between their Antarctic feeding grounds, where they spend the summer feeding, to their sub-tropical breeding grounds, where they give birth. Historically, this population was once hunted in both Antarctica and off Australia, however, since whaling ended in the early 1960s, this population has continued to recover. As the population continues to grow, we may now be witnessing “new” behaviors. For the first time, scientists have footage of humpback whales bubble-net feeding and feeding in “super-groups” of 20+ whales in Australian waters. This footage was collected by citizen scientists—regular citizens who help scientists monitor this whale population. These feeding observations are important for understanding how this whale population is changing—not just in numbers but also behaviors—and what we can do to protect whale populations into the future.

Sighting records of “Migaloo” the white humpback whale provide evidence of Australian site fidelity and use of New Zealand waters as a migratory route

ABSTRACT Observations of an all-white humpback whale (Megaptera novaeangliae) along the Australian east coast were first made in 1991 off Byron Bay, Australia. Genetic analysis of tissue samples collected from this individual confirmed this whale to be male and lacking pigmentation as a result of albinism. While there are observations of other predominately white humpback whales, this individual is the only known true white (albino) humpback whale in the Australian east coast population. Due to his unique appearance, this individual has since become known as “Migaloo”, which is a First Nations meaning for “white fella”. In this short note we present the first extensive sighting history of Migaloo collected via scientific and citizen science efforts. This provides evidence of Migaloo’s presence in both Australian and New Zealand waters confirmed through photographic evidence and genetic testing. We also detail gaps in sighting history and highlight variability in the east Australian humpback whale population migration. The collective annual effort to document Migaloo’s presence along the Australian east coast is a unique opportunity to connect a wide community of scientists and non-scientists through whale research. It also highlights variability in whale movement geographically and the potential impact changing oceans might have on this in the future.

Body condition and migration timing of east Australian humpback whales

In order to exploit seasonally favourable habitats for feeding and breeding, humpback whalesMegaptera novaeangliaeundertake one of the longest migrations in the animal kingdom. Stored energy is crucial for a successful migration, but few studies have investigated the relationship between migration timing and body condition in baleen whales. Using unmanned aerial vehicles, we quantified the body condition of east Australian humpback whales. We collected data on 513 individuals (48 calves, 166 juveniles, 251 adults, and 48 lactating females) during their northbound and southbound migrations between June and October 2020. For adults and juveniles, we explored the loss of body condition between migration direction (north versus south) as well as the relationship of migration timing (day of year) and body condition. We found a significant loss in body condition between the northbound and southbound migrations for both adults (9.8%) and juveniles (18.3%). However, migration timing did not influence body condition for either reproductive class. Cow/calf pairs were analysed using relative calf length (percentage of maternal length) as a proxy for days postpartum. We found a positive curvilinear relationship between migration timing and calf body condition. However, lactating females showed no relationship between migration timing and body condition. Whilst body condition is important for capital breeding whales, the lack of a correlation found for adults and juveniles suggests that body condition is not the main driver of migration timing from feeding or breeding grounds. However, calf body condition may be a significant factor for the migration timing of cow/calf pairs.

First evidence of bubble‐net feeding and the formation of ‘super‐groups’ by the east Australian population of humpback whales during their southward migration

Abstract The recovery of overexploited populations is likely to reveal behaviours that may have been present prior to harvest but are only now reappearing as the population size increases. The east Australian humpback whale (Megaptera novaeangliae) population (group V, stock E1) has recovered well from past exploitation and is now estimated to be close to the pre‐whaling population size. Humpback whales were thought to follow a ‘feast and famine’ model historically, feeding intensively in high‐latitude feeding grounds and then fasting while migrating and in calving grounds; however, there is growing evidence that animals may feed outside of known foraging grounds. This short article reports on the first photographically documented evidence of bubble‐net feeding by humpback whales in Australian coastal waters (n = 10 groups observed) and provides the first evidence of a second site in the southern hemisphere for the formation of ‘super‐groups’ (n = 6 super‐groups at discrete locations). The formation of super‐groups may be linked to changes in the type or density of prey available, either along the migratory route or in the feeding grounds of the previous summer. It is also possible that the increased population size following recovery make large group sizes while feeding more common. These findings strongly support evidence that feeding behaviour is not restricted to high‐latitude foraging grounds in the Southern Ocean, and that prey consumption prior to leaving the coastal waters of Australia may be a significant component of the migratory ecology of this population. Understanding how environmental variation influences the extent to which humpback whales depend on foraging opportunities along their migratory route, and where feeding occurs, will help to predict how future changes in the ocean will influence whale populations. This will also allow for more effective management measures to reduce the impact of threats during this important period of energy consumption.

Respiratory microbiota of humpback whales may be reduced in diversity and richness the longer they fast

Humpback whales endure several months of fasting while undertaking one of the longest annual migrations of any mammal, which depletes the whales’ energy stores and likely compromises their physiological state. Airway microbiota are linked to respiratory health in mammals. To illuminate the dynamics of airway microbiota in a physiologically challenged mammal, we investigated the bacterial communities in the blow of East Australian humpback whales at two stages of their migration: at the beginning (n = 20) and several months into their migration (n = 20), using barcoded tag sequencing of the bacterial 16S rRNA gene. We show that early in the fasting the whale blow samples had a higher diversity and richness combined with a larger number of core taxa and a different bacterial composition than later in the fasting. This study provides some evidence that the rich blow microbiota at the beginning of their fasting might reflect the whales’ uncompromised physiology and that changes in the microbiota occur during the whales’ migration.

Adult female-calf acoustic communication signals in migrating east Australian humpback whales

ABSTRACT Humpback whale (Megaptera novaeangliae) calf survival during migration is dependent upon them maintaining contact with their mothers, and acoustics likely plays a significant role in this. Here, we analysed calls (n = 255) produced by migrating humpback whale adult female-calf pairs (n = 15) off the east coast of Australia. First, we identified nine common call types that were then quantitatively separated into two distinct clusters. One cluster contained calls that were considerably longer in duration, lower in frequency, and narrower in bandwidth than those in the second cluster. These are proposed to have been produced by the adult females and calves, respectively. We then compared acoustic features within presumed age class. Minimum, peak, and maximum frequencies were significantly different across both adult females and calves (Kruskal-Wallis, p < 0.05), suggesting that their calls encode socially relevant information regarding physical signaller attributes (i.e. age and body size). This study established a baseline adult female-calf call repertoire produced during the migration of east Australian humpback whales. Potential vocal masking from anthropogenic noise is of particular concern for communications between adult females and their calves, as it may put calves at risk of becoming separated from their mothers.

Quantifying Ship Strike Risk to Breeding Whales in a Multiple-Use Marine Park: The Great Barrier Reef

Spatial risk assessments are an effective management tool used in multiple-use marine parks to balance the needs for conservation of natural properties and to provide for varying socio-economic demands for development. The multiple-use Great Barrier Reef Marine Park (GBRMP) has recently experienced substantial increases in current and proposed port expansions and subsequent shipping. Globally, large whale populations are recovering from commercial whaling and ship strike is a significant threat to some populations and a potential welfare issue for others. Within the GBRMP there is spatial conflict between the main breeding ground of the east Australian humpback whale population which overlaps the main inner shipping route that services several large natural resource export ports. The east coast humpback whale population is one of the largest humpback whale populations globally, exponentially increasing (11% per annum) close to the maximum potential rate and estimated to reach pre-exploitation population numbers in the next 4-5 years. We quantify the relative risk of ship strike to calving and mating humpback whales, with areas of highest relative risk coinciding with areas offshore of two major natural resource export ports. We found females with a dependent calf had a higher risk of ship strike compared to groups without a calf and their inshore movement and coastal dependence later in the breeding season increases their overlap with shipping although their lower relative abundance decreases risk. The formalisation of a two-way shipping route has provided little change to risk and projected risk estimates indicate a three- to five-fold increase in risk to humpback whales from ship strike over the next ten years. Currently, the whale Protection Area in the GBRMP does not cover the main mating and calving areas, whereas provisions within the legislation for establishment of a Special Management Area during the peak breeding season in high risk areas could occur. A common mitigation strategy of re-routing shipping lanes to reduce risk is not a viable option for the GBRMP due to physical spatial limitations imposed by the reef, whereas speed restrictions could be the most feasible based on current ship speeds if mitigation were deemed necessary.

A current affair: entanglement of humpback whales in coastal shark‐control nets

AbstractShark‐control nets pose an entanglement risk to East Australian humpback whales during their annual northward and southward migrations between the Southern Ocean and the Coral Sea. Rates of whale entanglement exhibit seasonal and interannual variation, suggesting that an understanding of the influence of variability in the broad‐scale physical environment along the migratory route would be useful in assessing risk of entanglement. This study provides a quantitative spatio‐temporal analysis of the probability of whale entanglement in shark‐control nets relative to the position and characteristics of the East Australian Current (EAC), the dominant oceanographic feature of the region. We use satellite‐derived sea‐surface temperature, and outputs from a data‐assimilating ocean model, to develop multivariate, data‐driven algorithms for detecting the edge of the EAC using Principal Components Analysis. We use outputs from these algorithms to model the likelihood of humpback entanglements in South‐east Queensland. We find that the likelihood of entanglement increases when the EAC edge is locally less structured and closer to shore in the vicinity of the corresponding net, or when the EAC is well resolved over the entire study domain. Our results suggest that migrating humpbacks use the gradient in physical characteristics that marks the EAC inner edge as a navigational aid. Thus, when the EAC inner edge encroaches on the coast, the whales’ migration range is compressed into nearshore waters, increasing the risk of entanglement. Our findings can help predict periods of elevated entanglement risk, which could underpin a more data‐driven approach to the management of shark‐control programs, and other activities that involve static fishing gear.

Presence of newborn humpback whale (Megaptera novaeangliae) calves in Gold Coast Bay, Australia

ABSTRACTThe majority of humpback whales (Megaptera novaeangliae) undertake an annual migration from high latitude feeding grounds to tropical/subtropical breeding grounds. Suitable calving habitat for this species includes warm (typically 19°C to 28°C), shallow, sheltered waters in tropical and subtropical waters. Here, we investigated occurrence of calving beyond the primary recognised breeding grounds (16° to 24°S) of the east Australian humpback whale population (E1). We examined location, depth (m), and SST (⁰C) associated with newborn observations in Gold Coast Bay, in southern Queensland, Australia from 2013 to 2016. A total of 74 newborns were recorded in the study area, with the majority observed in July and August. These findings may signify that the Gold Coast Bay provides an apparently suitable habitat for calving for this humpback whale population. As the area has not been classified as calving habitat, these findings will assist conservation managers in making informed management decisions regarding this species.

Distribution patterns of east Australian humpback whales (Megaptera novaeangliae) in Hervey Bay, Queensland: a historical perspective

Tourism activities are expanding in both terrestrial and marine environments, which can have detrimental effects on the target species. Balancing the amount of disturbance a population of animals receives against the educational value of tourism requires localised research and adaptive management. This study examined the distribution of humpback whales within Hervey Bay, Queensland, using data spanning 2004–16, just before the implementation of a commercial ‘swim-with-whales’ program. Spatial and temporal patterns of humpback whale calves were of particular interest given that they are more vulnerable to human-related disturbances than other group types. We found that humpback whales displayed a distinct spatial segregation in Hervey Bay based on pod composition. Most whales displayed a residency time of two to three days, with females having a somewhat shorter residency time than males. These findings suggest that humpback whales in Hervey Bay not only display temporal segregation dependent on maturation and reproductive status, but fine-scale spatial distribution based on pod composition. Understanding habitat preference and patterns of habitat use of humpback whales in Hervey Bay is critical for effective management of the newly sanctioned swim-with-whale tourism in Hervey Bay and the sustained recovery of humpback whales in this region.

Using self-organizing maps to classify humpback whale song units and quantify their similarity

Classification of vocal signals can be undertaken using a wide variety of qualitative and quantitative techniques. Using east Australian humpback whale song from 2002 to 2014, a subset of vocal signals was acoustically measured and then classified using a Self-Organizing Map (SOM). The SOM created (1) an acoustic dictionary of units representing the song's repertoire, and (2) Cartesian distance measurements among all unit types (SOM nodes). Utilizing the SOM dictionary as a guide, additional song recordings from east Australia were rapidly (manually) transcribed. To assess the similarity in song sequences, the Cartesian distance output from the SOM was applied in Levenshtein distance similarity analyses as a weighting factor to better incorporate unit similarity in the calculation (previously a qualitative process). SOMs provide a more robust and repeatable means of categorizing acoustic signals along with a clear quantitative measurement of sound type similarity based on acoustic features. This method can be utilized for a wide variety of acoustic databases especially those containing very large datasets and can be applied across the vocalization research community to help address concerns surrounding inconsistency in manual classification.

Creation of an acoustic dictionary to classify the vocal repertoire of humpback whale song

Animal vocal repertoires can be varied and complex, and it is often difficult to obtain a comprehensive picture. One of the primary reasons for this difficulty stems from the classification of acoustic signals, which has typically relied on qualitative and subjective methods. Vocal signals (units) were measured from east Australian humpback whale song from 2002-2014 and classified using self-organising maps (SOM). Humpback song was used here to provide an example of a particularly complex display of vocal signals. The use of SOM methodology takes an important step towards a more objective classification system. The resulting classifications were used to create a set of 149 hypothetical “exemplar” units to serve as an acoustic dictionary, representing the song’s repertoire. The intent is to use this dictionary to determine vocal repertoire, as well as to facilitate the transcription and sequential analysis of large numbers of recordings with only a small representative subset of units requiring intensive acoustic feature measurement. Acoustic dictionaries are integral to studies of information content, microstructure, and syntax, and this methodology is thus applicable across the vocalization research community.

Coastal Fronts Utilized by Migrating Humpback Whales, Megaptera novaeangliae, on the Gold Coast, Australia

ABSTRACT Reinke, J.; Lemckert, C., and Meynecke, J.-O., 2016. Coastal fronts utilised by migrating humpback whales, Megaptera novaeangliae, on the Gold Coast, Australia. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 552–556. Coconut Creek (Florida), ISSN 0749-0208. Large-scale migration patterns of humpback whales, Megaptera novaeangliae, are quite well known; however, small-scale distribution patterns and relationships with environmental conditions have received less attention. Protection from a range of threats, as well as predicting the effects of climate change, requires knowledge of preferred habitat and environmental conditions. East Australian humpback whales travel from the Southern Ocean towards the Great Barrier Reef to breed. The East Australian coastal environment is dominated by the East Australian Current that carries warm water po...

Effect of prey type on the fine-scale feeding behaviour of migrating east Australian humpback whales

For terrestrial migrants, feeding at migratory stopover sites is important, with prey quality linked to future survival and reproductive success. In contrast, the importance of this behaviour to marine species is unknown. The humpback whale Megaptera novaeangliae is a marine migrant that is thought to fast while migrating; however, recent studies suggest that feeding may occur during this time. The aims of this study were to determine how the prey type available on a migratory route off Eden, New South Wales, Australia, influenced whether whales fed or not, and to study the fine-scale behaviour of the whales. Digital acoustic recording tags (DTAGs) and focal follows were used to record whale behaviour. A larger proportion of groups were determined to be feeding when krill was observed at the surface. Whales encountering fish spent a small percentage (28%) of time feeding, behaving similarly to non-feeding whales on migration, with small groups, a higher proportion of males sampled, and relatively straight tracks. In contrast, whales encountering surface swarms of krill spent significantly more time feeding (92%) and behaved similarly to whales on feeding grounds, with larger groups, more females sampled, and tracks with high turning angles. Therefore, changes in the available prey type in - fluenced the amount of time spent feeding and the social dynamics of groups. Given the link between the amount of feeding completed on migration and the future survival and reproductive success of individuals in terrestrial species, the impact of such fluctuations on marine species such as the humpback whale deserves more attention.

Distribution patterns of migrating humpback whales (Megaptera novaeangliae) in Jervis Bay, Australia: A spatial analysis using geographical citizen science data

Increases in east Australian humpback whale populations, specifically in areas where sightings were previously infrequent, highlight the importance of understanding the usage patterns and habitat preferences for resting grounds along migration pathways. This study investigates the spatio-temporal distribution of humpback whales in Jervis Bay, Australia, based on pod composition, providing insight on the role of this shallow coastal embayment for mother-calf pods during the southern migration to polar feeding grounds. Geographical citizen science-based sighting data, collected from a commercial whale-watch platform during the 2007–2010 migration seasons, were used to examine variations in bay usage and pod composition. Differences in the distribution patterns of mother-calf and non-calf pod sightings were examined using spatial cluster analysis. The impact of sampling bias, introduced through non-specialist volunteer collected data, on spatial cluster detection was simulated. Observation error and spatial sampling bias may affect local spatial cluster detection. Sampling processes with potential to contribute to this bias should be recorded in the survey design of geographical citizen science based data collection programmes. Mother-calf pods showed a significant preference for the shallow waters of Jervis Bay during October and November, indicating the bay may function as a preferred resting location during their southern migration with important marine management implications.

Remote Antarctic feeding ground important for east Australian humpback whales

Understanding the dynamics of population recovery is particularly complex when an organism has multiple, remote breeding and feeding grounds separated by one of the longest known migration routes. This study reports on the most comprehensive assessment of humpback whale (Megaptera novaeangliae) movements between remote Antarctic waters south of New Zealand and east Australia (EA), and the migratory corridors and breeding grounds of Australia and Oceania. A total of 112 individual whales were identified; 57 from microsatellites and 61 by fluke with 23 % (n = 26) matched to sites outside Antarctica. Despite large datasets from other southern regions being included in the comparison, the whales were predominantly linked to EA (n = 24). Only two matches to the Oceania catalogues directly north was surprising; therefore the primary feeding grounds of these endangered whales still remain unknown. The confirmation of the Balleny Islands as an important feeding ground for EA whales could provide an insight into reasons behind the rapid recovery of this population. Determining the feeding grounds of Oceania’s whales may explain whether prey energetics or migration length are limiting factors to their recovery and will allow an understanding of future ecosystem changes in these whales.

Temporal stability and change in the social call repertoire of migrating humpback whales

Quantifying the stability of a species vocal repertoire is fundamental for further investigations into repertoire function and geographic variation. Changes to the repertoire of sounds used in the song displays of male humpback whales have been well studied. In contrast, little is known about the stability of this species' non-song vocal calls. The stability of the social call repertoire of east Australian humpback whales was investigated from 1997, 2003-2004, and 2008. Out of 46 qualitatively defined call types, 19 were classified as "song-unit calls" that tended to change with the song, and 15 were "inconsistent" and only found in one or two years. Twelve call types were "stable" and present in all years and were commonly produced (64.2% of calls). Stable calls tended to vary in some of the measured call parameters but there was no clear trend between years. This result could indicate that minor changes to calls are not permanent, but reflect individual differences in call production or the graded nature of calls within different social environments. This research has clearly identified stable calls in the call repertoire of humpback whales and while their function is not well understood, their stability suggests an important role in social interactions.

The social vocalization repertoire of east Australian migrating humpback whales (Megaptera novaeangliae)

Although the songs of humpback whales have been extensively studied, other vocalizations and percussive sounds, referred to as "social sounds," have received little attention. This study presents the social vocalization repertoire of migrating east Australian humpback whales from a sample of 660 sounds recorded from 61 groups of varying composition, over three years. The social vocalization repertoire of humpback whales was much larger than previously described with a total of 34 separate call types classified aurally and by spectrographic analysis as well as statistically. Of these, 21 call types were the same as units of the song current at the time of recording but used individually instead of as part of the song sequence, while the other 13 calls were stable over the three years of the study and were not part of the song. This study provides a catalog of sounds that can be used as a basis for future studies. It is an essential first step in determining the function, contextual use and cultural transmission of humpback social vocalizations.

Levels and probable origin of predatory scarring on humpback whales (Megaptera novaeangliae) in east Australian waters

To investigate the incidence of non-lethal predation in Southern Hemisphere whales, more than 3400 fluke-identification photographs from resight histories of 1436 east Australian humpback whales were examined for evidence of predatory markings. Photographs were obtained from 1984 to 1996 at various locations along the east coast of Australia, from northern Queensland to southern New South Wales. Photographs were classified in terms of the level and type of scarring. The possible predator and whether the markings appeared fresh were also noted. In all, 17% of identified east Australian humpbacks possessed some form of predatory scarring, 57% of which was minor and 43% major. Almost all predatory scarring was consistent with that inflicted by killer whales. Only three whales demonstrated an increase in the level of predatory scarring after their first sightings. Two incidents of fresh scarring were recorded, and one fatal killer whale attack on a humpback whale calf was directly observed. The overall level of predatory scarring found in this study is comparable to those found in studies for Northern Hemisphere humpback whales. The low incidence of adult whales showing their first sign of predatory scarring after their initial sighting, and the small number possessing recent scarring, support the idea that east Australian humpback whales experience most predatory attacks early in life.