Comparisons of morphometrics and body condition between two breeding populations of Australian humpback whales

Russell, Grace; Christiansen, Fredrik; Colefax, Andrew; Sprogis, Kate R.; Cagnazzi, Daniele

doi:10.1071/wr23026

Cited by 5 publications

(1 citation statement)

References 81 publications

(142 reference statements)

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“…Comparative studies of body condition in Australian humpbacks have found that adults, particularly lactating females from the west coast population have poorer body condition than their east coast counter parts, with potential links to environmental drivers such as the El Nino Southern Oscillation, Southern Antarctic Mode and Indian Ocean Dipole(Russell et al 2023). While humpback whales in Australia are considered to be recovered and are no longer listed as threatened within Australia (Threatened Species Scienti c Committee 2022), they remain protected as a migratory cetacean species under the EPBC Act.…”

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Increasing evidence of humpback whale calving in the south-west of Western Australia

Jolliffe,

Russell,

McPherson

et al. 2024

Preprint

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An understanding of the spatial and temporal range of marine mammals, and identification of habitats that support critical behaviours is fundamental for effective species management and conservation. The humpback whale, while considered to be recovered within Australian waters, is subject to increasing levels of anthropogenic pressure across its migratory range. Increasing population size, in concert with long term climatic change, is likely to lead to intra and inter-species competition for food resources and habitat. Historically, humpback whales have been known to calf in the Kimberley region, with recent records of calving extending into the Pilbara as far south as Ningaloo Reef, off Exmouth Western Australia. This paper presents empirical evidence of significant numbers of humpback whale calves being born over 1500 km further south in Ngari Marine Park, southwest Western Australia, along their northern migratory route, including live sightings of neonates, deceased strandings of neonate calves and evidence of killer whale predation events. The presence of calving behaviour outside of known calving grounds presents challenges for species conservation and management with effective mitigation and management of anthropogenic pressures contingent on a contemporary understanding of species presence and behaviour. Further, there is considerable concern for the viability of calves this far south on their migratory route where water temperatures are cooler and sheltered areas for resting are more limited.

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confidence: 99%

Increasing evidence of humpback whale calving in the south-west of Western Australia

Jolliffe,

Russell,

McPherson

et al. 2024

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

Evidence of humpback whale calving in south-west Western Australia

Jolliffe,

Russell,

McPherson

et al. 2024

Discov Anim

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An understanding of the spatial and temporal range of marine mammals, and identification of habitats that support critical behaviours is fundamental for effective species management and conservation. The humpback whale (Megaptera novaeangliae), while considered to be recovered in Australian waters, is subject to increasing levels of anthropogenic pressure across its migratory range. Historically, the Western Australian (WA) population has been known to calf in the north-west of WA in the Kimberley region (15–18° S), with recent records of calving extending as far south as Exmouth, Western Australia (21–22° S). This paper presents recent evidence of humpback whale calves being born over 1500 km further south in southwest WA (33–34° S), along their northern migratory route, including live sightings of neonates, and strandings of deceased neonate calves. The presence of neonates outside of known calving grounds presents challenges for species conservation and management with effective mitigation and management of anthropogenic pressures contingent on a contemporary understanding of species presence and behaviour. Further, there is considerable concern for the viability of calves this far south on their migratory route where water temperatures are cooler and sheltered areas for resting are more limited.

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Inferring dolphin population status: using unoccupied aerial systems to quantify age‐structure

Vivier,

Andrés,

Gonzalvo

et al. 2024

Animal Conservation

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Assessing trends in population abundance and demographics is crucial for managing long‐lived and slow‐reproducing species. Obtaining demographic data, and age‐structure information, is challenging, notably for cetaceans. To address this, we combined Unoccupied Aerial System (UAS; drone) photogrammetry data with long‐term (>20 years) photo identification data to assess the age‐structure of the critically endangered sub‐population of common bottlenose dolphins (Tursiops truncatus) of the Gulf of Ambracia, Greece. We compared our findings with two extensively studied non‐endangered bottlenose dolphin populations (T. aduncus in Shark Bay, Australia, and T. truncatus in Sarasota Bay, USA). Using a log‐linear model, we estimated the total body lengths (TL) of 160 known‐aged dolphins between 2021 and 2023 from blowhole‐to‐dorsal‐fin distance (BHDF) measurements collected during surfacing. Subsequently, we tested four growth models to establish an age‐length growth curve. We assessed the sub‐population's age‐structure using three methods: (1) UAS‐derived TL estimates, (2) age‐length growth curve and (3) long‐term monitoring data (i.e. actual age‐structure). UAS‐measured TL (247.6 ± 32.2 cm) and UAS‐estimated TL (246.0 ± 34.7 cm) of the Greek sub‐population showed no differences. The Richards Growth model suggested an asymptotic length of 258.5 cm. In Greece, resulting age‐structure estimates across the three methods revealed no significant differences (P > 0.1). The Gulf of Ambracia and Shark Bay populations shared similar age‐structures, while Sarasota had higher proportions of 2–10 year‐olds and lower proportions of 10+ year‐olds. All populations had a comparable proportion of 0–2 year‐olds (~14%), indicating a similar reproductive rate. Our findings suggest stability in the Greek sub‐population; however, additional monitoring of reproductive parameters is essential before concluding its status. We demonstrated the effectiveness of UAS‐photogrammetry in rapidly quantifying population age‐structure, including scenarios with limited or no demographic data. This technique shows promise for enhancing precision, timeliness, cost‐effectiveness and efficiency in population monitoring and informing timely conservation management decisions.

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Comparisons of morphometrics and body condition between two breeding populations of Australian humpback whales

Cited by 5 publications

References 81 publications

Increasing evidence of humpback whale calving in the south-west of Western Australia

Increasing evidence of humpback whale calving in the south-west of Western Australia

Evidence of humpback whale calving in south-west Western Australia

Inferring dolphin population status: using unoccupied aerial systems to quantify age‐structure

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