Luciana M. Möller

Understanding population demographics is crucial for the effective conservation of species. This is particularly important for apex predators, such as the killer whale ( Orcinus orca ), which play important roles in maintaining the structure and function of ecosystems. In this study, we used capture‐mark‐recapture (CMR) modeling to assess killer whale demographics at two distinct aggregation sites in Western Australia: the Ningaloo Reef (NW) and Bremer Sub‐basin (SW). Using 12 years of photo‐identification (photo‐ID) data from the NW and 6 years from the SW, we applied open population models (POPAN and Cormack–Jolly–Seber) to estimate the abundance ( N _total ), apparent survival ( Phi ), capture probability ( p ), and probability of entry ( pent ) of killer whales inhabiting these key areas. Abundance estimates in the NW, which combined females, males, and individuals of unknown sex ( N _total = 47 ± 2, 95% CI = 43–52), revealed a small, well‐marked, and frequently resighted population with high apparent survival ( Phi _female = 0.98 ± 0.016, 95% CI = 0.91–0.99; Phi _male = 0.88 ± 0.060, 95% CI = 0.71–0.96; Phi _unknown = 0.82 ± 0.064, 95% CI = 0.66–0.92). In contrast, abundance estimates in the SW, which separated sexed adults ( N _total = 102 ± 7, 95% CI = 88–117) from the unknown sex group, suggested a much larger and more transient population with variable apparent survival ( Phi _female = 0.98 ± 0.001, 95% CI = 0.97–0.98; Phi _male = 0.82 ± 0.012, 95% CI = 0.79–0.84; Phi _unknown(T) = 0.65 ± 0.177, 95% CI = 0.29–0.90; Phi _unknown(R) = 0.84 ± 0.185, 95% CI = 0.26–0.99). Variation in population demography between the two study areas likely reflects divergent ecological and evolutionary histories shaped by both genetic and environmental factors. Additionally, differences in habitat accessibility, individual distinctiveness, and sampling design may have influenced detectability and model outcomes. These results provide vital baseline demographic data for killer whales in Australian waters and highlight the need for standardized long‐term monitoring to inform conservation management strategies.

Introduction: Social structure plays a crucial role in shaping the transmission dynamics of infectious diseases within animal populations, yet its influence remains understudied in marine mammals. Aims: This review investigates links between marine mammal sociality and disease vulnerability, focusing on social network metrics and their influence on disease transmission. The study aimed to (1) identify patterns in disease transmission, (2) map gaps in current knowledge to inform strategic directions for future investigation and (3) discuss implications for conservation and disease management. Methods: Through systematic database searching, 14 studies were identified that investigated social network metrics and their influence on disease transmission in marine mammal social networks. Results: Results show that stronger associations and greater social connectivity increase disease prevalence, although this relationship varied across species. Central individuals acted as ‘super‐spreaders’, facilitating disease spread to conspecifics and vaccination efforts targeting these individuals are a recurrent proposed mitigation strategy. At the population level, network fragmentation reduced disease burden, while highly connected subgroups facilitated pathogen transmission. Research is concentrated on few key species, revealing significant gaps in taxonomic and geographic representation. Additionally, studies were geographically biased toward North America and Australia, with limited collaboration across research clusters, highlighting the need for broader representation and interdisciplinary partnerships. Conclusion: These findings underscore the need for interdisciplinary approaches integrating epidemiological modelling, social network analysis and conservation strategies to better predict and mitigate disease risks in marine mammal populations. Future research should expand species coverage and incorporate ecological and environmental variables to develop targeted disease management frameworks.

Understanding wildlife distribution is essential for identifying critical habitats, monitoring responses to environmental change and informing conservation strategies. We used long‐term sighting data (1993–2020) and generalised additive modelling (GAM) to quantify and characterise the long‐term spatiotemporal distribution of Indo‐Pacific bottlenose dolphins ( Tursiops aduncus ) in South Australia's urbanised Adelaide Dolphin Sanctuary (ADS). The top‐performing GAM indicated that dolphin presence was influenced by spatial (latitude and longitude) and temporal (year) variables, with seasonal variation in these relationships. Dolphin presence increased from 1993 to the early 2000s, with high probabilities of occurrence maintained over the last decade. Although some inter‐annual variability was evident, no clear long‐term decline was observed. Four major hotspots of dolphin use were identified in the ADS: Angas Inlet, North Arm, Light Passage and Outer Harbour. In winter, predicted presence was highest at Light Passage and Angas Inlet, whereas in spring, it was concentrated in the southern ADS, particularly around Angas Inlet and North Arm. Depth (m) as a predictor variable was not statistically significant; thus, these distribution patterns likely reflect fine‐scale habitat preferences and resource availability. The consistent use of specific areas indicates persistent habitat preferences and suggests that these locations are ecologically important. However, the ecological drivers of these preferences remain unclear. Future research should focus on fine‐scale, site‐specific data collection, including benthic habitat mapping, water quality monitoring, prey availability and spatial risk assessments, to improve understanding of ecosystem functioning in dolphin hotspots.

Skin lesions are valuable indicators of individual and population health in cetaceans. To understand the occurrence of skin and mucosal lesions among dolphins inhabiting South Australian waters, this study employs opportunistic sampling of deceased dolphins during 2021–2024. A total of 52 dolphins, comprising 23 Indo‐Pacific bottlenose dolphins ( Tursiops aduncus ) and 29 common dolphins ( Delphinus delphis ), underwent thorough macroscopic, microscopic, and ancillary diagnostics of identified lesions. Thirty‐three individuals displayed 115 skin and 12 mucosal lesions. The most common skin lesion sites were the head (23%–34%), peduncle (25%–26%), and lateral surfaces (17%–19%). A negative association was found between body condition and the number of infectious skin lesions in T. aduncus . Tattoo Skin Disease was identified in 13% of D. delphis skin lesions and 29% of T. aduncus skin lesions. Additional etiologies of skin lesions included bacteria (including Erysipelothrix rhusiopathiae , Mycobacterium marinum , Vibrio spp.), protozoa, physiological, and trauma‐related (propeller strike and shark bite). Opportunistic bacterial ulcerative dermatitis occurred predominantly in dolphins from the Adelaide Dolphin Sanctuary. Novel findings include the identification of herpesvirus in oral/genital papillomas, cutaneous lesions from an erysipelas‐infected animal, and M. marinum skin abscessation, not previously reported in free‐ranging Australian cetaceans. This study complements live‐animal observational studies and provides diagnostic insight into dolphin skin lesions, supporting their use as population and ecosystem health indicators.

Morphological variation within and among species plays a critical role in evolutionary processes, influencing adaptation, survival, and reproductive success. Killer whale ( Orcinus orca ) morphology is known to vary on both an individual and population level with several ecotypes or forms documented worldwide. However, the extent of morphological variation among killer whales in Australian waters remains unclear, both among individuals within the region and in comparison to those in other parts of the southern hemisphere. This study assessed eye patch and dorsal fin shape variation in Australian and Antarctic killer whales to explore the evolutionary relationships among these groups. A large dataset of imagery was compiled and processed to achieve this, which provided representative sample sizes for five separate study groups: northwest Australia (NW), southwest Australia (SW), southeast Australia (SE), Antarctic type A (AA) and Antarctic type B1 (AB). Elliptical Fourier analysis was used to extract the feature outlines and enable multivariate data analyses. Principal component analysis and pairwise comparisons revealed significant morphological differences both within and between Australian and Antarctic killer whales. Eye patch shape variation was driven by the degree of taper and overall width whereas dorsal fin shape variation was driven by falcateness and broadness at its base. Hierarchical cluster analysis revealed considerable variation amongst these features, while linear discriminate analysis indicated that individuals could not be reliably classified into their respective study groups based on eye patch and dorsal fin shape alone. Nonetheless, these findings suggest the presence of both a tropical and temperate form of killer whale in Australia, with the latter resembling both the Antarctic Type A and B2s morphologically. To better understand their connectivity and divergence, dedicated research is needed to assess the evolutionary history of these populations. Such knowledge will be vital in defining global conservation management units for killer whales which are still considered a single, data deficient species by the International Union for Conservation of Nature (IUCN).

The killer whale ( Orcinus orca ) is a globally distributed apex predator. This species is represented by distinct ecotypes or forms, which are well documented in the Northern Hemisphere and Antarctica. However, less is known about killer whales in Australia. While research efforts have been made to study these animals, a broader understanding of their range and drivers of occurrence is lacking. In this study, we model the spatial distribution of killer whales in Australian waters to identify potential areas of habitat suitability and conservation priority. A total of 1310 sightings were compiled, of which 1115 were used alongside a suite of static and dynamic predictor variables to build presence‐only MaxEnt species distribution models (SDMs) in three separate study areas: southeast (SE), southwest (SW) and northwest (NW) Australia. The SDMs identified potential areas of habitat suitability both within and outside of known locations for killer whales in Australia. All three models returned good discriminative power between presence and background points. However, good predictive power was only suggested for the SE and NW. The importance of certain predictor variables indicated a preference for different environmental conditions, supporting the notion of at least two ecologically distinct groups. Killer whales frequenting the SE and SW preferred temperate waters, whereas those in the NW preferred tropical waters. This work greatly increases our understanding of killer whales in Australian waters and identifies potential areas of biological importance for management and monitoring. It also complements ongoing research into their genetics, feeding ecology, and diversification, showcases the utility of citizen science data, and informs the conservation of this species, which is still considered data deficient and remains to be adequately protected under Australian Government legislation.

Blue whales (Balaenoptera musculus) are the largest living animal and, like other baleen whales, became endangered due to whaling. Here, we used population genomics to infer the number, distribution and other characteristics of subspecies and populations. We used the largest DNA dataset in blue whales, both in terms of genomic markers (16,661 SNPs and mtDNA) and geographic coverage (n = 276 for SNPs; n = 531 for mtDNA). We found greatest divergence among the eastern Pacific, Indo‐western Pacific and Antarctic blue whales. There were indications that natural selection in different environments promoted divergence among these groupings. Within these regions, there was divergence between the eastern North and eastern South Pacific, and among the eastern Indian Ocean, the western South Pacific and the northern Indian Ocean. There was no divergence within the Antarctic. These findings are consistent with the current classification of Antarctic and Indo‐western Pacific blue whales in the Southern Hemisphere as different subspecies but call into question the subspecies taxonomy of eastern Pacific blue whales. The study shows that opposite breeding seasons on either side of the equator do not necessarily inhibit connectivity across the equator, and reinforces that population structure needs to be well understood to conserve the diversity within species.

Climatic changes have caused major environmental restructuring throughout the world's oceans. Marine organisms have responded to novel conditions through various biological systems, including genomic adaptation. Growing accessibility of next-generation DNA sequencing methods to study nonmodel species has recently allowed genomic changes underlying environmental adaptations to be investigated. This study used double-digest restriction-site associated DNA (ddRAD) sequence data to investigate the genomic basis of ecotype formation across currently recognized species and subspecies of bottlenose dolphins (genus Tursiops) in the Southern Hemisphere. Subspecies-level genomic divergence was confirmed between the offshore common bottlenose dolphin (T. truncatus truncatus) and the inshore Lahille's bottlenose dolphin (T. t. gephyreus) from the southwestern Atlantic Ocean (SWAO). Similarly, subspecies-level divergence is suggested between inshore (eastern Australia) Indo-Pacific bottlenose dolphin (T. aduncus) and the proposed Burrunan dolphin (T. australis) from southern Australia. Inshore bottlenose dolphin lineages generally had lower genomic diversity than offshore lineages, a pattern particularly evident for T. t. gephyreus, which showed exceptionally low diversity. Genomic regions associated with cardiovascular, musculoskeletal, and energy production systems appear to have undergone repeated adaptive evolution in inshore lineages across the Southern Hemisphere. We hypothesize that comparable selective pressures in the inshore environment drove similar adaptive responses in each lineage, supporting parallel evolution of inshore bottlenose dolphins. With climate change altering marine ecosystems worldwide, it is crucial to gain an understanding of the adaptive capacity of local species and populations. Our study provides insights into key adaptive pathways that may be important for the long-term survival of cetaceans and other organisms in a changing marine environment.