Marine Mammal Science最新文献

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.

Age is important for studying population dynamics, but it is difficult to obtain reasonably accurate age estimates and associated uncertainty of free-ranging individuals, especially for cetaceans. We developed a protocol for deriving probabilistic age estimates using information commonly curated in marine mammal photo-identification catalogs and applied the approach to 81 biopsy-sampled and genetically sexed false killer whales (Pseudorca crassidens) from the endangered main Hawaiian Islands insular population. The protocol integrates qualitative evidence into a quantitative framework for deriving age estimates and plausible age ranges. Confidence ratings reflecting the strength of available evidence were developed to account for uncertainty. Estimates were then translated to statistical distributions to depict probabilistic age estimates that can be used in further analyses. Age estimates ranged from 3 to 40 years (minimum: 1–33; maximum: 5–65) and were strongly influenced by the estimated age when first seen and length of sighting history. Sensitivity analyses show that population-level age distribution estimates are robust to age class misclassifications and lack of auxiliary information, including sex. This protocol may provide a guide for aging individuals of some species from photo-identification catalogs and for which other aging methods from biological samples are not yet feasible or available.

Eumetopias jubatus (Steller sea lions) that breed on the Oregon coast are generally smaller than those found in Alaska. During the breeding season, male Zalophus californianus (California sea lions) move past E. jubatus rookeries in Oregon on their way to breeding rookeries in Southern California. Introgression by male Z. californianus could potentially explain the difference in size of Oregon E. jubatus relative to other E. jubatus populations. To assess whether morphologically detectable hybrids occur between Z. californianus and E. jubatus in Oregon, we used traditional skull morphometrics and Principal Component Analysis to identify individuals with intermediate morphological characteristics. Multiple range comparisons were used to determine which groups differed significantly. The comparisons revealed significant cranial morphological variation within each species' clusters and identified two male Z. californianus that overlapped with the male E. jubatus cluster, as well as two female E. jubatus that overlapped with the male Z. californianus cluster, suggesting potential hybrid status. These results support the possibility that long-term introgression between these two species may account for the observed size difference of the Oregon and Alaskan E. jubatus.

Photo-identification (photo-ID) is a widely used, non-invasive method for monitoring individual animals, including humpback whales (Megaptera novaeangliae; HBWs), and has provided valuable insights into their population dynamics, movement patterns, and social structures. Traditional identification relies on the trailing edge and ventral pigment patterns of the tail fluke (fluke-ID); however, not all whales present their flukes, limiting identification and re-sighting opportunities. We developed a novel aerial-identification (aerial-ID) approach using drone imagery to identify individual HBWs based on the arrangement of two features, tubercles (TB) and cookiecutter shark scars (CCS). Between January and March 2022, we sampled 1498 HBWs, including repeated individuals, capturing fluke-ID images for 772 and aerial-ID images for 1437. Fluke-ID yielded 164 re-sightings (76 lactating females, 88 others), while aerial-ID yielded 372 (249 and 123, respectively), representing a 227% increase for lactating females and 40% for others. We extended this approach to a multi-year, cross-regional dataset (2018–2025) of 54 individuals verified with fluke-ID. All were matched using aerial-ID, with the longest re-sight spanning 2737 days (6.5 years), representing the maximum interval within our study period. Aerial-ID thus offers a powerful complement to fluke-ID, expanding demographic coverage, increasing re-sighting rates, and enabling long-term, cross-regional monitoring.