February 2026 - MARMAM - devlists.uvic.ca

New publication: Orcas in Los Ríos Region, southern Chile
by "Keka" Henrike Niebaum 12 Feb '26

12 Feb '26

Dear MARMAM community, on behalf of my co-author, I am pleased to announce the recent publication of our article on orcas in (southern) Chile in the journal Polar Biology. Citation Niebaum H, Muñoz García NE (2026) Orcas (Orcinus orca Linnaeus, 1758) in southern Chilean Los Ríos Region: a first report—with a discussion of the state of knowledge on the species along the Chilean coast. Polar Biology 49:21. https://doi.org/10.1007/s00300-025-03443-0 Abstract Along the Chilean coast, at least one type of orca (Orcinus orca Linnaeus, 1758) is documented for Patagonia throughout the subtropical North. Here, first land-based anecdotal observations (2014/2015) from Los Ríos Region, northwardly adjacent to the Subantarctic, were complemented by records from a casual citizen science network (2021–2023). The 32 sightings included in the analysis suggest that orcas stay for 1–4, possibly up to 12 days in regional waters, without apparent seasonal patterns. Observed groups consisted of 1–9 (mean: 4.03) individuals. As in northern Chile, predation on South American sea lions (Otaria flavescens Shaw, 1800) includes the facilitation of prey access through purse seiners, and hints on cultural transmission were found. Nonetheless, a larger prey spectrum is suggested, wherein pelagic/demersal species possibly play a role, whereas other cetaceans appear to represent at least no preferred prey. Play and/or training with a live seabird was recorded, but so far no predation on birds. The observations on diet, behavior, and sociobiology reveal similarities not only to orcas in northern through Patagonian Chile, but also to orcas in Argentinian Patagonia, and to Pacific orcas further north. These as well as differences found both within and beyond the region point to the need for intensified studies to examine orca types/type-relatedness, behavior, and ecology—foremost in light of conservation. The article is openly accessible, and the online version contains a supplementary video compilation by my co-author, marine biologist and documentary filmmaker Nicolás Muñoz. We would like to emphasize our gratitude to all the scientific and citizen contributors, without whom this work would not have been possible. Kind regards, -- "Keka" Henrike Niebaum (she/her) Dipl.-Biol., BSc Osnabrück, Germany

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New Article on Abundance Estimate of Bottlenose Dolphins from the Eastern Mediterranean Sea
by DMAD Marine Mammals Research Association 12 Feb '26

12 Feb '26

Dear MARMAM members, We are very happy and excited to share that our recent article, “Producing Local Common Bottlenose Dolphin Abundance Estimates to Fill Species Knowledge Gaps in the Eastern Mediterranean Surrounding Türkiye,” has just been published in Marine Mammal Science. In this study, we highlight the importance of local-scale data for understanding and monitoring bottlenose dolphin populations. While large-scale surveys are essential, local efforts can provide precise abundance estimates and help track population trends over time. We hope this work contributes to a better understanding of bottlenose dolphin status in the Eastern Mediterranean and supports broader conservation efforts. We would very much welcome your thoughts and insights on the article. Abstract and its link can be found below: ABSTRACT The IUCN Red List status of the Mediterranean subpopulation of common bottlenose dolphins has recently been upgraded to Least Concern. Although large-scale surveys provide crucial information on the population status, local efforts often allow more robust estimation and the ability to monitor population trends. The current study used a standard line transect survey design during 21 surveys conducted between April 2018 and July 2025. The research boat covered 31,717 km with a survey coverage of 32,628 km2 across a total of 214 days. Overall, 93 encounters of bottlenose dolphins were recorded, 45 of which occurred while the vessel was ‘on-effort’, with a mean group size of four. We found no significant differences in the number of sightings between season and year when accounting for days of survey effort. Encounters were most frequent in the easternmost region of Türkiye. The abundance estimate of bottlenose dolphins after 500 bootstraps in the Eastern Mediterranean Sea of Türkiye was 1642 ± 440 individuals (CV = 0.27, 95% CI [749–2447]), varying considerably from previous basin-wide estimates. The local population estimates produced by this study extend our understanding of the status of bottlenose dolphins in the Eastern Mediterranean and contribute to basin-wide estimates. LINK https://onlinelibrary.wiley.com/doi/10.1111/mms.70140 Best Regards, DMAD&MDR Team

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New paper: Forecasting climate-driven distribution shifts of small cetaceans in the North Atlantic Ocean using species distribution models
by Jeremy Kiszka 11 Feb '26

11 Feb '26

Dear MARMAM community, The following paper has just been published in open access in Ecological Indicators: Chandelier, G. & Kiszka, J., 2026. Forecasting climate-driven distribution shifts of small cetaceans in the North Atlantic Ocean using species distribution models. Ecological Indicators, 183: 114675. Here are the highlights of the paper: * • We modeled current and future distributions of 12 small cetacean species in the North Atlantic Ocean. * • Poleward redistribution of 12 small cetaceans is projected by 2100. * • Small cetaceans exhibit contrasting responses among species. * • Tropical regions may become less suitable, leading to possible desertification. * • Temperate zones emerge as key refugia for an increasing number of species. Link to the paper (open access): https://www.sciencedirect.com/science/article/pii/S1470160X26000725 Please note that in Fig. 8, G. melas is at the top of the figure (A) and G. macrorhynchus is at the bottom (B). Best, Jeremy Kiszka, Ph.D. Associate Professor Institute of Environment, Coastlines and Oceans Division Department of Biological Sciences Florida International University https://environment.fiu.edu<https://environment.fiu.edu/> - Principal Investigator, Marine Mammal Ecology Laboratory 3000 NE 151 St., FL-33181, North Miami, USA. Office (direct): (305)-919-5234<tel:(305)-919-5234> [File:ResearchGate icon SVG.svg - Wikimedia Commons] ResearchGate<https://www.researchgate.net/profile/Jeremy-Kiszka/research> (publications) - President, Society for Marine Mammalogy https://marinemammalscience.org<https://marinemammalscience.org/> [cid:44bf5ef0-a84f-481a-95b2-8c12ff92d595]

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New Publication: POPs in bottlenose dolphins from SPSPA
by Nara Oliveira 11 Feb '26

11 Feb '26

Dear MARMAM colleagues, My co-authors and I would like to share our most recent research on POPs and natural organohalogen compounds in *Tursiops truncatus* from the Saint Peter Saint Paul Archipelago! Here's the link to the paper: POPs in bottlenose dolphins <https://doi.org/10.1016/j.marpolbul.2026.119371> *Abstract:* The Saint Peter Saint Paul archipelago (SPSPA) is situated in the central Equatorial Atlantic, approximately 1000 km from the northeastern coast of Brazil. A small population of common bottlenose dolphins (*Tursiops truncatus*) exhibits strong site fidelity to the remote archipelago. As apex predators, these dolphins can act as sentinels for the transport and bioaccumulation of organohalogen compounds in isolated marine environments. Remote biopsies were collected from nine individuals (*n* = 9) to investigate pollutant exposure. Blubber samples were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), and naturally produced methoxylated organobromines (MeO-BDEs), using gas chromatography coupled with electron capture detection or mass spectrometry. Skin samples were analyzed in an isotopic ratio mass spectrometer. The profile of the chemical markers observed in these bottlenose dolphins was dominated by high molecular weight PCBs and high δ13C, similar to coastal dolphin species. Atmospheric transport, adsorption to benthic substrates, and species-specific metabolic capacity possibly shape contaminant accumulation in this population. Naturally produced MeO-BDEs and carbon ratios suggest low oceanic-coastal dispersal of dolphins. These findings suggest the efficient transport of man-made pollutants to isolated locations and the key role of apex predators, such as bottlenose dolphins, as POPs reservoirs in oceanic zones. Please, feel free to contact me if you have any questions or comments! Warm regards, -- *Dra. Nara de Oliveira-Ferreira* _____________________________________________________________ *Laboratório de Mamíferos Aquáticos e Bioindicadores (MAQUA -UERJ)* Mestre em Ecologia e Evolução - Universidade do Estado do Rio de Janeiro Doutora em Biofísica - Universidade Federal do Rio de Janeiro Contato: + 55 21 98585.9916

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New publication: Movements, dive behavior, and predation observations of killer whales in Pacific Mexico
by Stewart, Joshua 10 Feb '26

10 Feb '26

Dear Colleagues, On behalf of my coauthors, I’m pleased to share our new publication on the movements and dive behavior of Eastern Tropical Pacific killer whales in Pacific Mexico: https://onlinelibrary.wiley.com/doi/10.1111/mms.70133 Stewart, J. D., R. L. Pitman, P. Martinez-Loustalot, N. Ransome, T.R. Azizeh, H. Rosales-Nanduca, I.A. Fonseca-Ponce, A.A. Zavala-Jimenez, J. Urban R., 2026. “Shelf Life: Nearshore Movements, Dive Behavior, and Ecotype Status of Satellite-Tagged Killer Whales in Pacific Mexico.” Marine Mammal Science https://doi.org/10.1111/mms.70133. Abstract: Relatively little is known about the ranging patterns, diving behavior, or prey preferences of killer whales (Orcinus orca) in tropical latitudes. However, they are suspected to be prey-generalists rather than the prey-specialists that are typically found in high latitudes. In February 2025, we satellite-tagged three killer whales from a pod of seven in Bahía de Banderas, Mexico. The tags transmitted for 8–41 days. The tagged whales traveled a total of 4002 km along a narrow, 1000 km stretch of coastline. While tagged, they remained within 50 km of shore 92.5% of the time and in water < 500 m deep 69% of the time, but ranged up to 87 km offshore, to water deeper than 1000 m. Dives were slightly deeper during the day (mean dive depth 44 m) than at night (34.5 m), and they dived deeper (max 528 m) in deeper water. The group was observed attacking/consuming marine mammals, including a humpback whale (Megaptera novaeangliae) calf, a dwarf sperm whale (Kogia sima), common bottlenose (Tursiops truncatus) and spinner (Stenella longirostris) dolphins, and attacking/harassing two species of sea turtles. These data provide the first high-resolution records of movements and dive behavior of killer whales in the Eastern Tropical Pacific and support the existence of a unique ecotype in the region. Joshua Stewart, Ph.D. Pronouns: He/Him Assistant Professor, Marine Mammal Institute Oregon State University, Hatfield Marine Science Center

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New Publication
by Isabella Livingston 10 Feb '26

10 Feb '26

Hello, My co-authors and I are excited to share our new research article exploring the genomic signatures of Urogenital Carcinoma in the California sea lion. This research uses cancer in California sea lions as a powerful comparative model to understand how tumors arise and evade the immune system across mammals. By identifying genomic changes shared between sea lion cancers and human cancers, the study provides insight into immune-related pathways that may inform future cancer immunotherapies and earlier diagnostic approaches. At the same time, the work underscores the role of wildlife as sentinels of environmental health, showing how studying naturally occurring cancers in wild species can benefit both conservation efforts and human medicine. Livingston, I.G.; Wise, C.F.; Dickey, A.N.; Thomas, R.; Demming, A.C.; Halaska, B.; Gulland, F.M.D.; Colegrove, K.M.; Duignan, P.; Breen, M. Cross-Species Exome Sequencing Reveals Recurrent Genomic Alterations in California Sea Lion (*Zalophus californianus*) Urogenital Carcinoma and Highlights a Recurrent PD-L1 Variant. *Genes* 2026, *17*, 222. https://doi.org/10.3390/genes17020222 Abstract: Background/Objectives: Human-driven environmental change can promote cancer development in wild species, yet the pathophysiology of wildlife cancers remain largely unexplored. Urogenital carcinoma (UGC) in the California sea lion (CSL) (Zalophus californianus) is one of the most common cancer types documented in any wild mammal. The pathogenesis of UGC in CSLs is known to be multifactorial, with links to environmental contaminant exposure and infection by Otarine Herpesvirus-1 (OtHV-1); however, the genomic features of these cancers have not been thoroughly explored. Understanding UGC pathogenesis in the CSL has important implications for the health of humans and other species that share environment and diet. Methods: We leveraged the evolutionary conservation between the domestic dog and CSL genomes to perform cross-species whole-exome sequencing (WES) of CSL UGC tumors and matched normal tissue pairs. We also used PCR and Sanger sequencing to investigate the prevalence of DNA from OtHV-1. Results: Bioinformatic analyses identified shared somatic variants and DNA copy number aberrations in UGC tumor samples, including recurrent exonic single-nucleotide variants in CD274/PD-L1, and recurrent copy number gains in CD274/PD-L1, TNFRSF14, CD200, CDK4, and PLCG2. In an extended cohort of 70 CSLs (tumor, matched normals, and controls), a recurrent C > T single-nucleotide variant in exon 4 of CD274/PD-L1 was identified in 54 of 68 (79.4%) CSLs with diagnosed UGC. OtHV-1 DNA was detected in 67 of 70 individuals (95.8%). Conclusions: These results demonstrate that cross-species exome capture provides a means to identify genomic alterations that may play a role in the molecular pathogenesis of UGC in the CSL and adds to the body of evidence for an association between OtHV-1 and UGC in this species. Link to paper: https://www.mdpi.com/2073-4425/17/2/222 Cheers, Isabella Livingston | she/her/hers Genetics and Genomics Ph.D.Candidate Genetics and Genomics Scholar GAANN Biotechnology Fellow Dept. of Molecular Biomedical Sciences, College of Veterinary Medicine North Carolina State University Raleigh, NC 27695 breenlab.org

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New Publication on the Impacts of Vessel Presence on Harbour Porpoise Buzz Vocalisations
by Rachel Lennon (PGR) 10 Feb '26

10 Feb '26

Dear MARMAM community, On behalf of all the co-authors and I, I am very pleased to share our recent publication entitled "Seasonal and Diurnal Patterns of Harbor Porpoise (Phocoena phocoena) Behavior and the Disruptive Effects of Vessel Presence in a High-Traffic Coastal Habitat" , published in Marine Mammal Science. Authors: Rachel L. Lennon, Shannon Merkle, Jonas Teilmann, Lorenzo Scala, Chris Pierpoint, Victoria Hobson Abstract: Chronic anthropogenic activity is an ongoing threat to the marine environment and presents unique challenges in shallow, coastal habitats where harbor porpoises reside. Harbor porpoises have high metabolic needs and are highly susceptible to negative environmental factors; however, no long-term studies have been conducted on wild populations to quantify the negative impacts of vessel presence on their behavior. To evaluate this impact on harbor porpoises in the Little Belt, Denmark, data from a static hydrophone array were used to distinguish porpoise click train events and quantify buzzes (vocalizations with an inter-click interval < 10 ms), used as an indication of foraging and social behavior, and Automated Identification System data were collected to identify vessels within a 3000 m radius of the study site. Using generalized additive models, we showed that harbor porpoises were most active during the night in summer months but most often overlapped with vessels during the day in the summer. Generalized linear models showed that harbor porpoise buzz rate was significantly reduced in the presence of vessels, particularly during daylight hours in the summer when vessel traffic peaked. These results suggest that porpoise foraging and socializing are negatively affected by vessel presence. Furthermore, high porpoise density, which is likely driven by prey availability as found in other studies, may prevent animals from moving to less trafficked areas. Mitigation measures to reduce impacts should be considered to help reduce the ongoing decline in the studied population. You can find the full publication (open access) here: https://doi.org/10.1111/mms.70123 Please do reach out if you have any questions. Happy reading! Best wishes, Rachel Rachel Lennon (She/Her) PhD Researcher | Marine Animal Health Scottish Marine Animal Stranding Scheme (SMASS) School of Biodiversity, One Health and Veterinary Medicine University of Glasgow | Graham Kerr | Room 321 BlueSky: @@rachlenn.bsky.social‬ | Tel: 07955233464

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New paper on a multi-stressor experiment suggesting that oil spills may exacerbate the effects of other stressors
by Enrico Pirotta 10 Feb '26

10 Feb '26

Dear MARMAM colleagues, We are pleased to announce that the following paper is now available online: Enrico Pirotta, Catriona M. Harris, Lori H. Schwacke, Len Thomas, Jason B. Allen, Aaron A. Barleycorn, Marco Casoli, Jonathan Crossman, Laura Aichinger Dias, Laura Engleby, Erin LaBrecque, Jenny Litz, Katherine A. McHugh, Patrick J. O. Miller, Michael J. Moore, Theoni Photopoulou, Brian M. Quigley, Cynthia R. Smith, Brandon L. Southall, Todd R. Speakman, Ryan Takeshita, Christina N. Toms, Randall S. Wells, Eric S. Zolman, Peter L. Tyack. An experimental approach to assess the combined effects of multiple stressors on a large vertebrate species. Conservation Biology. A PDF copy of the paper can be downloaded for free from: https://doi.org/10.1111/cobi.70224 Abstract: The design of experiments to investigate the combined effects of multiple stressors requires exposing target organisms to multiple combinations of stressor doses. Concurrent manipulation of stressors is often infeasible with wildlife, but long-lasting health effects allow individual health to be used as an integrator of prior stressor exposure. The population of bottlenose dolphins in Barataria Bay, Louisiana, experienced long-lasting health effects after exposure to oil from the *Deepwater Horizon* spill. We investigated whether compromised health status affects dolphins’ ability to respond to other stressors, specifically vessel traffic, potentially leading to increased collision risk. We used this case study to develop a hypothesis-driven experimental approach to assess the combined effects of multiple stressors in a large, long-lived vertebrate species. We conducted controlled vessel approaches to test whether the health status of targeted dolphins affected their behavioral responses. Our results highlighted some effects of health, suggesting that oil spills may exacerbate the effects of other stressors in coastal populations. For example, lung disease was associated with a delayed dive response, which could affect the ability to vertically avoid vessels and lead to increased collision risk. However, health effects on response probability were overall smaller than anticipated, and other contextual variables (e.g., sex, age, calf presence, prior experience, and exposure context) contributed to response variability. Our work demonstrated the value of formalizing stressor interactions as multidimensional dose–response functions and showed the feasibility of an experimental, multiple-stressor study in a wild system in which individual health status can be used as an integrator of prior stressor exposure. This approach has broad implications for other species that are difficult to handle experimentally. The quantification and management of the cumulative risk from multiple stressors on wildlife will require a combination of empirical and mechanistic approaches to inform long-term, population consequences. Keywords: bottlenose dolphins; controlled exposure experiments; dose-response functions; health; multiple stressors; oil spill; vessel traffic. Please do not hesitate to contact me for any questions regarding our work. Best Regards, Enrico Pirotta

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New Publication: the Cetacean Brain - Evolution of Nervous Systems
by Ksenia Orekhova 10 Feb '26

10 Feb '26

Dear all, On behalf of my co-authors, I am happy to share the publication of our new chapter on the *evolution of the cetacean brain* in the third edition of the Elsevier book series *Evolution of Nervous Systems*. Orekhova, K., Gerussi, T., Sacchini, S., Patzke, N., Maloney, B., Graïc, J.-M., & Hof, P. R. (2026). *The cetacean brain*. In J. H. Kaas & S. Herculano-Houzel (Eds.), *Evolution of nervous systems* (3rd ed., Vol. 2, pp. 111–162). Academic Press. https://doi.org/10.1016/B978-0-443-27380-3.00051-8 Abstract: Cetaceans can be considered the pinnacle of evolution in terms of brain size, with the iconic sperm whale (*Physeter macrocephalus*) sporting the largest brain in known evolutionary history. In this chapter, we explore behind the scenes of cetaceans’ encephalization quotient, understanding how an ensemble of increasingly multidisciplinary, comparative studies characterize the complexity of brain anatomy, cytoarchitecture, connectivity, and genetics in these aquatic specialists. While cetaceans are phylogenetically closer to hippopotamids, their brains are remarkably like those of humans and other large terrestrial animals, for example in being capable of complex social dynamics and prone to neurodegenerative disease, even though they diverged significantly in terms of their diving adaptations and their neuroanatomy. Understanding neural adaptations in cetaceans can help us understand the nature of cognition and its malfunctions in large, long-lived homeotherms. Keywords: Aquatic; Artiodactyls; Cetacean brain; Convergent; Cortical complexity; Cytoarchitecture; Diving; Dolphin; Encephalization quotient; Evolution; Genetics; Marine mammals; MRI; Mysticetes; Neuroimaging; Odontocetes; Whale The chapter is available here: https://doi.org/10.1016/B978-0-443-27380-3.00051-8. Feel free to reach out to the email address below if you are interested or have any questions. Best wishes, Ksenia Orekhova -- ________________________________________________________ Ksenia Orekhova, DVM, PhD Dipartimento di Biomedicina Comparata e Alimentazione (BCA) Università degli Studi di Padova (It) ksenia.orekhova(a)unipd.it <ksenia.orekhova(a)phd.unipd.it>

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New publication: Heart rates drop slowly and oscillate in diving Steller sea lions
by Rhea Storlund 09 Feb '26

09 Feb '26

Hi All, I'm pleased to share our recent publication on heart rate and diving in Steller sea lions. Storlund, R. L., Rosen, D. A. S., Haulena, M., Milsom, W. K., Shadwick, R. E., & Trites, A. W. (2026). Heart rates of Steller sea lions drop slowly and oscillate while diving. Journal of Comparative Physiology B. https://doi.org/10.1007/s00360-025-01645-w Abstract Lowering heart rate while diving helps marine mammals regulate blood pressure while redistributing blood flow and conserving oxygen during extended dives. However, the classic characterization of this dive response—as a pronounced and abrupt reduction in heart rate observed during forced dives in laboratory settings—contrasts with the higher minimum heart rates and oscillatory patterns observed in freely diving marine mammals in the wild. To assess this apparent discrepancy in cardiovascular control, we measured the heart rates of three Steller sea lions (Eumetopias jubatus) using subcutaneous cardiac monitors during trained stationary dives (3–4 m) in an aquarium pool. During 12 of the longest dives (76–161 s), heart rates decreased from an average of 95 to 34 bpm within the first 26 seconds of submergence. However, while mean HR at depth eventually averaged around 31 bpm, it also oscillated between 27 and 39 bpm every ~5–6 seconds (0.2 Hz) for much of the dive, before rising prior to surfacing. The observed relatively slow drops in heart rates were similar to those seen in other marine mammals, suggesting an optimal rate of decline that reflects the anticipated conditions of voluntary dives. We further hypothesize that the oscillating minimum heart rates of freely diving marine mammals reflect time delays in the baroreceptor reflex due to the prolongation of circulation time. Our findings suggest these delays shape the rate and pattern of heart rate decline, ultimately influencing cardiovascular control, gas management, and breath-hold duration in diving mammals. The article is not open access, but the full-text (view-only) is available here: https://rdcu.be/e1ut9 or you can download a PDF of the accepted version (pre-formatting) here: https://sites.google.com/view/rheastorlund/publications. Please get in touch if you have any questions. My email address is r.storlund(a)oceans.ubc.ca. All the best, Rhea Rhea Storlund Postdoctoral Research and Teaching Fellow University of British Columbia r.storlund(a)oceans.ubc.ca

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