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Item Dental Ageing Offers New Insights Into the First Epigenetic Clock for Common Dolphins (Delphinus delphis)(British Ecological Society, and John Wiley and Sons Limited, 2025-11) Hanninger E-MF; Peters KJ; Gerber L; Barratclough A; Betty EL; Palmer EI; Horvath S; Stockin KADetermining exact age in wild odontocetes is essential for understanding population dynamics, survival, and reproduction, yet remains logistically challenging. Although epigenetic ageing is emerging as a valuable approach, only nine species-specific clocks currently exist. Most have been calibrated using known-age animals in human care or well-studied wild populations. Only three previous studies have used dental ages from stranded or bycaught individuals. This is due to concerns that dental age inaccuracies, especially in older animals, may affect epigenetic clock performance. To explore this, we developed the first species-specific epigenetic clock for common dolphins (Delphinus delphis), analysing DNA methylation at 37,492 cytosine-phosphate-guanine sites in skin samples from stranded and bycaught dolphins with estimated dental ages. Elastic net models with Leave-One-Out Cross-Validation were applied to three subsets: the ‘relaxed’ subset (all individuals; n = 75, median absolute error (MAE) = 2.02, r = 0.81, R2 = 0.66), the ‘strict’ subset (excluding individuals with minimum dental age estimates only; n = 73, MAE = 2.29, r = 0.81, R2 = 0.66), and the ‘restricted’ subset (excluding outliers with prediction errors > 6 years; n = 63, MAE = 1.80, r = 0.91, R2 = 0.82) to compare performance. Our models consistently underestimated the age of dolphins > 16 years, even when minimum dental ages were applied, suggesting that absolute errors between dental and epigenetic estimates are unlikely to reflect the dental ageing error. Additionally, post-mortem decomposition condition code (DCC 1 to 3) did not affect age prediction, signalling promise for future epigenetic clocks calibrated with strandings and bycaught individuals.Item No place to hide: Marine habitat does not determine per- and polyfluoroalkyl substances (PFAS) in odontocetes(Elsevier B.V., 2025-12-10) Stockin KA; Peters KJ; Saltré F; Machovsky-Capuska GE; Betty EL; Tremblay LA; Yi SAs meso- and apex predators in food webs, marine mammals can bioconcentrate persistent environmental contaminants like per- and polyfluoroalkyl substances (PFAS). Although the presence of PFAS is widely reported in the marine environment, there is a lack of data for cetaceans in Oceania. We investigated whether ecological habitat influences bioconcentration patterns across a range of odontocete (toothed whale, dolphin and porpoise) species. We measured PFAS in liver samples (n = 127) from 16 cetacean species representing four families inhabiting four marine habitats along the Aotearoa New Zealand coastline. We analysed six perfluoroalkyl carboxylic acids, ten perfluoroalkyl sulphonic acids and four precursor compounds in the context of sex, body index, habitat and species/family using generalized linear mixed models. Results showed that marine habitat remained a weak predictor of PFAS burden. Instead, biological factors including sex and age class best explained the levels of PFAS detected across all species and habitats. We offer first important insights on PFAS levels across several new taxa globally, including endemic endangered species and poorly described polar vagrants. Our findings further highlight how the ubiquitous nature of PFAS pose a higher risk to odontocetes across different seascapes than previously anticipated.Item Out of habitat marine mammals – Identification, causes, and management recommendations(Elsevier Ltd, 2025-07) Nunny L; Bossley M; Boys RM; Brakes P; Genov T; Parsons ECM; Peters KJ; Rose NA; Simeone CA; Stockin KA; Vail CS; van der Linde K; Visser IN; Simmonds MPAn out of habitat (OOH) marine mammal is an individual found outside of their natural range, e.g., an Atlantic walrus (Odobenus rosmarus rosmarus) along the coastline of mainland Europe, or an individual within their natural range in habitat that is not optimal for their health or survival due to a lack of suitable conditions and/or because of potential conflict with humans. As the number of OOH marine mammals appears to be increasing, and following on from two international workshops, here we define what constitutes an OOH marine mammal and provide a detailed assessment of potential drivers. Climate change, habitat loss and/or degradation, disturbance, changes in prey distribution, and morbidity may all be reasons for a marine mammal being OOH. Appropriate management of OOH marine mammals is considered. This may simply involve monitoring to better understand the situation, to protect the welfare of the animal(s) and to ensure that members of the public are kept safe. However, on occasion, further intervention may be required, such as providing safe areas for the OOH marine mammal(s), encouraging the animal(s) to move, capture and translocation, or euthanasia. Regardless of the action taken, educating and communicating with the public are key elements of OOH marine mammal management. Lessons can be learned from human-wildlife conflict and rewilding scenarios. The potential for OOH marine mammals to be pioneers seeking new habitat, contributing to species resilience in the face of rapidly changing environments, and how to include them in conservation legislation and management planning are considered.Item Bryde’s whale (Balaenoptera edeni) occurrence and foraging behaviour along the east coast of Australia(Taylor and Francis Group, 2024-10-09) Pirotta V; Cagnazzi D; Dixon B; Millar S; Millar J; Pickering G; Butcher PA; Stockin KA; Peters KJDespite their global occurrence in warm-temperate waters and their suspected non-migratory lifestyle, Bryde’s whales (Balaenoptera edeni spp.) are considered the least-known large baleen whale species. In Australian waters, information on their distribution, ecology and behaviour is scarce. This study documents Bryde’s whale occurrence and foraging behaviours along the Australian East Coast using opportunistic citizen science sightings via drone aerial photography, vessel and land-based observations. We observed foraging in both shallow (seafloor visible, beach and breaking waves present) and deep waters. We observed a range of foraging behaviours including lunge feeding (exhibited by individual whales and in pairs), sub-surface and surface skim feeding (shallow waters only) and described multispecies associations. We describe a potentially novel feeding behaviour in shallow waters, where Bryde’s whales are feeding directly within or behind the surf break (shallow water surf feeding). We quantify the presence of mother-calf pairs in Australian waters, highlighting the use of these waters for potential calving. This study provides insights into Bryde’s whale occurrence and foraging behaviour in both shallow and deep waters of eastern Australia.Item On the rise: Climate change in New Zealand will cause sperm and blue whales to seek higher latitudes(Elsevier Ltd, 2022-09) Peters KJ; Stockin KA; Saltré FClimate impacts affect marine ecosystems worldwide with island nations such as New Zealand being extremely vulnerable because of their socio-economic and cultural dependence on the marine and costal environment. Cetaceans are ideal indicator species of ecosystem change and ocean health given their extended life span and cosmopolitan distribution, but limited data availability prevents anticipating change in distribution under future climate changes. We projected the range shifts of a key odontocete and mysticete species (Physeter macrocephalus and Balaenoptera musculus) in 2100 relative to present day in New Zealand waters, using an ensemble modelling approach, under three climate change scenarios of different severity. The results show a latitudinal shift in suitable habitat for both whale species, increasing in magnitude with severity of sea surface temperature warming. The most severe climate change scenario tested generated 61% and 42% loss and decrease of currently suitable habitat for sperm and blue whales, respectively, mostly in New Zealand's northern waters. These predicted changes will have a strong impact on the ecosystem functioning and services in New Zealand's northern waters but also in coastal areas (critical for the species’ foraging and survival). Not only do these simulated range shifts help to identify future potential climate refugia to mitigate a global warming, they also generate a range of socioeconomic consequences for island nations relying on wildlife tourism, industry, and environmental protection.Item Isotopic Niche Analysis of Long-Finned Pilot Whales (Globicephala melas edwardii) in Aotearoa New Zealand Waters(MDPI (Basel, Switzerland), 2022-09-28) Hinton B; Stockin KA; Bury SJ; Peters KJ; Betty EL; Calizza E; Careddu G; Costantini MLThe quantification of a species' trophic niche is important to understand the species ecology and its interactions with the ecosystem it resides in. Despite the high frequency of long-finned pilot whale (Globicephala melas edwardii) strandings on the Aotearoa New Zealand coast, their trophic niche remains poorly understood. To assess the isotopic niche of G. m. edwardii within New Zealand, ontogenetic (sex, total body length, age, maturity status, reproductive group) and spatiotemporal (stranding location, stranding event, and stranding year) variation were investigated. Stable isotopes of carbon (δ13C) and nitrogen (δ15N) were examined from skin samples of 125 G. m. edwardii (67 females and 58 males) collected at mass-stranding events at Onetahua Farewell Spit in 2009 (n = 20), 2011 (n = 20), 2014 (n = 27) and 2017 (n = 20) and at Rakiura Stewart Island in 2010 (n = 19) and 2011 (n = 19). Variations in δ34S values were examined for a subset of 36 individuals. General additive models revealed that stranding event was the strongest predictor for δ13C and δ15N values, whilst sex was the strongest predictor of δ34S isotopic values. Although similar within years, δ13C values were lower in 2014 and 2017 compared to all other years. Furthermore, δ15N values were higher within Farewell Spit 2017 compared to any other stranding event. This suggests that the individuals stranded in Farewell Spit in 2017 may have been feeding at a higher trophic level, or that the nitrogen baseline may have been higher in 2017 than in other years. Spatiotemporal differences explained isotopic variation of G. m. edwardii in New Zealand waters better than ontogenetic factors.Item Too Close for Comfort? Isotopic Niche Segregation in New Zealand's Odontocetes(MDPI (Basel, Switzerland), 2022-08-05) Peters KJ; Bury SJ; Hinton B; Betty EL; Casano-Bally D; Parra GJ; Stockin KA; Calizza E; Careddu G; Costantini MLSpecies occurring in sympatry and relying on similar and limited resources may partition resource use to avoid overlap and interspecific competition. Aotearoa, New Zealand hosts an extraordinarily rich marine megafauna, including 50% of the world's cetacean species. In this study, we used carbon and nitrogen stable isotopes as ecological tracers to investigate isotopic niche overlap between 21 odontocete (toothed whale) species inhabiting neritic, mesopelagic, and bathypelagic waters. Results showed a clear niche separation for the bathypelagic Gray's beaked whales (Mesoplodon grayi) and sperm whales (Physeter macrocephalus), but high isotopic niche overlap and potential interspecific competition for neritic and mesopelagic species. For these species, competition could be reduced via temporal or finer-scale spatial segregation or differences in foraging behaviour. This study represents the first insights into the coexistence of odontocetes in a biodiverse hotspot. The data presented here provide a critical baseline to a system already ongoing ecosystem change via ocean warming and subsequent effects on prey abundance and distributions.Item A piece of the puzzle: analyses of recent strandings and historical records reveal new genetic and ecological insights on New Zealand sperm whales(1/01/2022) Palmer E; Alexander A; Liggins L; Guerra M; Bury SJ; Hendriks H; Stockin KA; Peters KJCetacean strandings provide important opportunities to extend current knowledge on species or populations, particularly for species that are notoriously difficult to study, such as sperm whales Physeter macrocephalus (parāoa). Between 25 May and 9 June 2018, 13 male sperm whales stranded in Taranaki, New Zealand (NZ), with an additional male stranding 1 mo later in Clifford Bay, Marlborough. We profiled these 14 males for mitochondrial DNA (mtDNA) and carbon and nitrogen stable isotopes to examine their similarity to sperm whales from other geographic areas. Analyses of mtDNA revealed 7 haplotypes, including 1 not previously described (‘New’), and an additional haplotype (‘M’) new to NZ that had been previously reported in sperm whales of the Pacific region. Analysis of rare haplotypes found in NZ males suggested genetic links within NZ and the Southwest Pacific. Differences in stable isotope ratios indicated that, despite the close temporal proximity of these stranding events, individuals originated from at least 2 separate groups, with the whale stranded in Clifford Bay identified as being a regular visitor to Kaikōura, South Island. The analysis of stranding records in NZ dating back to 1873 indicated an increase in recorded single strandings since 1970, and a peak in single strandings in the austral summer months, but no seasonality for mass strandings. Sex predicted latitudinal location for single strandings, with 95.1% of female strandings occurring north of 42° S, fitting the general global distribution of female sperm whales limited to lower latitudes. This study provides the first temporal and spatial assessment of sperm whale strandings in NZ and highlights the need for future research on movements and genetic exchange between NZ sperm whales and sperm whales in the wider Pacific region.