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Arostegui MC, Muhling B, Culhane E, Dewar H, Koch SS, Braun CD. A shallow scattering layer structures the energy seascape of an open ocean predator. SCIENCE ADVANCES 2023; 9:eadi8200. [PMID: 37792940 PMCID: PMC10550225 DOI: 10.1126/sciadv.adi8200] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 09/01/2023] [Indexed: 10/06/2023]
Abstract
Large predators frequent the open ocean where subsurface light drives visually based trophic interactions. However, we lack knowledge on how predators achieve energy balance in the unproductive open ocean where prey biomass is minimal in well-lit surface waters but high in dim midwaters in the form of scattering layers. We use an interdisciplinary approach to assess how the bioenergetics of scattering layer forays by a model predator vary across biomes. We show that the mean metabolic cost rate of daytime deep foraging dives to scattering layers decreases as much as 26% from coastal to pelagic biomes. The more favorable energetics offshore are enabled by the addition of a shallow scattering layer that, if not present, would otherwise necessitate costlier dives to deeper layers. The unprecedented importance of this shallow scattering layer challenges assumptions that the globally ubiquitous primary deep scattering layer constitutes the only mesopelagic resource regularly targeted by apex predators.
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Affiliation(s)
- Martin C. Arostegui
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Barbara Muhling
- Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA
- Fisheries Resources Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA, USA
| | - Emmett Culhane
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Heidi Dewar
- Fisheries Resources Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA, USA
| | - Stephanie S. Koch
- Department of Biological Sciences, Thomas More University, Crestview Hills, KY, USA
| | - Camrin D. Braun
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
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Pérez-Jorge S, Oliveira C, Rivas EI, Prieto R, Cascão I, Wensveen PJ, Miller PJO, Silva MA. Predictive model of sperm whale prey capture attempts from time-depth data. MOVEMENT ECOLOGY 2023; 11:33. [PMID: 37291674 DOI: 10.1186/s40462-023-00393-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 05/11/2023] [Indexed: 06/10/2023]
Abstract
BACKGROUND High-resolution sound and movement recording tags offer unprecedented insights into the fine-scale foraging behaviour of cetaceans, especially echolocating odontocetes, enabling the estimation of a series of foraging metrics. However, these tags are expensive, making them inaccessible to most researchers. Time-Depth Recorders (TDRs), which have been widely used to study diving and foraging behaviour of marine mammals, offer a more affordable alternative. Unfortunately, data collected by TDRs are bi-dimensional (time and depth only), so quantifying foraging effort from those data is challenging. METHODS A predictive model of the foraging effort of sperm whales (Physeter macrocephalus) was developed to identify prey capture attempts (PCAs) from time-depth data. Data from high-resolution acoustic and movement recording tags deployed on 12 sperm whales were downsampled to 1 Hz to match the typical TDR sampling resolution and used to predict the number of buzzes (i.e., rapid series of echolocation clicks indicative of PCAs). Generalized linear mixed models were built for dive segments of different durations (30, 60, 180 and 300 s) using multiple dive metrics as potential predictors of PCAs. RESULTS Average depth, variance of depth and variance of vertical velocity were the best predictors of the number of buzzes. Sensitivity analysis showed that models with segments of 180 s had the best overall predictive performance, with a good area under the curve value (0.78 ± 0.05), high sensitivity (0.93 ± 0.06) and high specificity (0.64 ± 0.14). Models using 180 s segments had a small difference between observed and predicted number of buzzes per dive, with a median of 4 buzzes, representing a difference in predicted buzzes of 30%. CONCLUSIONS These results demonstrate that it is possible to obtain a fine-scale, accurate index of sperm whale PCAs from time-depth data alone. This work helps leveraging the potential of time-depth data for studying the foraging ecology of sperm whales and the possibility of applying this approach to a wide range of echolocating cetaceans. The development of accurate foraging indices from low-cost, easily accessible TDR data would contribute to democratize this type of research, promote long-term studies of various species in several locations, and enable analyses of historical datasets to investigate changes in cetacean foraging activity.
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Affiliation(s)
- Sergi Pérez-Jorge
- Institute of Marine Sciences - OKEANOS & Institute of Marine Research - IMAR, University of the Azores, Horta, Portugal.
| | - Cláudia Oliveira
- Institute of Marine Sciences - OKEANOS & Institute of Marine Research - IMAR, University of the Azores, Horta, Portugal
| | | | - Rui Prieto
- Institute of Marine Sciences - OKEANOS & Institute of Marine Research - IMAR, University of the Azores, Horta, Portugal
| | - Irma Cascão
- Institute of Marine Sciences - OKEANOS & Institute of Marine Research - IMAR, University of the Azores, Horta, Portugal
| | - Paul J Wensveen
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavik, Iceland
| | - Patrick J O Miller
- Sea Mammal Research Unit, School of Biology, University of St Andrews, St Andrews, Scotland
| | - Mónica A Silva
- Institute of Marine Sciences - OKEANOS & Institute of Marine Research - IMAR, University of the Azores, Horta, Portugal
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3
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Allegue H, Réale D, Picard B, Guinet C. Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator. MOVEMENT ECOLOGY 2023; 11:3. [PMID: 36681811 PMCID: PMC9862577 DOI: 10.1186/s40462-022-00361-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 12/17/2022] [Indexed: 06/08/2023]
Abstract
BACKGROUND Studying animal movement in the context of the optimal foraging theory has led to the development of simple movement metrics for inferring feeding activity. Yet, the predictive capacity of these metrics in natural environments has been given little attention, raising serious questions of the validity of these metrics. The aim of this study is to test whether simple continuous movement metrics predict feeding intensity in a marine predator, the southern elephant seal (SES; Mirounga leonine), and investigate potential factors influencing the predictive capacity of these metrics. METHODS We equipped 21 female SES from the Kerguelen Archipelago with loggers and recorded their movements during post-breeding foraging trips at sea. From accelerometry, we estimated the number of prey encounter events (nPEE) and used it as a reference for feeding intensity. We also extracted several track- and dive-based movement metrics and evaluated how well they explain and predict the variance in nPEE. We conducted our analysis at two temporal scales (dive and day), with two dive profile resolutions (high at 1 Hz and low with five dive segments), and two types of models (linear models and regression trees). RESULTS We found that none of the movement metrics predict nPEE with satisfactory power. The vertical transit rates (primarily the ascent rate) during dives had the best predictive performance among all metrics. Dive metrics performed better than track metrics and all metrics performed on average better at the scale of days than the scale of dives. However, the performance of the models at the scale of days showed higher variability among individuals suggesting distinct foraging tactics. Dive-based metrics performed better when computed from high-resolution dive profiles than low-resolution dive profiles. Finally, regression trees produced more accurate predictions than linear models. CONCLUSIONS Our study reveals that simple movement metrics do not predict feeding activity in free-ranging marine predators. This could emerge from differences between individuals, temporal scales, and the data resolution used, among many other factors. We conclude that these simple metrics should be avoided or carefully tested a priori with the studied species and the ecological context to account for significant influencing factors.
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Affiliation(s)
- Hassen Allegue
- Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, QC, Canada.
| | - Denis Réale
- Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, QC, Canada
| | - Baptiste Picard
- Centre d'Etudes Biologiques de Chizé, UMR7372 CNRS-La Rochelle Université, Villiers en Bois, France
| | - Christophe Guinet
- Centre d'Etudes Biologiques de Chizé, UMR7372 CNRS-La Rochelle Université, Villiers en Bois, France
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4
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Schwarz JFL, DeRango EJ, Zenth F, Kalberer S, Hoffman JI, Mews S, Piedrahita P, Trillmich F, Páez-Rosas D, Thiboult A, Krüger O. A stable foraging polymorphism buffers Galápagos sea lions against environmental change. Curr Biol 2022; 32:1623-1628.e3. [PMID: 35240048 DOI: 10.1016/j.cub.2022.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/20/2022] [Accepted: 02/01/2022] [Indexed: 11/26/2022]
Abstract
Understanding the ability of animals to cope with a changing environment is critical in a world affected by anthropogenic disturbance.1 Individual foraging strategies may influence the coping ability of entire populations, as these strategies can be adapted to contrasting conditions, allowing populations with foraging polymorphisms to be more resilient toward environmental change.2,3 However, environmentally dependent fitness consequences of individual foraging strategies and their effects on population dynamics have not been conclusively documented.4,5 Here, we use biologging data from endangered Galápagos sea lion females (Zalophus wollebaeki) to show that benthically foraging individuals dig after sand-dwelling prey species while pelagic foragers hunt in more open waters. These specialized foraging behaviors result in distinct and temporally stable patterns of vibrissae abrasion. Using vibrissae length as a visual marker for the benthic versus pelagic foraging strategies, we furthermore uncovered an environment-dependent fitness trade-off between benthic and pelagic foragers, suggesting that the foraging polymorphism could help to buffer the population against the negative effects of climate change. However, demographic projections suggest that this buffering effect is unlikely to be sufficient to reverse the ongoing population decline of the past four decades.6 Our study shows how crucial a deeper understanding of behavioral polymorphisms can be for predicting how populations cope within a rapidly changing world. VIDEO ABSTRACT.
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Affiliation(s)
- Jonas F L Schwarz
- Department of Animal Behaviour, Bielefeld University, Bielefeld, NRW 33615, Germany.
| | - Eugene J DeRango
- Department of Animal Behaviour, Bielefeld University, Bielefeld, NRW 33615, Germany
| | - Friederike Zenth
- Chair of Wildlife Ecology and Management, Freiburg University, Freiburg, BW 79106, Germany
| | - Stephanie Kalberer
- Department of Animal Behaviour, Bielefeld University, Bielefeld, NRW 33615, Germany
| | - Joseph I Hoffman
- Department of Animal Behaviour, Bielefeld University, Bielefeld, NRW 33615, Germany
| | - Sina Mews
- Department of Business Administration and Economics, Bielefeld University, Bielefeld, NRW 33615, Germany
| | - Paolo Piedrahita
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral, Guayaquil, GP 090902, Ecuador
| | - Fritz Trillmich
- Department of Animal Behaviour, Bielefeld University, Bielefeld, NRW 33615, Germany
| | - Diego Páez-Rosas
- Universidad San Francisco de Quito, Galápagos Science Center, Isla San Cristobal, Islas Galápagos 200101, Ecuador
| | - Antoine Thiboult
- Department of Civil and Water Engineering, Université Laval, Québec, QC G1V 0A6, Canada
| | - Oliver Krüger
- Department of Animal Behaviour, Bielefeld University, Bielefeld, NRW 33615, Germany
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DeRango EJ, Schwarz JFL, Piedrahita P, Páez‐Rosas D, Crocker DE, Krüger O. Hormone-mediated foraging strategies in an uncertain environment: Insights into the at-sea behavior of a marine predator. Ecol Evol 2021; 11:7579-7590. [PMID: 34188836 PMCID: PMC8216952 DOI: 10.1002/ece3.7590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 12/22/2022] Open
Abstract
Hormones are extensively known to be physiological mediators of energy mobilization and allow animals to adjust behavioral performance in response to their environment, especially within a foraging context.Few studies, however, have narrowed focus toward the consistency of hormonal patterns and their impact on individual foraging behavior. Describing these relationships can further our understanding of how individuals cope with heterogeneous environments and exploit different ecological niches.To address this, we measured between- and within-individual variation of basal cortisol (CORT), thyroid hormone T3, and testosterone (TEST) levels in wild adult female Galápagos sea lions (Zalophus wollebaeki) and analyzed how these hormones may be associated with foraging strategies. In this marine predator, females exhibit one of three spatially and temporally distinct foraging patterns (i.e., "benthic," "pelagic," and "night" divers) within diverse habitat types.Night divers differentiated from other strategies by having lower T3 levels. Considering metabolic costs, night divers may represent an energetically conservative strategy with shorter dive durations, depths, and descent rates to exploit prey which migrate up the water column based on vertical diel patterns.Intriguingly, CORT and TEST levels were highest in benthic divers, a strategy characterized by congregating around limited, shallow seafloors to specialize on confined yet reliable prey. This pattern may reflect hormone-mediated behavioral responses to specific risks in these habitats, such as high competition with conspecifics, prey predictability, or greater risks of predation.Overall, our study highlights the collective effects of hormonal and ecological variation on marine foraging. In doing so, we provide insights into how mechanistic constraints and environmental pressures may facilitate individual specialization in adaptive behavior in wild populations.
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Affiliation(s)
| | | | - Paolo Piedrahita
- Facultad de Ciencias de la VidaEscuela Superior Politécnica del LitoralGuayaquilEcuador
| | - Diego Páez‐Rosas
- Universidad San Francisco de QuitoGalápagos Science CenterIsla San CristobalEcuador
- Dirección Parque Nacional GalápagosOficina Técnica San CristóbalIsla San CristóbalEcuador
| | | | - Oliver Krüger
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
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Schwarz JFL, Mews S, DeRango EJ, Langrock R, Piedrahita P, Páez-Rosas D, Krüger O. Individuality counts: A new comprehensive approach to foraging strategies of a tropical marine predator. Oecologia 2021; 195:313-325. [PMID: 33491108 PMCID: PMC7882564 DOI: 10.1007/s00442-021-04850-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/04/2021] [Indexed: 11/24/2022]
Abstract
Foraging strategies are of great ecological interest, as they have a strong impact on the fitness of an individual and can affect its ability to cope with a changing environment. Recent studies on foraging strategies show a higher complexity than previously thought due to intraspecific variability. To reliably identify foraging strategies and describe the different foraging niches they allow individual animals to realize, high-resolution multivariate approaches which consider individual variation are required. Here we dive into the foraging strategies of Galápagos sea lions (Zalophus wollebaeki), a tropical predator confronted with substantial annual variation in sea surface temperature. This affects prey abundance, and El Niño events, expected to become more frequent and severe with climate change, are known to have dramatic effects on sea lions. This study used high-resolution measures of depth, GPS position and acceleration collected from 39 lactating sea lion females to analyze their foraging strategies at an unprecedented level of detail using a novel combination of automated broken stick algorithm, hierarchical cluster analysis and individually fitted multivariate hidden Markov models. We found three distinct foraging strategies (pelagic, benthic, and night divers), which differed in their horizontal, vertical and temporal distribution, most likely corresponding to different prey species, and allowed us to formulate hypotheses with regard to adaptive values under different environmental scenarios. We demonstrate the advantages of our multivariate approach and inclusion of individual variation to reliably gain a deeper understanding of the adaptive value and ecological relevance of foraging strategies of marine predators in dynamic environments.
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Affiliation(s)
- Jonas F L Schwarz
- Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany.
| | - Sina Mews
- Department of Business Administration and Economics, Bielefeld University, Bielefeld, Germany
| | - Eugene J DeRango
- Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany
| | - Roland Langrock
- Department of Business Administration and Economics, Bielefeld University, Bielefeld, Germany
| | - Paolo Piedrahita
- Facultad de Ciencias de La Vida, Escuela Superior Politécnica del Litoral, Guayaquil, Ecuador
| | - Diego Páez-Rosas
- Galápagos Science Center, Universidad San Francisco de Quito, Puerto Baquerizo Moreno, Ecuador.,Dirección Parque Nacional Galápagos, Unidad Técnica Operativa San Cristóbal, Puerto Baquerizo Moreno, Ecuador
| | - Oliver Krüger
- Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany
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Photopoulou T, Heerah K, Pohle J, Boehme L. Sex-specific variation in the use of vertical habitat by a resident Antarctic top predator. Proc Biol Sci 2020; 287:20201447. [PMID: 33081623 PMCID: PMC7661299 DOI: 10.1098/rspb.2020.1447] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Patterns of habitat use are commonly studied in horizontal space, but this does not capture the four-dimensional nature of ocean habitats (space, depth, and time). Deep-diving marine animals encounter varying oceanographic conditions, particularly at the poles, where there is strong seasonal variation in vertical ocean structuring. This dimension of space use is hidden if we only consider horizontal movement. To identify different diving behaviours and usage patterns of vertically distributed habitat, we use hidden Markov models fitted to telemetry data from an air-breathing top predator, the Weddell seal, in the Weddell Sea, Antarctica. We present evidence of overlapping use of high-density, continental shelf water masses by both sexes, as well as important differences in their preferences for oceanographic conditions. Males spend more time in the unique high-salinity shelf water masses found at depth, while females also venture off the continental shelf and visit warmer, shallower water masses. Both sexes exhibit a diurnal pattern in diving behaviour (deep in the day, shallow at night) that persists from austral autumn into winter. The differences in habitat use in this resident, sexually monomorphic Antarctic top predator suggest a different set of needs and constraints operating at the intraspecific level, not driven by body size.
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Affiliation(s)
- Theoni Photopoulou
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, UK.,Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, UK
| | - Karine Heerah
- Marine Bioacoustics Lab, Zoophysiology, Dept. Biology, Aarhus University, Aarhus, Denmark
| | - Jennifer Pohle
- Department of Business Administration and Economics, Bielefeld University, Bielefeld, Germany
| | - Lars Boehme
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, UK
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Abstract
Mesopelagic fish and squid occupy ocean depths extending below the photic zone and their vertical migrations represent a massive pathway moving energy and carbon through the water column. Their spatio-temporal distribution is however, difficult to map across remote regions particularly the vast Southern Ocean. This represents a key gap in understanding biogeochemical processes, marine ecosystem structure, and how changing ocean conditions will affect marine predators, which depend upon mesopelagic prey. We infer mesopelagic prey vertical distribution and relative abundance in the Indian sector of the Southern Ocean (20° to 130°E) with a novel approach using predator-derived indices. Fourteen years of southern elephant seal tracking and dive data, from the open ocean between the Antarctic Polar Front and the southern Antarctic Circumpolar Current front, clearly show that the vertical distribution of mesopelagic prey is influenced by the physical hydrographic processes that structure their habitat. Mesopelagic prey have a more restricted vertical migration and higher relative abundance closer to the surface where Circumpolar Deep Water rises to shallower depths. Combining these observations with a future projection of Southern Ocean conditions we show that changes in the coupling of surface and deep waters will potentially redistribute mesopelagic prey. These changes are small overall, but show important spatial variability: prey will increase in relative abundance to the east of the Kerguelen Plateau but decrease to the west. The consequences for deep-diving specialists such as elephant seals and whales over this time scale will likely be minor, but the changes in mesoscale vertical energy flow have implications for predators that forage within the mesopelagic zone as well as the broader pelagic ecosystem.
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9
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A quantitative, hierarchical approach for detecting drift dives and tracking buoyancy changes in southern elephant seals. Sci Rep 2019; 9:8936. [PMID: 31222003 PMCID: PMC6586652 DOI: 10.1038/s41598-019-44970-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 05/29/2019] [Indexed: 11/08/2022] Open
Abstract
Foraging behaviour of marine predators inferred from the analysis of horizontal or vertical movements commonly lack quantitative information about foraging success. Several marine mammal species are known to perform dives where they passively drift in the water column, termed “drift” dives. The drift rate is determined by the animal’s buoyancy, which can be used to make inference regarding body condition. Long term dive records retrieved via satellite uplink are often summarized before transmission. This loss of resolution hampers identification of drift dives. Here, we develop a flexible, hierarchically structured approach to identify drift dives and estimate the drift rate from the summarized time-depth profiles that are increasingly available to the global research community. Based on high-resolution dive data from southern elephant seals, we classify dives as drift/non-drift and apply a summarization algorithm. We then (i) automatically generate dive groups based on inflection point ordering using a ‘Reverse’ Broken-Stick Algorithm, (ii) develop a set of threshold criteria to apply across groups, ensuring non-drift dives are most efficiently rejected, and (iii) finally implement a custom Kalman filter to retain the remaining dives that are within the seals estimated drifting time series. Validation with independent data sets shows our method retains approximately 3% of all dives, of which 88% are true drift dives. The drift rate estimates are unbiased, with the upper 95% quantile of the mean squared error between the daily averaged summarized profiles using our method (SDDR) and the observed daily averaged drift rate (ODDR) being only 0.0015. The trend of the drifting time-series match expectations for capital breeders, showing the lowest body condition commencing foraging trips and a progressive improvement as they remain at sea. Our method offers sufficient resolution to track small changes in body condition at a fine temporal scale. This approach overcomes a long-term challenge for large existing and ongoing data collections, with potential application across other drift diving species. Enabling robust identification of foraging success at sea offers a rare and valuable opportunity for monitoring marine ecosystem productivity in space and time by tracking the success of a top predator.
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Siegelman L, O'Toole M, Flexas M, Rivière P, Klein P. Submesoscale ocean fronts act as biological hotspot for southern elephant seal. Sci Rep 2019; 9:5588. [PMID: 30944405 PMCID: PMC6447572 DOI: 10.1038/s41598-019-42117-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/25/2019] [Indexed: 01/22/2023] Open
Abstract
The area west of the Kerguelen Islands (20-70°E/45-60°S) is characterized by a weak mesoscale activity except for a standing meander region of the Antarctic Circumpolar Current (ACC) localized between 20 and 40°E. A unique bio-physical dataset at high-resolution collected by a southern elephant seal (Mirounga leonina) reveals a conspicuous increase in foraging activity at the standing meander site up to 5 times larger than during the rest of her three-month trip west of the Kerguelen Islands. Here, we propose a physical explanation for such high biological activity based on the study of small-scale fronts with scales of 5 to 20 km, also called submesoscales. The standing meander is associated with intensified frontal dynamics at submesoscale, not observed in the rest of the region. Results shed new light on the spatial distribution of submesoscale fronts in the under-sampled area west of the Kerguelen plateau and emphasize their importance for upper trophic levels. Despite that most elephant seals target foraging grounds east of the Kerguelen Plateau, our findings suggest that excursions to the west are not accidental, and may be explained by the recurrently elevated physical and biological activity of the site. As such, other standing meanders of the ACC may also act as biological hotspots where trophic interactions are stimulated by submesoscale turbulence.
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Affiliation(s)
- Lia Siegelman
- Univ. Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France. .,California Institute of Technology, Pasadena, CA, USA. .,Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
| | - Malcolm O'Toole
- UWA Oceans Institute, Indian Ocean Marine Research Centre, University of Western Australia, Crawley, WA, 6009, Australia
| | - Mar Flexas
- California Institute of Technology, Pasadena, CA, USA
| | - Pascal Rivière
- Univ. Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France
| | - Patrice Klein
- California Institute of Technology, Pasadena, CA, USA.,Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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Mikkelsen L, Johnson M, Wisniewska DM, van Neer A, Siebert U, Madsen PT, Teilmann J. Long-term sound and movement recording tags to study natural behavior and reaction to ship noise of seals. Ecol Evol 2019; 9:2588-2601. [PMID: 30891202 PMCID: PMC6405890 DOI: 10.1002/ece3.4923] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/18/2018] [Accepted: 12/27/2018] [Indexed: 12/17/2022] Open
Abstract
The impact of anthropogenic noise on marine fauna is of increasing conservation concern with vessel noise being one of the major contributors. Animals that rely on shallow coastal habitats may be especially vulnerable to this form of pollution.Very limited information is available on how much noise from ship traffic individual animals experience, and how they may react to it due to a lack of suitable methods. To address this, we developed long-duration audio and 3D-movement tags (DTAGs) and deployed them on three harbor seals and two gray seals in the North Sea during 2015-2016.These tags recorded sound, accelerometry, magnetometry, and pressure continuously for up to 21 days. GPS positions were also sampled for one seal continuously throughout the recording period. A separate tag, combining a camera and an accelerometer logger, was deployed on two harbor seals to visualize specific behaviors that helped interpret accelerometer signals in the DTAG data.Combining data from depth, accelerometer, and audio sensors, we found that animals spent 6.6%-42.3% of the time hauled out (either on land or partly submerged), and 5.3%-12.4% of their at-sea time resting at the sea bottom, while the remaining time was used for traveling, resting at surface, and foraging. Animals were exposed to audible vessel noise 2.2%-20.5% of their time when in water, and we demonstrate that interruption of functional behaviors (e.g., resting) in some cases coincides with high-level vessel noise. Two-thirds of the ship noise events were traceable by the AIS vessel tracking system, while one-third comprised vessels without AIS.This preliminary study demonstrates how concomitant long-term continuous broadband on-animal sound and movement recordings may be an important tool in future quantification of disturbance effects of anthropogenic activities at sea and assessment of long-term population impacts on pinnipeds.
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Affiliation(s)
| | - Mark Johnson
- Sea Mammal Research UnitUniversity of St. AndrewsSt. AndrewsUK
- Department of BioscienceAarhus UniversityAarhus CDenmark
| | - Danuta Maria Wisniewska
- Department of BioscienceAarhus UniversityRoskildeDenmark
- Hopkins Marine StationStanford UniversityStanfordCalifornia
| | - Abbo van Neer
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW)University of Veterinary Medicine HannoverFoundationGermany
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW)University of Veterinary Medicine HannoverFoundationGermany
| | - Peter Teglberg Madsen
- Department of BioscienceAarhus UniversityAarhus CDenmark
- Aarhus Institute for Advanced StudiesAarhus UniversityAarhus CDenmark
| | - Jonas Teilmann
- Department of BioscienceAarhus UniversityRoskildeDenmark
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12
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Heerah K, Cox SL, Blevin P, Guinet C, Charrassin JB. Validation of Dive Foraging Indices Using Archived and Transmitted Acceleration Data: The Case of the Weddell Seal. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Fish prey of Weddell seals, Leptonychotes weddellii, at Hope Bay, Antarctic Peninsula, during the late summer. Polar Biol 2018. [DOI: 10.1007/s00300-018-2255-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Cox SL, Orgeret F, Gesta M, Rodde C, Heizer I, Weimerskirch H, Guinet C, O'Hara RB. Processing of acceleration and dive data on-board satellite relay tags to investigate diving and foraging behaviour in free-ranging marine predators. Methods Ecol Evol 2018; 9:64-77. [PMID: 29456829 PMCID: PMC5812097 DOI: 10.1111/2041-210x.12845] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 06/06/2017] [Indexed: 11/29/2022]
Abstract
Biologging technologies are changing the way in which the marine environment is observed and monitored. However, because device retrieval is typically required to access the high-resolution data they collect, their use is generally restricted to those animals that predictably return to land. Data abstraction and transmission techniques aim to address this, although currently these are limited in scope and do not incorporate, for example, acceleration measurements which can quantify animal behaviours and movement patterns over fine-scales.In this study, we present a new method for the collection, abstraction and transmission of accelerometer data from free-ranging marine predators via the Argos satellite system. We test run the technique on 20 juvenile southern elephant seals Mirounga leonina from the Kerguelen Islands during their first months at sea following weaning. Using retrieved archival data from nine individuals that returned to the colony, we compare and validate abstracted transmissions against outputs from established accelerometer processing procedures.Abstracted transmissions included estimates, across five segments of a dive profile, of time spent in prey catch attempt (PrCA) behaviours, swimming effort and pitch. These were then summarised and compared to archival outputs across three dive phases: descent, bottom and ascent. Correlations between the two datasets were variable but generally good (dependent on dive phase, marginal R2 values of between .45 and .6 to >.9) and consistent between individuals. Transmitted estimates of PrCA behaviours and swimming effort were positively biased to those from archival processing.Data from this study represent some of the first remotely transmitted quantifications from accelerometers. The methods presented and analysed can be used to provide novel insight towards the behaviours and movements of free-ranging marine predators, such as juvenile southern elephant seals, from whom logger retrieval is challenging. Future applications could however benefit from some adaption, particularly to reduce positive bias in transmitted PrCA behaviours and swimming effort, for which this study provides useful insight.
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Affiliation(s)
- Sam L. Cox
- Centre d'Etudes Biologique de ChizéU.M.R. 7372 – CNRS & Universitié de La RochelleVilliers‐en‐BoisFrance
| | - Florian Orgeret
- Centre d'Etudes Biologique de ChizéU.M.R. 7372 – CNRS & Universitié de La RochelleVilliers‐en‐BoisFrance
| | - Mathieu Gesta
- Centre d'Etudes Biologique de ChizéU.M.R. 7372 – CNRS & Universitié de La RochelleVilliers‐en‐BoisFrance
| | - Charles Rodde
- Centre d'Etudes Biologique de ChizéU.M.R. 7372 – CNRS & Universitié de La RochelleVilliers‐en‐BoisFrance
| | | | - Henri Weimerskirch
- Centre d'Etudes Biologique de ChizéU.M.R. 7372 – CNRS & Universitié de La RochelleVilliers‐en‐BoisFrance
| | - Christophe Guinet
- Centre d'Etudes Biologique de ChizéU.M.R. 7372 – CNRS & Universitié de La RochelleVilliers‐en‐BoisFrance
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15
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Heerah K, Hindell M, Andrew-Goff V, Field I, McMahon CR, Charrassin JB. Contrasting behavior between two populations of an ice-obligate predator in East Antarctica. Ecol Evol 2017; 7:606-618. [PMID: 28116057 PMCID: PMC5243189 DOI: 10.1002/ece3.2652] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/04/2016] [Accepted: 11/08/2016] [Indexed: 11/23/2022] Open
Abstract
The Austral autumn–winter is a critical period for capital breeders such as Weddell seals that must optimize resource acquisition and storage to provision breeding in the subsequent spring. However, how Weddell seals find food in the winter months remains poorly documented. We equipped adult Weddell seals after their annual molt with satellite‐relayed data loggers at two sites in East Antarctica: Dumont D'Urville (n = 12, DDU) and Davis (n = 20). We used binomial generalized mixed‐effect models to investigate Weddell seals’ behavioral response (i.e., “hunting” vs. “transit”) to physical aspects of their environment (e.g., ice concentration). Weddell seal foraging was concentrated to within 5 km of a breathing hole, and they appear to move between holes as local food is depleted. There were regional differences in behavior so that seals at Davis traveled greater distances (three times more) and spent less time in hunting mode (half the time) than seals at DDU. Despite these differences, hunting dives at both locations were pelagic, concentrated in areas of high ice concentration, and over areas of complex bathymetry. There was also a seasonal change in diving behavior from transiting early in the season to more hunting during winter. Our observations suggest that Weddell seal foraging behavior is plastic and that they respond behaviorally to changes in their environment to maximize food acquisition and storage. Such plasticity is a hallmark of animals that live in very dynamic environments such as the high Antarctic where resources are unpredictable.
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Affiliation(s)
- Karine Heerah
- LOCEAN Laboratory Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN Paris France; Institute for Marine and Antarctic Studies University of Tasmania Hobart Tas. Australia
| | - Mark Hindell
- Institute for Marine and Antarctic Studies University of Tasmania Hobart Tas. Australia; Antarctic Climate and Ecosystem Cooperative Research Centre University of Tasmania Hobart Tas. Australia
| | - Virginia Andrew-Goff
- Institute for Marine and Antarctic Studies University of Tasmania Hobart Tas. Australia
| | - Iain Field
- Department of Biological Sciences Macquarie University Sydney NSW Australia
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16
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Leos‐Barajas V, Photopoulou T, Langrock R, Patterson TA, Watanabe YY, Murgatroyd M, Papastamatiou YP. Analysis of animal accelerometer data using hidden Markov models. Methods Ecol Evol 2016. [DOI: 10.1111/2041-210x.12657] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vianey Leos‐Barajas
- Department of Statistics Iowa State University Snedecor Hall Ames IA 50011 USA
| | - Theoni Photopoulou
- Department of Statistical Sciences Centre for Statistics in Ecology, Environment and Conservation University of Cape Town Cape Town Rondebosch 7701 South Africa
- Department of Zoology Institute for Coastal and Marine Research Nelson Mandela Metropolitan University Port Elizabeth 6031 South Africa
| | - Roland Langrock
- Department of Business Administration and Economics Bielefeld University Postfach 100131 33501 Bielefeld Germany
| | | | - Yuuki Y. Watanabe
- National Institute of Polar Research 10‐3, Midori‐cho Tachikawa Tokyo 190‐8518 Japan
- SOKENDAI (The Graduate University for Advanced Studies) 10‐3, Midori‐cho Tachikawa Tokyo 190‐8518 Japan
| | - Megan Murgatroyd
- Animal Demography Unit Department of Biological Sciences University of Cape Town Cape Town Rondebosch 7701 South Africa
- Percy FitzPatrick Institute of African Ornithology Department of Biological Sciences University of Cape Town Cape Town Rondebosch 7701 South Africa
| | - Yannis P. Papastamatiou
- School of Biology Scottish Oceans Institute University of St Andrews St Andrews KY16 8LB UK
- Department of Biological Sciences Florida International University 3000 NE 151st, MSB 350 North Miami FL 33181 USA
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17
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Arthur B, Hindell M, Bester MN, Oosthuizen WC, Wege M, Lea M. South for the winter? Within‐dive foraging effort reveals the trade‐offs between divergent foraging strategies in a free‐ranging predator. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12636] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Benjamin Arthur
- Institute for Marine and Antarctic Studies University of Tasmania 20 Castray Esplanade, Battery Point Hobart TAS 7004 Australia
- Antarctic Climate and Ecosystems Cooperative Research Centre University of Tasmania Hobart TAS 7004 Australia
| | - Mark Hindell
- Institute for Marine and Antarctic Studies University of Tasmania 20 Castray Esplanade, Battery Point Hobart TAS 7004 Australia
- Antarctic Climate and Ecosystems Cooperative Research Centre University of Tasmania Hobart TAS 7004 Australia
| | - Marthan N. Bester
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - W. Chris Oosthuizen
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - Mia Wege
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - Mary‐Anne Lea
- Institute for Marine and Antarctic Studies University of Tasmania 20 Castray Esplanade, Battery Point Hobart TAS 7004 Australia
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18
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Foo D, Semmens JM, Arnould JP, Dorville N, Hoskins AJ, Abernathy K, Marshall GJ, Hindell MA. Testing optimal foraging theory models on benthic divers. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2015.11.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Carter MID, Bennett KA, Embling CB, Hosegood PJ, Russell DJF. Navigating uncertain waters: a critical review of inferring foraging behaviour from location and dive data in pinnipeds. MOVEMENT ECOLOGY 2016; 4:25. [PMID: 27800161 PMCID: PMC5080796 DOI: 10.1186/s40462-016-0090-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 10/17/2016] [Indexed: 05/09/2023]
Abstract
In the last thirty years, the emergence and progression of biologging technology has led to great advances in marine predator ecology. Large databases of location and dive observations from biologging devices have been compiled for an increasing number of diving predator species (such as pinnipeds, sea turtles, seabirds and cetaceans), enabling complex questions about animal activity budgets and habitat use to be addressed. Central to answering these questions is our ability to correctly identify and quantify the frequency of essential behaviours, such as foraging. Despite technological advances that have increased the quality and resolution of location and dive data, accurately interpreting behaviour from such data remains a challenge, and analytical methods are only beginning to unlock the full potential of existing datasets. This review evaluates both traditional and emerging methods and presents a starting platform of options for future studies of marine predator foraging ecology, particularly from location and two-dimensional (time-depth) dive data. We outline the different devices and data types available, discuss the limitations and advantages of commonly-used analytical techniques, and highlight key areas for future research. We focus our review on pinnipeds - one of the most studied taxa of marine predators - but offer insights that will be applicable to other air-breathing marine predator tracking studies. We highlight that traditionally-used methods for inferring foraging from location and dive data, such as first-passage time and dive shape analysis, have important caveats and limitations depending on the nature of the data and the research question. We suggest that more holistic statistical techniques, such as state-space models, which can synthesise multiple track, dive and environmental metrics whilst simultaneously accounting for measurement error, offer more robust alternatives. Finally, we identify a need for more research to elucidate the role of physical oceanography, device effects, study animal selection, and developmental stages in predator behaviour and data interpretation.
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Affiliation(s)
- Matt Ian Daniel Carter
- Marine Biology & Ecology Research Centre, School of Marine Science & Engineering, Plymouth University, PL4 8AA Plymouth, UK
| | - Kimberley A. Bennett
- School of Science, Engineering & Technology, Abertay University, DD1 1HG Dundee, UK
| | - Clare B. Embling
- Marine Biology & Ecology Research Centre, School of Marine Science & Engineering, Plymouth University, PL4 8AA Plymouth, UK
| | - Philip J. Hosegood
- Centre for Coast and Ocean Science & Engineering, School of Marine Science & Engineering, Plymouth University, PL4 8AA Plymouth, UK
| | - Debbie J. F. Russell
- Sea Mammal Research Unit, University of St. Andrews, KY16 8LB St. Andrews, UK
- Centre for Research into Ecological and Environmental Modelling, University of St. Andrews, KY16 9LZ St. Andrews, UK
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20
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Gordine SA, Fedak M, Boehme L. Fishing for drifts: detecting buoyancy changes of a top marine predator using a step-wise filtering method. J Exp Biol 2015; 218:3816-24. [PMID: 26486362 PMCID: PMC4712810 DOI: 10.1242/jeb.118109] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 10/04/2015] [Indexed: 11/20/2022]
Abstract
In southern elephant seals (Mirounga leonina), fasting- and foraging-related fluctuations in body composition are reflected by buoyancy changes. Such buoyancy changes can be monitored by measuring changes in the rate at which a seal drifts passively through the water column, i.e. when all active swimming motion ceases. Here, we present an improved knowledge-based method for detecting buoyancy changes from compressed and abstracted dive profiles received through telemetry. By step-wise filtering of the dive data, the developed algorithm identifies fragments of dives that correspond to times when animals drift. In the dive records of 11 southern elephant seals from South Georgia, this filtering method identified 0.8-2.2% of all dives as drift dives, indicating large individual variation in drift diving behaviour. The obtained drift rate time series exhibit that, at the beginning of each migration, all individuals were strongly negatively buoyant. Over the following 75-150 days, the buoyancy of all individuals peaked close to or at neutral buoyancy, indicative of a seal's foraging success. Independent verification with visually inspected detailed high-resolution dive data confirmed that this method is capable of reliably detecting buoyancy changes in the dive records of drift diving species using abstracted data. This also affirms that abstracted dive profiles convey the geometric shape of drift dives in sufficient detail for them to be identified. Further, it suggests that, using this step-wise filtering method, buoyancy changes could be detected even in old datasets with compressed dive information, for which conventional drift dive classification previously failed.
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Affiliation(s)
- Samantha Alex Gordine
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - Michael Fedak
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - Lars Boehme
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
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