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McRae TM, Volpov BL, Sidrow E, Fortune SME, Auger-Méthé M, Heckman N, Trites AW. Killer whale respiration rates. PLoS One 2024; 19:e0302758. [PMID: 38748652 PMCID: PMC11095751 DOI: 10.1371/journal.pone.0302758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 04/08/2024] [Indexed: 05/19/2024] Open
Abstract
Measuring breathing rates is a means by which oxygen intake and metabolic rates can be estimated to determine food requirements and energy expenditure of killer whales (Orcinus orca) and other cetaceans. This relatively simple measure also allows the energetic consequences of environmental stressors to cetaceans to be understood but requires knowing respiration rates while they are engaged in different behaviours such as resting, travelling and foraging. We calculated respiration rates for different behavioural states of southern and northern resident killer whales using video from UAV drones and concurrent biologging data from animal-borne tags. Behavioural states of dive tracks were predicted using hierarchical hidden Markov models (HHMM) parameterized with time-depth data and with labeled tracks of drone-identified behavioural states (from drone footage that overlapped with the time-depth data). Dive tracks were sequences of dives and surface intervals lasting ≥ 10 minutes cumulative duration. We calculated respiration rates and estimated oxygen consumption rates for the predicted behavioural states of the tracks. We found that juvenile killer whales breathed at a higher rate when travelling (1.6 breaths min-1) compared to resting (1.2) and foraging (1.5)-and that adult males breathed at a higher rate when travelling (1.8) compared to both foraging (1.7) and resting (1.3). The juveniles in our study were estimated to consume 2.5-18.3 L O2 min-1 compared with 14.3-59.8 L O2 min-1 for adult males across all behaviours based on estimates of mass-specific tidal volume and oxygen extraction. Our findings confirm that killer whales take single breaths between dives and indicate that energy expenditure derived from respirations requires using sex, age, and behavioural-specific respiration rates. These findings can be applied to bioenergetics models on a behavioural-specific basis, and contribute towards obtaining better predictions of dive behaviours, energy expenditure and the food requirements of apex predators.
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Affiliation(s)
- Tess M. McRae
- Institute for the Oceans and Fisheries, Marine Mammal Research Unit, University of British Columbia, Vancouver, BC, Canada
| | - Beth L. Volpov
- Institute for the Oceans and Fisheries, Marine Mammal Research Unit, University of British Columbia, Vancouver, BC, Canada
| | - Evan Sidrow
- Department of Statistics, University of British Columbia, Vancouver, BC, Canada
| | - Sarah M. E. Fortune
- Institute for the Oceans and Fisheries, Marine Mammal Research Unit, University of British Columbia, Vancouver, BC, Canada
| | - Marie Auger-Méthé
- Department of Statistics, University of British Columbia, Vancouver, BC, Canada
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC, Canada
| | - Nancy Heckman
- Department of Statistics, University of British Columbia, Vancouver, BC, Canada
| | - Andrew W. Trites
- Institute for the Oceans and Fisheries, Marine Mammal Research Unit, University of British Columbia, Vancouver, BC, Canada
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2
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Videsen SKA, Simon M, Christiansen F, Friedlaender A, Goldbogen J, Malte H, Segre P, Wang T, Johnson M, Madsen PT. Cheap gulp foraging of a giga-predator enables efficient exploitation of sparse prey. SCIENCE ADVANCES 2023; 9:eade3889. [PMID: 37352356 PMCID: PMC10289661 DOI: 10.1126/sciadv.ade3889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 05/22/2023] [Indexed: 06/25/2023]
Abstract
The giant rorqual whales are believed to have a massive food turnover driven by a high-intake lunge feeding style aptly described as the world's largest biomechanical action. This high-drag feeding behavior is thought to limit dive times and constrain rorquals to target only the densest prey patches, making them vulnerable to disturbance and habitat change. Using biologging tags to estimate energy expenditure as a function of feeding rates on 23 humpback whales, we show that lunge feeding is energetically cheap. Such inexpensive foraging means that rorquals are flexible in the quality of prey patches they exploit and therefore more resilient to environmental fluctuations and disturbance. As a consequence, the food turnover and hence the ecological role of these marine giants have likely been overestimated.
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Affiliation(s)
- Simone K. A. Videsen
- Zoophysiology, Department of Biology, Aarhus University, Denmark
- Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Malene Simon
- Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Fredrik Christiansen
- Aarhus Institute of Advanced Studies, Aarhus University, DK-8000 Aarhus C, Denmark
- Marine Mammal Research, Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark
| | - Ari Friedlaender
- Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Jeremy Goldbogen
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA, USA
| | - Hans Malte
- Zoophysiology, Department of Biology, Aarhus University, Denmark
| | - Paolo Segre
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA, USA
| | - Tobias Wang
- Zoophysiology, Department of Biology, Aarhus University, Denmark
| | - Mark Johnson
- Zoophysiology, Department of Biology, Aarhus University, Denmark
- Aarhus Institute of Advanced Studies, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Peter T. Madsen
- Zoophysiology, Department of Biology, Aarhus University, Denmark
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3
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Hewitt DE, Johnson DD, Suthers IM, Taylor MD. Crabs ride the tide: incoming tides promote foraging of Giant Mud Crab (Scylla serrata). MOVEMENT ECOLOGY 2023; 11:21. [PMID: 37069648 PMCID: PMC10108527 DOI: 10.1186/s40462-023-00384-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/06/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND Effective fisheries management of mobile species relies on robust knowledge of animal behaviour and habitat-use. Indices of behaviour can be useful for interpreting catch-per-unit-effort data which acts as a proxy for relative abundance. Information about habitat-use can inform stocking release strategies or the design of marine protected areas. The Giant Mud Crab (Scylla serrata; Family: Portunidae) is a swimming estuarine crab that supports significant fisheries harvest throughout the Indo-West Pacific, but little is known about the fine-scale movement and behaviour of this species. METHODS We tagged 18 adult Giant Mud Crab with accelerometer-equipped acoustic tags to track their fine-scale movement using a hyperbolic positioning system, alongside high temporal resolution environmental data (e.g., water temperature), in a temperate south-east Australian estuary. A hidden Markov model was used to classify movement (i.e., step length, turning angle) and acceleration data into discrete behaviours, while also considering the possibility of individual variation in behavioural dynamics. We then investigated the influence of environmental covariates on these behaviours based on previously published observations. RESULTS We fitted a model with two well-distinguished behavioural states describing periods of inactivity and foraging, and found no evidence of individual variation in behavioural dynamics. Inactive periods were most common (79% of time), and foraging was most likely during low, incoming tides; while inactivity was more likely as the high tide receded. Model selection removed time (hour) of day and water temperature (°C) as covariates, suggesting that they do not influence Giant Mud Crab behavioural dynamics at the temporal scale investigated. CONCLUSIONS Our study is the first to quantitatively link fine-scale movement and behaviour of Giant Mud Crab to environmental variation. Our results suggest Giant Mud Crab are a predominantly sessile species, and support their status as an opportunistic scavenger. We demonstrate a relationship between the tidal cycle and foraging that is likely to minimize predation risk while maximizing energetic efficiency. These results may explain why tidal covariates influence catch rates in swimming crabs, and provide a foundation for standardisation and interpretation of catch-per-unit-effort data-a commonly used metric in fisheries science.
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Affiliation(s)
- Daniel E Hewitt
- Fisheries and Marine Environmental Research Lab, Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Science, University of New South Wales, NSW, Sydney, 2052, Australia.
- New South Wales Department of Primary Industries, Port Stephens Fisheries Institute, NSW, Locked Bag 1, Nelson Bay, 2315, Australia.
| | - Daniel D Johnson
- New South Wales Department of Primary Industries, Port Stephens Fisheries Institute, NSW, Locked Bag 1, Nelson Bay, 2315, Australia
| | - Iain M Suthers
- Fisheries and Marine Environmental Research Lab, Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Science, University of New South Wales, NSW, Sydney, 2052, Australia
- Sydney Institute of Marine Science, Mosman, NSW, Australia
| | - Matthew D Taylor
- Fisheries and Marine Environmental Research Lab, Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Science, University of New South Wales, NSW, Sydney, 2052, Australia
- New South Wales Department of Primary Industries, Port Stephens Fisheries Institute, NSW, Locked Bag 1, Nelson Bay, 2315, Australia
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4
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Booth CG, Guilpin M, Darias-O’Hara AK, Ransijn JM, Ryder M, Rosen D, Pirotta E, Smout S, McHuron EA, Nabe-Nielsen J, Costa DP. Estimating energetic intake for marine mammal bioenergetic models. CONSERVATION PHYSIOLOGY 2023; 11:coac083. [PMID: 36756464 PMCID: PMC9900471 DOI: 10.1093/conphys/coac083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 11/08/2022] [Accepted: 12/21/2022] [Indexed: 06/18/2023]
Abstract
Bioenergetics is the study of how animals achieve energetic balance. Energetic balance results from the energetic expenditure of an individual and the energy they extract from their environment. Ingested energy depends on several extrinsic (e.g prey species, nutritional value and composition, prey density and availability) and intrinsic factors (e.g. foraging effort, success at catching prey, digestive processes and associated energy losses, and digestive capacity). While the focus in bioenergetic modelling is often on the energetic costs an animal incurs, the robust estimation of an individual's energy intake is equally critical for producing meaningful predictions. Here, we review the components and processes that affect energy intake from ingested gross energy to biologically useful net energy (NE). The current state of knowledge of each parameter is reviewed, shedding light on research gaps to advance this field. The review highlighted that the foraging behaviour of many marine mammals is relatively well studied via biologging tags, with estimates of success rate typically assumed for most species. However, actual prey capture success rates are often only assumed, although we note studies that provide approaches for its estimation using current techniques. A comprehensive collation of the nutritional content of marine mammal prey species revealed a robust foundation from which prey quality (comprising prey species, size and energy density) can be assessed, though data remain unavailable for many prey species. Empirical information on various energy losses following ingestion of prey was unbalanced among marine mammal species, with considerably more literature available for pinnipeds. An increased understanding and accurate estimate of each of the components that comprise a species NE intake are an integral part of bioenergetics. Such models provide a key tool to investigate the effects of disturbance on marine mammals at an individual and population level and to support effective conservation and management.
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Affiliation(s)
- Cormac G Booth
- Corresponding author: SMRU Consulting, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, KY16 8LB, UK.
| | | | - Aimee-Kate Darias-O’Hara
- SMRU Consulting, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, KY16 8LB, UK
| | - Janneke M Ransijn
- Sea Mammal Research Unit, Scottish Oceans Institute, East Sands, University of St. Andrews, St. Andrews, KY16 8LB, UK
| | - Megan Ryder
- SMRU Consulting, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, KY16 8LB, UK
| | - Dave Rosen
- Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall,
Vancouver, BC V6T 1Z4, Canada
| | - Enrico Pirotta
- Centre for Research into Ecological and Environmental Modelling,
The Observatory, Buchanan
Gardens, University of St. Andrews, St. Andrews,
KY16 9LZ, UK
| | - Sophie Smout
- Sea Mammal Research Unit, Scottish Oceans Institute, East Sands, University of St. Andrews, St. Andrews, KY16 8LB, UK
| | - Elizabeth A McHuron
- Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, 3737 Brooklyn Ave NE, Seattle, WA, 98105, USA
| | - Jacob Nabe-Nielsen
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Aarhus, DK-4000
Roskilde, Denmark
| | - Daniel P Costa
- Ecology and Evolutionary Biology Department, University of California Santa Cruz, 130
McAlister Way, Santa Cruz, CA, 95064, USA
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Hinton B, Stockin KA, Bury SJ, Peters KJ, Betty EL. Isotopic Niche Analysis of Long-Finned Pilot Whales (Globicephala melas edwardii) in Aotearoa New Zealand Waters. BIOLOGY 2022; 11:biology11101414. [PMID: 36290319 PMCID: PMC9598128 DOI: 10.3390/biology11101414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/26/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022]
Abstract
Simple Summary Isotopic niche analyses can elucidate a species’ foraging ecology. Using isotopic values of δ13C, δ15N and δ34S, the isotopic niche of long-finned pilot whales (Globicephala melas edwardii) in Aotearoa New Zealand was investigated for animals that stranded in six different events across two locations between 2009 and 2017. Generalised additive models revealed that stranding event was a stronger predictor for δ13C and δ15N values than body length, sex, or reproductive status, indicating that spatiotemporal differences explained isotopic variation of G. m. edwardii in New Zealand waters better than ontogenetic factors. Abstract The 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.
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Affiliation(s)
- Bethany Hinton
- Cetacean Ecology Research Group, School of Natural Sciences, Massey University, Auckland 0745, New Zealand
- Correspondence: (B.H.); (E.L.B.)
| | - Karen A. Stockin
- Cetacean Ecology Research Group, School of Natural Sciences, Massey University, Auckland 0745, New Zealand
| | - Sarah J. Bury
- Environmental Isotopes and Molecular Biology Group, National Institute of Water and Atmospheric Research, Wellington 6021, New Zealand
| | - Katharina J. Peters
- Cetacean Ecology Research Group, School of Natural Sciences, Massey University, Auckland 0745, New Zealand
- School of Earth and Environment, University of Canterbury, Christchurch 8041, New Zealand
- Evolutionary Genetics Group, Department of Anthropology, University of Zurich, 8057 Zurich, Switzerland
- Global Ecology, College of Science and Engineering, Flinders University, Adelaide, SA 5001, Australia
| | - Emma L. Betty
- Cetacean Ecology Research Group, School of Natural Sciences, Massey University, Auckland 0745, New Zealand
- Correspondence: (B.H.); (E.L.B.)
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Behavioral responses to predatory sounds predict sensitivity of cetaceans to anthropogenic noise within a soundscape of fear. Proc Natl Acad Sci U S A 2022; 119:e2114932119. [PMID: 35312354 PMCID: PMC9060435 DOI: 10.1073/pnas.2114932119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Acoustic signals travel efficiently in the marine environment, allowing soniferous predators and prey to eavesdrop on each other. Our results with four cetacean species indicate that they use acoustic information to assess predation risk and have evolved mechanisms to reduce predation risk by ceasing foraging. Species that more readily gave up foraging in response to predatory sounds of killer whales also decreased foraging more during 1- to 4-kHz sonar exposures, indicating that species exhibiting costly antipredator responses also have stronger behavioral reactions to anthropogenic noise. This advance in our understanding of the drivers of disturbance helps us to predict what species and habitats are likely to be most severely impacted by underwater noise pollution in oceans undergoing increasing anthropogenic activities. As human activities impact virtually every animal habitat on the planet, identifying species at-risk from disturbance is a priority. Cetaceans are an example taxon where responsiveness to anthropogenic noise can be severe but highly species and context specific, with source–receiver characteristics such as hearing sensitivity only partially explaining this variability. Here, we predicted that ecoevolutionary factors that increase species responsiveness to predation risk also increase responsiveness to anthropogenic noise. We found that reductions in intense-foraging time during exposure to 1- to 4-kHz naval sonar and predatory killer whale sounds were highly correlated (r = 0.92) across four cetacean species. Northern bottlenose whales ceased foraging completely during killer whale and sonar exposures, followed by humpback, long-finned pilot, and sperm whales, which reduced intense foraging by 48 to 97%. Individual responses to sonar were partly predicted by species-level responses to killer whale playbacks, implying a similar level of perceived risk. The correlation cannot be solely explained by hearing sensitivity, indicating that species- and context-specific antipredator adaptations also shape cetacean responses to human-made noise. Species that are more responsive to predator presence are predicted to be more disturbance sensitive, implying a looming double whammy for Arctic cetaceans facing increased anthropogenic and predator activity with reduced ice cover.
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Sidrow E, Heckman N, Fortune SME, Trites AW, Murphy I, Auger‐Méthé M. Modelling multi‐scale, state‐switching functional data with hidden Markov models. CAN J STAT 2021. [DOI: 10.1002/cjs.11673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Evan Sidrow
- Department of Statistics University of British Columbia Vancouver V6T 1Z4 British Columbia Canada
| | - Nancy Heckman
- Department of Statistics University of British Columbia Vancouver V6T 1Z4 British Columbia Canada
| | - Sarah M. E. Fortune
- Marine Mammal Research Unit University of British Columbia Vancouver V6T 1Z4 British Columbia Canada
| | - Andrew W. Trites
- Department of Zoology University of British Columbia Vancouver V6T 1Z4 British Columbia Canada
- Institute for the Oceans and Fisheries University of British Columbia Vancouver V6T 1Z4 British Columbia Canada
| | - Ian Murphy
- Department of Biostatistics University of Florida Gainesville 32611 FL U.S.A
| | - Marie Auger‐Méthé
- Department of Statistics University of British Columbia Vancouver V6T 1Z4 British Columbia Canada
- Institute for the Oceans and Fisheries University of British Columbia Vancouver V6T 1Z4 British Columbia Canada
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8
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Hin V, Harwood J, de Roos AM. Density dependence can obscure nonlethal effects of disturbance on life history of medium-sized cetaceans. PLoS One 2021; 16:e0252677. [PMID: 34081741 PMCID: PMC8174747 DOI: 10.1371/journal.pone.0252677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 05/20/2021] [Indexed: 11/19/2022] Open
Abstract
Nonlethal disturbance of animals can cause behavioral and physiological changes that affect individual health status and vital rates, with potential consequences at the population level. Predicting these population effects remains a major challenge in ecology and conservation. Monitoring fitness-related traits may improve detection of upcoming population changes, but the extent to which individual traits are reliable indicators of disturbance exposure is not well understood, especially for populations regulated by density dependence. Here we study how density dependence affects a population’s response to disturbance and modifies the disturbance effects on individual health and vital rates. We extend an energy budget model for a medium-sized cetacean (the long-finned pilot whale Globicephala melas) to an individual-based population model in which whales feed on a self-replenishing prey base and disturbance leads to cessation of feeding. In this coupled predator-prey system, the whale population is regulated through prey depletion and the onset of yearly repeating disturbances on the whale population at carrying capacity decreased population density and increased prey availability due to reduced top-down control. In populations faced with multiple days of continuous disturbance each year, female whales that were lactating their first calf experienced increased mortality due to depletion of energy stores. However, increased prey availability led to compensatory effects and resulted in a subsequent improvement of mean female body condition, mean age at first reproduction and higher age-specific reproductive output. These results indicate that prey-mediated density dependence can mask negative effects of disturbance on fitness-related traits and vital rates, a result with implications for the monitoring and management of marine mammal populations.
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Affiliation(s)
- Vincent Hin
- Department of Theoretical and Computational Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
| | - John Harwood
- Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, United Kingdom
| | - André M. de Roos
- Department of Theoretical and Computational Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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McClintock BT. Worth the effort? A practical examination of random effects in hidden Markov models for animal telemetry data. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13619] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Brett T. McClintock
- Marine Mammal Laboratory Alaska Fisheries Science Center NOAA National Marine Fisheries Service Seattle WA USA
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10
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Nelms SE, Alfaro-Shigueto J, Arnould JPY, Avila IC, Bengtson Nash S, Campbell E, Carter MID, Collins T, Currey RJC, Domit C, Franco-Trecu V, Fuentes MMPB, Gilman E, Harcourt RG, Hines EM, Hoelzel AR, Hooker SK, Johnston DW, Kelkar N, Kiszka JJ, Laidre KL, Mangel JC, Marsh H, Maxwell SM, Onoufriou AB, Palacios DM, Pierce GJ, Ponnampalam LS, Porter LJ, Russell DJF, Stockin KA, Sutaria D, Wambiji N, Weir CR, Wilson B, Godley BJ. Marine mammal conservation: over the horizon. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01115] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Marine mammals can play important ecological roles in aquatic ecosystems, and their presence can be key to community structure and function. Consequently, marine mammals are often considered indicators of ecosystem health and flagship species. Yet, historical population declines caused by exploitation, and additional current threats, such as climate change, fisheries bycatch, pollution and maritime development, continue to impact many marine mammal species, and at least 25% are classified as threatened (Critically Endangered, Endangered or Vulnerable) on the IUCN Red List. Conversely, some species have experienced population increases/recoveries in recent decades, reflecting management interventions, and are heralded as conservation successes. To continue these successes and reverse the downward trajectories of at-risk species, it is necessary to evaluate the threats faced by marine mammals and the conservation mechanisms available to address them. Additionally, there is a need to identify evidence-based priorities of both research and conservation needs across a range of settings and taxa. To that effect we: (1) outline the key threats to marine mammals and their impacts, identify the associated knowledge gaps and recommend actions needed; (2) discuss the merits and downfalls of established and emerging conservation mechanisms; (3) outline the application of research and monitoring techniques; and (4) highlight particular taxa/populations that are in urgent need of focus.
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Affiliation(s)
- SE Nelms
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
| | - J Alfaro-Shigueto
- ProDelphinus, Jose Galvez 780e, Miraflores, Perú
- Facultad de Biologia Marina, Universidad Cientifica del Sur, Lima, Perú
| | - JPY Arnould
- School of Life and Environmental Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - IC Avila
- Grupo de Ecología Animal, Departamento de Biología, Facultad de Ciencias Naturales y Exactas, Universidad del Valle, Cali, Colombia
| | - S Bengtson Nash
- Environmental Futures Research Institute (EFRI), Griffith University, Nathan Campus, 170 Kessels Road, Nathan, QLD 4111, Australia
| | - E Campbell
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
- ProDelphinus, Jose Galvez 780e, Miraflores, Perú
| | - MID Carter
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, KY16 8LB, UK
| | - T Collins
- Wildlife Conservation Society, 2300 Southern Blvd., Bronx, NY 10460, USA
| | - RJC Currey
- Marine Stewardship Council, 1 Snow Hill, London, EC1A 2DH, UK
| | - C Domit
- Laboratory of Ecology and Conservation, Marine Study Center, Universidade Federal do Paraná, Brazil
| | - V Franco-Trecu
- Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Uruguay
| | - MMPB Fuentes
- Marine Turtle Research, Ecology and Conservation Group, Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USA
| | - E Gilman
- Pelagic Ecosystems Research Group, Honolulu, HI 96822, USA
| | - RG Harcourt
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - EM Hines
- Estuary & Ocean Science Center, San Francisco State University, 3150 Paradise Dr. Tiburon, CA 94920, USA
| | - AR Hoelzel
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - SK Hooker
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, KY16 8LB, UK
| | - DW Johnston
- Duke Marine Lab, 135 Duke Marine Lab Road, Beaufort, NC 28516, USA
| | - N Kelkar
- Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Srirampura, Jakkur PO, Bangalore 560064, Karnataka, India
| | - JJ Kiszka
- Department of Biological Sciences, Coastlines and Oceans Division, Institute of Environment, Florida International University, Miami, FL 33199, USA
| | - KL Laidre
- Polar Science Center, APL, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, USA
| | - JC Mangel
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
- ProDelphinus, Jose Galvez 780e, Miraflores, Perú
| | - H Marsh
- James Cook University, Townsville, QLD 48111, Australia
| | - SM Maxwell
- School of Interdisciplinary Arts and Sciences, University of Washington Bothell, Bothell WA 98011, USA
| | - AB Onoufriou
- School of Biology, University of St Andrews, Fife, KY16 8LB, UK
- Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - DM Palacios
- Marine Mammal Institute, Hatfield Marine Science Center, Oregon State University, Newport, OR, 97365, USA
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97330, USA
| | - GJ Pierce
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
- Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Cientificas, Eduardo Cabello 6, 36208 Vigo, Pontevedra, Spain
| | - LS Ponnampalam
- The MareCet Research Organization, 40460 Shah Alam, Malaysia
| | - LJ Porter
- SMRU Hong Kong, University of St. Andrews, Hong Kong
| | - DJF Russell
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, KY16 8LB, UK
- Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, Fife, KY16 8LB, UK
| | - KA Stockin
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North, New Zealand
| | - D Sutaria
- School of Interdisciplinary Arts and Sciences, University of Washington Bothell, Bothell WA 98011, USA
| | - N Wambiji
- Kenya Marine and Fisheries Research Institute, P.O. Box 81651, Mombasa-80100, Kenya
| | - CR Weir
- Ketos Ecology, 4 Compton Road, Kingsbridge, Devon, TQ7 2BP, UK
| | - B Wilson
- Scottish Association for Marine Science, Oban, Argyll, PA37 1QA, UK
| | - BJ Godley
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
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11
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Kok ACM, van Kolfshoten L, Campbell JA, von Benda-Beckmann AM, Miller PJO, Slabbekoorn H, Visser F. Diving apart together: call propagation in diving long-finned pilot whales. J Exp Biol 2020; 223:jeb207878. [PMID: 32321748 DOI: 10.1242/jeb.207878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 04/09/2020] [Indexed: 11/20/2022]
Abstract
Group-living animals must communicate to stay in contact. In long-finned pilot whales, there is a trade-off between the benefits of foraging individually at depth and the formation of tight social groups at the surface. Using theoretical modelling and empirical data of tagged pairs within a group, we examined the potential of pilot whale social calls to reach dispersed group members during foraging periods. Both theoretical predictions and empirical data of tag pairs showed a potential for communication between diving and non-diving group members over separation distances up to 385 m (empirical) and 1800 m (theoretical). These distances match or exceed pilot whale dive depths recorded across populations. Call characteristics and environmental characteristics were analysed to investigate determinants of call detectability. Longer calls with a higher sound pressure level (SPL) that were received in a quieter environment were more often detected than their shorter, lower SPL counterparts within a noisier environment. In a noisier environment, calls were louder and had a lower peak frequency, indicating mechanisms for coping with varying conditions. However, the vulnerability of pilot whales to anthropogenic noise is still of concern as the ability to cope with increasing background noise may be limited. Our study shows that combining propagation modelling and actual tag recordings provides new insights into the communicative potential for social calls in orientation and reunion with group members for deep-diving pilot whales.
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Affiliation(s)
- Annebelle C M Kok
- Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands
| | - Lisette van Kolfshoten
- Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands
- Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands
| | - James A Campbell
- Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands
| | | | - Patrick J O Miller
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife, KY16 8LB, UK
| | - Hans Slabbekoorn
- Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands
| | - Fleur Visser
- Department of Freshwater and Marine Ecology, IBED, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands
- Department of Coastal Systems, NIOZ and Utrecht University, P.O. Box 59, 1790 AB Den Burg, The Netherlands
- Kelp Marine Research, 1624 CJ Hoorn, The Netherlands
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12
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Carter MID, McClintock BT, Embling CB, Bennett KA, Thompson D, Russell DJF. From pup to predator: generalized hidden Markov models reveal rapid development of movement strategies in a naïve long‐lived vertebrate. OIKOS 2020. [DOI: 10.1111/oik.06853] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Matt I. D. Carter
- Sea Mammal Research Unit, Scottish Oceans Inst., Univ. of St Andrews St Andrews KY16 8LB UK
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, Univ. of Plymouth Plymouth UK
| | - Brett T. McClintock
- Marine Mammal Laboratory, Alaska Fisheries Science Center, NOAA NMFS Seattle USA
| | - Clare B. Embling
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, Univ. of Plymouth Plymouth UK
| | | | - Dave Thompson
- Sea Mammal Research Unit, Scottish Oceans Inst., Univ. of St Andrews St Andrews KY16 8LB UK
| | - Debbie J. F. Russell
- Sea Mammal Research Unit, Scottish Oceans Inst., Univ. of St Andrews St Andrews KY16 8LB UK
- Centre for Research into Ecological and Environmental Modelling, Univ. of St Andrew St Andrews UK
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13
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Tennessen JB, Holt MM, Ward EJ, Hanson MB, Emmons CK, Giles DA, Hogan JT. Hidden Markov models reveal temporal patterns and sex differences in killer whale behavior. Sci Rep 2019; 9:14951. [PMID: 31628371 PMCID: PMC6802385 DOI: 10.1038/s41598-019-50942-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 09/18/2019] [Indexed: 11/09/2022] Open
Abstract
Behavioral data can be important for effective management of endangered marine predators, but can be challenging to obtain. We utilized suction cup-attached biologging tags equipped with stereo hydrophones, triaxial accelerometers, triaxial magnetometers, pressure and temperature sensors, to characterize the subsurface behavior of an endangered population of killer whales (Orcinus orca). Tags recorded depth, acoustic and movement behavior on fish-eating killer whales in the Salish Sea between 2010-2014. We tested the hypotheses that (a) distinct behavioral states can be characterized by integrating movement and acoustic variables, (b) subsurface foraging occurs in bouts, with distinct periods of searching and capture temporally separated from travel, and (c) the probabilities of transitioning between behavioral states differ by sex. Using Hidden Markov modeling of two acoustic and four movement variables, we identified five temporally distinct behavioral states. Persistence in the same state on a subsequent dive had the greatest likelihood, with the exception of deep prey pursuit, indicating that behavior was clustered in time. Additionally, females spent more time at the surface than males, and engaged in less foraging behavior. These results reveal significant complexity and sex differences in subsurface foraging behavior, and underscore the importance of incorporating behavior into the design of conservation strategies.
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Affiliation(s)
- Jennifer B Tennessen
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA. .,Lynker Technologies, Leesburg, VA, USA.
| | - Marla M Holt
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | - Eric J Ward
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | - M Bradley Hanson
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | - Candice K Emmons
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | - Deborah A Giles
- Department of Wildlife, Fish, & Conservation Biology, University of California, Davis, CA, USA.,University of Washington, Friday Harbor Laboratories, Friday Harbor, WA, USA
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14
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Hin V, Harwood J, de Roos AM. Bio-energetic modeling of medium-sized cetaceans shows high sensitivity to disturbance in seasons of low resource supply. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01903. [PMID: 30980583 PMCID: PMC6618318 DOI: 10.1002/eap.1903] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 02/05/2019] [Accepted: 03/19/2019] [Indexed: 05/28/2023]
Abstract
Understanding the full scope of human impact on wildlife populations requires a framework to assess the population-level repercussions of nonlethal disturbance. The Population Consequences of Disturbance (PCoD) framework provides such an approach, by linking the effects of disturbance on the behavior and physiology of individuals to their population-level consequences. Bio-energetic models have been used as implementations of PCoD, as these integrate the behavioral and physiological state of an individual with the state of the environment, to mediate between disturbance and biological significant changes in vital rates (survival, growth, and reproduction). To assess which levels of disturbance lead to adverse effects on population growth rate requires a bio-energetic model that covers the complete life cycle of the organism under study. In a density-independent setting, the expected lifetime reproductive output of a single female can then be used to predict the level of disturbance that leads to population decline. Here, we present such a model for a medium-sized cetacean, the long-finned pilot whale (Globicephala melas). Disturbance is modeled as a yearly recurrent period of no resource feeding for the pilot whale female and her calf. Short periods of disturbance lead to the pre-weaned death of the first one or more calves of the young female. Higher disturbance levels also affect survival of calves produced later in the life of the female, in addition to degrading female survival. The level of disturbance that leads to a negative population growth rate strongly depends on the available resources in the environment. This has important repercussion for the timing of disturbance if resource availability fluctuates seasonally. The model predicts that pilot whales can tolerate on average three times longer periods of disturbance in seasons of high resource availability, compared to disturbance happening when resources are low. Although our model is specifically parameterized for pilot whales, it provides useful insights into the general consequences of nonlethal disturbance. If appropriate data on life history and energetics are available, it can be used to provide management advice for specific species or populations.
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Affiliation(s)
- Vincent Hin
- Institute for Biodiversity and Ecosystem DynamicsUniversity of Amsterdam1090 GEAmsterdamThe Netherlands
| | - John Harwood
- Centre for Research into Ecological and Environmental ModellingUniversity of St AndrewsSt AndrewsFife KY16 9LZUnited Kingdom
| | - André M. de Roos
- Institute for Biodiversity and Ecosystem DynamicsUniversity of Amsterdam1090 GEAmsterdamThe Netherlands
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15
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Evidence for discrimination between feeding sounds of familiar fish and unfamiliar mammal-eating killer whale ecotypes by long-finned pilot whales. Anim Cogn 2019; 22:863-882. [PMID: 31230140 DOI: 10.1007/s10071-019-01282-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/05/2019] [Accepted: 06/12/2019] [Indexed: 12/23/2022]
Abstract
Killer whales (KW) may be predators or competitors of other cetaceans. Since their foraging behavior and acoustics differ among populations ('ecotypes'), we hypothesized that other cetaceans can eavesdrop on KW sounds and adjust their behavior according to the KW ecotype. We performed playback experiments on long-finned pilot whales (Globicephala melas) in Norway using familiar fish-eating KW sounds (fKW) simulating a sympatric population that might compete for foraging areas, unfamiliar mammal-eating KW sounds (mKW) simulating a potential predator threat, and two control sounds. We assessed behavioral responses using animal-borne multi-sensor tags and surface visual observations. Pilot whales barely changed behavior to a broadband noise (CTRL-), whereas they were attracted and exhibited spyhops to fKW, mKW, and to a repeated-tonal upsweep signal (CTRL+). Whales never stopped nor started feeding in response to fKW, whereas they reduced or stopped foraging to mKW and CTRL+. Moreover, pilot whales joined other subgroups in response to fKW and CTRL+, whereas they tightened individual spacing within group and reduced time at surface in response to mKW. Typical active intimidation behavior displayed to fKW might be an antipredator strategy to a known low-risk ecotype or alternatively a way of securing the habitat exploited by a heterospecific sympatric population. Cessation of feeding and more cohesive approach to mKW playbacks might reflect an antipredator behavior towards an unknown KW ecotype of potentially higher risk. We conclude that pilot whales are able to acoustically discriminate between familiar and unfamiliar KW ecotypes, enabling them to adjust their behavior according to the perceived disturbance type.
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16
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van Beest FM, Mews S, Elkenkamp S, Schuhmann P, Tsolak D, Wobbe T, Bartolino V, Bastardie F, Dietz R, von Dorrien C, Galatius A, Karlsson O, McConnell B, Nabe-Nielsen J, Olsen MT, Teilmann J, Langrock R. Classifying grey seal behaviour in relation to environmental variability and commercial fishing activity - a multivariate hidden Markov model. Sci Rep 2019; 9:5642. [PMID: 30948786 PMCID: PMC6449369 DOI: 10.1038/s41598-019-42109-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 03/25/2019] [Indexed: 02/06/2023] Open
Abstract
Classifying movement behaviour of marine predators in relation to anthropogenic activity and environmental conditions is important to guide marine conservation. We studied the relationship between grey seal (Halichoerus grypus) behaviour and environmental variability in the southwestern Baltic Sea where seal-fishery conflicts are increasing. We used multiple environmental covariates and proximity to active fishing nets within a multivariate hidden Markov model (HMM) to quantify changes in movement behaviour of grey seals while at sea. Dive depth, dive duration, surface duration, horizontal displacement, and turning angle were used to identify travelling, resting and foraging states. The likelihood of seals foraging increased in deeper, colder, more saline waters, which are sites with increased primary productivity and possibly prey densities. Proximity to active fishing net also had a pronounced effect on state occupancy. The probability of seals foraging was highest <5 km from active fishing nets (51%) and decreased as distance to nets increased. However, seals used sites <5 km from active fishing nets only 3% of their time at sea highlighting an important temporal dimension in seal-fishery interactions. By coupling high-resolution oceanographic, fisheries, and grey seal movement data, our study provides a scientific basis for designing management strategies that satisfy ecological and socioeconomic demands on marine ecosystems.
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Affiliation(s)
- Floris M van Beest
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark.
| | - Sina Mews
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Svenja Elkenkamp
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Patrick Schuhmann
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Dorian Tsolak
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Till Wobbe
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Valerio Bartolino
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, Lysekil, SE-45321, Sweden
| | - Francois Bastardie
- National Institute for Aquatic Resources, Technical University of Denmark, Kemitorvet, Kgs. Lyngby, DK-2800, Denmark
| | - Rune Dietz
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Christian von Dorrien
- Thünen Institute of Baltic Sea Fisheries, Alter Hafen Süd 2, D-18069, Rostock, Germany
| | - Anders Galatius
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Olle Karlsson
- Department of Environmental Research and Monitoring, Swedish Museum of Natural History, Box 50007, SE-104 05, Stockholm, Sweden
| | - Bernie McConnell
- Sea Mammal Research Unit, University of St Andrews, St Andrews, KY16 8LB, United Kingdom
| | - Jacob Nabe-Nielsen
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Morten Tange Olsen
- Evolutionary Genomics Section, Natural History Museum of Denmark, Department of Biology, University of Copenhagen, Øster Voldgade 5-7, DK-1350, Copenhagen K, Denmark
| | - Jonas Teilmann
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Roland Langrock
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
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17
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Isojunno S, Miller PJO. Movement and Biosonar Behavior During Prey Encounters Indicate That Male Sperm Whales Switch Foraging Strategy With Depth. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00200] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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18
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Isojunno S, Aoki K, Curé C, Kvadsheim PH, Miller PJO. Breathing Patterns Indicate Cost of Exercise During Diving and Response to Experimental Sound Exposures in Long-Finned Pilot Whales. Front Physiol 2018; 9:1462. [PMID: 30459631 PMCID: PMC6232938 DOI: 10.3389/fphys.2018.01462] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/26/2018] [Indexed: 02/05/2023] Open
Abstract
Air-breathing marine predators that target sub-surface prey have to balance the energetic benefit of foraging against the time, energetic and physiological costs of diving. Here we use on-animal data loggers to assess whether such trade-offs can be revealed by the breathing rates (BR) and timing of breaths in long-finned pilot whales (Globicephela melas). We used the period immediately following foraging dives in particular, for which respiratory behavior can be expected to be optimized for gas exchange. Breath times and fluke strokes were detected using onboard sensors (pressure, 3-axis acceleration) attached to animals using suction cups. The number and timing of breaths were quantified in non-linear mixed models that incorporated serial correlation and individual as a random effect. We found that pilot whales increased their BR in the 5–10 min period prior to, and immediately following, dives that exceeded 31 m depth. While pre-dive BRs did not vary with dive duration, the initial post-dive BR was linearly correlated with duration of >2 min dives, with BR then declining exponentially. Apparent net diving costs were 1.7 (SE 0.2) breaths per min of diving (post-dive number of breaths, above pre-dive breathing rate unrelated to dive recovery). Every fluke stroke was estimated to cost 0.086 breaths, which amounted to 80–90% average contribution of locomotion to the net diving costs. After accounting for fluke stroke rate, individuals in the small body size class took a greater number of breaths per diving minute. Individuals reduced their breathing rate (from the rate expected by diving behavior) by 13–16% during playbacks of killer whale sounds and their first exposure to 1–2 kHz naval sonar, indicating similar responses to interspecific competitor/predator and anthropogenic sounds. Although we cannot rule out individuals increasing their per-breath O2 uptake to match metabolic demand, our results suggest that behavioral responses to experimental sound exposures were not associated with increased metabolic rates in a stress response, but metabolic rates instead appear to decrease. Our results support the hypothesis that maximal performance leads to predictable (optimized) breathing patterns, which combined with further physiological measurements could improve proxies of field metabolic rates and per-stroke energy costs from animal-borne behavior data.
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Affiliation(s)
- Saana Isojunno
- Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, United Kingdom
| | - Kagari Aoki
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| | | | | | - Patrick James O'Malley Miller
- Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, United Kingdom
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