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Groß J, Franco-Santos RM, Virtue P, Nichols PD, Totterdell J, Marcondes MCC, Garrigue C, Botero-Acosta N, Christiansen F, Castrillon J, Caballero SJ, Friedlaender AS, Kawaguchi S, Double MC, Bell EM, Makabe R, Moteki M, Hoem N, Fry B, Burford M, Bengtson Nash S. No distinct local cuisines among humpback whales: A population diet comparison in the Southern Hemisphere. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 931:172939. [PMID: 38701928 DOI: 10.1016/j.scitotenv.2024.172939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 04/24/2024] [Accepted: 04/30/2024] [Indexed: 05/05/2024]
Abstract
Southern hemisphere humpback whale (Megaptera novaeangliae, SHHW) breeding populations follow a high-fidelity Antarctic krill (Euphausia superba) diet while feeding in distinct sectors of the Southern Ocean. Their capital breeding life history requires predictable ecosystem productivity to fuel migration and migration-related behaviours. It is therefore postulated that populations feeding in areas subject to the strongest climate change impacts are more likely to show the first signs of a departure from a high-fidelity krill diet. We tested this hypothesis by investigating blubber fatty acid profiles and skin stable isotopes obtained from five SHHW populations in 2019, and comparing them to Antarctic krill stable isotopes sampled in three SHHW feeding areas in the Southern Ocean in 2019. Fatty acid profiles and δ13C and δ15N varied significantly among all five populations, however, calculated trophic positions did not (2.7 to 3.1). Similarly, fatty acid ratios, 16:1ω7c/16:0 and 20:5ω3/22:6ω3 were above 1, showing that whales from all five populations are secondary heterotrophs following an omnivorous diet with a diatom-origin. Thus, evidence for a potential departure from a high-fidelity Antarctic krill diet was not seen in any population. δ13C of all populations were similar to δ13C of krill sampled in productive upwelling areas or the marginal sea-ice zone. Consistency in trophic position and diet origin but significant fatty acid and stable isotope differences demonstrate that the observed variability arises at lower trophic levels. Our results indicate that, at present, there is no evidence of a divergence from a high-fidelity krill diet. Nevertheless, the characteristic isotopic signal of whales feeding in productive upwelling areas, or in the marginal sea-ice zone, implies that future cryosphere reductions could impact their feeding ecology.
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Affiliation(s)
- Jasmin Groß
- Centre for Planetary Health and Food Security, Southern Ocean Persistent Organic Pollutants Program, Griffith University, 4111 Nathan, QLD, Australia; Alfred-Wegener-Institute Helmholtz-Centre for Polar and Marine Research, Bremerhaven, Germany; Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Ammerländer Heerstrasse 231, 26129 Oldenburg, Germany.
| | - Rita M Franco-Santos
- Institute for Marine and Antarctic Studies, University of Tasmania, 7004 Hobart, TAS, Australia
| | - Patti Virtue
- Institute for Marine and Antarctic Studies, University of Tasmania, 7004 Hobart, TAS, Australia; CSIRO Environment, 7004 Hobart, TAS, Australia
| | - Peter D Nichols
- Institute for Marine and Antarctic Studies, University of Tasmania, 7004 Hobart, TAS, Australia; CSIRO Environment, 7004 Hobart, TAS, Australia
| | | | | | - Claire Garrigue
- UMR 250/9220 ENTROPIE, IRD, Université de La Réunion, Université de la Nouvelle-Calédonie, CNRS, Ifremer, Laboratoired'Excellence-CORAIL, BPA5 Nouméa, New Caledonia; Opération Cétacés, Nouméa, New Caledonia
| | | | - Fredrik Christiansen
- Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark; Aarhus Institute of Advanced Studies, Aarhus C, Denmark
| | - Juliana Castrillon
- Centre for Planetary Health and Food Security, Southern Ocean Persistent Organic Pollutants Program, Griffith University, 4111 Nathan, QLD, Australia
| | - Susana J Caballero
- Laboratorio de Ecología Molecular de Vertebrados Acuáticos (LEMVA), Departamento de Ciencias Biológicas, Universidad de los Andes, 18A-10 Bogotá, Colombia
| | | | - So Kawaguchi
- Australian Antarctic Division, Kingston, TAS, Australia
| | | | - Elanor M Bell
- Australian Antarctic Division, Kingston, TAS, Australia
| | - Ryosuke Makabe
- National Institute of Polar Research, 10-3 Midoricho, Tachikawa, Tokyo 190-8518, Japan; Department of Ocean Sciences, Tokyo University of Marine Science and Technology, 4-5-7Konan, Minato-ku, Tokyo 108-8477, Japan; Department of Polar Science, The Graduate University for Advanced Studies, SOKENDAI, 10-3, Midori-cho, Tachikawa, Tokyo 190-851, Japan
| | - Masato Moteki
- National Institute of Polar Research, 10-3 Midoricho, Tachikawa, Tokyo 190-8518, Japan; Department of Ocean Sciences, Tokyo University of Marine Science and Technology, 4-5-7Konan, Minato-ku, Tokyo 108-8477, Japan
| | - Nils Hoem
- Aker BioMarine Antarctic AS, NO-1327 Lysaker, Norway
| | - Brian Fry
- Australian Rivers Institute, Griffith University, 4111 Nathan, QLD, Australia
| | - Michele Burford
- Australian Rivers Institute, Griffith University, 4111 Nathan, QLD, Australia
| | - Susan Bengtson Nash
- Centre for Planetary Health and Food Security, Southern Ocean Persistent Organic Pollutants Program, Griffith University, 4111 Nathan, QLD, Australia
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Kok ACM, Hildebrand MJ, MacArdle M, Martinez A, Garrison LP, Soldevilla MS, Hildebrand JA. Kinematics and energetics of foraging behavior in Rice's whales of the Gulf of Mexico. Sci Rep 2023; 13:8996. [PMID: 37268677 DOI: 10.1038/s41598-023-35049-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 05/11/2023] [Indexed: 06/04/2023] Open
Abstract
Rorqual foraging behavior varies with species, prey type and foraging conditions, and can be a determining factor for their fitness. Little is known about the foraging ecology of Rice's whales (Balaenoptera ricei), an endangered species with a population of fewer than 100 individuals. Suction cup tags were attached to two Rice's whales to collect information on their diving kinematics and foraging behavior. The tagged whales primarily exhibited lunge-feeding near the sea bottom and to a lesser extent in the water-column and at the sea surface. During 6-10 min foraging dives, the whales typically circled their prey before executing one or two feeding lunges. Longer duration dives and dives with more feeding-lunges were followed by an increase in their breathing rate. The median lunge rate of one lunge per dive of both animals was much lower than expected based on comparative research on other lunge-feeding baleen whales, and may be associated with foraging on fish instead of krill or may be an indication of different foraging conditions. Both animals spent extended periods of the night near the sea surface, increasing the risk for ship strike. Furthermore, their circling before lunging may increase the risk for entanglement in bottom-longline fishing gear. Overall, these data show that Rice's whale foraging behavior differs from other lunge feeding rorqual species and may be a significant factor in shaping our understanding of their foraging ecology. Efforts to mitigate threats to Rice's whales will benefit from improved understanding of patterns in their habitat use and fine-scale ecology.
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Affiliation(s)
- Annebelle C M Kok
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Maya J Hildebrand
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA
| | - Maria MacArdle
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA
| | - Anthony Martinez
- Marine Mammal and Turtle Division, Southeast Fisheries Science Center, National Marine Fisheries Service, Miami, FL, USA
| | - Lance P Garrison
- Marine Mammal and Turtle Division, Southeast Fisheries Science Center, National Marine Fisheries Service, Miami, FL, USA
| | - Melissa S Soldevilla
- Marine Mammal and Turtle Division, Southeast Fisheries Science Center, National Marine Fisheries Service, Miami, FL, USA
| | - John A Hildebrand
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA
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3
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Social exploitation of extensive, ephemeral, environmentally controlled prey patches by supergroups of rorqual whales. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Potvin J, Cade DE, Werth AJ, Shadwick RE, Goldbogen JA. Rorqual Lunge-Feeding Energetics Near and Away from the Kinematic Threshold of Optimal Efficiency. Integr Org Biol 2021; 3:obab005. [PMID: 34104873 PMCID: PMC8179629 DOI: 10.1093/iob/obab005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Humpback and blue whales are large baleen-bearing cetaceans, which use a unique prey-acquisition strategy—lunge feeding—to engulf entire patches of large plankton or schools of forage fish and the water in which they are embedded. Dynamically, and while foraging on krill, lunge-feeding incurs metabolic expenditures estimated at up to 20.0 MJ. Because of prey abundance and its capture in bulk, lunge feeding is carried out at high acquired-to-expended energy ratios of up to 30 at the largest body sizes (∼27 m). We use bio-logging tag data and the work-energy theorem to show that when krill-feeding at depth while using a wide range of prey approach swimming speeds (2–5 m/s), rorquals generate significant and widely varying metabolic power output during engulfment, typically ranging from 10 to 50 times the basal metabolic rate of land mammals. At equal prey field density, such output variations lower their feeding efficiency two- to three-fold at high foraging speeds, thereby allowing slow and smaller rorquals to feed more efficiently than fast and larger rorquals. The analysis also shows how the slowest speeds of harvest so far measured may be connected to the biomechanics of the buccal cavity and the prey’s ability to collectively avoid engulfment. Such minimal speeds are important as they generate the most efficient lunges. Sommaire Les rorquals à bosse et rorquals bleus sont des baleines à fanons qui utilisent une technique d’alimentation unique impliquant une approche avec élan pour engouffrer de larges quantités de plancton et bancs de petits poissons, ainsi que la masse d’eau dans laquelle ces proies sont situés. Du point de vue de la dynamique, et durant l’approche et engouffrement de krill, leurs dépenses énergétiques sont estimées jusqu’à 20.0 MJ. À cause de l’abondance de leurs proies et capture en masse, cette technique d’alimentation est effectuée à des rapports d’efficacité énergétique (acquise -versus- dépensée) estimés aux environs de 30 dans le cas des plus grandes baleines (27 m). Nous utilisons les données recueillies par des capteurs de bio-enregistrement ainsi que le théorème reliant l’énergie à l’effort pour démontrer comment les rorquals s’alimentant sur le krill à grandes profondeurs, et à des vitesses variant entre 2 et 5 m/s, maintiennent des taux de dépenses énergétiques entre 10 et 50 fois le taux métabolique basal des mammifères terrestres. À densités de proies égales, ces variations d’énergie utilisée peuvent réduire le rapport d’efficacité énergétique par des facteurs entre 2x et 3x, donc permettant aux petits et plus lents rorquals de chasser avec une efficacité comparable à celle des rorquals les plus grands et rapides. Notre analyse démontre aussi comment des vitesses d’approche plus lentes peuvent être reliées à la biomécanique de leur poche ventrale extensible, et à l’habilitée des proies à éviter d’être engouffrer. Ces minimums de vitesses sont importants car ils permettent une alimentation plus efficace énergétiquement.
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Affiliation(s)
- J Potvin
- Department of Physics, Saint Louis University, St. Louis, MO 63103, USA
| | - D E Cade
- Institute of Marine Sciences, University of California Santa Cruz, Sant Cruz, CA 95060, USA
| | - A J Werth
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA
| | - R E Shadwick
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - J A Goldbogen
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
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Cade DE, Seakamela SM, Findlay KP, Fukunaga J, Kahane‐Rapport SR, Warren JD, Calambokidis J, Fahlbusch JA, Friedlaender AS, Hazen EL, Kotze D, McCue S, Meÿer M, Oestreich WK, Oudejans MG, Wilke C, Goldbogen JA. Predator‐scale spatial analysis of intra‐patch prey distribution reveals the energetic drivers of rorqual whale super‐group formation. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13763] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David E. Cade
- Hopkins Marine Station Stanford University Pacific Grove CA USA
- Institute of Marine Science University of California, Santa Cruz Santa Cruz CA USA
| | - S. Mduduzi Seakamela
- Department of Environment, Forestry and Fisheries, Branch: Oceans and Coasts, Victoria & Alfred Waterfront Cape Town South Africa
| | - Ken P. Findlay
- Oceans Economy Cape Peninsula University of Technology Cape Town South Africa
- MRI Whale Unit Department of Zoology and Entomology University of Pretoria Hatfield South Africa
| | - Julie Fukunaga
- Hopkins Marine Station Stanford University Pacific Grove CA USA
| | | | - Joseph D. Warren
- School of Marine and Atmospheric Sciences Stony Brook University Southampton NY USA
| | | | - James A. Fahlbusch
- Hopkins Marine Station Stanford University Pacific Grove CA USA
- Cascadia Research Collective Olympia WA USA
| | - Ari S. Friedlaender
- Institute of Marine Science University of California, Santa Cruz Santa Cruz CA USA
| | - Elliott L. Hazen
- Environmental Research Division/Southwest Fisheries Science Center/National Marine Fisheries Service/National Oceanic and Atmospheric Administration Monterey CA USA
| | - Deon Kotze
- Department of Environment, Forestry and Fisheries, Branch: Oceans and Coasts, Victoria & Alfred Waterfront Cape Town South Africa
| | - Steven McCue
- Department of Environment, Forestry and Fisheries, Branch: Oceans and Coasts, Victoria & Alfred Waterfront Cape Town South Africa
| | - Michael Meÿer
- Department of Environment, Forestry and Fisheries, Branch: Oceans and Coasts, Victoria & Alfred Waterfront Cape Town South Africa
| | | | | | - Christopher Wilke
- Department of Environment, Forestry and Fisheries, Branch: Fisheries Management Cape Town South Africa
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Schall E, Thomisch K, Boebel O, Gerlach G, Spiesecke S, Van Opzeeland I. Large-scale spatial variabilities in the humpback whale acoustic presence in the Atlantic sector of the Southern Ocean. ROYAL SOCIETY OPEN SCIENCE 2020; 7:201347. [PMID: 33489279 PMCID: PMC7813260 DOI: 10.1098/rsos.201347] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/09/2020] [Indexed: 06/12/2023]
Abstract
Southern Hemisphere humpback whales (Megaptera novaeangliae) inhabit a wide variety of ecosystems including both low- and high-latitude areas. Understanding the habitat selection of humpback whale populations is key for humpback whale stock management and general ecosystem management. In the Atlantic sector of the Southern Ocean (ASSO), the investigation of baleen whale distribution by sighting surveys is temporally restricted to the austral summer. The implementation of autonomous passive acoustic monitoring, in turn, allows the study of vocal baleen whales year-round. This study describes the results of analysing passive acoustic data spanning 12 recording positions throughout the ASSO applying a combination of automatic and manual analysis methods to register humpback whale acoustic activity. Humpback whales were present at nine recording positions with higher acoustic activities towards lower latitudes and the eastern and western edges of the ASSO. During all months, except December (the month with the fewest recordings), humpback whale acoustic activity was registered in the ASSO. The acoustic presence of humpback whales at various locations in the ASSO confirms previous observations that part of the population remains in high-latitude waters beyond austral summer, presumably to feed. The spatial and temporal extent of humpback whale presence in the ASSO suggests that this area may be used by multiple humpback whale breeding populations as a feeding ground.
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Affiliation(s)
- Elena Schall
- Ocean Acoustics Lab, Alfred Wegener Institute for Polar and Marine Research, Klußmannstraße 3d, 27570 Bremerhaven, Germany
| | - Karolin Thomisch
- Ocean Acoustics Lab, Alfred Wegener Institute for Polar and Marine Research, Klußmannstraße 3d, 27570 Bremerhaven, Germany
| | - Olaf Boebel
- Ocean Acoustics Lab, Alfred Wegener Institute for Polar and Marine Research, Klußmannstraße 3d, 27570 Bremerhaven, Germany
| | - Gabriele Gerlach
- Helmholtz Institute for Functional Marine Biodiversity, Carl von Ossietzky University Oldenburg, Ammerländer Heerstraße 231, 26129 Oldenburg, Germany
- Animal Biodiversity and Evolutionary Biology, Carl von Ossietzky University Oldenburg, Ammerländer Heerstraße 114-118, 26129 Oldenburg, Germany
| | - Stefanie Spiesecke
- Ocean Acoustics Lab, Alfred Wegener Institute for Polar and Marine Research, Klußmannstraße 3d, 27570 Bremerhaven, Germany
| | - Ilse Van Opzeeland
- Ocean Acoustics Lab, Alfred Wegener Institute for Polar and Marine Research, Klußmannstraße 3d, 27570 Bremerhaven, Germany
- Helmholtz Institute for Functional Marine Biodiversity, Carl von Ossietzky University Oldenburg, Ammerländer Heerstraße 231, 26129 Oldenburg, Germany
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7
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Interannual variability in the lipid and fatty acid profiles of east Australia-migrating humpback whales (Megaptera novaeangliae) across a 10-year timeline. Sci Rep 2020; 10:18274. [PMID: 33106590 PMCID: PMC7589506 DOI: 10.1038/s41598-020-75370-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 10/12/2020] [Indexed: 02/02/2023] Open
Abstract
Southern hemisphere humpback whales are classified as high-fidelity Antarctic krill consumers and as such are vulnerable to variability and long-term changes in krill biomass. Evidence of heterogeneous feeding patterns of east coast of Australia migrating humpback whales has been observed, warranting a comprehensive assessment of interannual variability in their diet. We examined the lipid and fatty acid profiles of individuals of the east coast of Australia migrating stock sampled between 2008 and 2018. The use of live-sampled blubber biopsies showed that fatty acid profiles varied significantly among all years. The two trophic indicator fatty acids for Antarctic krill, 20:5ω3 and 22:6ω3 remained largely unchanged across the 10-year period, suggesting that Antarctic krill is the principal prey item. A distance-based linear model showed that 33% of the total variation in fatty acid profiles was explained by environmental variables and climate indices. Most of the variation was explained by the Southern Annular Mode (23.7%). The high degree of variability observed in this study was unexpected for a species that is thought to feed primarily on one prey item. We propose that the observed variability likely arises from changes in the diet of Antarctic krill rather than changes in the whale’s diet.
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8
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Torres LG, Barlow DR, Chandler TE, Burnett JD. Insight into the kinematics of blue whale surface foraging through drone observations and prey data. PeerJ 2020; 8:e8906. [PMID: 32351781 PMCID: PMC7183305 DOI: 10.7717/peerj.8906] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 03/12/2020] [Indexed: 11/20/2022] Open
Abstract
To understand how predators optimize foraging strategies, extensive knowledge of predator behavior and prey distribution is needed. Blue whales employ an energetically demanding lunge feeding method that requires the whales to selectively feed where energetic gain exceeds energetic loss, while also balancing oxygen consumption, breath holding capacity, and surface recuperation time. Hence, blue whale foraging behavior is primarily driven by krill patch density and depth, but many studies have not fully considered surface feeding as a significant foraging strategy in energetic models. We collected predator and prey data on a blue whale (Balaenoptera musculus brevicauda) foraging ground in New Zealand in February 2017 to assess the distributional and behavioral response of blue whales to the distribution and density of krill prey aggregations. Krill density across the study region was greater toward the surface (upper 20 m), and blue whales were encountered where prey was relatively shallow and more dense. This relationship was particularly evident where foraging and surface lunge feeding were observed. Furthermore, New Zealand blue whales also had relatively short dive times (2.83 ± 0.27 SE min) as compared to other blue whale populations, which became even shorter at foraging sightings and where surface lunge feeding was observed. Using an unmanned aerial system (UAS; drone) we also captured unique video of a New Zealand blue whale's surface feeding behavior on well-illuminated krill patches. Video analysis illustrates the whale's potential use of vision to target prey, make foraging decisions, and orient body mechanics relative to prey patch characteristics. Kinematic analysis of a surface lunge feeding event revealed biomechanical coordination through speed, acceleration, head inclination, roll, and distance from krill patch to maximize prey engulfment. We compared these lunge kinematics to data previously reported from tagged blue whale lunges at depth to demonstrate strong similarities, and provide rare measurements of gape size, and krill response distance and time. These findings elucidate the predator-prey relationship between blue whales and krill, and provide support for the hypothesis that surface feeding by New Zealand blue whales is an important component to their foraging ecology used to optimize their energetic efficiency. Understanding how blue whales make foraging decisions presents logistical challenges, which may cause incomplete sampling and biased ecological knowledge if portions of their foraging behavior are undocumented. We conclude that surface foraging could be an important strategy for blue whales, and integration of UAS with tag-based studies may expand our understanding of their foraging ecology by examining surface feeding events in conjunction with behaviors at depth.
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Affiliation(s)
- Leigh G. Torres
- Geospatial Ecology of Marine Megafauna Lab, Marine Mammal Institute, Department of Fisheries and Wildlife, Oregon State University, Newport, OR, United States of America
| | - Dawn R. Barlow
- Geospatial Ecology of Marine Megafauna Lab, Marine Mammal Institute, Department of Fisheries and Wildlife, Oregon State University, Newport, OR, United States of America
| | - Todd E. Chandler
- Geospatial Ecology of Marine Megafauna Lab, Marine Mammal Institute, Oregon State University, Newport, OR, United States of America
| | - Jonathan D. Burnett
- Aerial Information Systems Laboratory, Forest Engineering, Resources and Management, Oregon State University, Corvallis, OR, United States of America
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Foord CS, Rowe KMC, Robb K. Cetacean biodiversity, spatial and temporal trends based on stranding records (1920-2016), Victoria, Australia. PLoS One 2019; 14:e0223712. [PMID: 31600321 PMCID: PMC6786658 DOI: 10.1371/journal.pone.0223712] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 09/26/2019] [Indexed: 11/19/2022] Open
Abstract
Cetacean stranding records can provide vital information on species richness and diversity through space and time. Here we collate stranding records from Victoria, Australia and assess them for temporal, spatial and demographic trends. Between 1920 and 2016, 424 stranding events involving 907 individuals were recorded across 31 Cetacea species from seven families, including five new species records for the state. Seven of these events were mass strandings, and six mother and calf strandings were recorded. Importantly, 48% of the species recorded are recognised as data deficient on the IUCN Red List. The most commonly recorded taxa were Tursiops spp. (n = 146) and Delphinus delphis (common dolphins, n = 81), with the greatest taxonomic richness (n = 24) and highest incidence of stranding events documented within the Otways mesoscale bioregion. We found no seasonal stranding patterns anywhere in the state. While our findings improve understanding of the spatial and temporal patterns of cetacean diversity within Victoria, we suggest greater effort to collect demographic data at stranding events in order to better study state-wide patterns through time. We conclude with guidelines for minimum data collection standards for future strandings to maximise information capture from each event.
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Affiliation(s)
| | - Karen M. C. Rowe
- Sciences Department, Museums Victoria, Carlton, Victoria, Australia
- School of BioSciences, University of Melbourne, Parkville, Victoria, Australia
| | - Kate Robb
- Marine Mammal Foundation, Mentone, Victoria, Australia
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10
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New insights into prime Southern Ocean forage grounds for thriving Western Australian humpback whales. Sci Rep 2019; 9:13988. [PMID: 31562374 PMCID: PMC6764985 DOI: 10.1038/s41598-019-50497-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Accepted: 09/13/2019] [Indexed: 02/07/2023] Open
Abstract
Humpback whale populations migrate extensively between winter breeding grounds and summer feeding grounds, however known links to remote Antarctic feeding grounds remain limited in many cases. New satellite tracks detail humpback whale migration pathways from Western Australia into the Southern Ocean. These highlight a focal feeding area during austral spring and early summer at the southern Kerguelen plateau, in a western boundary current where a sharp northward turn and retroflection of ocean fronts occurs along the eastern plateau edge. The topographic steering of oceanographic features here likely supports a predictable, productive and persistent forage ground. The spatial distribution of whaling catches and Discovery era mark-recaptures confirms the importance of this region to Western Australian humpback whales since at least historical times. Movement modelling discriminates sex-related behaviours, with females moving faster during both transit and resident periods, which may be a consequence of size or indicate differential energetic requirements. Relatively short and directed migratory pathways overall, together with high-quality, reliable forage resources may provide a partial explanation for the ongoing strong recovery demonstrated by this population. The combination of new oceanographic information and movement data provides enhanced understanding of important biological processes, which are relevant within the context of the current spatial management and conservation efforts in the Southern Ocean.
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11
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Humpback whale migrations to Antarctic summer foraging grounds through the southwest Pacific Ocean. Sci Rep 2018; 8:12333. [PMID: 30120303 PMCID: PMC6098068 DOI: 10.1038/s41598-018-30748-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/31/2018] [Indexed: 02/05/2023] Open
Abstract
Humpback whale (Megaptera novaeangliae) populations typically undertake seasonal migrations, spending winters in low latitude breeding grounds and summers foraging in high latitude feeding grounds. Until recently, a broad scale understanding of whale movement has been derived from whaling records, Discovery marks, photo identification and genetic analyses. However, with advances in satellite tagging technology and concurrent development of analytical methodologies we can now detail finer scale humpback whale movement, infer behavioural context and examine how these animals interact with their physical environment. Here we describe the temporal and spatial characteristics of migration along the east Australian seaboard and into the Southern Ocean by 30 humpback whales satellite tagged over three consecutive austral summers. We characterise the putative Antarctic feeding grounds and identify supplemental foraging within temperate, migratory corridors. We demonstrate that Antarctic foraging habitat is associated with the marginal ice zone, with key predictors of inferred foraging behaviour including distance from the ice edge, ice melt rate and variability in ice concentration two months prior to arrival. We discuss the highly variable ice season within the putative foraging habitat and the implications that this and other environmental factors may have on the continued strong recovery of this humpback whale population.
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