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Feyrer LJ, Stanistreet JE, Moors-Murphy HB. Navigating the unknown: assessing anthropogenic threats to beaked whales, family Ziphiidae. R Soc Open Sci 2024; 11:240058. [PMID: 38633351 PMCID: PMC11021932 DOI: 10.1098/rsos.240058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/07/2024] [Accepted: 03/08/2024] [Indexed: 04/19/2024]
Abstract
This review comprehensively evaluates the impacts of anthropogenic threats on beaked whales (Ziphiidae)-a taxonomic group characterized by cryptic biology, deep dives and remote offshore habitat, which have challenged direct scientific observation. By synthesizing information published in peer-reviewed studies and grey literature, we identified available evidence of impacts across 14 threats for each Ziphiidae species. Threats were assessed based on their pathways of effects on individuals, revealing many gaps in scientific understanding of the risks faced by beaked whales. By applying a comprehensive taxon-level analysis, we found evidence that all beaked whale species are affected by multiple stressors, with climate change, entanglement and plastic pollution being the most common threats documented across beaked whale species. Threats assessed as having a serious impact on individuals included whaling, military sonar, entanglement, depredation, vessel strikes, plastics and oil spills. This review emphasizes the urgent need for targeted research to address a range of uncertainties, including cumulative and population-level impacts. Understanding the evidence and pathways of the effects of stressors on individuals can support future assessments, guide practical mitigation strategies and advance current understanding of anthropogenic impacts on rare and elusive marine species.
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Affiliation(s)
- Laura J. Feyrer
- Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, Nova ScotiaB2Y 4A2, Canada
- Department of Biology, Dalhousie University, Halifax, Nova ScotiaB3H 4R2, Canada
| | - Joy E. Stanistreet
- Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, Nova ScotiaB2Y 4A2, Canada
| | - Hilary B. Moors-Murphy
- Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, Nova ScotiaB2Y 4A2, Canada
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2
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Sacchini S, Bombardi C, Arbelo M, Herráez P. The Hypothalamus of the Beaked Whales: The Paraventricular, Supraoptic, and Suprachiasmatic Nuclei. Biology (Basel) 2023; 12:1319. [PMID: 37887029 PMCID: PMC10604544 DOI: 10.3390/biology12101319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/30/2023] [Accepted: 10/06/2023] [Indexed: 10/28/2023]
Abstract
The hypothalamus is the body's control coordinating center. It is responsible for maintaining the body's homeostasis by directly influencing the autonomic nervous system or managing hormones. Beaked whales are the longest divers among cetaceans and their brains are rarely available for study. Complete hypothalamic samples from a female Cuvier's beaked whale and a male Blainville's beaked whale were processed to investigate the paraventricular (PVN) and supraoptic (SON) nuclei, using immunohistochemical staining against vasopressin. The PVN occupied the preoptic region, where it reached its maximum size, and then regressed in the anterior or suprachiasmatic region. The SON was located from the preoptic to the tuberal hypothalamic region, encompassing the optical structures. It was composed of a retrochiasmatic region (SONr), which bordered and infiltrated the optic tracts, and a principal region (SONp), positioned more medially and dorsally. A third vasopressin-positive nucleus was also detected, i.e., the suprachiasmatic nucleus (SCN), which marked the end of the SON. This is the first description of the aforementioned nuclei in beaked whales-and in any marine mammals-as well as their rostro-caudal extent and immunoreactivity. Moreover, the SCN has been recognized for the first time in any marine mammal species.
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Affiliation(s)
- Simona Sacchini
- Veterinary Histology and Pathology, Atlantic Center for Cetacean Research, University Institute of Animal Health and Food Safety (IUSA), Veterinary School, University of Las Palmas de Gran Canaria, c/Transmontaña, s/n, 35416 Arucas, Spain; (M.A.); (P.H.)
- Department of Morphology, Campus Universitario de San Cristobal, University of Las Palmas de Gran Canaria, c/Blas Cabrera Felipe s/n, 35016 Las Palmas de Gran Canaria, Spain
| | - Cristiano Bombardi
- Department of Veterinary Medical Science, University of Bologna, Ozzano dell’Emilia, 40064 Bologna, Italy;
| | - Manuel Arbelo
- Veterinary Histology and Pathology, Atlantic Center for Cetacean Research, University Institute of Animal Health and Food Safety (IUSA), Veterinary School, University of Las Palmas de Gran Canaria, c/Transmontaña, s/n, 35416 Arucas, Spain; (M.A.); (P.H.)
| | - Pedro Herráez
- Veterinary Histology and Pathology, Atlantic Center for Cetacean Research, University Institute of Animal Health and Food Safety (IUSA), Veterinary School, University of Las Palmas de Gran Canaria, c/Transmontaña, s/n, 35416 Arucas, Spain; (M.A.); (P.H.)
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3
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Jones‐Todd CM, Pirotta E, Durban JW, Claridge DE, Baird RW, Falcone EA, Schorr GS, Watwood S, Thomas L. Discrete-space continuous-time models of marine mammal exposure to Navy sonar. Ecol Appl 2022; 32:e02475. [PMID: 34653299 PMCID: PMC9786920 DOI: 10.1002/eap.2475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 02/01/2021] [Accepted: 05/19/2021] [Indexed: 06/13/2023]
Abstract
Assessing the patterns of wildlife attendance to specific areas is relevant across many fundamental and applied ecological studies, particularly when animals are at risk of being exposed to stressors within or outside the boundaries of those areas. Marine mammals are increasingly being exposed to human activities that may cause behavioral and physiological changes, including military exercises using active sonars. Assessment of the population-level consequences of anthropogenic disturbance requires robust and efficient tools to quantify the levels of aggregate exposure for individuals in a population over biologically relevant time frames. We propose a discrete-space, continuous-time approach to estimate individual transition rates across the boundaries of an area of interest, informed by telemetry data collected with uncertainty. The approach allows inferring the effect of stressors on transition rates, the progressive return to baseline movement patterns, and any difference among individuals. We apply the modeling framework to telemetry data from Blainville's beaked whale (Mesoplodon densirostris) tagged in the Bahamas at the Atlantic Undersea Test and Evaluation Center (AUTEC), an area used by the U.S. Navy for fleet readiness training. We show that transition rates changed as a result of exposure to sonar exercises in the area, reflecting an avoidance response. Our approach supports the assessment of the aggregate exposure of individuals to sonar and the resulting population-level consequences. The approach has potential applications across many applied and fundamental problems where telemetry data are used to characterize animal occurrence within specific areas.
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Affiliation(s)
| | - Enrico Pirotta
- Department of Mathematics and StatisticsWashington State University14204 NE Salmon Creek AvenueVancouverWashington98686USA
- School of Biological, Earth and Environmental SciencesUniversity College CorkNorth MallDistillery FieldsCorkT23 N73KIreland
- Centre for Research into Ecological and Environmental ModellingThe ObservatoryUniversity of St AndrewsSt AndrewsKY16 9LZUK
| | - John W. Durban
- Southall Environmental Associates Inc.9099 Soquel Drive, Suite 8AptosCalifornia95003USA
| | - Diane E. Claridge
- Bahamas Marine Mammal Research OrganizationMarsh HarbourAbacoBahamas
| | - Robin W. Baird
- Cascadia Research Collective218 ½ W. 4th AvenueOlympiaWashington98501USA
| | - Erin A. Falcone
- Marine Ecology and Telemetry Research2420 Nellita Road NWSeabeckWashington98380USA
| | - Gregory S. Schorr
- Marine Ecology and Telemetry Research2420 Nellita Road NWSeabeckWashington98380USA
| | - Stephanie Watwood
- Naval Undersea Warfare Center DivisionCode 70TNewportRhode Island02841USA
| | - Len Thomas
- Centre for Research into Ecological and Environmental ModellingThe ObservatoryUniversity of St AndrewsSt AndrewsKY16 9LZUK
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4
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Alcázar-Treviño J, Johnson M, Arranz P, Warren VE, Pérez-González CJ, Marques T, Madsen PT, Aguilar de Soto N. Deep-diving beaked whales dive together but forage apart. Proc Biol Sci 2021; 288:20201905. [PMID: 33402065 DOI: 10.1098/rspb.2020.1905] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Echolocating animals that forage in social groups can potentially benefit from eavesdropping on other group members, cooperative foraging or social defence, but may also face problems of acoustic interference and intra-group competition for prey. Here, we investigate these potential trade-offs of sociality for extreme deep-diving Blainville's and Cuvier's beaked whales. These species perform highly synchronous group dives as a presumed predator-avoidance behaviour, but the benefits and costs of this on foraging have not been investigated. We show that group members could hear their companions for a median of at least 91% of the vocal foraging phase of their dives. This enables whales to coordinate their mean travel direction despite differing individual headings as they pursue prey on a minute-by-minute basis. While beaked whales coordinate their echolocation-based foraging periods tightly, individual click and buzz rates are both independent of the number of whales in the group. Thus, their foraging performance is not affected by intra-group competition or interference from group members, and they do not seem to capitalize directly on eavesdropping on the echoes produced by the echolocation clicks of their companions. We conclude that the close diving and vocal synchronization of beaked whale groups that quantitatively reduces predation risk has little impact on foraging performance.
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Affiliation(s)
- Jesús Alcázar-Treviño
- BIOECOMAC, Departamento de Biología Animal, Edafología y Geología, Universidad de La Laguna (ULL), Avenida Astrofísico F. Sánchez, s/n. 38206, San Cristóbal de La Laguna (Tenerife), Spain
| | - Mark Johnson
- Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, 8000, Aarhus C, Denmark
| | - Patricia Arranz
- BIOECOMAC, Departamento de Biología Animal, Edafología y Geología, Universidad de La Laguna (ULL), Avenida Astrofísico F. Sánchez, s/n. 38206, San Cristóbal de La Laguna (Tenerife), Spain.,Centre for Research into Ecological and Environmental Modelling, University of St Andrews, Fife, KY16 8LB, UK
| | - Victoria E Warren
- Institute of Marine Science, Leigh Marine Laboratory, University of Auckland, 160 Goat Island Road, Leigh 0985, New Zealand
| | - Carlos J Pérez-González
- Departamento de Matemáticas, Estadística e Investigación Operativa, Universidad de La Laguna (ULL), Avenida Astrofísico F. Sánchez, s/n. 38206, San Cristóbal de La Laguna (Tenerife), Spain
| | - Tiago Marques
- Centre for Research into Ecological and Environmental Modelling, University of St Andrews, Fife, KY16 8LB, UK.,Departamento de Biologia Animal, Centro de Estatística e Aplicações, Faculdade de Ciências, Universidade de Lisboa, Bloco C6 - Piso 4, Campo Grande, 1749-016 Lisboa, Portugal
| | - Peter T Madsen
- Zoophysiology, Department of Biology, Aarhus University, C.F. Moellers Allé 3, 8000, Aarhus C, Denmark
| | - Natacha Aguilar de Soto
- BIOECOMAC, Departamento de Biología Animal, Edafología y Geología, Universidad de La Laguna (ULL), Avenida Astrofísico F. Sánchez, s/n. 38206, San Cristóbal de La Laguna (Tenerife), Spain
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5
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Simonis AE, Brownell RL, Thayre BJ, Trickey JS, Oleson EM, Huntington R, Baumann-Pickering S. Co-occurrence of beaked whale strandings and naval sonar in the Mariana Islands, Western Pacific. Proc Biol Sci 2020; 287:20200070. [PMID: 32070257 PMCID: PMC7062028 DOI: 10.1098/rspb.2020.0070] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mid-frequency active sonar (MFAS), used for antisubmarine warfare (ASW), has been associated with multiple beaked whale (BW) mass stranding events. Multinational naval ASW exercises have used MFAS offshore of the Mariana Archipelago semi-annually since 2006. We report BW and MFAS acoustic activity near the islands of Saipan and Tinian from March 2010 to November 2014. Signals from Cuvier's (Ziphius cavirostris) and Blainville's beaked whales (Mesoplodon densirostris), and a third unidentified BW species, were detected throughout the recording period. Both recorders documented MFAS on 21 August 2011 before two Cuvier's beaked whales stranded on 22–23 August 2011. We compared the history of known naval operations and BW strandings from the Mariana Archipelago to consider potential threats to BW populations. Eight BW stranding events between June 2006 and January 2019 each included one to three animals. Half of these strandings occurred during or within 6 days after naval activities, and this co-occurrence is highly significant. We highlight strandings of individual BWs can be associated with ASW, and emphasize the value of ongoing passive acoustic monitoring, especially for beaked whales that are difficult to visually detect at sea. We strongly recommend more visual monitoring efforts, at sea and along coastlines, for stranded cetaceans before, during and after naval exercises.
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Affiliation(s)
- Anne E Simonis
- Contractor to Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, HI, USA
| | - Robert L Brownell
- Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration, Monterey, CA, USA
| | - Bruce J Thayre
- Scripps Institution of Oceanography, UCSD, La Jolla, CA, USA
| | | | - Erin M Oleson
- Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, HI, USA
| | - Roderick Huntington
- Scripps Institution of Oceanography, UCSD, La Jolla, CA, USA.,Mount Edgecumbe High School, Sitka, AK, USA
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6
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Bernaldo de Quirós Y, Fernandez A, Baird RW, Brownell RL, Aguilar de Soto N, Allen D, Arbelo M, Arregui M, Costidis A, Fahlman A, Frantzis A, Gulland FMD, Iñíguez M, Johnson M, Komnenou A, Koopman H, Pabst DA, Roe WD, Sierra E, Tejedor M, Schorr G. Advances in research on the impacts of anti-submarine sonar on beaked whales. Proc Biol Sci 2020; 286:20182533. [PMID: 30963955 DOI: 10.1098/rspb.2018.2533] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Mass stranding events (MSEs) of beaked whales (BWs) were extremely rare prior to the 1960s but increased markedly after the development of naval mid-frequency active sonar (MFAS). The temporal and spatial associations between atypical BW MSEs and naval exercises were first observed in the Canary Islands, Spain, in the mid-1980s. Further research on BWs stranded in association with naval exercises demonstrated pathological findings consistent with decompression sickness (DCS). A 2004 ban on MFASs around the Canary Islands successfully prevented additional BW MSEs in the region, but atypical MSEs have continued in other places of the world, especially in the Mediterranean Sea, with examined individuals showing DCS. A workshop held in Fuerteventura, Canary Islands, in September 2017 reviewed current knowledge on BW atypical MSEs associated with MFAS. Our review suggests that the effects of MFAS on BWs vary among individuals or populations, and predisposing factors may contribute to individual outcomes. Spatial management specific to BW habitat, such as the MFAS ban in the Canary Islands, has proven to be an effective mitigation tool and mitigation measures should be established in other areas taking into consideration known population-level information.
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Affiliation(s)
- Y Bernaldo de Quirós
- 1 Institute of Animal Health, University of Las Palmas de Gran Canaria, Veterinary School , C/Transmontaña s/n, 35416, Arucas, Las Palmas , Spain
| | - A Fernandez
- 1 Institute of Animal Health, University of Las Palmas de Gran Canaria, Veterinary School , C/Transmontaña s/n, 35416, Arucas, Las Palmas , Spain
| | - R W Baird
- 2 Cascadia Research Collective , 218½ W. 4th Avenue, Olympia, WA 98501 , USA
| | - R L Brownell
- 3 NOAA Fisheries, Southwest Fisheries Science Center , Monterey, CA 93940 , USA
| | - N Aguilar de Soto
- 4 BIOECOMAC. Dept. Animal Biology, Geology and Edaphology, University of La Laguna , Tenerife , Spain
| | - D Allen
- 5 US Marine Mammal Commission , 4340 East-West Highway, Suite 700, Bethesda, MD 20814 , USA
| | - M Arbelo
- 1 Institute of Animal Health, University of Las Palmas de Gran Canaria, Veterinary School , C/Transmontaña s/n, 35416, Arucas, Las Palmas , Spain
| | - M Arregui
- 1 Institute of Animal Health, University of Las Palmas de Gran Canaria, Veterinary School , C/Transmontaña s/n, 35416, Arucas, Las Palmas , Spain
| | - A Costidis
- 6 Virginia Aquarium & Marine Science Center Stranding Response Program , 717 General Booth Blvd, Virginia Beach, VA 23451 , USA
| | - A Fahlman
- 7 Fundación Oceanogràfic de la Comunitat Valenciana , Gran Vía Marqués del Turia 19, 46005, Valencia , Spain
| | - A Frantzis
- 8 Pelagos Cetacean Research Institute , Terpsichoris 21, 16671 Vouliagmeni , Greece
| | - F M D Gulland
- 5 US Marine Mammal Commission , 4340 East-West Highway, Suite 700, Bethesda, MD 20814 , USA.,9 The Marine Mammal Center , 2000 Bunker Road, Sausalito, CA 94965 , USA
| | - M Iñíguez
- 10 Fundación Cethus and WDC , Cap J. Bermúdez 1598, (1636), Olivos, Prov. Buenos Aires , Argentina
| | - M Johnson
- 11 Sea Mammal Research Unit, University of St Andrews , St Andrews , UK
| | - A Komnenou
- 12 School of Veterinary Medicine, Aristotle University of Thessaloniki , Thessaloniki , Greece
| | - H Koopman
- 13 Department of Biology and Marine Biology, University of North Carolina Wilmington , Wilmington, NC 28403 , USA
| | - D A Pabst
- 13 Department of Biology and Marine Biology, University of North Carolina Wilmington , Wilmington, NC 28403 , USA
| | - W D Roe
- 14 Massey University , Palmerston North, PN4222 , New Zealand
| | - E Sierra
- 1 Institute of Animal Health, University of Las Palmas de Gran Canaria, Veterinary School , C/Transmontaña s/n, 35416, Arucas, Las Palmas , Spain
| | - M Tejedor
- 15 Canary Islands Stranding Network , Irlanda 7, Playa Blanca, 35580, Lanzarote , Spain
| | - G Schorr
- 16 Marine Ecology & Telemetry Research , 2468 Camp McKenzie Tr NW, Seabeck, WA 98380 , USA
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7
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Cholewiak D, DeAngelis AI, Palka D, Corkeron PJ, Van Parijs SM. Beaked whales demonstrate a marked acoustic response to the use of shipboard echosounders. R Soc Open Sci 2017; 4:170940. [PMID: 29308236 PMCID: PMC5750003 DOI: 10.1098/rsos.170940] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/14/2017] [Indexed: 05/24/2023]
Abstract
The use of commercial echosounders for scientific and industrial purposes is steadily increasing. In addition to traditional navigational and fisheries uses, commercial sonars are used extensively for oceanographic research, benthic habitat mapping, geophysical exploration, and ecosystem studies. Little is known about the effects of these acoustic sources on marine animals, though several studies have already demonstrated behavioural responses of cetaceans to shipboard echosounders. Some species of cetaceans are known to be particularly sensitive to acoustic disturbance, including beaked whales. In 2011 and 2013, we conducted cetacean assessment surveys in the western North Atlantic in which a suite of Simrad EK60 echosounders was used to characterize the distribution of prey along survey tracklines. Echosounders were alternated daily between active and passive mode, to determine whether their use affected visual and acoustic detection rates of beaked whales. A total of 256 groups of beaked whales were sighted, and 118 definitive acoustic detections were recorded. Regression analyses using generalized linear models (GLM) found that sea state and region were primary factors in determining visual sighting rates, while echosounder state was the primary driver for acoustic detections, with significantly fewer detections (only 3%) occurring when echosounders were active. These results indicate that beaked whales both detect and change their behaviour in response to commercial echosounders. The mechanism of this response is unknown, but could indicate interruption of foraging activity or vessel avoidance, with potential implications for management and mitigation of anthropogenic impacts.
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Patel S, Thompson KF, Santure AW, Constantine R, Millar CD. Genetic Kinship Analyses Reveal That Gray's Beaked Whales Strand in Unrelated Groups. J Hered 2017; 108:456-461. [PMID: 28498990 DOI: 10.1093/jhered/esx021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 02/16/2017] [Indexed: 11/12/2022] Open
Abstract
Some marine mammals are so rarely seen that their life history and social structure remain a mystery. Around New Zealand, Gray's beaked whales (Mesoplodon grayi) are almost never seen alive, yet they are a commonly stranded species. Gray's are unique among the beaked whales in that they frequently strand in groups, providing an opportunity to investigate their social organization. We examined group composition and genetic kinship in 113 Gray's beaked whales with samples collected over a 20-year period. Fifty-six individuals stranded in 19 groups (2 or more individuals), and 57 whales stranded individually. Mitochondrial control region haplotypes and microsatellite genotypes (16 loci) were obtained for 103 whales. We estimated pairwise relatedness between all pairs of individuals and average relatedness within, and between, groups. We identified 6 mother-calf pairs and 2 half-siblings, including 2 whales in different strandings 17 years and 1500 km apart. Surprisingly, none of the adults stranding together were related suggesting that groups are not formed through the retention of kin. These data suggest that both sexes may disperse from their mothers, and groups consisting of unrelated subadults are common. We also found no instances of paternity within the groups. Our results provide the first insights into dispersal, social organization, and the mating system in this rarely sighted species. Why whales strand is still unknown but, in Gray's beaked whales, the dead can tell us much about the living.
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Affiliation(s)
- Selina Patel
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Kirsten F Thompson
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.,Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope, Stocker Road, Exeter EX4 4QD, UK
| | - Anna W Santure
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Rochelle Constantine
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Craig D Millar
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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9
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Coomber F, Moulins A, Tepsich P, Rosso M. Sexing free-ranging adult Cuvier's beaked whales ( Ziphius cavirostris ) using natural marking thresholds and pigmentation patterns. J Mammal 2016; 97:879-890. [PMID: 29692471 PMCID: PMC5909803 DOI: 10.1093/jmammal/gyw033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Sex identification of adult cetaceans is an important ecological parameter that should be incorporated into studies such as population dynamics and animal behavior. In Cuvier’s beaked whale (
Ziphius cavirostris
), sex determination may be achieved through genetics, observation of genitals, the presence/absence of erupted teeth, and calf association. However, these features are difficult to ascertain due to the shy behavior of this species. Therefore, this study aimed to create a robust sex identification method using only external characteristics. Particularly, this work analyzed pigmentation patterns and levels of natural marks from adult individuals of known sex in order to identify gender differences, using frequency analysis and generalized linear models. Photographic captures of 73 free-ranging animals were utilized. The frequencies of the individual pigmentation patterns were found to be sex dependent. The 63% of the animals could be classified into either a “soft” or “sharp” pigmentation cluster. The “soft” cluster was only displayed by females, while the “sharp” cluster was present in both the sexes. However, the model selection process indicated that natural marking is the best determinative factor for sex classification. The density of the visible intraspecific natural marks was found to differ between the sexes (
P
value < 0.001) and was incorporated as a predictor variable into several candidate models. All candidate models had a high predictive power (mean area under the curve 0.973) and correctly predicted the sex, by means of a density threshold value, in 85–90% of the analyzed animals. The density threshold ranged from 4.1% to 6.4% according to the different body area analyzed. These density threshold values represent a robust post hoc sexing method to classify individuals to sex from opportunistic photos in the absence of other sexing methods.
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Affiliation(s)
- Frazer Coomber
- CIMA Research Foundation , Via Magliotto 2, 17100 Savona , Italy (FC, AM, PT, MR).,DIBRIS, University of Genova , Via Balbi 5, 16126 Genova , Italy (FC, PT)
| | - Aurelie Moulins
- CIMA Research Foundation , Via Magliotto 2, 17100 Savona , Italy (FC, AM, PT, MR).,DIBRIS, University of Genova , Via Balbi 5, 16126 Genova , Italy (FC, PT)
| | - Paola Tepsich
- CIMA Research Foundation , Via Magliotto 2, 17100 Savona , Italy (FC, AM, PT, MR).,DIBRIS, University of Genova , Via Balbi 5, 16126 Genova , Italy (FC, PT)
| | - Massimiliano Rosso
- CIMA Research Foundation , Via Magliotto 2, 17100 Savona , Italy (FC, AM, PT, MR).,DIBRIS, University of Genova , Via Balbi 5, 16126 Genova , Italy (FC, PT)
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