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Sascha K Hooker - One of the best experts on this subject based on the ideXlab platform.
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CLICK CHARACTERISTICS OF NORTHERN BOTTLENOSE WHALES (Hyperoodon AMPULLATUS)
Marine Mammal Science, 2020Co-Authors: Sascha K Hooker, Hal WhiteheadAbstract:Sounds produced by northern bottlenose whales (Hyperoodon ampullatus) recorded in the Gully, a submarine canyon off Nova Scotia, consisted predominately of clicks. In 428 min of recordings no whistles were heard which could unequivocally be attributed to bottlenose whales. There were two major types of click series, initially distinguished by large differences in received amplitude. Loud clicks (produced by nearby whales socializing at the surface) were rapid, with short and variable interclick intervals (mean 0.07 sec; CV 71%). The frequency spectra of these were variable and often multimodal, with peak frequencies ranging between 2 and 22 kHz (mean 11 kHz, CV 59%). Clicks received at low amplitude (produced by distant whales, presumably foraging at depth) had more consistent interclick intervals (mean 0.40 sec, CV 12.5%), generally unimodal frequency spectra with a mean peak frequency of 24 kHz (CV 7%) and 3 dB bandwidth of 4 kHz. Echolocation interclick intervals may reflect the approximate search distance of an animal, in this case 300 m, comparable to that found for sperm whales. The relationship between click frequency and the size of object being investigated, suggests that 24 kHz would be optimal for an object of approximately 6 cm or more, consistent with the size range of their squid prey.
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Future directions in research on beaked whales
Frontiers in Marine Science, 2019Co-Authors: Sascha K Hooker, Natacha Aguilar De Soto, Patrick J O Miller, Laura Joan Feyrer, Robin W. Baird, Emma L. Carroll, Diane Claridge, Aubrie Onoufriou, Greg Schorr, Eilidh M. SiegalAbstract:Until the 1990s, beaked whales were one of the least understood groups of large mammals. Information on northern bottlenose whales (Hyperoodon ampullatus) and Baird’s beaked whales (Berardius bairdii) was available from data collected during whaling, however, little information existed on the smaller species other than occasional data gleaned from beach-cast animals. Recent research advances have been plentiful. Increasing global survey effort, together with morphometric and genetic analyses have shown at least 22 species in this group. Longitudinal field studies of at least four species (H. ampullatus, B. bairdii, Ziphius cavirostris, Mesoplodon densirostris) have become established over the last three decades. Several long-term studies support photo-identification catalogues providing insights into life history, social structure and population size. Tag-based efforts looking at diving, movements and acoustics have provided detail on individual behaviour as well as population structure and ranges. Passive acoustic monitoring has allowed long-term and seasonal monitoring of populations. Genetic studies have uncovered cryptic species and revealed contrasting patterns of genetic diversity and connectivity amongst the few species examined. Conservation concern for these species was sparked by mass strandings coincident with military mid-frequency sonar use. Fat and gas emboli have been symptomatic indicators of mortalities related to sonar exposure, suggesting that their vulnerability stems from the physiological exertion of extreme diving for medium-sized whales. Behavioural response experiments have now shown that beaked whales appear to cease foraging and delay their return to foraging and/or leave the area in association with exposure to mid-frequency signals at low acoustic levels. Future priorities for these species will be to (1) continue field-studies to better understand smaller-scale habitat use, vital rates and social structure; (2) develop better detection methods for larger-scale survey work; (3) improve methodology for monitoring energetics, individual body condition and health; (4) develop tools to better understand physiology; (5) use recent genetic advances with improved sample databanks to re-examine global and local beaked whale relationships; (6) further quantify anthropogenic impacts (both sonar and other noise) and their population consequences (7) apply acquired data for realistic mitigation of sonar and other anthropogenic impacts for beaked whale conservation.
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uncertain status of the northern bottlenose whale Hyperoodon ampullatus population fragmentation legacy of whaling and current threats
Endangered Species Research, 2012Co-Authors: Hal Whitehead, Sascha K HookerAbstract:The northern bottlenose whale Hyperoodon ampullatus is the best-known beaked whale species, but its conservation status remains very uncertain. A medium-sized cetacean that lives in the deeper waters of the northern North Atlantic, it is remarkable for its deep dives and inquisitiveness towards ships. There seem to have been of the order of 100 000 whales prior to 40 yr of intense whaling beginning in the 1880s, and this population was undoubtedly heavily reduced by 1920. The effects of a second phase of whaling between 1937 and 1973 are con- tentious, and current abundance estimates are patchy. There are suggestions of metapopulation structure (even at the scale of 50 km) in the western Atlantic among populations that do not appear to migrate. In the eastern Atlantic, data on population structure and migrations are few and confusing. Whales are incidentally caught in fishing gear and interact with fisheries off Labrador, Canada. They may also be affected by underwater noise. However, the population con- sequences of these and other anthropogenic stressors, particularly within this unknown metapop- ulation structure, are very uncertain. In some respects, such as the paucity of sightings on major whaling grounds off mainland Norway and Labrador, the picture that we have is disturbing. Analyses of genes, contaminants and vocalizations, as well as photoidentification and satellite tag data, can inform about population structure, migrations, life history parameters, current popula- tion sizes, and threats.
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Toothed Whales, Overview
Encyclopedia of Marine Mammals, 2009Co-Authors: Sascha K HookerAbstract:Publisher Summary This chapter provides the overview of toothed whales. Toothed whales comprise the suborder Odontoceti of the order Cetacea. This suborder includes 10 diverse families, 2 of which contain large numbers of species. There are at least 71 species in all, including the true dolphins, monodontids, river dolphins, porpoises, beaked whales, and sperm whales. These species occur in three primary clades, the superfamilies Delphinoidea (true dolphins, monodontids, and porpoises), Ziphoidea (beaked whales), and Physeteroidea (sperm whales), whereas the affinities of the river dolphins remain uncertain. With the exception of the sperm whale (males of which reach up to 18 m) and the larger beaked whale species (Berardius and Hyperoodon spp.), most odontocetes are small to medium-sized cetaceans, ranging in size from the Hector's dolphin (1.5 m) to the killer whale (8.5 m). These species show a range of distributions, with some such as river dolphins found only in quite specific areas, whereas others such as sperm whales or killer whales show a global distribution. Toothed whales have developed specialized sound production and reception mechanisms for the use of biosonar. All modern odontocetes are thought to use echolocation, in the same manner as bats, to gain an “image” of their environment. Although only a few species of odontocete are unequivocally known to echolocate, all odontocetes known to produce pulse-like sounds in the wild are assumed to be able to echolocate. Toothed whales are particularly well known for their brain size and rich social lives. The absolute brain size of odontocetes ranges from 840 g in common dolphins to 7820 g in sperm whales. However, a more useful way to compare brain sizes is to use the ratio of brain size to body size, the encephalization quotient (EQ).
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Could beaked whales get the bends? Effect of diving behaviour and physiology on modelled gas exchange for three species: Ziphius cavirostris, Mesoplodon densirostris and Hyperoodon ampullatus.
Respiratory Physiology & Neurobiology, 2009Co-Authors: Sascha K Hooker, Robin W. Baird, Andreas FahlmanAbstract:Abstract A mathematical model, based on current knowledge of gas exchange and physiology of marine mammals, was used to predict blood and tissue tension N 2 ( P N 2 ) using field data from three beaked whale species: northern bottlenose whales, Cuvier's beaked whales, and Blainville's beaked whales. The objective was to determine if physiology (body mass, diving lung volume, dive response) or dive behaviour (dive depth and duration, changes in ascent rate, diel behaviour) would lead to differences in P N 2 levels and thereby decompression sickness (DCS) risk between species. Diving lung volume and extent of the dive response had a large effect on end-dive P N 2 . The dive profile had a larger influence on end-dive P N 2 than body mass differences between species. Despite diel changes in dive behaviour, P N 2 levels showed no consistent trend. Model output suggested that all three species live with tissue P N 2 levels that would cause a significant proportion of DCS cases in terrestrial mammals. Cuvier's beaked whale diving behaviour appears to put them at higher risk than the other species, which may explain their prevalence in strandings after the use of mid-frequency sonar.
Hal Whitehead - One of the best experts on this subject based on the ideXlab platform.
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Prolonged maternal investment in northern bottlenose whales alters our understanding of beaked whale reproductive life history.
PLOS ONE, 2020Co-Authors: Laura Joan Feyrer, Hal Whitehead, Shu Ting Zhao, Cory J. D. MatthewsAbstract:Nursing and weaning periods are poorly understood in cetaceans due to the difficulty of assessing underwater behaviour in the wild. However, the onset and completion of weaning are critical turning points for individual development and survival, with implications for a species’ life history including reproductive potential. δ15N and δ13C deposited in odontocete teeth annuli provide a lifetime record of diet, offering an opportunity to investigate variation and trends in fundamental biology. While available reproductive parameters for beaked whales have largely been inferred from single records of stranded or hunted animals and extrapolated across species, here we examine the weaning strategy and nursing duration in northern bottlenose whales (Hyperoodon ampullatus) by measuring stable isotopes deposited in dentine growth layer groups (GLGs). Using a collection of H. ampullatus teeth taken from whales killed during the whaling era (N = 48) and from two stranded specimens, we compared ontogenetic variation of δ15N and δ13C found in annual GLGs across all individuals, by sex and by region. We detected age-based trends in both δ15N and δ13C that are consistent across regions and males and females, and indicate that nursing is prolonged and weaning does not conclude until whales are 3–4 years old, substantially later than previous estimates of 1 year. Incorporating a prolonged period of maternal care into H. ampullatus life history significantly reduces their reproductive potential, with broad implications for models of beaked whale life history, energetics and the species’ recovery from whaling.
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PHOTOGRAPHIC IDENTIFICATION OF NORTHERN BOTTLENOSE WHALES (Hyperoodon AMPULLATUS): SOURCES OF HETEROGENEITY FROM NATURAL MARKS
Marine Mammal Science, 2020Co-Authors: Shannon Gowans, Hal WhiteheadAbstract:The use of natural marks in capture-recapture studies can lead to unequal capture probabilities. This paper examined a catalog of northern bottlenose whale (Hyperoodon ampullatus) photographs from the Gully, Nova Scotia, to identify potential sources of heterogeneity. This information can be used to select appropriate individuals and photographs to include in analyses. Individual northern bottlenose whales were sufficiently marked to uniquely identify individuals (x = 14.5 marks/individual; range 1-67), but not all mark types persisted over time. Reliable marks were defined as mark types that were not lost over the nine-year study period (notches, back indentation, and mottled patches). Individuals were considered reliably marked if they possessed at least one back indentation or mottled patch (located within one dorsal fin width, at the base of the dorsal fin) or a notch on the dorsal fin. Sixty-six percent (SE = 5%) of the population were reliably marked. Long-term analyses (months to years) should use only reliably marked individuals, and the results scaled to account for the rest of the population. Our results also showed that photographic quality affected an observer's ability to identify individuals. For this catalog, quantitative analysis indicated only photographs of Q ≥ 4 (on a 6-point scale with 6 representing the highest quality) should be included in mark-recapture analyses sensitive to heterogeneity.
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CLICK CHARACTERISTICS OF NORTHERN BOTTLENOSE WHALES (Hyperoodon AMPULLATUS)
Marine Mammal Science, 2020Co-Authors: Sascha K Hooker, Hal WhiteheadAbstract:Sounds produced by northern bottlenose whales (Hyperoodon ampullatus) recorded in the Gully, a submarine canyon off Nova Scotia, consisted predominately of clicks. In 428 min of recordings no whistles were heard which could unequivocally be attributed to bottlenose whales. There were two major types of click series, initially distinguished by large differences in received amplitude. Loud clicks (produced by nearby whales socializing at the surface) were rapid, with short and variable interclick intervals (mean 0.07 sec; CV 71%). The frequency spectra of these were variable and often multimodal, with peak frequencies ranging between 2 and 22 kHz (mean 11 kHz, CV 59%). Clicks received at low amplitude (produced by distant whales, presumably foraging at depth) had more consistent interclick intervals (mean 0.40 sec, CV 12.5%), generally unimodal frequency spectra with a mean peak frequency of 24 kHz (CV 7%) and 3 dB bandwidth of 4 kHz. Echolocation interclick intervals may reflect the approximate search distance of an animal, in this case 300 m, comparable to that found for sperm whales. The relationship between click frequency and the size of object being investigated, suggests that 24 kHz would be optimal for an object of approximately 6 cm or more, consistent with the size range of their squid prey.
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evolutionary impacts differ between two exploited populations of northern bottlenose whale Hyperoodon ampullatus
Ecology and Evolution, 2019Co-Authors: Laura Joan Feyrer, Ian G Paterson, Hal Whitehead, Paul Bentzen, Anthony L EinfeldtAbstract:Interpretation of conservation status should be informed by an appreciation of genetic diversity, past demography, and overall trends in population size, which contribute to a species' evolutionary potential and resilience to genetic risks. Low genetic diversity can be symptomatic of rapid demographic declines and impose genetic risks to populations, but can also be maintained by natural processes. The northern bottlenose whale Hyperoodon ampullatus has the lowest known mitochondrial diversity of any cetacean and was intensely whaled in the Northwest Atlantic over the last century, but whether exploitation imposed genetic risks that could limit recovery is unknown. We sequenced full mitogenomes and genotyped 37 novel microsatellites for 128 individuals from known areas of abundance in the Scotian Shelf, Northern and Southern Labrador, Davis Strait, and Iceland, and a newly discovered group off Newfoundland. Despite low diversity and shared haplotypes across all regions, both markers supported the Endangered Scotian Shelf population as distinct from the combined northern regions. The genetic affinity of Newfoundland was uncertain, suggesting an area of mixing with no clear population distinction for the region. Demographic reconstruction using mitogenomes suggests that the northern region underwent population expansion following the last glacial maximum, but for the peripheral Scotian Shelf population, a stable demographic trend was followed by a drastic decline over a temporal scale consistent with increasing human activity in the Northwest Atlantic. Low connectivity between the Scotian Shelf and the rest of the Atlantic likely compounded the impact of intensive whaling for this species, potentially imposing genetic risks affecting recovery of this population. We highlight how the combination of historical environmental conditions and modern exploitation of this species has had very different evolutionary impacts on structured populations of northern bottlenose whales across the western North Atlantic.
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uncertain status of the northern bottlenose whale Hyperoodon ampullatus population fragmentation legacy of whaling and current threats
Endangered Species Research, 2012Co-Authors: Hal Whitehead, Sascha K HookerAbstract:The northern bottlenose whale Hyperoodon ampullatus is the best-known beaked whale species, but its conservation status remains very uncertain. A medium-sized cetacean that lives in the deeper waters of the northern North Atlantic, it is remarkable for its deep dives and inquisitiveness towards ships. There seem to have been of the order of 100 000 whales prior to 40 yr of intense whaling beginning in the 1880s, and this population was undoubtedly heavily reduced by 1920. The effects of a second phase of whaling between 1937 and 1973 are con- tentious, and current abundance estimates are patchy. There are suggestions of metapopulation structure (even at the scale of 50 km) in the western Atlantic among populations that do not appear to migrate. In the eastern Atlantic, data on population structure and migrations are few and confusing. Whales are incidentally caught in fishing gear and interact with fisheries off Labrador, Canada. They may also be affected by underwater noise. However, the population con- sequences of these and other anthropogenic stressors, particularly within this unknown metapop- ulation structure, are very uncertain. In some respects, such as the paucity of sightings on major whaling grounds off mainland Norway and Labrador, the picture that we have is disturbing. Analyses of genes, contaminants and vocalizations, as well as photoidentification and satellite tag data, can inform about population structure, migrations, life history parameters, current popula- tion sizes, and threats.
Shannon Gowans - One of the best experts on this subject based on the ideXlab platform.
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PHOTOGRAPHIC IDENTIFICATION OF NORTHERN BOTTLENOSE WHALES (Hyperoodon AMPULLATUS): SOURCES OF HETEROGENEITY FROM NATURAL MARKS
Marine Mammal Science, 2020Co-Authors: Shannon Gowans, Hal WhiteheadAbstract:The use of natural marks in capture-recapture studies can lead to unequal capture probabilities. This paper examined a catalog of northern bottlenose whale (Hyperoodon ampullatus) photographs from the Gully, Nova Scotia, to identify potential sources of heterogeneity. This information can be used to select appropriate individuals and photographs to include in analyses. Individual northern bottlenose whales were sufficiently marked to uniquely identify individuals (x = 14.5 marks/individual; range 1-67), but not all mark types persisted over time. Reliable marks were defined as mark types that were not lost over the nine-year study period (notches, back indentation, and mottled patches). Individuals were considered reliably marked if they possessed at least one back indentation or mottled patch (located within one dorsal fin width, at the base of the dorsal fin) or a notch on the dorsal fin. Sixty-six percent (SE = 5%) of the population were reliably marked. Long-term analyses (months to years) should use only reliably marked individuals, and the results scaled to account for the rest of the population. Our results also showed that photographic quality affected an observer's ability to identify individuals. For this catalog, quantitative analysis indicated only photographs of Q ≥ 4 (on a 6-point scale with 6 representing the highest quality) should be included in mark-recapture analyses sensitive to heterogeneity.
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Bottlenose Whales: Hyperoodon ampullatus and H. planifrons
Encyclopedia of Marine Mammals, 2020Co-Authors: Shannon GowansAbstract:Publisher Summary This chapter describes the bottlenose or bottlenosed whales, large and robust beaked whales (6–9 m) distinguished by their large bulbous forehead and short dolphin-like beak. They are chocolate brown to yellow in color, being lighter on the flanks and belly. This coloration is believed to be caused by a thin diatom layer. Newborns are gray with dark eye patches and a light-colored forehead. The maxillary crests of males become larger and heavier with age, leading to a change in the shape of the forehead, with mature males having a flat, squared-off forehead whereas females/immature males have a smooth rounded forehead. The dense bone in the male's forehead may be used for male–male competition, as males head-butt one another. Males possess a single pair of conical teeth at the tip of the lower jaw (in females, they remain unerupted); however, these teeth are rarely visible in live animals. Northern (H. ampullatus) and southern (H. planifrons) bottlenose whales are the only recognized species within the genus Hyperoodon in the family Ziphiidae. Recent molecular work on southern bottlenose whales indicates that there may be more than one species. Sightings of a large beaked whale in the tropical Pacific has been identified in the past as a bottlenose whale (either H. planifrons or a third, undescribed Hyperoodon sp.); however, recent evidence suggests these whales are Longman's beaked whales (Indopacetus pacificus).
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Bottlenose whales: Hyperoodon ampullatus and H. planifrons
Encyclopedia of Marine Mammals, 2009Co-Authors: Shannon GowansAbstract:This chapter describes the bottlenose or bottlenosed whales, large and robust beaked whales (6-9 m) distinguished by their large bulbous forehead and short dolphin-like beak. They are chocolate brown to yellow in color, being lighter on the flanks and belly. This coloration is believed to be caused by a thin diatom layer. Newborns are gray with dark eye patches and a light-colored forehead. The maxillary crests of males become larger and heavier with age, leading to a change in the shape of the forehead, with mature males having a flat, squared-off forehead whereas females/immature males have a smooth rounded forehead. The dense bone in the male's forehead may be used for male-male competition, as males head-butt one another. Males possess a single pair of conical teeth at the tip of the lower jaw (in females, they remain unerupted); however, these teeth are rarely visible in live animals. Northern (. H. ampullatus) and southern (. H. planifrons) bottlenose whales are the only recognized species within the genus Hyperoodon in the family Ziphiidae. Recent molecular work on southern bottlenose whales indicates that there may be more than one species. Sightings of a large beaked whale in the tropical Pacific has been identified in the past as a bottlenose whale (either H. planifrons or a third, undescribed Hyperoodon sp.); however, recent evidence suggests these whales are Longman's beaked whales (. Indopacetus pacificus). © 2009 Copyright © 2009 Elsevier Inc. All rights reserved.
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Ecosystem consideration in conservation planning: energy demand of foraging bottlenose whales (Hyperoodon ampullatus) in a marine protected area
Biological Conservation, 2002Co-Authors: Sascha K Hooker, Hal Whitehead, Shannon GowansAbstract:The Gully, a submarine canyon off eastern Canada, was nominated as a pilot Marine Protected Area (MPA) in 1998, largely to safeguard the vulnerable population of northern bottlenose whales (Hyperoodon ampullatus) found there. The boundaries and ultimate management regime for the MPA for this area remain under review. We have estimated the energy consumption of bottlenose whales in the Gully based on the number of whales present at any time, their trophic level, the food requirements of each whale, and the rates of energy transfer between trophic levels. These calculations suggest that there must be a substantial spatial subsidy in the underlying foodweb of the submarine canyon to support the bottlenose whales using the Gully. A substantial area beyond the distribution of bottlenose whales in the area will therefore require protection. Conservation priorities to protect such subsidies will primarily involve additional protection at the level of the sea floor. Spatial subsidies are probably common in the marine environment, urging careful ecological analysis in the establishment of marine reserves and suggesting that conservation priorities need to take into account key ecological linkages and processes that are vital for sustaining species and habitats of concern.
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Fluctuations in distribution and patterns of individual range use of northern bottlenose whales
Marine Ecology Progress Series, 2002Co-Authors: Sascha K Hooker, Shannon Gowans, Hal Whitehead, Robin W. BairdAbstract:This study investigated the pattern and scale of distribution, movements and range use of the northern bottlenose whale Hyperoodon ampullatus above a submarine canyon, the Gully, off eastern Canada between 1988 and 1998. Locations and individual identification photographs were collected during encounters with whales. Whales showed a discrete distribution within the canyon associated with water depth (500 to 1500 m) and relatively steep topography. Encounter rate and distribution showed some variation between years. Changes in distribution were observed toward the north or south of the canyon, probably a consequence of changes in prey distribution. Individual whales within the canyon displaced 4 to 5 km over 24 h, with negligible further increase in displace- ment over time scales up to 20 d (their approximate residency period). Short-term VHF radio-track- ing of 5 individuals provided an independent source of movement data, showing displacements of approximately 2 km in 1 h and 5 to 10 km in 1 d. The relative lack of movement observed for these whales supports the hypothesis that the canyon contains a profitable and localized food source. Movements of whales best fit a model of short-term residence within ranges of approximately 25 km 2 , although the range size of mature males was smaller than that of females and immature males. Photo- resightings were also used to investigate variation in the positions of individual whales within the Gully. Within years, individuals showed some separation of ranges associated with periods of high whale abundance, but there was no separation between different age-sex classes. Between years, mature males showed consistent spatial orientations relative to each other, suggesting preferred locations possibly related to mating opportunities.
Robin W. Baird - One of the best experts on this subject based on the ideXlab platform.
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Future directions in research on beaked whales
Frontiers in Marine Science, 2019Co-Authors: Sascha K Hooker, Natacha Aguilar De Soto, Patrick J O Miller, Laura Joan Feyrer, Robin W. Baird, Emma L. Carroll, Diane Claridge, Aubrie Onoufriou, Greg Schorr, Eilidh M. SiegalAbstract:Until the 1990s, beaked whales were one of the least understood groups of large mammals. Information on northern bottlenose whales (Hyperoodon ampullatus) and Baird’s beaked whales (Berardius bairdii) was available from data collected during whaling, however, little information existed on the smaller species other than occasional data gleaned from beach-cast animals. Recent research advances have been plentiful. Increasing global survey effort, together with morphometric and genetic analyses have shown at least 22 species in this group. Longitudinal field studies of at least four species (H. ampullatus, B. bairdii, Ziphius cavirostris, Mesoplodon densirostris) have become established over the last three decades. Several long-term studies support photo-identification catalogues providing insights into life history, social structure and population size. Tag-based efforts looking at diving, movements and acoustics have provided detail on individual behaviour as well as population structure and ranges. Passive acoustic monitoring has allowed long-term and seasonal monitoring of populations. Genetic studies have uncovered cryptic species and revealed contrasting patterns of genetic diversity and connectivity amongst the few species examined. Conservation concern for these species was sparked by mass strandings coincident with military mid-frequency sonar use. Fat and gas emboli have been symptomatic indicators of mortalities related to sonar exposure, suggesting that their vulnerability stems from the physiological exertion of extreme diving for medium-sized whales. Behavioural response experiments have now shown that beaked whales appear to cease foraging and delay their return to foraging and/or leave the area in association with exposure to mid-frequency signals at low acoustic levels. Future priorities for these species will be to (1) continue field-studies to better understand smaller-scale habitat use, vital rates and social structure; (2) develop better detection methods for larger-scale survey work; (3) improve methodology for monitoring energetics, individual body condition and health; (4) develop tools to better understand physiology; (5) use recent genetic advances with improved sample databanks to re-examine global and local beaked whale relationships; (6) further quantify anthropogenic impacts (both sonar and other noise) and their population consequences (7) apply acquired data for realistic mitigation of sonar and other anthropogenic impacts for beaked whale conservation.
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Could beaked whales get the bends? Effect of diving behaviour and physiology on modelled gas exchange for three species: Ziphius cavirostris, Mesoplodon densirostris and Hyperoodon ampullatus.
Respiratory Physiology & Neurobiology, 2009Co-Authors: Sascha K Hooker, Robin W. Baird, Andreas FahlmanAbstract:Abstract A mathematical model, based on current knowledge of gas exchange and physiology of marine mammals, was used to predict blood and tissue tension N 2 ( P N 2 ) using field data from three beaked whale species: northern bottlenose whales, Cuvier's beaked whales, and Blainville's beaked whales. The objective was to determine if physiology (body mass, diving lung volume, dive response) or dive behaviour (dive depth and duration, changes in ascent rate, diel behaviour) would lead to differences in P N 2 levels and thereby decompression sickness (DCS) risk between species. Diving lung volume and extent of the dive response had a large effect on end-dive P N 2 . The dive profile had a larger influence on end-dive P N 2 than body mass differences between species. Despite diel changes in dive behaviour, P N 2 levels showed no consistent trend. Model output suggested that all three species live with tissue P N 2 levels that would cause a significant proportion of DCS cases in terrestrial mammals. Cuvier's beaked whale diving behaviour appears to put them at higher risk than the other species, which may explain their prevalence in strandings after the use of mid-frequency sonar.
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Fluctuations in distribution and patterns of individual range use of northern bottlenose whales
Marine Ecology Progress Series, 2002Co-Authors: Sascha K Hooker, Shannon Gowans, Hal Whitehead, Robin W. BairdAbstract:This study investigated the pattern and scale of distribution, movements and range use of the northern bottlenose whale Hyperoodon ampullatus above a submarine canyon, the Gully, off eastern Canada between 1988 and 1998. Locations and individual identification photographs were collected during encounters with whales. Whales showed a discrete distribution within the canyon associated with water depth (500 to 1500 m) and relatively steep topography. Encounter rate and distribution showed some variation between years. Changes in distribution were observed toward the north or south of the canyon, probably a consequence of changes in prey distribution. Individual whales within the canyon displaced 4 to 5 km over 24 h, with negligible further increase in displace- ment over time scales up to 20 d (their approximate residency period). Short-term VHF radio-track- ing of 5 individuals provided an independent source of movement data, showing displacements of approximately 2 km in 1 h and 5 to 10 km in 1 d. The relative lack of movement observed for these whales supports the hypothesis that the canyon contains a profitable and localized food source. Movements of whales best fit a model of short-term residence within ranges of approximately 25 km 2 , although the range size of mature males was smaller than that of females and immature males. Photo- resightings were also used to investigate variation in the positions of individual whales within the Gully. Within years, individuals showed some separation of ranges associated with periods of high whale abundance, but there was no separation between different age-sex classes. Between years, mature males showed consistent spatial orientations relative to each other, suggesting preferred locations possibly related to mating opportunities.
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Behavioral reactions of northern bottlenose whales (Hyperoodon ampullatus) to biopsy darting and tag attachment procedures
2001Co-Authors: Sascha K Hooker, Shannon Gowans, Robin W. Baird, S. Al-omari, Hal WhiteheadAbstract:The nonlethal fi ring of projectiles at whales and dolphins is increasingly being used, both in order to obtain skin and blubber samples (e.g. Lambertsen, 1987) and to attach data-recording or transmitting devices (e.g. Mate and Harvey, 1983; Goodyear, 1993; Baird, 1998; Mate et al., 1998). Data collected with these techniques are important for management and conservation purposes but may come at some cost (usually a behavioral disturbance) to the individuals involved. This cost may vary for different species or populations (see e.g. Schneider et al., 1998), therefore the impacts should be assessed each time a study is conducted. Reactions of various species of cetaceans to biopsy darting have generally been mild (e.g. International Whaling Commission, 1989; Whitehead et al., 1990; Brown et al., 1991; Weinrich et al., 1991, 1992; Barrett-Lennard et al., 1996; Weller et al., 1997). The most common response is a “startle” reaction, although the level of reaction varies slightly between species, and also between populations and individuals. In contrast, the reaction of cetaceans to tagging with suction-cup–attached tags has been found to vary dramatically. Although reactions of killer whales (Orcinus orca) and Dall’s porpoises (Phocoenoides dalli) to the technique were minor (Baird, 1994; Hanson and Baird, 1998), those of bottlenose dolphins (Tursiops sp.) were strong and relatively long-lasting (Schneider et al., 1998). The family Ziphiidae (the beaked whales) is the second largest family of cetaceans, yet no studies have reported their reactions to tagging or biopsy techniques. In this paper we compare the reactions of northern bottlenose whales (Hyperoodon ampullatus) to both techniques and investigate factors affecting the behavioral reactions observed. These results are particularly relevant to agencies that grant research permits (e.g. the National Marine Fisheries Service in the USA), which often require some discussion of the implications of research techniques in terms of animal care. Additionally, assessment of the magnitude and duration of any behavioral response caused by the process of attaching a tag is vital in ensuring that the attachment of the tag does not confound the behavioral data it records.
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Ingestion of Plastic and Unusual Prey by a Juvenile Harbour Porpoise
Marine Pollution Bulletin, 2000Co-Authors: Robin W. Baird, Sascha K HookerAbstract:Considerable quantities of plastic debris are found throughout the world’s oceans (e.g., Dufault and Whitehead, 1994), and may impact a diversity of species, including marine turtles, birds and mammals (Laist, 1997). Since many species of whales and dolphins live in waters far from shore, and may sink upon death, opportunities to record instances of ingestion of marine debris by cetaceans are infrequent. Despite this, there are several cases where ingestion of plastic or other marine debris has been documented for cetaceans, with published reports existing for 21 species of odontocetes (Laist, 1997). We know of an additional five species of odontocetes for which marine debris ingestion has been documented: the killer whale (Orcinus orca; K. Evans, pers. comm.), northern bottlenose whale (Hyperoodon ampullatus; R. Michaud, pers. comm..), finless porpoise (Neophocoena phocoenoides; C. Parsons, pers. comm.), white-beaked dolphin (Lagenorhynchus albirostris; R. Kastelein, pers. comm.), and pantropical spotted dolphin (Stenella attenuata; K. Robertson, pers. comm.). For most species of odontocetes, only one or a few records have been reported. Here we document the third reported case of plastic ingestion by a harbour porpoise (Phocoena phocoena), and discuss factors that might have contributed to its ingestion.
Patrick J O Miller - One of the best experts on this subject based on the ideXlab platform.
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Predicting acoustic dose associated with marine mammal behavioural responses to sound as detected with fixed acoustic recorders and satellite tags
Journal of the Acoustical Society of America, 2019Co-Authors: A.m. Von Benda-beckmann, Saana Isojunno, Paul J Wensveen, Petter H Kvadsheim, M. Prior, Ainslie, Rune Roland Hansen, Patrick J O MillerAbstract:To understand the consequences of underwater noise exposure for cetaceans, there is a need for assessments of behavioural responses over increased spatial and temporal scales. Bottom-moored acoustic recorders and satellite tags provide such long-term and large spatial coverage of behaviour compared to short-duration acoustic-recording tags. However, these tools result in a decreased resolution of data from which an animal response can be inferred, and no direct recording of the sound received at the animal. This study discusses the consequence of the decreased resolution of data from satellite tags and fixed acoustic recorders on the acoustic dose estimated by propagation modelling and presents a method for estimating the range of sound levels that animals observed with these methods have received. This problem is illustrated using experimental results obtained during controlled exposures of northern bottlenose whales (Hyperoodon ampullatus) exposed to naval sonar, carried out near Jan Mayen, Norway. It is shown that variability and uncertainties in the sound field, resulting from limited sampling of the acoustic environment, as well as decreased resolution in animal locations, can lead to quantifiable uncertainties in the estimated acoustic dose associated with the behavioural response (in this case avoidance and cessation of foraging). © 2019 Acoustical Society of America.
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Future directions in research on beaked whales
Frontiers in Marine Science, 2019Co-Authors: Sascha K Hooker, Natacha Aguilar De Soto, Patrick J O Miller, Laura Joan Feyrer, Robin W. Baird, Emma L. Carroll, Diane Claridge, Aubrie Onoufriou, Greg Schorr, Eilidh M. SiegalAbstract:Until the 1990s, beaked whales were one of the least understood groups of large mammals. Information on northern bottlenose whales (Hyperoodon ampullatus) and Baird’s beaked whales (Berardius bairdii) was available from data collected during whaling, however, little information existed on the smaller species other than occasional data gleaned from beach-cast animals. Recent research advances have been plentiful. Increasing global survey effort, together with morphometric and genetic analyses have shown at least 22 species in this group. Longitudinal field studies of at least four species (H. ampullatus, B. bairdii, Ziphius cavirostris, Mesoplodon densirostris) have become established over the last three decades. Several long-term studies support photo-identification catalogues providing insights into life history, social structure and population size. Tag-based efforts looking at diving, movements and acoustics have provided detail on individual behaviour as well as population structure and ranges. Passive acoustic monitoring has allowed long-term and seasonal monitoring of populations. Genetic studies have uncovered cryptic species and revealed contrasting patterns of genetic diversity and connectivity amongst the few species examined. Conservation concern for these species was sparked by mass strandings coincident with military mid-frequency sonar use. Fat and gas emboli have been symptomatic indicators of mortalities related to sonar exposure, suggesting that their vulnerability stems from the physiological exertion of extreme diving for medium-sized whales. Behavioural response experiments have now shown that beaked whales appear to cease foraging and delay their return to foraging and/or leave the area in association with exposure to mid-frequency signals at low acoustic levels. Future priorities for these species will be to (1) continue field-studies to better understand smaller-scale habitat use, vital rates and social structure; (2) develop better detection methods for larger-scale survey work; (3) improve methodology for monitoring energetics, individual body condition and health; (4) develop tools to better understand physiology; (5) use recent genetic advances with improved sample databanks to re-examine global and local beaked whale relationships; (6) further quantify anthropogenic impacts (both sonar and other noise) and their population consequences (7) apply acquired data for realistic mitigation of sonar and other anthropogenic impacts for beaked whale conservation.
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correction body density and diving gas volume of the northern bottlenose whale Hyperoodon ampullatus
The Journal of Experimental Biology, 2016Co-Authors: Patrick J O Miller, Saana Isojunno, Tomoko Narazaki, Kagari Aoki, Sophie Smout, Katsufumi SatoAbstract:There was an error published in J. Exp. Biol. 219 , [2458-2468][1]. Eqn 1 was presented incorrectly. A ‘−1’ was missing after the ratio of densities, and the subscript of the first instance of the density of seawater (ρsw) was given incorrectly as ‘w’ instead of ‘sw’. The original
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body density and diving gas volume of the northern bottlenose whale Hyperoodon ampullatus
The Journal of Experimental Biology, 2016Co-Authors: Saana Isojunno, Patrick J O Miller, Tomoko Narazaki, Kagari Aoki, Sophie Smout, Katsufumi SatoAbstract:Diving lung volume and tissue density, reflecting lipid store volume, are important physiological parameters that have only been estimated for a few breath-hold diving species. We fitted 12 northern bottlenose whales with data loggers that recorded depth, 3-axis acceleration and speed either with a fly-wheel or from change of depth corrected by pitch angle. We fitted measured values of the change in speed during 5 s descent and ascent glides to a hydrodynamic model of drag and buoyancy forces using a Bayesian estimation framework. The resulting estimate of diving gas volume was 27.4±4.2 (95% credible interval, CI) ml kg−1, closely matching the measured lung capacity of the species. Dive-by-dive variation in gas volume did not correlate with dive depth or duration. Estimated body densities of individuals ranged from 1028.4 to 1033.9 kg m−3 at the sea surface, indicating overall negative tissue buoyancy of this species in seawater. Body density estimates were highly precise with ±95% CI ranging from 0.1 to 0.4 kg m−3, which would equate to a precision of <0.5% of lipid content based upon extrapolation from the elephant seal. Six whales tagged near Jan Mayen (Norway, 71°N) had lower body density and were closer to neutral buoyancy than six whales tagged in the Gully (Nova Scotia, Canada, 44°N), a difference that was consistent with the amount of gliding observed during ascent versus descent phases in these animals. Implementation of this approach using longer-duration tags could be used to track longitudinal changes in body density and lipid store body condition of free-ranging cetaceans.
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gait switches in deep diving beaked whales biomechanical strategies for long duration dives
The Journal of Experimental Biology, 2015Co-Authors: Lucia Martina Martin Lopez, Natacha Aguilar De Soto, Patrick J O Miller, Mark P. JohnsonAbstract:ABSTRACT Diving animals modulate their swimming gaits to promote locomotor efficiency and so enable longer, more productive dives. Beaked whales perform extremely long and deep foraging dives that probably exceed aerobic capacities for some species. Here, we use biomechanical data from suction-cup tags attached to three species of beaked whales (Mesoplodon densirostris, N=10; Ziphius cavirostris, N=9; and Hyperoodon ampullatus, N=2) to characterize their swimming gaits. In addition to continuous stroking and stroke-and-glide gaits described for other diving mammals, all whales produced occasional fluke-strokes with distinctly larger dorso-ventral acceleration, which we termed ‘type-B’ strokes. These high-power strokes occurred almost exclusively during deep dive ascents as part of a novel mixed gait. To quantify body rotations and specific acceleration generated during strokes we adapted a kinematic method combining data from two sensors in the tag. Body rotations estimated with high-rate magnetometer data were subtracted from accelerometer data to estimate the resulting surge and heave accelerations. Using this method, we show that stroke duration, rotation angle and acceleration were bi-modal for these species, with B-strokes having 76% of the duration, 52% larger body rotation and four times more surge than normal strokes. The additional acceleration of B-strokes did not lead to faster ascents, but rather enabled brief glides, which may improve the overall efficiency of this gait. Their occurrence towards the end of long dives leads us to propose that B-strokes may recruit fast-twitch fibres that comprise ∼80% of swimming muscles in Blainville9s beaked whales, thus prolonging foraging time at depth.
