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1.
Jorge Acevedo Carlos Olavarr��a Jorge Plana Anelio Aguayo-Lobo Antonio Larrea Luis A. Pastene 《Polar Biology》2011,34(2):313-318
The occurrence of dwarf minke whales (Balaenoptera acutorostrata subsp.) around the Antarctic Peninsula was examined based on 406 sightings of minke whales recorded during the Chilean Antarctic
Scientific Expeditions and other opportunistic cetacean surveys. Identification of the species was made only for the whales
sighted in the proximity of the vessels when the specific diagnostic characters could be confirmed. Of the 406 sightings,
296 were assigned to Antarctic (519 individuals), nine (11 individuals) to dwarf and 101 to unidentified minke whales (149
individuals). Dwarf minke whales were identified by the reported external diagnostic characters for this species. Seven animals
occurred around the South Shetland Island and four in the Gerlache Strait. In addition, another two animals were identified
as dwarf minke whales in the Bellinghausen Sea in winter 1993, being these the most southern records for this species. These
results confirm the occurrence of dwarf minke whales around the Antarctic Peninsula during the summer seasons, as well as
in the Bellinghausen Sea in winter. The geographical range of these sightings was comprised between 61°03′ and 69°25′S and
between 55°29′ and 86°53′W. These results also suggest that some dwarf minke whales remain in the Antarctic during the austral
winter. 相似文献
2.
Luis A. Pastene Jorge Acevedo Mutsuo Goto Alexandre N. Zerbini Paola Acu?a Anelio Aguayo-Lobo 《Conservation Genetics》2010,11(4):1553-1558
Mitochondrial DNA control region sequences were analyzed to investigate population structure and possible migratory links
of common minke whales (Balaenoptera acutorostrata) in two ocean basins: western South Atlantic (WSA) and western South Pacific (WSP). The results of several different phylogenetic
estimations consistently grouped all haplotypes but one (n = 1) from these two ocean basins into two separate clades. South and North Atlantic haplotypes were more closely related
to each other than either was to haplotypes from the WSP. The interpopulation genetic distance between WSA and WSP whales
was similar to that reported between North Pacific and North Atlantic common minke whales (0.0234). The migration rate between
the two ocean basins was estimated at near-zero using MDIV. The genetic evidence presented here was consistent with the hypothesis
of migratory links among Brazil, Chilean Patagonia and the Antarctic Peninsula, and between low-latitude and Antarctic waters
of the WSP. The results suggest multiple populations of common minke whales in the Southern Hemisphere, which may have conservation
as well as taxonomic implications. Our single locus results should be corroborated by additional analyses in a larger number
of samples and at more genetic markers. 相似文献
3.
There are no published accounts of blue whales (Balaenoptera musculus) feeding in Antarctic waters. This note describes the behaviour of two groups of blue whales feeding in Antarctic pelagic
waters. Whales were observed during the 18th IWC/IDCR southern hemisphere minke whale assessment cruise. Feeding behaviour
in both cases resembled those described previously for both northern hemisphere blue whales and fin whales (B. physalus). These observations suggest that a programme of comparative behavioural observations could be developed to test the “feeding
competition” hypothesis, which suggests that recovery of populations of blue whales will be impeded by feeding competition
with sympatric minke whales.
Accepted: 29 April 1999 相似文献
4.
Seasonality of Antarctic minke whale (Balaenoptera bonaerensis) calls off the western Antarctic Peninsula 下载免费PDF全文
The Antarctic minke whale (Balaenoptera bonaerensis) is a difficult species to study because of its low visual detectability and preference for living within the sea ice habitat, accessible only by ice‐strengthened vessels. Recent identification of the Antarctic minke whale as the source of the seasonally ubiquitous bio‐duck call has allowed the use of this sound, as well as downsweeps, to investigate seasonality trends and diel patterns in Antarctic minke whale call production, and their relationship to sea ice cover. Passive acoustic data were collected using an autonomous Acoustic Recording Package (ARP) off the western Antarctic Peninsula. Bio‐duck calls were classified into four distinct call variants, with one variant having two subtypes. Bio‐duck calls were detected between April and November, with increasing call duration during the austral winter, indicating a strong seasonality in call production. Downsweeps, which were also attributed to Antarctic minke whales, were present throughout most months during the recording period, with a peak in July, and an absence in March and April. Both bio‐duck and downsweeps were significantly correlated with sea ice cover. No diel patterns were observed in bio‐duck calls or in downsweep call production at this site. 相似文献
5.
Interspecific relationships in density among a whale community in Antarctic feeding grounds were examined using the sightings
data derived from the systematic surveys conducted between 1978/1979 and 1987/1988. A clear difference in densities against
the physiographic variables (the sea floor-slope type) was identified between baleen whales and toothed whales. Densities
of sperm whales and ziphiids were low in the waters over the continental shelf where minke whales' densities were highest.
This led to an apparent negative correlation in the density between minke and sperm whales, and minke whale and ziphiids.
A significant positive correlation in density between minke and blue whales was identified. No association in density between
minke and humpback whales was observed. Distribution of killer whales shows strong positive correlation with that of minke
whales. The positive correlation existed between minke and blue whales, and minke and killer whales even when the effect of
environmental variables was excluded. Analysis also revealed that the environmental variables, including physiographic variables,
are major factors affecting the distributions and density of whales, especially between baleen whales and toothed whales.
Accepted: 8 December 1999 相似文献
6.
We report here the first published observations of killer whales (Orcinus orca) feeding on penguins in Antarctica. The sightings took place in the Gerlache Strait off the western Antarctic Peninsula during February 2010. Two species of pygoscelid penguins were taken—gentoo (Pygoscelis papua, at least four individuals) and chinstrap (P. antarctica, 2). From remains left at the surface, it was clear that the killer whales fed mainly on the breast muscles, although some penguins may have been swallowed whole. The killer whales were ecotype B, which are purported seal specialists, but we also saw ecotype A, prey specialists on Antarctic minke whales Balaenoptera bonaerensis, chase, but not catch penguins. Because of their small relative size, if penguins are regularly targeted by killer whales in Antarctica, the impact on their populations could be significant. 相似文献
7.
Denise Risch Nicholas J. Gales Jason Gedamke Lars Kindermann Douglas P. Nowacek Andrew J. Read Ursula Siebert Ilse C. Van Opzeeland Sofie M. Van Parijs Ari S. Friedlaender 《Biology letters》2014,10(4)
For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action. 相似文献
8.
Kenji Konishi Takashi Hakamada Hiroshi Kiwada Toshihide Kitakado Lars Walløe 《Polar Biology》2014,37(2):205-215
The Antarctic minke whale (Balaenoptera bonaerensis) is one of the major krill predators in Antarctic waters. A reported decline in energy storage over almost two decades indicates that food availability for the whales may also have declined recently. To test this hypothesis, catch data from 20 survey years in the Japanese Whale Research Program in the Antarctic (JARPA) and its second phase (JARPA II) (1990/91–2009/10), which covered the longitudinal sector between 35°E and 145°W south of 58°S, were used to investigate whether there was any annual trend in the stomach contents weight of Antarctic minke whales. A linear mixed-effects analysis showed a 31 % (95 % CI 12.6–45.3 %) decrease in the weight of stomach contents over the 20 years since 1990/1991. A similar pattern of decrease was found in both males and females, except in the case of females sampled at higher latitude in the Ross Sea. These results suggest a decrease in the availability of krill for Antarctic minke whales in the lower latitudinal range of the research area. The results are consistent with the decline in energy storage reported previously. The decrease in krill availability could be due to environmental changes or to an increase in the abundance of other krill-feeding predators. The latter appears somewhat more likely, given the recent rapid recovery of humpback whale. Furthermore, humpback whales are not found in the Ross Sea, where both Antarctic krill and ice krill (Euphausia crystallorophias) are available, and where no change in prey availability for Antarctic minke whales is indicated. 相似文献
9.
In September 2001, 21 satellite‐monitored radio tags were deployed on southern right whales in South African waters, 15 of which transmitted for 25–161 d. Most coastwise movement on the south coast occurred in a westerly direction with cow‐calf pairs moving slowest. Three whales tagged on the west coast and one tagged on the south coast moved north into St Helena Bay, a probable feeding ground, where residence times were 36–100 d. Five animals tracked after leaving the coast maintained a bearing of 201°–220° before branching out over the southeast Atlantic from 37° to 60°S and between 13°W and 16°E, traveling 3,800–8,200 km over the ensuing 53–110 d before transmissions ceased. Their locations were categorized as migrating or nonmigrating based on the relative orientation of the track and net speed. An average of 42% of nonmigrating locations were between 37°S and 45°S, and 53% were south of 52°S, possibly associated with the Subtropical Convergence and Antarctic Polar Front, respectively. Whaling data suggest right whales fed largely on copepods at the former and euphausiids at the latter. If the nonmigrating locations represented feeding at these frontal zones, switching between them would seem to have obvious cost‐benefit implications. 相似文献
10.
Using calls as an indicator for Antarctic blue whale occurrence and distribution across the southwest Pacific and southeast Indian Oceans 下载免费PDF全文
Naysa E. Balcazar Holger Klinck Sharon L. Nieukirk David K. Mellinger Karolin Klinck Robert P. Dziak Tracey L. Rogers 《Marine Mammal Science》2017,33(1):172-186
Understanding species distribution and behavior is essential for conservation programs of migratory species with recovering populations. The critically endangered Antarctic blue whale (Balaenoptera musculus intermedia) was heavily exploited during the whaling era. Because of their low numbers, highly migratory behavior, and occurrence in remote areas, their distribution and range are not fully understood, particularly in the southwest Pacific Ocean. This is the first Antarctic blue whale study covering the southwest Pacific Ocean region from temperate to tropical waters (32°S to 15°S). Passive acoustic data were recorded between 2010 and 2011 across the southwest Pacific (SWPO) and southeast Indian (SEIO) oceans. We detected Antarctic blue whale calls in previously undocumented SWPO locations off eastern Australia (32°S, 152°E) and within the Lau Basin (20°S, 176°W and 15°S, 173°W), and SEIO off northwest Australia (19°S, 115°E).In temperate waters, adjacent ocean basins had similar seasonal occurrence, in that calling Antarctic blue whales were present for long periods, almost year round in some areas. In northern tropical waters, calling whales were mostly present during the austral winter. Clarifying the occurrence and distribution of critically endangered species is fundamental for monitoring population recovery, marine protected area planning, and in mitigating anthropogenic threats. 相似文献
11.
Catherine R. M. Attard Luciano B. Beheregaray K. Curt S. Jenner Peter C. Gill Micheline‐Nicole Jenner Margaret G. Morrice Kelly M. Robertson Luciana M. Möller 《Molecular ecology》2012,21(23):5715-5727
Understanding the degree of genetic exchange between subspecies and populations is vital for the appropriate management of endangered species. Blue whales (Balaenoptera musculus) have two recognized Southern Hemisphere subspecies that show differences in geographic distribution, morphology, vocalizations and genetics. During the austral summer feeding season, the Antarctic blue whale (B. m. intermedia) is found in polar waters and the pygmy blue whale (B. m. brevicauda) in temperate waters. Here, we genetically analyzed samples collected during the feeding season to report on several cases of hybridization between the two recognized blue whale Southern Hemisphere subspecies in a previously unconfirmed sympatric area off Antarctica. This means the pygmy blue whales using waters off Antarctica may migrate and then breed during the austral winter with the Antarctic subspecies. Alternatively, the subspecies may interbreed off Antarctica outside the expected austral winter breeding season. The genetically estimated recent migration rates from the pygmy to Antarctic subspecies were greater than estimates of evolutionary migration rates and previous estimates based on morphology of whaling catches. This discrepancy may be due to differences in the methods or an increase in the proportion of pygmy blue whales off Antarctica within the last four decades. Potential causes for the latter are whaling, anthropogenic climate change or a combination of these and may have led to hybridization between the subspecies. Our findings challenge the current knowledge about the breeding behaviour of the world's largest animal and provide key information that can be incorporated into management and conservation practices for this endangered species. 相似文献
12.
Cetacean mitochondrial DNA control region: sequences of all extant baleen whales and two sperm whale species 总被引:6,自引:0,他引:6
The sequence of the mitochondrial control region was determined in all 10
extant species commonly assigned to the suborder Mysticeti (baleen or
whalebone whales) and to two odontocete (toothed whale) species (the sperm
and the pygmy sperm whale). In the mysticetes, both the length and the
sequence of the control region were very similar, with differences
occurring primarily in the first approximately 160 bp of the 5' end of the
L-strand of the region. There were marked differences between the mysticete
and sperm whale sequences and also between the two sperm whales. The
control region, less its variable portion, was used in a comparison
including the 10 mysticete sequences plus the same region of an Antarctic
minke whale specimen and the two sperm whales. The difference between the
minke whales from the North Atlantic and the Antarctic was greater than
that between any acknowledged species belonging to the same genus
(Balaenoptera). The difference was similar to that between the families
Balaenopteridae (rorquals) and Eschrichtiidae (gray whales). The findings
suggest that the Antarctic minke whale should have a full species status,
B. bonaerensis. Parsimony analysis separated the bowhead and the right
whale (family Balaenidae) from all remaining mysticetes, including the
pygmy right whale. The pygmy right whale is usually included in family
Balaenidae. The analysis revealed a close relationship between the gray
whale (family Eschrichtiidae) sequence and those of the rorquals (family
Balaenopteridae). The gray whale was included in a clade together with the
sei, Bryde's, fin, blue, and humpback whales. This clade was separated from
the two minke whale types, which branched together.
相似文献
13.
Ari S. Friedlaender Gareth L. Lawson † Patrick N. Halpin ‡ 《Marine Mammal Science》2009,25(2):402-415
For closely related sympatric species to coexist, they must differ to some degree in their ecological requirements or niches ( e.g. , diets) to avoid interspecific competition. Baleen whales in the Antarctic feed primarily on krill, and the large sympatric prewhaling community suggests resource partitioning among these species or a nonlimiting prey resource. In order to examine ecological differences between sympatric humpback and minke whales around the Western Antarctic Peninsula, we made measurements of the physical environment, observations of whale distribution, and concurrent acoustic measurements of krill aggregations. Mantel's tests and classification and regression tree models indicate both similarities and differences in the spatial associations between humpback and minke whales, environmental features, and prey. The data suggest (1) similarities (proximity to shore) and differences (prey abundance versus deep water temperatures) in horizontal spatial distribution patterns, (2) unambiguous vertical resource partitioning with minke whales associating with deeper krill aggregations across a range of spatial scales, and (3) that interference competition between these two species is unlikely. These results add to the paucity of ecological knowledge relating baleen whales and their prey in the Antarctic and should be considered in conservation and management efforts for Southern Ocean cetaceans and ecosystems. 相似文献
14.
CETACEAN OCCURRENCE PATTERNS IN THE AMUNDSEN AND SOUTHERN BELLINGSHAUSEN SEA SECTOR, SOUTHERN OCEAN 总被引:1,自引:0,他引:1
David G. Ainley Katie M. Dugger † Viola Toniolo ‡ Ian Gaffney § 《Marine Mammal Science》2007,23(2):287-305
We conducted 239.5 h and 3,494 km of cetacean surveys in the Amundsen and Bellingshausen seas, from 15 February to 31 March 1994; most of the area, the large portion of which was ice covered, had never before nor has it since been surveyed for cetaceans, even to the date when this paper was prepared (2006). Logistic regression and an information-theoretic approach related the occurrence of Antarctic minke whales Balaenoptera bonaerensis (the most abundant species) to whether we were in open- or pack-ice-covered pelagic or neritic waters, in or out of the marginal ice zone (MIZ), and north or south of the Antarctic Circumpolar Current southern boundary. Other variables included date and distance to the MIZ and shelfbreak front. Statistical analysis showed that the probability of sighting a minke, as well as killer whale—but not the case for an index to whale density—was related to the proximity of coastal polynyas in early autumn, switching offshore to the MIZ once waters within the pack began to freeze persistently later in the season. Probability of detection was higher with distance into the MIZ. Supporting these findings, the density index was strongly related to ice concentration in an inverse relationship. The strong relationship to polynyas and the MIZ indicate that sea-ice divergence altered by decadal or longer-term climate change, as described in the recent literature, could well affect any apparent, long-term trends evident in this species' abundance if surveyed only in open or near-to-ice waters. We speculate on how the minke whale's pagophilic nature (1) could have been encouraged by large-scale industrial whaling and by competition with species more characteristic of open waters and the outer MIZ, and (2) may have protected the population somewhat during industrial whaling resulting in the much greater abundance of this species now compared to other targeted species. 相似文献
15.
The population size of Antarctic minke whales Balaenoptera bonaerensis has been changing simultaneously with profound changes in the physics, i.e., mesopredator habitat features, of the Southern
Ocean. Although the two trends may not be related, distinguishing among the factors responsible requires a better understanding
of minke whale habitat preferences. For the first time at a large geographic scale, i.e., between 140° E and 35° W, we use
data not constrained by vessels needing to avoid sea ice to model the habitat affinities of this pagophilic mesopredator.
Using Maxent, we modeled minke whale proximity to the Antarctic Shelf Break Front (ASBF) and the southern boundary of Antarctic
Circumpolar Current (sbACC), as well as association with sea ice, given that global climate change is altering the positions
or intensity of these features. We also included water depth and chlorophyll (proxy for productivity) as variables. Minke
whale presence data were gathered using strip and line census on 55 cruises on board icebreakers during late spring and summer,
1976–2005. The most important variable was distance to ASBF, followed by water depth and sea-ice concentration. That is, found
principally in waters south of the sbACC during summer, minke whales were most abundant near the outer edge of the continental
shelf (shallow depth), including areas heavily covered by sea ice. We propose that as the sbACC moves south and sea ice disappears,
as projected by global climate models, minke whale habitat will shrink, and likely intra- and inter-specific competition will
increase. 相似文献
16.
Past and present distribution, densities and movements of blue whales Balaenoptera musculus in the Southern Hemisphere and northern Indian Ocean 总被引:3,自引:0,他引:3
T. A. BRANCH K. M. STAFFORD D. M. PALACIOS C. ALLISON J. L. BANNISTER C. L. K. BURTON E. CABRERA C. A. CARLSON B. GALLETTI VERNAZZANI P. C. GILL R. HUCKE‐GAETE K. C. S. JENNER M.‐N. M. JENNER K. MATSUOKA Y. A. MIKHALEV T. MIYASHITA M. G. MORRICE S. NISHIWAKI V. J. STURROCK D. TORMOSOV R. C. ANDERSON A. N. BAKER P. B. BEST P. BORSA R. L. BROWNELL JR S. CHILDERHOUSE K. P. FINDLAY T. GERRODETTE A. D. ILANGAKOON M. JOERGENSEN B. KAHN D. K. LJUNGBLAD B. MAUGHAN R. D. MCCAULEY S. MCKAY T. F. NORRIS S. RANKIN F. SAMARAN D. THIELE K. VAN WAEREBEEK R. M. WARNEKE 《Mammal Review》2007,37(2):116-175
- 1 Blue whale locations in the Southern Hemisphere and northern Indian Ocean were obtained from catches (303 239), sightings (4383 records of ≥8058 whales), strandings (103), Discovery marks (2191) and recoveries (95), and acoustic recordings.
- 2 Sighting surveys included 7 480 450 km of effort plus 14 676 days with unmeasured effort. Groups usually consisted of solitary whales (65.2%) or pairs (24.6%); larger feeding aggregations of unassociated individuals were only rarely observed. Sighting rates (groups per 1000 km from many platform types) varied by four orders of magnitude and were lowest in the waters of Brazil, South Africa, the eastern tropical Pacific, Antarctica and South Georgia; higher in the Subantarctic and Peru; and highest around Indonesia, Sri Lanka, Chile, southern Australia and south of Madagascar.
- 3 Blue whales avoid the oligotrophic central gyres of the Indian, Pacific and Atlantic Oceans, but are more common where phytoplankton densities are high, and where there are dynamic oceanographic processes like upwelling and frontal meandering.
- 4 Compared with historical catches, the Antarctic (‘true’) subspecies is exceedingly rare and usually concentrated closer to the summer pack ice. In summer they are found throughout the Antarctic; in winter they migrate to southern Africa (although recent sightings there are rare) and to other northerly locations (based on acoustics), although some overwinter in the Antarctic.
- 5 Pygmy blue whales are found around the Indian Ocean and from southern Australia to New Zealand. At least four groupings are evident: northern Indian Ocean, from Madagascar to the Subantarctic, Indonesia to western and southern Australia, and from New Zealand northwards to the equator. Sighting rates are typically much higher than for Antarctic blue whales.
- 6 South‐east Pacific blue whales have a discrete distribution and high sighting rates compared with the Antarctic. Further work is needed to clarify their subspecific status given their distinctive genetics, acoustics and length frequencies.
- 7 Antarctic blue whales numbered 1700 (95% Bayesian interval 860–2900) in 1996 (less than 1% of original levels), but are increasing at 7.3% per annum (95% Bayesian interval 1.4–11.6%). The status of other populations in the Southern Hemisphere and northern Indian Ocean is unknown because few abundance estimates are available, but higher recent sighting rates suggest that they are less depleted than Antarctic blue whales.
17.
Borsa P 《Comptes rendus biologies》2006,329(4):277-288
18.
Observations of cetaceans in the south-east Atlantic sector of the Southern Ocean,during summer 2008
Knowledge of cetacean species composition and their distribution in the south-east Atlantic sector of the Southern Ocean is scarce. During a survey in February–March 2008, systematic whale sightings were carried out along transect lines following the 5° and 15° E meridians between 35° and 67° S. In total, 67 toothed whales and 126 baleen whales were observed. Both fin whales (four animals) and Antarctic minke whales Balaenoptera bonaerenses (three animals) in addition to 16 individuals of unidentified species were among the observed baleen whales. The dominating baleen whale species in our study was humpback whales Megaptera novaeangliae with 108 individuals observed. They occurred single or in groups up to seven individuals (N mean = 2.5 ind) and eight of the counts were of calves. The relationship between humpback whale occurrence and environmental variables including Antarctic krill (Euphausia superba) abundance from acoustic recordings, hydrography, bathymetry and production was tested using general additive models. Only temperature increased the predictive power of the model with whale occurrence increasing with the decreasing temperature in more southern areas. 相似文献
19.
Estimation of minke whale abundance from an acoustic line transect survey of the Mariana Islands 下载免费PDF全文
Thomas F. Norris Kerry J. Dunleavy Tina M. Yack Elizabeth L. Ferguson 《Marine Mammal Science》2017,33(2):574-592
The minke whale is one of the most abundant species of baleen whales worldwide, yet is rarely sighted in subtropical waters. In the North Pacific, they produce a distinctive sound known as the “boing,” which can be used to acoustically localize individuals. A vessel‐based survey using both visual and passive acoustic monitoring was conducted during the spring of 2007 in a large (616,000 km2) study area encompassing the Mariana Islands. We applied line transect methods to data collected from a towed hydrophone array to estimate the abundance of calling minke whales in our study area. No minke whales were sighted, but there were hundreds of acoustic detections of boings. Computer algorithms were developed to localize calling minke whales from acoustic recordings, resulting in over 30 independent localizations, a six‐fold increase over those estimated during the survey. The two best estimates of abundance of calling minke whales were determined to be 80 and 91 animals (0.13 and 0.15 animals per 1,000 km2, respectively; CV = 34%). These are the first density and abundance estimates for calling minke whales using towed hydrophone array surveys, and the first estimates for this species in the Mariana Islands region. These are considered minimum estimates of the true number of minke whales in the study area. 相似文献
20.
John K. B. Ford Graeme M. Ellis Dena R. Matkin Kenneth C. Balcomb David Briggs Alexandra B. Morton 《Marine Mammal Science》2005,21(4):603-618
We describe nine incidents of predation or attempted predation of minke whales ( Balaenoptera acutorostrata ) by mammal-hunting "transient" killer whales ( Orcinus orca ) in coastal waters of British Columbia, Washington, and southeastern Alaska. Pursuits of minke whales were characterized by prolonged chases on a straight heading at velocities of 15–30 km/h. In four of the nine cases the adultsized minke whale gradually outdistanced the killer whales, which abandoned the high-speed pursuit after 0.5–1 h. In one case the minke beached itself and died. Four attacks were successful. In one instance a subadult minke was killed in open water following a chase. In two cases the fleeing minke entered a confined bay and was killed by the killer whales. One adult minke was taken after apparently attempting to seek cover beside a large sailboat. Minke whales made no attempt to physically defend themselves and were killed by repeated ramming or by asphyxiation. Although killer whales are capable of sprinting speeds greater than those of minke whales, it appears that adult minkes can maintain higher sustained speeds and evade capture if sufficient space for an extended escape trajectory is available. Successful predation of minke whales in coastal waters is rare compared to pinnipeds and small cetaceans, the main prey of transient killer whales. 相似文献