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1
Acebes, Jo Marie Vera, Joshua Neal Silberg, Timothy John Gardner, et al. "First confirmed sightings of Blue Whales Balaenoptera musculus Linnaeus, 1758 (Mammalia: Cetartiodactyla: Balaenopteridae) in the Philippines since the 19th century." Journal of Threatened Taxa 13, no. 3 (2021): 17875–88. http://dx.doi.org/10.11609/jott.6483.13.3.17875-17888.
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For over two centuries there were no records of Blue Whales Balaenoptera musculus in the Philippines. Whalers recorded Blue Whales in the Philippines in the 19th century, and the next confirmed sighting in the country was of a mother and calf in 2004. Since then 33 subsequent Blue Whale sightings of potentially one individual were recorded between 2004 and 2019, all within the central region of the Philippines around the Bohol Sea. This individual, recognized through photo-identification, was sighted on at least 13 occasions during eight different years: 2010, 2011, 2012, 2015, 2016, 2017, 2018, and 2019. The geographic location and timing of the sightings (January to July) suggest that Blue Whales in the Philippines may extend the outer range edge of the Indo-Australian population that migrate between western Australia, Indonesia, and East Timor. Blue Whale sightings in the Bohol Sea coincide with times of high ocean productivity, although further investigation is needed to determine if they are actually feeding in this region. Acoustic studies and photo-identification matching with other Blue Whale catalogues will clarify the stock identity of Blue Whales in the Philippines and their relation to the rest of the Blue Whale population, with implications for the conservation of this endangered species across multiple jurisdictions.
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Torres, Leigh G., Dawn R. Barlow, Todd E. Chandler, and Jonathan D. Burnett. "Insight into the kinematics of blue whale surface foraging through drone observations and prey data." PeerJ 8 (April 22, 2020): e8906. http://dx.doi.org/10.7717/peerj.8906.
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To understand how predators optimize foraging strategies, extensive knowledge of predator behavior and prey distribution is needed. Blue whales employ an energetically demanding lunge feeding method that requires the whales to selectively feed where energetic gain exceeds energetic loss, while also balancing oxygen consumption, breath holding capacity, and surface recuperation time. Hence, blue whale foraging behavior is primarily driven by krill patch density and depth, but many studies have not fully considered surface feeding as a significant foraging strategy in energetic models. We collected predator and prey data on a blue whale (Balaenoptera musculus brevicauda) foraging ground in New Zealand in February 2017 to assess the distributional and behavioral response of blue whales to the distribution and density of krill prey aggregations. Krill density across the study region was greater toward the surface (upper 20 m), and blue whales were encountered where prey was relatively shallow and more dense. This relationship was particularly evident where foraging and surface lunge feeding were observed. Furthermore, New Zealand blue whales also had relatively short dive times (2.83 ± 0.27 SE min) as compared to other blue whale populations, which became even shorter at foraging sightings and where surface lunge feeding was observed. Using an unmanned aerial system (UAS; drone) we also captured unique video of a New Zealand blue whale’s surface feeding behavior on well-illuminated krill patches. Video analysis illustrates the whale’s potential use of vision to target prey, make foraging decisions, and orient body mechanics relative to prey patch characteristics. Kinematic analysis of a surface lunge feeding event revealed biomechanical coordination through speed, acceleration, head inclination, roll, and distance from krill patch to maximize prey engulfment. We compared these lunge kinematics to data previously reported from tagged blue whale lunges at depth to demonstrate strong similarities, and provide rare measurements of gape size, and krill response distance and time. These findings elucidate the predator-prey relationship between blue whales and krill, and provide support for the hypothesis that surface feeding by New Zealand blue whales is an important component to their foraging ecology used to optimize their energetic efficiency. Understanding how blue whales make foraging decisions presents logistical challenges, which may cause incomplete sampling and biased ecological knowledge if portions of their foraging behavior are undocumented. We conclude that surface foraging could be an important strategy for blue whales, and integration of UAS with tag-based studies may expand our understanding of their foraging ecology by examining surface feeding events in conjunction with behaviors at depth.
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Calderan, SV, A. Black, TA Branch, et al. "South Georgia blue whales five decades after the end of whaling." Endangered Species Research 43 (November 19, 2020): 359–73. http://dx.doi.org/10.3354/esr01077.
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Blue whales Balaenoptera musculus at South Georgia were heavily exploited during 20th century industrial whaling, to the point of local near-extirpation. Although legal whaling for blue whales ceased in the 1960s, and there were indications of blue whale recovery across the wider Southern Ocean area, blue whales were seldom seen in South Georgia waters in subsequent years. We collated 30 yr of data comprising opportunistic sightings, systematic visual and acoustic surveys and photo-identification to assess the current distribution of blue whales in the waters surrounding South Georgia. Over 34000 km of systematic survey data between 1998 and 2018 resulted in only a single blue whale sighting, although opportunistic sightings were reported over that time period. However, since 2018 there have been increases in both sightings of blue whales and detections of their vocalisations. A survey in 2020 comprising visual line transect surveys and directional frequency analysis and recording (DIFAR) sonobuoy deployments resulted in 58 blue whale sightings from 2430 km of visual effort, including the photo-identification of 23 individual blue whales. Blue whale vocalisations were detected on all 31 sonobuoys deployed (114 h). In total, 41 blue whales were photo-identified from South Georgia between 2011 and 2020, none of which matched the 517 whales in the current Antarctic catalogue. These recent data suggest that blue whales have started to return to South Georgia waters, but continued visual and acoustic surveys are required to monitor any future changes in their distribution and abundance.
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Shabangu, FW, RK Andrew, D. Yemane, and KP Findlay. "Acoustic seasonality, behaviour and detection ranges of Antarctic blue and fin whales under different sea ice conditions off Antarctica." Endangered Species Research 43 (September 3, 2020): 21–37. http://dx.doi.org/10.3354/esr01050.
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Descriptions of seasonal occurrence and behaviour of Antarctic blue and fin whales in the Southern Ocean are of pivotal importance for the effective conservation and management of these endangered species. We used an autonomous acoustic recorder to collect bioacoustic data from January through September 2014 to describe the seasonal occurrence, behaviour and detection ranges of Antarctic blue and fin whale calls off the Maud Rise, Antarctica. From 2479 h of recordings, we detected D- and Z-calls plus the 27 Hz chorus of blue whales, the 20 and 99 Hz pulses of fin whales and the 18-28 Hz chorus of blue and fin whales. Blue whale calls were detected throughout the hydrophone deployment period with a peak occurrence in February, indicating continuous presence of whales in a broad Southern Ocean area (given the modelled detection ranges). Fin whale calls were detected from January through July when sea ice was present on the latter dates. No temporal segregation in peaks of diel calling rates of blue and fin whales was observed in autumn, but a clear temporal segregation was apparent in summer. Acoustic propagation models suggest that blue and fin whale calls can be heard as far as 1700 km from the hydrophone position in spring. Random forest models ranked month of the year as the most important predictor of call occurrence and call rates (i.e. behaviour) for these whales. Our work highlights areas around the Maud Rise as important habitats for blue and fin whales in the Southern Ocean.
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Goldbogen, Jeremy A., John Calambokidis, Ari S. Friedlaender, et al. "Underwater acrobatics by the world's largest predator: 360° rolling manoeuvres by lunge-feeding blue whales." Biology Letters 9, no. 1 (2013): 20120986. http://dx.doi.org/10.1098/rsbl.2012.0986.
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The extreme body size of blue whales requires a high energy intake and therefore demands efficient foraging strategies. As an obligate lunge feeder on aggregations of small zooplankton, blue whales engulf a large volume of prey-laden water in a single, rapid gulp. The efficiency of this feeding mechanism is strongly dependent on the amount of prey that can be captured during each lunge, yet food resources tend to be patchily distributed in both space and time. Here, we measured the three-dimensional kinematics and foraging behaviour of blue whales feeding on krill, using suction-cup attached multi-sensor tags. Our analyses revealed 360° rolling lunge-feeding manoeuvres that reorient the body and position the lower jaws so that a krill patch can be engulfed with the whale's body inverted. We also recorded these rolling behaviours when whales were in a searching mode in between lunges, suggesting that this behaviour also enables the whale to visually process the prey field and maximize foraging efficiency by surveying for the densest prey aggregations. These results reveal the complex manoeuvrability that is required for large rorqual whales to exploit prey patches and highlight the need to fully understand the three-dimensional interactions between predator and prey in the natural environment.
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Leslie, MS, CM Perkins-Taylor, JW Durban, et al. "Body size data collected non-invasively from drone images indicate a morphologically distinct Chilean blue whale (Balaenoptera musculus) taxon." Endangered Species Research 43 (November 5, 2020): 291–304. http://dx.doi.org/10.3354/esr01066.
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The blue whale Balaenoptera musculus (Linnaeus, 1758) was the target of intense commercial whaling in the 20th century, and current populations remain drastically below pre-whaling abundances. Reducing uncertainty in subspecific taxonomy would enable targeted conservation strategies for the recovery of unique intraspecific diversity. Currently, there are 2 named blue whale subspecies in the temperate to polar Southern Hemisphere: the Antarctic blue whale B. m. intermedia and the pygmy blue whale B. m. brevicauda. These subspecies have distinct morphologies, genetics, and acoustics. In 2019, the Society for Marine Mammalogy’s Committee on Taxonomy agreed that evidence supports a third (and presently unnamed) subspecies of Southern Hemisphere blue whale subspecies, the Chilean blue whale. Whaling data indicate that the Chilean blue whale is intermediate in body length between pygmy and Antarctic blue whales. We collected body size data from blue whales in the Gulfo Corcovado, Chile, during the austral summers of 2015 and 2017 using aerial photogrammetry from a remotely controlled drone to test the hypothesis that the Chilean blue whale is morphologically distinct from other Southern Hemisphere blue whale subspecies. We found the Chilean whale to be morphologically intermediate in both overall body length and relative tail length, thereby joining other diverse data in supporting the Chilean blue whale as a unique subspecific taxon. Additional photogrammetry studies of Antarctic, pygmy, and Chilean blue whales will help examine unique morphological variation within this species of conservation concern. To our knowledge, this is the first non-invasive small drone study to test a hypothesis for systematic biology.
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Acevedo-Gutiérrez, A., D. A. Croll, and B. R. Tershy. "High feeding costs limit dive time in the largest whales." Journal of Experimental Biology 205, no. 12 (2002): 1747–53. http://dx.doi.org/10.1242/jeb.205.12.1747.
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SUMMARY Large body size usually extends dive duration in air-breathing vertebrates. However, the two largest predators on earth, the blue whale (Balaenoptera musculus) and the fin whale (B. physalus), perform short dives for their size. Here, we test the hypothesis that the foraging behavior of these two species (lunge-feeding) is energetically expensive and limits their dive duration. We estimated the cost of lunge-feeding in both species using an approach that combined attaching time/depth recorders to seven blue whales and eight fin whales and comparing the collected dive information with predictions made by optimality models of dive behavior. We show that the rate at which whales recovered from a foraging dive was twice that of a non-foraging dive and that the cost of foraging relative to the cost of travel to and from the prey patch was 3.15 in blue whales (95 % CI 2.58-3.72) and 3.60 in fin whales(95 % CI 2.35-4.85). Whales foraged in small areas (<1 km2) and foraging bouts lasted more than one dive, indicating that prey did not disperse and thus that prey dispersal could not account for the limited dive durations of the whales. Despite the enormous size of blue whales and fin whales, the high energetic costs of lunge-feeding confine them to short durations of submergence and to areas with dense prey aggregations. As a corollary, because of their limited foraging time under water, these whales may be particularly vulnerable to perturbations in prey abundance.
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Calambokidis, John, Greg S. Schorr, Gretchen H. Steiger, et al. "Insights into the Underwater Diving, Feeding, and Calling Behavior of Blue Whales from a Suction-Cup-Attached Video-Imaging Tag (Crittercam)." Marine Technology Society Journal 41, no. 4 (2007): 19–29. http://dx.doi.org/10.4031/002533207787441980.
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We examined the underwater behavior of blue whales using a suction-cup-attached video-imaging instrument (Crittercam). We made 13 successful deployments (defined as tag duration of >15 min and successful recovery of the tag and data) totaling 19 hours of Crittercams on blue whales off California and in the Sea of Cortez from spring through fall (26 February to 30 September) between 1999 and 2003. Whale diving depth and behavior varied widely by region and period, although deployments on different individuals in the same area and period often showed very similar feeding behavior. One deployment extending into night showed a diurnal shift in diving behavior with progressively shallower feeding dives as it became dark, with shift to shallow, apparently non-feeding dives during the night. Data and video from tags demonstrated that the characteristic series of vertical movements blue whales make at depth are lunges into dense aggregations of krill. These krill were visible streaming by the camera immediately before these lunges and more clearly when the whales' forward motion stopped as a result of the lunge. The progression of events leading up to and during the lunge could be documented from the head movement of whales and occasional views of the expanding throat pleats or lower jaw, and by changes in flow noise past the tag, indicating a rapid deceleration. One set of deployments in the Southern California Bight revealed consistent feeding at depths of 250-300 m, deeper than has been previously reported for blue whales. A loud blue whale vocalization was heard on only one deployment on a male blue whale in an interacting trio of animals.
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Schoenherr, Jill R. "Blue whales feeding on high concentrations of euphausiids around Monterey Submarine Canyon." Canadian Journal of Zoology 69, no. 3 (1991): 583–94. http://dx.doi.org/10.1139/z91-088.
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An unusually high concentration of blue whales, Balaenoptera musculus, fed on euphausiids that were concentrated in deep scattering layers and daytime surface swarms in Monterey Bay, California, during the fall of 1986. Blue whales were closely associated with deep scattering layers that were elongated along the southeast edge of the Monterey Submarine Canyon throughout most of November 1986. These scattering layers contained euphausiids, primarily Thysanoessa spinifera, which accounted for 45.4% of the total biomass of zooplankton tows taken through deep scattering layers. Tows taken above or outside the layers consisted of only 4.0% euphausiids. The greatest concentrations of blue whales were observed in areas of thick scattering layers that contained high krill biomass. In addition, surface-lunging blue whales fed on daytime surface swarms of Thysanoessa spinifera near the head of Monterey Submarine Canyon on 11 and 12 November 1986. Surface tows taken in whale feeding areas were dominated by T. spinifera, which accounted for 64.4% of the total zooplankton biomass, while surface tows taken outside whale areas consisted of only 0.3% euphausiids. Euphausiid densities in surface swarms were slightly higher and more variable than in deep layers. Thysanoessa spinifera size frequency distributions showed that surface swarms may be similar to the deep layer in some areas, but they may contain larger, sexually mature individuals in other areas. Blue whale fecal samples confirmed that the whales were feeding on euphausiids. The disappearance of the blue whales from Monterey Bay was accompanied by a decline in krill biomass along the southeast edge of the submarine canyon. This coincided with the cessation of a prolonged upwelling period that persisted in Monterey Bay throughout November 1986.
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Silva, Mónica A., Asunción Borrell, Rui Prieto, et al. "Stable isotopes reveal winter feeding in different habitats in blue, fin and sei whales migrating through the Azores." Royal Society Open Science 6, no. 8 (2019): 181800. http://dx.doi.org/10.1098/rsos.181800.
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Knowing the migratory movements and behaviour of baleen whales is fundamental to understanding their ecology. We compared δ 15 N and δ 13 C values in the skin of blue ( Balaenoptera musculus ), fin ( Balaenoptera physalus ) and sei ( Balaenoptera borealis ) whales sighted in the Azores in spring with the values of potential prey from different regions within the North Atlantic using Bayesian mixing models to investigate their trophic ecology and migration patterns. Fin whale δ 15 N values were higher than those recorded in blue and sei whales, reflecting feeding at higher trophic levels. Whales' skin δ 15 N and δ 13 C values did not reflect prey from high-latitude summer foraging grounds; instead mixing models identified tropical or subtropical regions as the most likely feeding areas for all species during winter and spring. Yet, differences in δ 13 C values among whale species suggest use of different regions within this range. Blue and sei whales primarily used resources from the Northwest African upwelling and pelagic tropical/subtropical regions, while fin whales fed off Iberia. However, determining feeding habitats from stable isotope values remains difficult. In conclusion, winter feeding appears common among North Atlantic blue, fin and sei whales, and may play a crucial role in determining their winter distribution. A better understanding of winter feeding behaviour is therefore fundamental for the effective conservation of these species.
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Goldbogen, Jeremy. "Blue whales." Current Biology 30, no. 23 (2020): R1399—R1400. http://dx.doi.org/10.1016/j.cub.2020.10.068.
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Ahonen, H., KM Stafford, C. Lydersen, CL Berchok, SE Moore, and KM Kovacs. "Interannual variability in acoustic detection of blue and fin whale calls in the Northeast Atlantic High Arctic between 2008 and 2018." Endangered Species Research 45 (July 15, 2021): 209–24. http://dx.doi.org/10.3354/esr01132.
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Northern Hemisphere blue and fin whales are regular summer migrants to Arctic waters. Given the profound changes the Arctic is currently undergoing due to global warming, changes in habitat use and distribution of these migratory species are predicted. In this study, 3 passive acoustic recorders, 2 in Fram Strait about 95 km apart and 1 north of the Svalbard Archipelago (Atwain), were used to investigate the spatial and temporal vocal occurrence of these species in the Northeast Atlantic High Arctic. Acoustic data were available for 7 years for western Fram Strait (WFS), 2.5 years for central Fram Strait (CFS) and 3 years for Atwain. At both Fram Strait locations, most blue whale call detections occurred from August through October, though recently (2015-2018) in WFS a clear increase in blue whale call rates was detected in June/July, suggesting an expansion of the seasonal occurrence of blue whales. In WFS, fin whale calls were detected intermittently, at low levels, almost year-round. In CFS, fin whale calls were more frequent but occurred mainly from July through December. At Atwain, blue whale detections commenced in July, both species were recorded in September/October and fin whale calls extended into November. Results from this study provide novel long-term baseline information about the occurrence of blue and fin whales at extreme northerly locations, where traditional ship-based survey methods are seasonally limited. Continued sampling will support investigation of how environmental change influences cetacean distribution and habitat use.
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Anderson, R. C., and A. Alagiyawadu. "Observations of cetaceans off southern Sri Lanka, April 2007–2013." IWC Journal of Cetacean Research and Management 20, no. 1 (2019): 13–25. http://dx.doi.org/10.47536/jcrm.v20i1.236.
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Cetaceans were observed off the South coast of Sri Lanka in the month of April, every year over a seven-year period, 2007–13. During 48 days atsea a total of 290 cetacean sightings were recorded. Blue whales were abundant, accounting for 61% (n = 177) of all sightings. This concentrationof blue whales was predicted and discovered based on a migration hypothesis and there was evidence of the expected net westward movement inApril. Nevertheless, most blue whales seen were not obviously on passage and many appeared to be feeding. Mothers with calves and likelyreproductive behaviour (breaching and rushing) were also observed. There were five sightings of Bryde’s-type whales (B. brydei/edeni); four wereidentified as B. brydei, one was identified as B. edeni. Sperm whales were sighted 16 times within a narrow band centred just outside the 1,000misobath. Modal group size was 10–12; based on size most individuals appeared to be mature females or immatures. Spinner dolphin (n = 35 sightings)was the most abundant species, accounting for 67% of all cetaceans seen by number of individuals. They were frequently associated with tuna andseabirds. Risso’s dolphin was only seen once, despite being reported as common around Sri Lanka in the early 1980s. They were taken in largenumbers by local fisheries, which may have reduced local abundance. Other species recorded were: dwarf sperm whale (n = 3 sightings); shortfinnedpilot whale (n = 3); common bottlenose dolphin (n = 9); Indo-Pacific bottlenose dolphin (n = 3); pantropical spotted dolphin (n = 4); andstriped dolphin (n = 4). Since the discovery of blue whales off southern Sri Lanka, commercial whale watching centred on the fishing port of Mirissahas developed rapidly, bringing new revenue to the region but also the potential for disturbance to the whales.
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Gregr, Edward J., and Andrew W. Trites. "Predictions of critical habitat for five whale species in the waters of coastal British Columbia." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 7 (2001): 1265–85. http://dx.doi.org/10.1139/f01-078.
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Whaling records from British Columbia coastal whaling stations reliably report the positions of 9592 whales killed between 1948 and 1967. We used this positional information and oceanographic data (bathymetry, temperature, and salinity) to predict critical habitat off the coast of British Columbia for sperm (Physeter macrocephalus), sei (Balaenoptera borealis), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae), and blue (Balaenoptera musculus) whales. We used generalized linear models at annual and monthly time scales to relate whale occurrence to six predictor variables (month, depth, slope, depth class, and sea surface temperature and salinity). The models showed critical habitat for sei, fin, and male sperm whales along the continental slope and over a large area off the northwest coast of Vancouver Island. Habitat models for blue, humpback, and female sperm whales were relatively insensitive to the predictor variables, owing partially to the smaller sample sizes for these groups. The habitat predictions lend support to recent hypotheses about sperm whale breeding off British Columbia and identify humpback whale habitat in sheltered bays and straits throughout the coast. The habitat models also provide insights about the nature of the linkages between the environment and the distribution of whales in the North Pacific Ocean.
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Gavrishev, A. A. "ON THE EVALUATION OF THE CREST FACTOR OF BIONIC SIGNALS USED IN HYDROACOUSTIC COMMUNICATION SYSTEMS." NAUCHNOE PRIBOROSTROENIE 31, no. 3 (2021): 37–45. http://dx.doi.org/10.18358/np-31-3-i3745.
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In this article, the authors evaluated the crest factor of bionic signals used in hydroacoustic communication systems, using the example of the study of signals based on the use of recordings of sounds of various whale species. The calculations and literature analysis show that the sound recordings of the following whale species have an acceptable crest factor value (p ≤ 4): Blue whale, Alaska humpback whale, Atlantic blue whale and Northeast Pacific blue whale. Recordings of the sounds of these types of whales should be used in the appropriate hydroacoustic communication systems. In contrast, recordings of the sounds of such whale species as Atlantic fin whale, Atlantic minke whale, South Pacific blue whale, and Western Pacific blue whale have an increased crest factor value (p > 4) and without adaptation, it is impractical to use them in appropriate hydroacousticcommunication systems. It is established that bionic signals used in hydroacoustic communication systems, based on the example of the study of signals based on the use of recordings of sounds of various species of whales, can have both an acceptable value of the crest factor or an increased one. It is advisable to pay attention of the de-velopers and manufacturers of the corresponding hydroacoustic communication systems to this conclusion during designing, testing and implementation of such systems.
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Edds, Peggy L., and J. Andrew F. Macfarlane. "Occurrence and general behavior of balaenopterid cetaceans summering in the St. Lawrence Estuary, Canada." Canadian Journal of Zoology 65, no. 6 (1987): 1363–76. http://dx.doi.org/10.1139/z87-216.
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Baleen whale movements were monitored from a hillside on the north shore of the St. Lawrence Estuary from 28 June to 27 September 1979. No diurnal or tidal relationships were apparent for the two most abundant species, the minke and finback. Single minke whales were seen almost daily. Adult pairs were only seen on four dates, and no adult-calf pairs were observed. Twenty-two small minkes were observed; three were possibly 1st-year calves. Finbacks occurred singly and in groups, particularly later in the field season. Resightings of distinctive finbacks indicate that adult pairings are temporary. One finback had been seen in the area in 1973–1975. Adult–calf pairs and seven single juveniles were also seen. Observations of finbacks pursued by whale watchers provide evidence that some regulation of the rapidly growing whale-watching industry may be warranted. Blue whales and humpback whales were seen far less frequently than minkes and finbacks. The relative abundances of minke, finback, and humpback were similar to 1973–1974 in the same area: however, blue whales were seen far more frequently in the past.
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Hucke-Gaete, Rodrigo, Luis Bedriñana-Romano, Francisco A. Viddi, Jorge E. Ruiz, Juan Pablo Torres-Florez, and Alexandre N. Zerbini. "From Chilean Patagonia to Galapagos, Ecuador: novel insights on blue whale migratory pathways along the Eastern South Pacific." PeerJ 6 (April 30, 2018): e4695. http://dx.doi.org/10.7717/peerj.4695.
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Background The most traditional scheme for migration among baleen whales comprises yearly migrations between productive waters at high latitude summer feeding grounds and warmer waters at lower latitudes where whales calve and mate, but rarely feed. Evidence indicates, however, that large departures from this scheme exist among populations and individuals. Furthermore, for some populations there is virtually no information on migratory pathways and destinations. Such is the case of Chilean blue whales throughout the Eastern South Pacific; hence, the goal of this study was to assess its migratory behavior. Methods Dedicated marine surveys and satellite tagging efforts were undertaken during the austral summer and early autumn on blue whale feeding grounds off Chilean Northern Patagonia (CNP) during 2013, 2015 and 2016. Positional data derived from satellite tags regarding movement patterns and behavior were analyzed using Bayesian switching first-difference correlated random walk models. Results We instrumented 10 CNP blue whales with satellite transmitters and documented individual variation in departure time, northbound migratory routes and potential wintering grounds. The onset of migration occurred from mid/late austral autumn to well into the austral winter. Blue whales moved in various directions, but ultimately converged toward a general NW movement direction along a wide corridor exceeding 2,000 km. Area-Restricted Search behavior was exhibited within fjords and channels of CNP and also South of Galapagos Archipelago (GA) and northern Peru, but never during migration. Interestingly, dive profiles for one whale that reached GA showed a sharp and consistent increase in depth north of 5°S and extreme deep dives of up to 330 m. Discussion Information derived from satellite tagged blue whales in this study is the first of its kind off the Eastern Southern Pacific. Our results provide valuable information on their migratory timing, routes and behavior on their northbound migration, particularly regarding the varied migratory plasticity for this particular population. Our results also highlight the first record of two complete migratory paths between CNP and GA and strengthen the hypothesis that GA waters correspond to a potential wintering destination for CNP blue whales. We further hypothesize that this area might be selected because of its biological productivity, which could provide feeding opportunities during the breeding season. Our results suggest that special efforts should be put forward to identify blue whale critical areas and understand key behavioral aspects in order to provide the basis for their conservation on a regional context (i.e., reducing potential ship strike and promote Marine Protected Area (MPA) implementation in Chile, Ecuador and Peru). Indeed, we suggest joint blue whale conservation efforts at the regional level in order to identify and determine potential threats and impacts and, most importantly, implement prospective management actions.
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Goldbogen, Jeremy A., Brandon L. Southall, Stacy L. DeRuiter, et al. "Blue whales respond to simulated mid-frequency military sonar." Proceedings of the Royal Society B: Biological Sciences 280, no. 1765 (2013): 20130657. http://dx.doi.org/10.1098/rspb.2013.0657.
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Mid-frequency military (1–10 kHz) sonars have been associated with lethal mass strandings of deep-diving toothed whales, but the effects on endangered baleen whale species are virtually unknown. Here, we used controlled exposure experiments with simulated military sonar and other mid-frequency sounds to measure behavioural responses of tagged blue whales ( Balaenoptera musculus ) in feeding areas within the Southern California Bight. Despite using source levels orders of magnitude below some operational military systems, our results demonstrate that mid-frequency sound can significantly affect blue whale behaviour, especially during deep feeding modes. When a response occurred, behavioural changes varied widely from cessation of deep feeding to increased swimming speed and directed travel away from the sound source. The variability of these behavioural responses was largely influenced by a complex interaction of behavioural state, the type of mid-frequency sound and received sound level. Sonar-induced disruption of feeding and displacement from high-quality prey patches could have significant and previously undocumented impacts on baleen whale foraging ecology, individual fitness and population health.
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Flammang, Brooke E., Simone Marras, Erik J. Anderson, et al. "Remoras pick where they stick on blue whales." Journal of Experimental Biology 223, no. 20 (2020): jeb226654. http://dx.doi.org/10.1242/jeb.226654.
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ABSTRACTAnimal-borne video recordings from blue whales in the open ocean show that remoras preferentially adhere to specific regions on the surface of the whale. Using empirical and computational fluid dynamics analyses, we show that remora attachment was specific to regions of separating flow and wakes caused by surface features on the whale. Adhesion at these locations offers remoras drag reduction of up to 71–84% compared with the freestream. Remoras were observed to move freely along the surface of the whale using skimming and sliding behaviors. Skimming provided drag reduction as high as 50–72% at some locations for some remora sizes, but little to none was available in regions where few to no remoras were observed. Experimental work suggests that the Venturi effect may help remoras stay near the whale while skimming. Understanding the flow environment around a swimming blue whale will inform the placement of biosensor tags to increase attachment time for extended ecological monitoring.
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Di Iorio, Lucia, and Christopher W. Clark. "Exposure to seismic survey alters blue whale acoustic communication." Biology Letters 6, no. 1 (2009): 51–54. http://dx.doi.org/10.1098/rsbl.2009.0651.
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The ability to perceive biologically important sounds is critical to marine mammals, and acoustic disturbance through human-generated noise can interfere with their natural functions. Sounds from seismic surveys are intense and have peak frequency bands overlapping those used by baleen whales, but evidence of interference with baleen whale acoustic communication is sparse. Here we investigated whether blue whales ( Balaenoptera musculus ) changed their vocal behaviour during a seismic survey that deployed a low-medium power technology (sparker). We found that blue whales called consistently more on seismic exploration days than on non-exploration days as well as during periods within a seismic survey day when the sparker was operating. This increase was observed for the discrete, audible calls that are emitted during social encounters and feeding. This response presumably represents a compensatory behaviour to the elevated ambient noise from seismic survey operations.
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Ingman, Kaytlin, Ellen Hines, Piero L. F. Mazzini, R. Cotton Rockwood, Nadav Nur, and Jaime Jahncke. "Modeling changes in baleen whale seasonal abundance, timing of migration, and environmental variables to explain the sudden rise in entanglements in California." PLOS ONE 16, no. 4 (2021): e0248557. http://dx.doi.org/10.1371/journal.pone.0248557.
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We document changes in the number of sightings and timing of humpback (Megaptera novaeangliae), blue (Balaenoptera musculus), and gray (Eschrichtius robustus) whale migratory phases in the vicinity of the Farallon Islands, California. We hypothesized that changes in the timing of migration off central California were driven by local oceanography, regional upwelling, and basin-scale climate conditions. Using 24 years of daily whale counts collected from Southeast Farallon Island, we developed negative binomial regression models to evaluate trends in local whale sightings over time. We then used linear models to assess trends in the timing of migration, and to identify potential environmental drivers. These drivers included local, regional and basin-scale patterns; the latter included the El Niño Southern Oscillation, the Pacific Decadal Oscillation, and the North Pacific Gyre Oscillation, which influence, wind-driven upwelling, and overall productivity in the California Current System. We then created a forecast model to predict the timing of migration. Humpback whale sightings significantly increased over the study period, but blue and gray whale counts did not, though there was variability across the time series. Date of breeding migration (departure) for all species showed little to no change, whereas date of migration towards feeding areas (arrival) occurred earlier for humpback and blue whales. Timing was significantly influenced by a mix of local oceanography, regional, and basin-scale climate variables. Earlier arrival time without concomitant earlier departure time results in longer periods when blue and humpback whales are at risk of entanglement in the Gulf of the Farallones. We maintain that these changes have increased whale exposure to pot and trap fishery gear off the central California coast during the spring, elevating the risk of entanglements. Humpback entanglement rates were significantly associated with increased counts and early arrival in central California. Actions to decrease the temporal overlap between whales and pot/trap fishing gear, particularly when whales arrive earlier in warm water years, would likely decrease the risk of entanglements.
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Rockwood, RC, J. Adams, G. Silber, and J. Jahncke. "Estimating effectiveness of speed reduction measures for decreasing whale-strike mortality in a high-risk region." Endangered Species Research 43 (September 24, 2020): 145–66. http://dx.doi.org/10.3354/esr01056.
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Recent estimates of blue (Balaenoptera musculus) and humpback (Megaptera novaeangliae) whale ship-strike deaths on the US west coast are above the Potential Biological Removal limit determined by the National Marine Fisheries Service. Beginning in 2015, the National Oceanographic and Atmospheric Administration requested voluntary Vessel Speed Reductions (VSR) in the designated shipping routes off San Francisco, California, USA, in order to decrease whale mortality from ship strikes. We applied a ship strike model based on whale density and Automatic Identification System (AIS) vessel data. We bootstrapped speeds from vessels that transited when no VSR was in place to assess the effect of the VSR on strike mortality rates. Finally, we calculated the expected mortality for hypothetical compliance scenarios by programmatically imposing speed caps. Average predicted mortality for the region was 2.7 blue whales and 7.0 humpback whales in a 4 month period. Compared to years prior to the VSR (2012-2014), vessel speeds during the VSR were slower. This lowered blue whale deaths within the shipping lanes by 11-13% and humpback whale deaths by 9-10% in 2016-2017. If 95% of mariners adhered to recommended 10 knot (kn) limits in the shipping lanes alone, we predicted twice as many blue whale and 3 times as many humpback whale deaths would be avoided relative to current adherence. Adding a 10 kn speed limit (with 95% cooperation) at the ends of each of the lanes would result in about 5- and 4-fold reductions in blue whale and humpback whale mortality, respectively, relative to current practices. Our approach can evaluate ship strikes and mitigation measures for whale populations around the globe.
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Solvang, Hiroko K., Tore Haug, Tor Knutsen, et al. "Distribution of rorquals and Atlantic cod in relation to their prey in the Norwegian high Arctic." Polar Biology 44, no. 4 (2021): 761–82. http://dx.doi.org/10.1007/s00300-021-02835-2.
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AbstractRecent warming in the Barents Sea has led to changes in the spatial distribution of both zooplankton and fish, with boreal communities expanding northwards. A similar northward expansion has been observed in several rorqual species that migrate into northern waters to take advantage of high summer productivity, hence feeding opportunities. Based on ecosystem surveys conducted during August–September in 2014–2017, we investigated the spatial associations among the three rorqual species of blue, fin, and common minke whales, the predatory fish Atlantic cod, and their main prey groups (zooplankton, 0-group fish, Atlantic cod, and capelin) in Arctic Ocean waters to the west and north of Svalbard. During the surveys, whale sightings were recorded by dedicated whale observers on the bridge of the vessel, whereas the distribution and abundance of cod and prey species were assessed using trawling and acoustic methods. Based on existing knowledge on the dive habits of these rorquals, we divided our analyses into two depth regions: the upper 200 m of the water column and waters below 200 m. Since humpback whales were absent in the area in 2016 and 2017, they were not included in the subsequent analyses of spatial association. No association or spatial overlap between fin and blue whales and any of the prey species investigated was found, while associations and overlaps were found between minke whales and zooplankton/0-group fish in the upper 200 m and between minke whales and Atlantic cod at depths below 200 m. A prey detection range of more than 10 km was suggested for minke whales in the upper water layers.
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Thums, Michele, Luciana C. Ferreira, Curt Jenner, et al. "Understanding pygmy blue whale movement and distribution off north Western Australia." APPEA Journal 61, no. 2 (2021): 505. http://dx.doi.org/10.1071/aj20202.
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The blue whale (Balaenoptera musculus) is a listed endangered species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. A distinct population of blue whales, the eastern Indian Ocean pygmy blue (EIOPB) whale, migrates along the Western Australian coast to the Banda Sea in Indonesia. Their distribution and the delineation of biologically important areas (BIAs) in the north west marine region of the Australian coast are based on limited data with two possible foraging areas identified in the Blue Whale Conservation Management Plan – off Ningaloo and Scott Reef. This uncertainty is a problem because effective management of the many anthropogenic activities associated with industrial development in this area (e.g. oil and gas, commercial shipping and fishing) relies on robust data. To this end, we combined new satellite tag deployments on EIOPB whales off Ningaloo Reef with existing satellite tracking data to provide sufficient data to understand the spatial and temporal extent of the population’s distribution and the movement behaviour in the north west. We also deployed passive acoustic instruments at North West Cape and combined these with existing passive acoustic data from the north west, including 18 deployed instruments and 14 ocean bottom seismometers (OBSs). To fill data gaps in our understanding of EIOPB whale broad scale distribution on their northern and southern migration, we undertook three passive acoustic surveys using ocean gliders, thereby providing extensive spatial coverage across the north west.
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Menze, Sebastian, Daniel P. Zitterbart, Ilse van Opzeeland, and Olaf Boebel. "The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound." Royal Society Open Science 4, no. 1 (2017): 160370. http://dx.doi.org/10.1098/rsos.160370.
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This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales ( Balaenoptera musculus intermedia ), fin whales ( Balaenoptera physalus ), Antarctic minke whales ( Balaenoptera bonaerensis ) and leopard seals ( Hydrurga leptonyx ). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.
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Simard, Peter, Jennifer L. Lawlor, and Shannon Gowans. "Temporal Variability of Cetaceans near Halifax, Nova Scotia." Canadian Field-Naturalist 120, no. 1 (2006): 93. http://dx.doi.org/10.22621/cfn.v120i1.252.
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Annual and seasonal trends in sightings of coastal cetaceans near Halifax, Nova Scotia, were studied using observations from whale watching and dedicated research vessels from late spring to early fall of 1996 to 2005. Four species of cetaceans routinely used the area during the summer: White-beaked and Atlantic White-sided dolphins (Lagenorhynchus albirostris and L. acutus), Harbour Porpoises (Phocoena phocoena), and Minke Whales (Balaenoptera acutorostrata). The dolphin species were temporally separated, with White-beaked Dolphins being common earlier in the summer than White-sided Dolphins. White-sided Dolphins were unusually abundant in 1997, and were found in larger groups (mean = 46.5 ± 46.19 sd) than Whitebeaked Dolphins (mean = 9.1 ± 5.19 SD). The area also appears to be an important habitat for dolphin calves and juveniles of both species. Fin Whales (B. physalus) were commonly observed in relatively large groups in 1997, but were uncommon or absent in other years. Humpback Whales (Megaptera novaeangliae), Blue Whales (B. musculus) and North Atlantic Right Whales (Eubalaena glacialis) were uncommon in the area, although Humpback Whales were sighted frequently in 1997. Increased numbers of White-sided Dolphins, Fin and Humpback whales in 1997 may be explained by increased prey abundance and decreased sea-surface temperatures.
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Nanayakkara, Ranil P., and H. M. J. C. B. Herath. "Report on 14 Large Whales That Died due to Ship Strikes off the Coast of Sri Lanka, 2010–2014." Journal of Marine Biology 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/6235398.
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The greatest threat to cetaceans in Sri Lankan waters was considered to be the direct take of small- and medium-sized cetaceans using harpoons and/or as bycatch until recently. However, ship strikes have probably been occurring for years but have not been recognized for what they were. For the current study, only animals with visible and prominent injuries related to collisions were evaluated. Data gathered between 2010 and 2014 included the species, morphometry, location, and date; tissue samples were collected for genetic analysis. When possible, a complete necropsy was conducted; otherwise, partial necropsies were conducted. The study confirmed 14 reports of ship strikes between whales and vessels out of all the strandings reported from 2010 to 2014. Most strikes (n=09, 64%) involved blue whales (Balaenoptera musculus), although three other species were also documented, one Cuvier’s beaked whale, two great sperm whales, and one Bryde’s whale, as well as one unidentified baleen whale. Collision hotspots such as the southern waters of Sri Lanka are areas that warrant special attention in the form of vessel routing measures or speed limits, research on cetacean ecology, distribution, daily and seasonal movements, public service announcements, increased law enforcement presence, and other measures.
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Attard, Catherine R. M., Luciano B. Beheregaray, K. Curt S. Jenner, et al. "Low genetic diversity in pygmy blue whales is due to climate-induced diversification rather than anthropogenic impacts." Biology Letters 11, no. 5 (2015): 20141037. http://dx.doi.org/10.1098/rsbl.2014.1037.
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Unusually low genetic diversity can be a warning of an urgent need to mitigate causative anthropogenic activities. However, current low levels of genetic diversity in a population could also be due to natural historical events, including recent evolutionary divergence, or long-term persistence at a small population size. Here, we determine whether the relatively low genetic diversity of pygmy blue whales ( Balaenoptera musculus brevicauda ) in Australia is due to natural causes or overexploitation. We apply recently developed analytical approaches in the largest genetic dataset ever compiled to study blue whales (297 samples collected after whaling and representing lineages from Australia, Antarctica and Chile). We find that low levels of genetic diversity in Australia are due to a natural founder event from Antarctic blue whales ( Balaenoptera musculus intermedia ) that occurred around the Last Glacial Maximum, followed by evolutionary divergence. Historical climate change has therefore driven the evolution of blue whales into genetically, phenotypically and behaviourally distinct lineages that will likely be influenced by future climate change.
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Lewis, Leah A., John Calambokidis, Alison K. Stimpert, et al. "Context-dependent variability in blue whale acoustic behaviour." Royal Society Open Science 5, no. 8 (2018): 180241. http://dx.doi.org/10.1098/rsos.180241.
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Acoustic communication is an important aspect of reproductive, foraging and social behaviours for many marine species. Northeast Pacific blue whales ( Balaenoptera musculus ) produce three different call types—A, B and D calls. All may be produced as singular calls, but A and B calls also occur in phrases to form songs. To evaluate the behavioural context of singular call and phrase production in blue whales, the acoustic and dive profile data from tags deployed on individuals off southern California were assessed using generalized estimating equations. Only 22% of all deployments contained sounds attributed to the tagged animal. A larger proportion of tagged animals were female (47%) than male (13%), with 40% of unknown sex. Fifty per cent of tags deployed on males contained sounds attributed to the tagged whale, while only a few (5%) deployed on females did. Most calls were produced at shallow depths (less than 30 m). Repetitive phrasing (singing) and production of singular calls were most common during shallow, non-lunging dives, with the latter also common during surface behaviour. Higher sound production rates occurred during autumn than summer and they varied with time-of-day: singular call rates were higher at dawn and dusk, while phrase production rates were highest at dusk and night.
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Russell, Grace, Marcus Bridge, and Maja Nimak-Wood. "Blue whales off the Southern coast of Sri Lanka during the Southwest Monsoon Season." IWC Journal of Cetacean Research and Management 21, no. 1 (2020): 1–7. http://dx.doi.org/10.47536/jcrm.v21i1.189.
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Observations of 37 individual blue whales (Balaenoptera musculus) were recorded off the southern coast of Sri Lanka during the Southwest Monsoon Season (SWM). Sightings were made during a scientific geophysical survey campaign conducted in July and August 2017. Whilst blue whales are regularly recorded on the continental slope of southern Sri Lanka during the Northeast Monsoon Season (NEM) (December - March) and during the two inter-monsoonal periods (March - April and September - October), limited data is available for the SWM (May - September) mostly due to unfavourable weather conditions and very little survey effort. In the northern hemisphere blue whales undertake seasonal migrations from higher latitude feeding grounds to lower latitude breeding and wintering areas. However it has been suggested that a population of blue whales in the Northern India Ocean (NIO) remains in lower latitudes year round taking advantage of the rich upwelling areas off Somalia, southwest Arabia and western Sri Lanka. Data from this study nevertheless support a theory that a certain number of individuals remain off the southern coast off Sri Lanka during the SWM, suggesting that the productivity in this region is sufficient to support their year-round presence. This study therefore fills a knowledge gap regarding the presence and movement of blue whales in the NIO highlighting the importance of data obtained from platforms of opportunity.
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Segre, P. S., D. E. Cade, J. Calambokidis, et al. "Body Flexibility Enhances Maneuverability in the World’s Largest Predator." Integrative and Comparative Biology 59, no. 1 (2018): 48–60. http://dx.doi.org/10.1093/icb/icy121.
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Abstract Blue whales are often characterized as highly stable, open-ocean swimmers who sacrifice maneuverability for long-distance cruising performance. However, recent studies have revealed that blue whales actually exhibit surprisingly complex underwater behaviors, yet little is known about the performance and control of these maneuvers. Here, we use multi-sensor biologgers equipped with cameras to quantify the locomotor dynamics and the movement of the control surfaces used by foraging blue whales. Our results revealed that simple maneuvers (rolls, turns, and pitch changes) are performed using distinct combinations of control and power provided by the flippers, the flukes, and bending of the body, while complex trajectories are structured by combining sequences of simple maneuvers. Furthermore, blue whales improve their turning performance by using complex banked turns to take advantage of their substantial dorso-ventral flexibility. These results illustrate the important role body flexibility plays in enhancing control and performance of maneuvers, even in the largest of animals. The use of the body to supplement the performance of the hydrodynamically active surfaces may represent a new mechanism in the control of aquatic locomotion.
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Hazen, Elliott Lee, Ari Seth Friedlaender, and Jeremy Arthur Goldbogen. "Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density." Science Advances 1, no. 9 (2015): e1500469. http://dx.doi.org/10.1126/sciadv.1500469.
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Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency.
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Knight, Kathryn. "Sonar disturbs blue whales when feeding." Journal of Experimental Biology 222, no. 5 (2019): jeb199893. http://dx.doi.org/10.1242/jeb.199893.
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Melcón, Mariana L., Amanda J. Cummins, Sara M. Kerosky, Lauren K. Roche, Sean M. Wiggins, and John A. Hildebrand. "Blue Whales Respond to Anthropogenic Noise." PLoS ONE 7, no. 2 (2012): e32681. http://dx.doi.org/10.1371/journal.pone.0032681.
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Attard, Catherine R. M., Luciano B. Beheregaray, Jonathan Sandoval-Castillo, et al. "From conservation genetics to conservation genomics: a genome-wide assessment of blue whales ( Balaenoptera musculus ) in Australian feeding aggregations." Royal Society Open Science 5, no. 1 (2018): 170925. http://dx.doi.org/10.1098/rsos.170925.
Full textAbstract:
Genetic datasets of tens of markers have been superseded through next-generation sequencing technology with genome-wide datasets of thousands of markers. Genomic datasets improve our power to detect low population structure and identify adaptive divergence. The increased population-level knowledge can inform the conservation management of endangered species, such as the blue whale ( Balaenoptera musculus ). In Australia, there are two known feeding aggregations of the pygmy blue whale ( B. m. brevicauda ) which have shown no evidence of genetic structure based on a small dataset of 10 microsatellites and mtDNA. Here, we develop and implement a high-resolution dataset of 8294 genome-wide filtered single nucleotide polymorphisms, the first of its kind for blue whales. We use these data to assess whether the Australian feeding aggregations constitute one population and to test for the first time whether there is adaptive divergence between the feeding aggregations. We found no evidence of neutral population structure and negligible evidence of adaptive divergence. We propose that individuals likely travel widely between feeding areas and to breeding areas, which would require them to be adapted to a wide range of environmental conditions. This has important implications for their conservation as this blue whale population is likely vulnerable to a range of anthropogenic threats both off Australia and elsewhere.
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Goldbogen, J. A., D. E. Cade, J. Calambokidis, et al. "Extreme bradycardia and tachycardia in the world’s largest animal." Proceedings of the National Academy of Sciences 116, no. 50 (2019): 25329–32. http://dx.doi.org/10.1073/pnas.1914273116.
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The biology of the blue whale has long fascinated physiologists because of the animal’s extreme size. Despite high energetic demands from a large body, low mass-specific metabolic rates are likely powered by low heart rates. Diving bradycardia should slow blood oxygen depletion and enhance dive time available for foraging at depth. However, blue whales exhibit a high-cost feeding mechanism, lunge feeding, whereby large volumes of prey-laden water are intermittently engulfed and filtered during dives. This paradox of such a large, slowly beating heart and the high cost of lunge feeding represents a unique test of our understanding of cardiac function, hemodynamics, and physiological limits to body size. Here, we used an electrocardiogram (ECG)-depth recorder tag to measure blue whale heart rates during foraging dives as deep as 184 m and as long as 16.5 min. Heart rates during dives were typically 4 to 8 beats min−1 (bpm) and as low as 2 bpm, while after-dive surface heart rates were 25 to 37 bpm, near the estimated maximum heart rate possible. Despite extreme bradycardia, we recorded a 2.5-fold increase above diving heart rate minima during the powered ascent phase of feeding lunges followed by a gradual decrease of heart rate during the prolonged glide as engulfed water is filtered. These heart rate dynamics explain the unique hemodynamic design in rorqual whales consisting of a large-diameter, highly compliant, elastic aortic arch that allows the aorta to accommodate blood ejected by the heart and maintain blood flow during the long and variable pauses between heartbeats.
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Bianucci, Giovanni, Felix G. Marx, Alberto Collareta, et al. "Rise of the titans: baleen whales became giants earlier than thought." Biology Letters 15, no. 5 (2019): 20190175. http://dx.doi.org/10.1098/rsbl.2019.0175.
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Baleen whales (Mysticeti) are major ecosystem engineers, thanks to their enormous size and bulk filter feeding strategy. Their signature gigantism is thought to be a relatively recent phenomenon, resulting from a Plio-Pleistocene mode shift in their body size evolution. Here, we report the largest whale fossil ever described: an Early Pleistocene (1.5–1.25 Ma) blue whale from Italy with an estimated body length of up to 26 m. Macroevolutionary modelling taking into account this specimen, as well as additional material from the Miocene of Peru, reveals that the proposed mode shift occurred either somewhat earlier, or perhaps not at all. Large-sized mysticetes comparable to most extant species have existed since at least the Late Miocene, suggesting a long-term impact on global marine ecosystems.
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Lavery, Trish J., Ben Roudnew, Justin Seymour, James G. Mitchell, Victor Smetacek, and Steve Nicol. "Whales sustain fisheries: Blue whales stimulate primary production in the Southern Ocean." Marine Mammal Science 30, no. 3 (2014): 888–904. http://dx.doi.org/10.1111/mms.12108.
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Coghlan, Andy. "Whales tan too, basking in the blue." New Scientist 219, no. 2933 (2013): 16. http://dx.doi.org/10.1016/s0262-4079(13)62178-8.
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D’Spain, Gerald L., Aaron M. Thode, and William A. Kuperman. "Three‐dimensional localizations of vocalizing blue whales." Journal of the Acoustical Society of America 102, no. 5 (1997): 3212. http://dx.doi.org/10.1121/1.420977.
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Clarke, Robert. "Male Nipples in Blue and Fin Whales and Their Absence in Sperm Whales." Aquatic Mammals 31, no. 1 (2005): 124–32. http://dx.doi.org/10.1578/am.31.1.2005.124.
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Dungan, Sarah Z., and Belinda S. W. Chang. "Epistatic interactions influence terrestrial–marine functional shifts in cetacean rhodopsin." Proceedings of the Royal Society B: Biological Sciences 284, no. 1850 (2017): 20162743. http://dx.doi.org/10.1098/rspb.2016.2743.
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Like many aquatic vertebrates, whales have blue-shifting spectral tuning substitutions in the dim-light visual pigment, rhodopsin, that are thought to increase photosensitivity in underwater environments. We have discovered that known spectral tuning substitutions also have surprising epistatic effects on another function of rhodopsin, the kinetic rates associated with light-activated intermediates. By using absorbance spectroscopy and fluorescence-based retinal release assays on heterologously expressed rhodopsin, we assessed both spectral and kinetic differences between cetaceans (killer whale) and terrestrial outgroups (hippo, bovine). Mutation experiments revealed that killer whale rhodopsin is unusually resilient to pleiotropic effects on retinal release from key blue-shifting substitutions (D83N and A292S), largely due to a surprisingly specific epistatic interaction between D83N and the background residue, S299. Ancestral sequence reconstruction indicated that S299 is an ancestral residue that predates the evolution of blue-shifting substitutions at the origins of Cetacea. Based on these results, we hypothesize that intramolecular epistasis helped to conserve rhodopsin's kinetic properties while enabling blue-shifting spectral tuning substitutions as cetaceans adapted to aquatic environments. Trade-offs between different aspects of molecular function are rarely considered in protein evolution, but in cetacean and other vertebrate rhodopsins, may underlie multiple evolutionary scenarios for the selection of specific amino acid substitutions.
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Moore, Sue E., Bruce M. Howe, Kathleen M. Stafford, and Michael L. Boyd. "Including Whale Call Detection in Standard Ocean Measurements: Application of Acoustic Seagliders." Marine Technology Society Journal 41, no. 4 (2007): 53–57. http://dx.doi.org/10.4031/002533207787442033.
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Over the past decade, fixed recorders have come into increasing use for long-term sampling of whale calls in remote ocean regions. Concurrently, the development of several types of autonomous underwater vehicles has demonstrated measurement capabilities that promise to revolutionize ocean science. These two lines of technical development were merged with the addition of broadband (5 Hz to 30 kHz) omni-directional hydrophones to seagliders. In August 2006, the capability of three Acoustic Seagliders (ASGs) to detect whale calls was tested in an experiment offshore Monterey, California. In total, 401 dives were completed and over 107 hours of acoustic data recorded. Blue whale calls were detected on all but two of the 76 dives where acoustic data were analyzed in detail, while humpback and sperm whale calls were detected on roughly 20% of those dives. Various whistles, clicks and burst calls, similar to those produced by dolphins and small whales, were also detected, suggesting that the capability of ASGs can be expanded to sample a broad range of marine mammal species. The potential to include whale call detection in the suite of standard oceanographic measures is unprecedented and provides a foundation for mobile sampling strategies at scales that better match the vertical and horizontal movements of the whales themselves. This capability opens new doors for investigation of cetacean habitats and their role in marine ecosystems, as envisioned in future ocean observing systems.
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The Lancet Infectious Diseases. "Microbiome studies and “blue whales in the Himalayas”." Lancet Infectious Diseases 18, no. 9 (2018): 925. http://dx.doi.org/10.1016/s1473-3099(18)30503-6.
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Durban, John W., Michael J. Moore, Gustavo Chiang, et al. "Photogrammetry of blue whales with an unmanned hexacopter." Marine Mammal Science 32, no. 4 (2016): 1510–15. http://dx.doi.org/10.1111/mms.12328.
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Lavigne, D. M., S. Innes, G. A. J. Worthy, and Elizabeth F. Edwards. "Lower critical temperatures of blue whales, Balaenoptera musculus." Journal of Theoretical Biology 144, no. 2 (1990): 249–57. http://dx.doi.org/10.1016/s0022-5193(05)80323-6.
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Flores-Cascante, L., and D. Gendron. "Application of McMaster's technique in live blue whales." Veterinary Record 171, no. 9 (2012): 220.1–220. http://dx.doi.org/10.1136/vr.100749.
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Friedlaender, Ari S., James E. Herbert-Read, Elliott L. Hazen, et al. "Context-dependent lateralized feeding strategies in blue whales." Current Biology 27, no. 22 (2017): R1206—R1208. http://dx.doi.org/10.1016/j.cub.2017.10.023.
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Corkeron, Peter J., Paul Ensor, and Koji Matsuoka. "Observations of blue whales feeding in Antarctic waters." Polar Biology 22, no. 3 (1999): 213–15. http://dx.doi.org/10.1007/s003000050412.
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Cerchio, S., A. Willson, EC Leroy, et al. "A new blue whale song-type described for the Arabian Sea and Western Indian Ocean." Endangered Species Research 43 (December 17, 2020): 495–515. http://dx.doi.org/10.3354/esr01096.
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Blue whales Balaenoptera musculus in the Indian Ocean (IO) are currently thought to represent 2 or 3 subspecies (B. m. intermedia, B. m. brevicauda, B. m. indica), and believed to be structured into 4 populations, each with a diagnostic song-type. Here we describe a previously unreported song-type that implies the probable existence of a population that has been undetected or conflated with another population. The novel song-type was recorded off Oman in the northern IO/Arabian Sea, off the western Chagos Archipelago in the equatorial central IO, and off Madagascar in the southwestern IO. As this is the only blue whale song that has been identified in the western Arabian Sea, we label it the ‘Northwest Indian Ocean’ song-type to distinguish it from other regional song-types. Spatiotemporal variation suggested a distribution west of 70°E, with potential affinity for the northern IO/Arabian Sea, and only minor presence in the southwestern IO. Timing of presence off Oman suggested that intensive illegal Soviet whaling that took 1294 blue whales in the 1960s likely targeted this population, as opposed to the more widely distributed ‘Sri Lanka’ acoustic population as previously assumed. Based upon geographic distribution and potential aseasonal reproduction found in the Soviet catch data, we suggest that if there is a northern IO subspecies (B. m. indica), it is likely this population. Moreover, the potentially restricted range, intensive historic whaling, and the fact that the song-type has been previously undetected, suggests a small population that is in critical need of status assessment and conservation action.