Buoyant balaenids: the ups and downs of buoyancy in right whales

Nowacek, Doug; Johnson, Mark; Tyack, Peter L.; Shorter, K. Alex; McLellan, William A.; Pabst, D. Ann

doi:10.1098/rspb.2001.1730

Cited by 122 publications

(133 citation statements)

References 26 publications

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“…For example, grey seals and New Zealand fur seals like elephant seals are aided by negative buoyancy during the descent phase [26,59], suggesting that they passively glide on descent and stroke on ascent. However, right whales and deep-diving sperm whales are positively buoyant and stroke on descent and passively glide on ascent [60,61]. Given that the parameters which govern the costs of locomotion are the same, we would expect that these species also would have an increased cost of locomotion as they deviate from neutral buoyancy.…”

Section: Discussion (A) Buoyancy Determines Locomotor Costs Of Swimmingmentioning

confidence: 99%

The foraging benefits of being fat in a highly migratory marine mammal

et al. 2014

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Foraging theory predicts that breath-hold divers adjust the time spent foraging at depth relative to the energetic cost of swimming, which varies with buoyancy (body density). However, the buoyancy of diving animals varies as a function of their body condition, and the effects of these changes on swimming costs and foraging behaviour have been poorly examined. A novel animalborne accelerometer was developed that recorded the number of flipper strokes, which allowed us to monitor the number of strokes per metre swam (hereafter, referred to as strokes-per-metre) by female northern elephant seals over their months-long, oceanic foraging migrations. As negatively buoyant seals increased their fat stores and buoyancy, the strokes-per-metre increased slightly in the buoyancy-aided direction (descending), but decreased significantly in the buoyancy-hindered direction (ascending), with associated changes in swim speed and gliding duration. Overall, the round-trip strokes-per-metre decreased and reached a minimum value when seals achieved neutral buoyancy. Consistent with foraging theory, seals stayed longer at foraging depths when their round-trip strokes-per-metre was less. Therefore, neutrally buoyant divers gained an energetic advantage via reduced swimming costs, which resulted in an increase in time spent foraging at depth, suggesting a foraging benefit of being fat.

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Section: Discussion (A) Buoyancy Determines Locomotor Costs Of Swimmingmentioning

confidence: 99%

The foraging benefits of being fat in a highly migratory marine mammal

et al. 2014

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“…A filter-feeding balaenid passes through several body forms in a foraging dive from high buoyancy near the surface when the lungs are full of air to a lower buoyancy, more streamlined body form at greater depths (Nowacek et al 2001). A third change in body form occurs when the whale opens its mouth to Filter feeding bowhead whales M. Simon et al 3823…”

Section: Discussionmentioning

confidence: 99%

Behaviour and kinematics of continuous ram filtration in bowhead whales (Balaena mysticetus)

et al. 2009

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Balaenid whales perform long breath-hold foraging dives despite a high drag from their ram filtration of zooplankton. To maximize the volume of prey acquired in a dive with limited oxygen supplies, balaenids must either filter feed only occasionally when prey density is particularly high, or they must swim at slow speeds while filtering to reduce drag and oxygen consumption. Using digital tags with three-axis accelerometers, we studied bowhead whales feeding off West Greenland and present here, to our knowledge, the first detailed data on the kinematics and swimming behaviour of a balaenid whale filter feeding at depth. Bowhead whales employ a continuous fluking gait throughout the bottom phase of foraging dives, moving at very slow speeds (less than 1 m s 21 ), allowing them to filter feed continuously at depth. Despite the slow speeds, the large mouth aperture provides a water filtration rate of approximately 3 m 3 s 21 , amounting to some 2000 tonnes of water and prey filtered per dive. We conclude that a food niche of dense, slow-moving zooplankton prey has led balaenids to evolve locomotor and filtering systems adapted to work against a high drag at swimming speeds of less than 0.07 body length s 21 using a continuous fluking gait very different from that of nekton-feeding, aquatic predators.

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“…Nowacek et al, 2001Nowacek et al, , 2004, humpback whale (Wiley et al, 1994;Laist et al, 2001;Lammers et al, 2007) and fin whale (e.g. Panigada et al, 2006), a general lack of understanding of the circumstances and factors that cause vessels to collide with cetaceans can at least in part be traced back to a shortage of authenticated datasets.…”

Section: Global Standardised Databasementioning

confidence: 99%

“…Anaerobic physiological stress could compromise avoidance capabilities including evasive fast diving. Similarly, the highest risk to right whales is also thought to occur when emerging under a vessel from a dive (Nowacek et al, 2001). Beaked whales have a low probability of being detected visually, compromising any potential avoidance manoeuvres by the vessel (Barlow and Gisiner, 2006 (Shelden and Rugh, 1995).…”

Section: Incidence In Southern Hemisphere Large Whalesmentioning

confidence: 99%

“…Floating carcasses may be damaged, potentially confounding interpretations of traumatic lesions, especially when in advanced decomposition (state 4 or 5). However with the exception of Balaenidae (Slijper, 1979;Nowacek et al, 2001), most cetaceans sink immediately after death and resurface, belly-up, only after bloating sets in. The likelihood for a ship to collide with a floating carcass that, if significantly bloated can be spotted by naked eye or radar from a great distance, needs to be evaluated.…”

Section: Global Standardised Databasementioning

confidence: 99%

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Vessel collisions with small cetaceans worldwide and with large whales in the Southern Hemisphere, an initial assessment

Waerebeek¹,

Baker²,

Félix³

et al. 2007

Lat. Am. J. Aquat. Mamm.

166

165

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ABSTRACT:Collisions with vessels are a well-documented conservation problem for some populations of large whales (LW) in the Northern Hemisphere. Less attention has been given to incidents in the Southern Hemisphere or to small cetaceans (SC) worldwide, therefore an experimental database was compiled (N=256; 119 LW, 137 SC) to allow a rapid assessment. Confirmed collision records were identified for 25 species (7 LW, 18 SC) and unconfirmed but probable records for 10 other species (2 LW, 8 SC). Among LW, ship-caused mortality and traumatic injuries seem to affect primarily southern right (56 reported cases), humpback (15) and Bryde's whales (13), but also sperm (8), blue (5), sei (4) and fin whales (2) are involved, and probably Antarctic minke and dwarf minke whales. Southern right whale populations off South Africa and off eastern South America (Brazil, Uruguay and Argentina) suffer significant mortality. Incidence and potential population impact vary widely among the 26 small cetacean species for which collision records exist. Vessel strikes in at least two populations each of the Indo-Pacific humpback dolphin (Xiamen and Hong Kong/Pearl River, possibly western Taiwan), Irrawaddy dolphin (Mahakam River, Chilika Lagoon, possibly Laos) and finless porpoise (Yangtze River, Hong Kong) may directly compromise long-term survival. Annual vessel-caused mortality (min. 2.9% of population) for Irrawaddy dolphins in the Mahakam River may not be sustainable. The quasi-extinction of the baiji warns for a potential similar fate for the Yangtze River finless porpoise and Ganges river dolphin. Two calves of the endangered Hector's dolphin are known killed by boats. All highly impacted species have a neritic, estuarine or fluviatile habitat, areas where vessel traffic is concentrated. Species that may receive a moderate impact from collisions but which may be sustainable at species level (because many strikes are nonlethal), include common bottlenose dolphins, killer whales, short-finned pilot whales and pygmy sperm whales. Almost 2% of common bottlenose dolphins in the Gulf of Guayaquil showed propeller-inflicted injuries and scars. Propeller guards should be made compulsory for all boat-based cetacean tourism, as habituation to boat traffic seems a contributing factor in accidents. Low impact occurs in 15 small cetacean species with only few reported vessel strikes. However, vast underreporting is thought to be the norm and there is a need for a global, standardised database. RESUMEN:Las colisiones con barcos constituyen un problema de conservación bien documentado en el caso de ballenas grandes (BG) en el hemisferio norte. Menos atención se le ha brindado a los incidentes en el hemisferio sur y a los cetáceos menores (CM) alrededor del mundo. A fin de realizar una evaluación rápida de este problema se ha compilado una base de datos preliminar (N=256; 119 BG, 137 CM), la cual incluye registros confirmados de colisión para 25 especies (7 BG, 18 CM) y registros no confirmados pero probables para otras 10 (2 BG, 8 CM). Entre B...

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Buoyant balaenids: the ups and downs of buoyancy in right whales

Cited by 122 publications

References 26 publications

The foraging benefits of being fat in a highly migratory marine mammal

The foraging benefits of being fat in a highly migratory marine mammal

Behaviour and kinematics of continuous ram filtration in bowhead whales (Balaena mysticetus)

Vessel collisions with small cetaceans worldwide and with large whales in the Southern Hemisphere, an initial assessment

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