Unravelling the mysteries of a mesopelagic diet: a large apex predator specializes on small prey

Naito, Yoshiro; Costa, Daniel P.; Adachi, Taiki; Robinson, Patrick W.; Fowler, Melinda A.; Takahashi, Akinori

doi:10.1111/1365-2435.12083

Cited by 152 publications

(159 citation statements)

References 51 publications

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“…swim up and down; e.g. [40]), and the swimming costs during bottom phase may decrease as seals approach neutral buoyancy in the same manner to the transit phase. However, alternative hypotheses might explain the effect of prey patch quality or increased body size on bottom duration of dives.…”

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

confidence: 99%

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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%

“…We considered the descent and the ascent phases as transit phases, and the bottom phase as the time spent at foraging depth [40].…”

Section: (B) Data Analysis (I) Dive Phase Definitionmentioning

confidence: 99%

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

et al. 2014

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“…Davis et al 1999, Ponganis et al 2000, Watanabe et al 2004, Watanuki et al 2008, Kokubun et al 2013, Naito et al 2013, Narazaki et al 2013, Watanabe & Takahashi 2013, Nakamura & Sato 2014, Heaslip et al 2014, our systems did not allow us to observe direct feeding events of sperm whales, owing to 3 possible factors.…”

Section: Considerations For Future Improvement Of Suction-cup-attachementioning

confidence: 81%

“…The present versions of animal-borne cameras have succeeded in providing new insights not only into a predator's prey type, but also into the foraging habitats of several other taxa, including pinnipeds (Watanabe et al 2004, Naito et al 2013, penguins (Kokubun et al 2011(Kokubun et al , 2013, shags (Watanuki et al 2008), and sunfishes (Nakamura & Sato 2014). However, we found it was difficult to obtain images of prey from sperm whales using the present systems.…”

Section: Considerations For Future Improvement Of Suction-cup-attachementioning

confidence: 99%

Visual and behavioral evidence indicates active hunting by sperm whales

Aoki¹,

Amano²,

Kubodera³

et al. 2015

Mar. Ecol. Prog. Ser.

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It is hypothesized that sperm whales employ active pursuit strategies for hunting prey, mainly deep-sea squid at great depths, but no visual evidence has been obtained to confirm this. We recorded the hunting behavior of sperm whales using animal-borne cameras and accelerometers simultaneously deployed on 17 whales, and obtained 42.8 h of diving data, including 17 715 images. A statistical comparison indicated no clear effect of light (with or without flashing white lights from cameras) on diving behavior of tagged whales. Although 98.5% of the still images were of empty water and uninformative, 5 classes of images with visible material were identified: (1) suspended material, possibly squid ink (n = 17), (2) unidentified particles (n = 4), (3) possible animal body parts (n = 2), (4) other sperm whales (n = 221), and (5) the seafloor (n = 8). All image classes were recorded at deeper depths (mean ± SD = 785 ± 140 m), except Class 4 images, which were recorded only at depths < 339 m, suggesting that tagged whales swam alone while foraging at great depths. Simultaneous use of speed and image sensors revealed that Class 1 images were associated with bursts of speed up to approximately twice (3.3 ± 1.0 m s

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“…Dragon et al 2012a), accelerometers (Naito et al 2010 and camera systems (e.g. Naito et al 2013) is allowing more detailed and fine-scale assessments of marine animal movements and behaviour. Furthermore, the addition of various sensors to biologging instruments is contributing increasingly to our understanding of ocean physical properties (Fedak 2013) and how marine mammals adjust their behaviour in relation to them (e.g.…”

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Trends in tagging of marine mammals: a review of marine mammal biologging studies

McIntyre¹

2014

African Journal of Marine Science

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science of biologging is somewhat older and is recognised to have started as early as the 1940s, when depth gauges were used on whales and seals (Scholander 1940). After Scholander, the earliest biologging devices used on marine animals are generally recognised to be the maximum-depth recorder (DeVries and Wohlschlag 1964) and time-depth recorders (Kooyman 1965), all of which were deployed on Weddell seals Leptonychotes weddellii (Evans et al. 2013).Technological advances are increasingly allowing for the miniaturisation of devices, as well as the incorporation of more sophisticated sensors into animal-borne instruments. For example, the use of fast-loc GPS technology (e.g. Dragon et al. 2012a), accelerometers (Naito et al. 2010 and camera systems (e.g. Naito et al. 2013) is allowing more detailed and fine-scale assessments of marine animal movements and behaviour. Furthermore, the addition of various sensors to biologging instruments is contributing increasingly to our understanding of ocean physical properties (Fedak 2013) and how marine mammals adjust their behaviour in relation to them (e.g. McIntyre et al. 2011a;Jaud et al. 2012;Bestley et al. 2013). Although the technological advances are clear, it is of interest to know how these technologies are applied in scientific studies and what specific questions are being addressed.Biologging devices are currently used in scientific studies of numerous taxa, including terrestrial mammals (e.g. Hetem et al. 2012;McFarland et al. 2013), reptiles (e.g. Dubois et al. 2009;Watanabe et al. 2013), birds (e.g. Dean et al. 2013;Phipps et al. 2013), fish (e.g. Bonfil et al. 2005Yasuda et al. 2013) and even invertebrates (e.g. Stewart et al. 2012;Watts et al. 2012). Given the obvious difficulties in observing animals at sea directly, the use of biologging technologies is ideally suited for studies involving marine animals, particularly semi-aquatic species that haul out on land, thereby providing opportunities for the deployment of instruments. Marine biologists (and marine mammalogists in particular) are increasingly making use of biologging technology. This is exemplified by the study species reported in the titles and abstracts of presentations (n  Trends in tagging of marine mammals: a review of marine mammal biologging studies T McIntyre Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa e-mail: tmcintyre@zoology.up.ac.zaThe number of scientific papers resulting from biologging instruments deployed on marine mammals is increasing as improved technologies result in smaller devices and improved sensor-, storage-and transmission capabilities. I undertook a comprehensive review of papers resulting from biologging deployments on free-ranging marine mammals between 1965 and 2013 (n = 620) to summarise where (e.g. on which species, as well as in which geographic areas) deployment efforts were focused, the impacts of the resulting papers, and where there are shortcomings in the literature. Species-, sex-and age-class...

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Unravelling the mysteries of a mesopelagic diet: a large apex predator specializes on small prey

Cited by 152 publications

References 51 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

Visual and behavioral evidence indicates active hunting by sperm whales

Trends in tagging of marine mammals: a review of marine mammal biologging studies

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