Linking mesopelagic prey abundance and distribution to the foraging behavior of a deep-diving predator, the northern elephant seal

Saijo, Daisuke; Mitani, Yoko; Abe, Takuzo; Sasaki, Hidetada; Goetsch, Chandra; Costa, Daniel P.; Miyashita, Kazushi

doi:10.1016/j.dsr2.2016.11.007

Cited by 46 publications

(21 citation statements)

References 43 publications

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“…Our study, which aimed to reveal how marine mammals forage efficiently in the biota‐poor OMZ, depended on the accuracy of measurements of energy gain by the jaw motion recorder, that is, accuracy in the number of JME as a comparative index of the amount of prey consumed by the seals. From our previous study, we predicted that JME was a reliable index of digested prey mass based on the following empirical reasons related to the narrow prey size distribution: (1) They use a suction feeding mode functional for feeding on small prey (Bloodworth & Marshall, ; Marshall, Kovacs, & Lydersen, ; Suzuki, Naito, Folkow, Miyazaki, & Blix, ); (2) their morphologically degenerate molar teeth are less functional for feeding on large prey (Abbott & Verstraete, ); (3) small fish, that is, micronekton, are dominant in the mesopelagic zone (Cherel et al., ; Irigoien et al., ; Naito et al., ; Robinson, Steinberg, et al., ; Robison, ); and (4) the body size distribution of the dominant animals captured by mesopelagic trawling in the 400–800 m depth in the same area of the Northeast Pacific is very small (Saijo et al., ).…”

Section: Discussionmentioning

confidence: 99%

“…They use a suction feeding mode functional for feeding on small prey (Bloodworth & Marshall, 2005;Marshall, Kovacs, & Lydersen, 2008;Suzuki, Naito, Folkow, Miyazaki, & Blix, 2009); (2) their morphologically degenerate molar teeth are less functional for feeding on large prey (Abbott & Verstraete, 2005); (3) small fish, that is, micronekton, are dominant in the mesopelagic zone (Cherel et al, 2008;Irigoien et al, 2014;Naito et al, 2013;Robinson, Steinberg, et al, 2010;Robison, 2004); and (4) the body size distribution of the dominant animals captured by mesopelagic trawling in the 400-800 m depth in the same area of the Northeast Pacific is very small (Saijo et al, 2017).…”

Section: Body Mass Effect and The Size Of Preymentioning

confidence: 99%

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Oxygen minimum zone: An important oceanographic habitat for deep‐diving northern elephant seals,Mirounga angustirostris

Naito

Costa

Adachi

et al. 2017

Ecology and Evolution

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Little is known about the foraging behavior of top predators in the deep mesopelagic ocean. Elephant seals dive to the deep biota‐poor oxygen minimum zone (OMZ) (>800 m depth) despite high diving costs in terms of energy and time, but how they successfully forage in the OMZ remains largely unknown. Assessment of their feeding rate is the key to understanding their foraging behavior, but this has been challenging. Here, we assessed the feeding rate of 14 female northern elephant seals determined by jaw motion events (JME) and dive cycle time to examine how feeding rates varied with dive depth, particularly in the OMZ. We also obtained video footage from seal‐mounted videos to understand their feeding in the OMZ. While the diel vertical migration pattern was apparent for most depths of the JME, some very deep dives, beyond the normal diel depth ranges, occurred episodically during daylight hours. The midmesopelagic zone was the main foraging zone for all seals. Larger seals tended to show smaller numbers of JME and lower feeding rates than smaller seals during migration, suggesting that larger seals tended to feed on larger prey to satisfy their metabolic needs. Larger seals also dived frequently to the deep OMZ, possibly because of a greater diving ability than smaller seals, suggesting their dependency on food in the deeper depth zones. Video observations showed that seals encountered the rarely reported ragfish (Icosteus aenigmaticus) in the depths of the OMZ, which failed to show an escape response from the seals, suggesting that low oxygen concentrations might reduce prey mobility. Less mobile prey in OMZ would enhance the efficiency of foraging in this zone, especially for large seals that can dive deeper and longer. We suggest that the OMZ plays an important role in structuring the mesopelagic ecosystem and for the survival and evolution of elephant seals.

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Section: Discussionmentioning

confidence: 99%

Section: Body Mass Effect and The Size Of Preymentioning

confidence: 99%

Oxygen minimum zone: An important oceanographic habitat for deep‐diving northern elephant seals,Mirounga angustirostris

Naito

Costa

Adachi

et al. 2017

Ecology and Evolution

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“…This transect was determined at sea by the real-time Argos locations of 16 concurrently tracked female elephant seals (Figure 1), and sampling was conducted at depths where elephant seals routinely forage (Robinson et al, 2012). Potential prey samples were collected during four midwater trawls (10 mm mesh at the cod end, 314 m 2 net mouth, and tow speed of 3.5-4 knots; Saijo et al, 2017), two during the day (maximum depths of 730 and 720 m), and two at night (both at 650 m). Automatic squid jigs (surface to 650 m, Towa-denki Seisakusho Co., Ltd.) were also used to collect samples of active, vertically migrating squid.…”

Section: Collecting the Prey Librarymentioning

confidence: 99%

Energy-Rich Mesopelagic Fishes Revealed as a Critical Prey Resource for a Deep-Diving Predator Using Quantitative Fatty Acid Signature Analysis

et al. 2018

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“…It seems very plausible that sperm whales are targeting warty squid during their dives to 400-600 m in mid-water during the day, and possibly during demersal foraging at night. Strong associations with the DSL have been shown for many deep-diving top predators including pilot whales (Abecassis et al 2015), elephant seals (Saijo et al 2016) and Blainville's beaked whales (Arranz et al 2011), for which circadian changes in foraging behaviour have been associated with changes in the vertical distribution of their prey.…”

Section: Sperm Whale Preymentioning

confidence: 99%

Diverse foraging strategies by a marine top predator: Sperm whales exploit pelagic and demersal habitats in the Kaikōura submarine canyon

Guerra

Hickmott

Hoop

et al. 2017

Deep Sea Research Part I: Oceanographic Research Papers

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The submarine canyon off Kaikōura (New Zealand) is an extremely productive deep-sea habitat, and an important foraging ground for male sperm whales (Physeter macrocephalus). We used highresolution archival tags to study the diving behaviour of sperm whales, and used the echoes from their echolocation sounds to estimate their distance from the seafloor. Diving depths and distance above the seafloor were obtained for 28 dives from six individuals. Whales foraged at depths between 284 and 1433 m, targeting mesopelagic and demersal prey layers. The majority of foraging buzzes occurred within one of three vertical strata: within 50 m of the seafloor, mid-water at depths of 700-900 m, and mid-water at depths of 400-600 m. Sperm whales sampled during this study performed more demersal foraging than that reported in any previous studies -including at Kaikōura in further inshore waters. This suggests that the extreme benthic productivity of the Kaikōura Canyon is reflected in the trophic preferences of these massive top predators. We found some evidence for circadian patterns in the foraging behaviour of sperm whales, which might be related to vertical movements of their prey following the deep scattering layer. We explored the ecological implications of the whales' foraging preferences on their habitat use, highlighting the need for further research on how submarine canyons facilitate top predator hotspots.

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Linking mesopelagic prey abundance and distribution to the foraging behavior of a deep-diving predator, the northern elephant seal

Cited by 46 publications

References 43 publications

Oxygen minimum zone: An important oceanographic habitat for deep‐diving northern elephant seals,Mirounga angustirostris

Oxygen minimum zone: An important oceanographic habitat for deep‐diving northern elephant seals,Mirounga angustirostris

Energy-Rich Mesopelagic Fishes Revealed as a Critical Prey Resource for a Deep-Diving Predator Using Quantitative Fatty Acid Signature Analysis

Diverse foraging strategies by a marine top predator: Sperm whales exploit pelagic and demersal habitats in the Kaikōura submarine canyon

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