North Atlantic right whale foraging ecology and its role in human-caused mortality

Baumgartner, Mark F.; Wenzel, Frederick W.; Lysiak, Nadine S. J.; Patrician, Melissa R.

doi:10.3354/meps12315

Cited by 35 publications

(30 citation statements)

References 45 publications

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“…The data presented here support the findings by Baumgartner et al (2017) that right whales dive to the seafloor in most study areas. In that study, the authors found that 15 of the 55 tagged whales dove to within 0 to 10 m of the seafloor and they did so in 5 out of the 6 study sites.…”

Section: Discussionsupporting

confidence: 91%

“…These concentrations primarily occur near the sur-face, just above the bottom mixed layer (approximately 50−75 m above the seafloor), or as close as 5 m off the seafloor. Baumgartner et al (2017) found nearly one-quarter of the 55 whales tagged dove to the seafloor and they did so in all but one habitat. Most, but not all, of those whales appeared to be feeding near the seafloor.…”

Section: Introductionmentioning

confidence: 93%

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Frequent encounters with the seafloor increase right whales’ risk of entanglement in fishing groundlines

Hamilton¹,

Kraus²

2019

Endang. Species. Res.

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North Atlantic right whales Eubalaena glacialis utilize the entire water column and are frequently entangled in ropes from fishing gear. Data from telemetry tags have shown that right whales can swim/feed at or near the seafloor. Because those data are limited, some uncertainty remains regarding the frequency of dives to the seafloor and thus the likelihood of right whale encounters with fishing ropes there. The North Atlantic right whale photo-identification catalog was used to determine the number of sightings of right whales with seafloor sediment on their bodies and the relative frequency and geographic location of those seafloor encounters. Between 1980 and 2016, there were 2053 detections of right whales with 'mud' on their bodies, which represents 2.9% of all sightings (n = 70 593), or 58.2% of all cataloged whales (n = 730). Although muddy right whales were found throughout their range and in all months, 92.7% of all detections occurred in the Bay of Fundy in the summer where there was an average annual detection rate of 7.3%, with a maximum of 26% of sightings in 2010. Mud was found on whales of all age classes including calves of the year, and equally among males and females. These seafloor encounters suggest that any rope resting on, or floating above, the seafloor could pose an entanglement hazard. The use of sinking groundlines likely reduces the risk of entanglements for whales swimming near the seafloor, but may not eliminate the risk for whales making contact with the sediment.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 93%

Frequent encounters with the seafloor increase right whales’ risk of entanglement in fishing groundlines

Hamilton¹,

Kraus²

2019

Endang. Species. Res.

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“…Irrespective of these errors, pseudo tracks do, however, capture the qualitative nature of animal movement and can be useful in inferring how animals move, rather than where they go; for our purpose, these tracks illustrate the degree to which right whales move horizontally within dives (Figure ). The variation in the horizontal movement patterns of whales foraging at depth (Figure ) as well as small‐scale changes in the vertical dimension between dives (Figure S3) further suggest that right whales are capable of detecting fine‐scale variations in prey density and adjusting their foraging behaviour accordingly (Baumgartner et al, ; Kenney, Mayo, & Winn, ; Mayo & Goldman, ; Mayo & Marx, ). Simultaneous measurements of the vertical distribution of prey and right whale diving behaviour made in foraging habitats have shown how right whales are able to repeatedly target the depth of maximum copepod concentrations (Baumgartner & Mate, ; Parks et al, ).…”

Section: Discussionmentioning

confidence: 98%

“…We hypothesized that if whales were consistently diving to their aerobic dive limit, they would have filtered lower total volumes of water in deeper dives, due to the time required to transit to the foraging patch (Thompson & Fedak, ). However, the lack of a significant effect of dive depth on the total volume filtered per dive and the low explanatory power of depth on foraging duration emphasizes that by completing many shorter, aerobic dives with steep ascents and descents and short surface intervals right whales maximize the time spent foraging in a consistent prey patch, regardless of its depth (Baumgartner et al, ). While individuals are able to optimize their time foraging in high‐density prey layers, they apparently will also go without foraging for extended periods of time (2+ hr; Figure S1) in this otherwise rich environment.…”

Section: Discussionmentioning

confidence: 99%

“…Right whales target prey patches above 10 3 copepods/m 3 (Murison & Gaskin, 1989) and up to 10 5 copepods/m 3 (Baumgartner & Mate, 2003;Baumgartner, Wenzel, Lysiak, & Patrician, 2017;Mayo & Marx, 1990). In the Grand Manan Basin in the Bay of Fundy, a right whale critical habitat and summer foraging area (Brown et al, 2009), individual diving behaviour is strongly correlated with the depth of maximum Calanus abundance between 100 and 150 m (Baumgartner & Mate, 2003;Baumgartner et al, 2017). There, 4-8 km patches of copepods with energy densities above 15 J/m 3 develop; within the large patch, concentration and energy density can vary on spatial scales of 500 m (Michaud & Taggart, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Foraging rates of ram‐filtering North Atlantic right whales

et al. 2019

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North Atlantic right whales spend their summer months foraging primarily in American and Canadian Atlantic waters on high‐energy‐density prey. Here, they rapidly accumulate and store energy obtained within a few months to support future migrations and reproduction while fasting. High drag from their ram‐filter foraging strategy places a limit on what prey densities will be energetically efficient to target. Our understanding of the volume of prey‐laden water filtered by right whales during a dive or foraging bout, and what information they use to decide to forage or not, has been limited by the difficulties of measuring when they feed at depth, how fast they swim during continuous ram filtration and how often they might swallow accumulated prey. We used 10 DTAG deployments from right whales in the Bay of Fundy, Canada, to quantify swimming speeds and estimate the volume of prey‐laden water filtered per dive. We used the tag's inertial sensors to evaluate the timing of frequent biomechanical changes that likely indicate the truncation of continuous filtration, and whether the number or timing of these fluking bouts relates to longer feeding dives or other foraging decisions. During foraging dives, right whales descended at 1.4 (±0.2 SD) m/s and slowed to swim at 1.1 (±0.3) m/s while filtering. We found consistent pauses in the fluking behaviour of foraging right whales, every 56 (±22) s. Whales filtered on average 78 (±30) m3 of water per fluking bout and on average 673 (±201) m3 per dive. Right whales filter large volumes of water at low speeds with a high duty cycle, but require sufficiently high prey energy densities to compensate for a high‐drag foraging strategy. Closely related bowhead whales have a larger gape but swim more slowly, filtering greater volumes with lower drag. Our findings highlight that right whales acquire their energy in a relatively short period of intense foraging; even moderate changes in their feeding behaviour or their prey energy density are likely to negatively impact their yearly energy budgets and therefore reduce fitness substantially. A plain language summary is available for this article.

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