Distribution of blue whale populations in the Southern Indian Ocean based on a decade of acoustic monitoring

Torterotot, Maelle; Samaran, Flore; Stafford, Kathleen M.; Royer, Jean‐Yves

doi:10.1016/j.dsr2.2020.104874

Cited by 20 publications

(18 citation statements)

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“…ABW calls in the SO show a seasonal pattern, with low acoustic detections in winter Branch et al, 2007;Thomisch et al, 2016) and a more evident year-round presence at PAM stations at lower rather than higher latitudes (Širović et al, 2009). The ABW year-round presence at the SO's high latitudes is not an exception: ABWs are acoustically detected year-round at midlatitude locations in the sub-Antarctic and subtropical sections of the Indian Ocean (Samaran et al, 2010(Samaran et al, , 2013Leroy et al, 2016Leroy et al, , 2018Torterotot et al, 2020) and off Namibia (Thomisch et al, 2019). The definite nature of ABWs migration (and probably other baleen whale species) is not yet clear and can include either partial or differential migration or a mixture of both (Thomisch, 2017).…”

Section: Antarctic Blue Whalesmentioning

confidence: 99%

“…The migratory pattern of ABWs is complex and nonobligatory (Leroy et al, 2016;Thomisch et al, 2016;Torterotot et al, 2020). PAM data show evidence that at least some animals overwinter at high latitudes (Širović et al, 2009); e.g., off the Antarctic Peninsula Dziak et al, 2015), East Antarctica (Širović et al, 2009;Gedamke and Robinson, 2010), the Weddell Sea (Thomisch et al, 2016), and off Maud Rise (Shabangu et al, 2020a).…”

Section: Antarctic Blue Whalesmentioning

confidence: 99%

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Dynamic Species Distribution Models in the Marine Realm: Predicting Year-Round Habitat Suitability of Baleen Whales in the Southern Ocean

et al. 2021

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Species distribution models (SDMs) relate species information to environmental conditions to predict potential species distributions. The majority of SDMs are static, relating species presence information to long-term average environmental conditions. The resulting temporal mismatch between species information and environmental conditions can increase model inference’s uncertainty. For SDMs to capture the dynamic species-environment relationships and predict near-real-time habitat suitability, species information needs to be spatiotemporally matched with environmental conditions contemporaneous to the species’ presence (dynamic SDMs). Implementing dynamic SDMs in the marine realm is highly challenging, particularly due to species and environmental data paucity and spatiotemporally biases. Here, we implemented presence-only dynamic SDMs for four migratory baleen whale species in the Southern Ocean (SO): Antarctic minke, Antarctic blue, fin, and humpback whales. Sightings were spatiotemporally matched with their respective daily environmental predictors. Background information was sampled daily to describe the dynamic environmental conditions in the highly dynamic SO. We corrected for spatial sampling bias by sampling background information respective to the seasonal research efforts. Independent model evaluation was performed on spatial and temporal cross-validation. We predicted the circumantarctic year-round habitat suitability of each species. Daily predictions were also summarized into bi-weekly and monthly habitat suitability. We identified important predictors and species suitability responses to environmental changes. Our results support the propitious use of dynamic SDMs to fill species information gaps and improve conservation planning strategies. Near-real-time predictions can be used for dynamic ocean management, e.g., to examine the overlap between habitat suitability and human activities. Nevertheless, the inevitable spatiotemporal biases in sighting data from the SO call for the need for improving sampling effort in the SO and using alternative data sources (e.g., passive acoustic monitoring) in future SDMs. We further discuss challenges of calibrating dynamic SDMs on baleen whale species in the SO, with a particular focus on spatiotemporal sampling bias issues and how background information should be sampled in presence-only dynamic SDMs. We also highlight the need to integrate visual and acoustic data in future SDMs on baleen whales for better coverage of environmental conditions suitable for the species and avoid constraints of using either data type alone.

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Section: Antarctic Blue Whalesmentioning

confidence: 99%

Section: Antarctic Blue Whalesmentioning

confidence: 99%

Dynamic Species Distribution Models in the Marine Realm: Predicting Year-Round Habitat Suitability of Baleen Whales in the Southern Ocean

et al. 2021

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“…Blue whales in different geographic areas produce different song patterns, consisting of repeated sequences of 'phrases' made up of recurring pulsed sounds or 'units' [25], which are thought to function as a reproductive display [25][26][27]. Blue whale songs have usually been attributed to males [25,28,29] and have been reported to occur along entire migratory routes, from summer feeding areas to winter breeding grounds [30][31][32]. Different song types are typically characterized by differences in unit characteristics (frequency, duration, modulation, inter-unit time intervals), ordering of song units within each phrase (song phrasing), and song phrase duration [25,27,33,34].…”

Section: Introductionmentioning

confidence: 99%

Seasonal Trends and Diel Patterns of Downsweep and SEP Calls in Chilean Blue Whales

Redaelli

Woods

Landea

et al. 2022

JMSE

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To learn more about the occurrence and behaviour of a recently discovered population of blue whales, passive acoustic data were collected between January 2012 and April 2013 in the Chiloense ecoregion of southern Chile. Automatic detectors and manual auditing were used to detect blue whale songs (SEP calls) and D calls, which were then analysed to gain insights into temporal calling patterns. We found that D call rates were extremely low during winter (June–August) but gradually increased in spring and summer, decreasing again later during fall. SEP calls were absent for most winter and spring months (July–November) but increased in summer and fall, peaking between March and April. Thus, our results support previous studies documenting the austral summer residency of blue whales in this region, while suggesting that some individuals stay longer, highlighting the importance of this area as a blue whale habitat. We also investigated the daily occurrence of each call type and found that D calls occurred more frequently during dusk and night hours compared to dawn and day periods, whereas SEP calls did not show any significant diel patterns. Overall, these findings help to understand the occurrence and behaviour of endangered Chilean blue whales, enhancing our ability to develop conservation strategies in this important Southern Hemisphere habitat.

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“…This is not likely to be the case off Lakshadweep as we detected relatively few songs overall. Unit 3 is the signal targeted by automatic detection for the NIO song type (e.g., Miksis‐Olds et al, 2018; Stafford et al, 2011; Torterotot et al, 2020), which may be why the variation described here has not been reported previously. If modifying the song by leaving units out or adding some in as reported by Joliffe et al (2019) for SEIO blue whales is a common occurrence, it will not have been noticed in studies that use only unit 3 to detect the presence of NIO PBW.…”

Section: Figurementioning

confidence: 87%

Northern Indian Ocean blue whale songs recorded off the coast of India

Panicker

Stafford

2021

Marine Mammal Science

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Distribution of blue whale populations in the Southern Indian Ocean based on a decade of acoustic monitoring

Cited by 20 publications

References 50 publications

Dynamic Species Distribution Models in the Marine Realm: Predicting Year-Round Habitat Suitability of Baleen Whales in the Southern Ocean

Dynamic Species Distribution Models in the Marine Realm: Predicting Year-Round Habitat Suitability of Baleen Whales in the Southern Ocean

Seasonal Trends and Diel Patterns of Downsweep and SEP Calls in Chilean Blue Whales

Northern Indian Ocean blue whale songs recorded off the coast of India

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