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  • 1
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    Seasonal trends and diel patterns of downsweep and SEP calls in Chilean blue whales (2022)
    MDPI
    Details
    Publication Date: 2022-06-27
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Redaelli, L., Mangia Woods, S., Landea, R., & Sayigh, L. Seasonal trends and diel patterns of downsweep and SEP calls in Chilean blue whales. Journal of Marine Science and Engineering, 10(3), (2022): 316, https://doi.org/10.3390/jmse10030316.
    Description: 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.
    Description: Financial support for expeditions, deployments, and retrievals of MARUs, and for some of the data analysis, was provided by Fundacion MERI, Av. Pdte. Kennedy 5682, Vitacure, Región Metropolitana, Chile. The data analysis for this study was carried out without external funding.
    Keywords: Chilean blue whales ; marine bioacoustics ; Balaenoptera musculus chilensis ; Chile ; D calls ; SEP calls ; diel patterns ; seasonal trends ; marine conservation
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    Characterizing Chilean blue whale vocalizations with DTAGs : a test of using tag accelerometers for caller identification (2017)
    Company of Biologists
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © Company of Biologists, 2017. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 220 (2017): 4119-4129, doi: 10.1242/jeb.151498.
    Description: Vocal behavior of blue whales (Balaenoptera musculus) in the Gulf of Corcovado, Chile, was analysed using both audio and accelerometer data from digital acoustic recording tags (DTAGs). Over the course of three austral summers (2014, 2015 and 2016), seventeen tags were deployed, yielding 124 h of data. We report the occurrence of Southeast Pacific type 2 (SEP2) calls, which exhibit peak frequencies, durations and timing consistent with previous recordings made using towed and moored hydrophones. We also describe tonal downswept (D) calls, which have not been previously described for this population. As being able to accurately assign vocalizations to individual whales is fundamental for studying communication and for estimating population densities from call rates, we further examine the feasibility of using high-resolution DTAG accelerometers to identify low-frequency calls produced by tagged blue whales. We cross-correlated acoustic signals with simultaneous tri-axial accelerometer readings in order to analyse the phase match as well as the amplitude of accelerometer signals associated with low-frequency calls, which provides a quantitative method of determining if a call is associated with a detectable acceleration signal. Our results suggest that vocalizations from nearby individuals are also capable of registering accelerometer signals in the tagged whale's DTAG record. We cross-correlate acceleration vectors between calls to explore the possibility of using signature acceleration patterns associated with sounds produced within the tagged whale as a new method of identifying which accelerometer-detectable calls originate from the tagged animal.
    Description: Fieldwork for this project was funded by the Melimoyu Ecosystem Research Institute Foundation and the Woods Hole Oceanographic Institution. Analysis was supported by a Woods Hole Oceanographic Institution Summer Student Fellowship.
    Description: 2018-09-07
    Keywords: Balaenoptera musculus ; Acoustic behavior ; DTAG ; Downsweep call ; D call ; Cross-correlation
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
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    A preliminary investigation into the ecology and behavior of blue whales (Balaenoptera musculus) in the Gulf of Corcovado, Chile (2015)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: A joint effort between WHOI and the Melimoyu Ecosystem Research Institute (MERI) sought to gain a better understanding of a population of blue whales (Balaenoptera musculus) in the Gulf of Corcovado, Chile. A cruise in March 2014 resulted in the deployment of 5 DTAGs, which are miniature sound and orientation recording tags that are attached via suction cups. A total of five tag deployments on four individual whales were achieved, totaling 21 hr 11 min. Dives were predominantly between 10 and 50 m in depth, with a maximum of 139 m. Sloughed skin found on the suction cups of recovered tags and fecal samples were preserved to be used for genetic, dietary and pollutant analyses. Acoustic data on the tags revealed numerous calls from distant blue whales, and an apparent call exchange was recorded between a tagged juvenile whale and a distant animal. Photo-identification images and acoustic recordings of all marine mammal species encountered were obtained whenever possible; these included humpback whales (Megaptera novaeangliae), Peale’s dolphins (Lagenorhynchus australis), Chilean dolphins (Cephalorhynchus eutropia), and bottlenose dolphins (Tursiops truncatus). Continuation of this collaboration has great potential to provide information to policy makers regarding how to protect the unique habitats in this region.
    Description: Funding was provided by the Melimoyu Ecosystem Research Institute
    Keywords: Animal radio tracking
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: application/pdf
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  • 4
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    Seasonal trends and diel patterns of downsweep and SEP calls in Chilean blue whales (Balaenoptera musculus) (2022)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-10-21
    Description: To learn more about occurrence and behavior of a recently discovered population of blue whales, passive acoustic data were collected for 15 consecutive months (January 2012 – 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 analyzed to gain insights into temporal calling patterns. We found a year-round acoustic presence of D calls, with the majority occurring during austral summer (December to April), with several sub-monthly peaks. On the other hand, no SEP calls were found during austral winter. Thus, our results support previous studies documenting austral summer residency of blue whales in the Chiloense ecoregion, although they suggest that some individuals remain in the area year-round, highlighting the importance of the Chiloense ecoregion as blue whale habitat. We also investigated 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 differences. Overall, these findings contribute to a better understanding of occurrence and behavior of endangered Chilean blue whales, which can enhance our ability to develop conservation strategies in this important southern hemisphere habitat.
    Keywords: Chilean blue whales ; Marine bioacoustics ; Balaenoptera musculus ; Chile ; D calls ; SEP calls ; Diel patterns ; Seasonal trends ; Marine conservation
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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  • 5
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    Temporal trends and effects of noise on upsweep calls of Eastern South Pacific southern right whales (2022)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-10-21
    Description: Eastern South Pacific southern right whales (ESPSRW) are a subpopulation of southern right whales (Eubalaena australis) off the coasts of Peru and Chile recognized by the International Union for the Conservation of Nature (IUCN) as critically endangered as a result of heavy whaling efforts in the late 18th to 20th centuries. Most recent population estimates put their numbers around 50 individuals. To test for the efficacy of passive acoustic monitoring of this population, we recorded five months of continuous acoustic data (January 2012-June 2012) off the southwestern tip of Isla de Chiloé. To test for trends in occurrence, we identified a total of 11,313 individual ESPSRW upsweep calls, which have been associated with maintaining contact with conspecifics. Calls increased over the course of the deployment and peaked between April and June, indicating an increase in use of the habitat consistent with the concurrent blue whale migration in the area. A clear diel pattern in which upsweep calls were predominately detected during dusk and night hours was identified, indicating that ESPSRW are likely foraging during daylight hours, as upsweep calls are known to be inversely related to foraging behavior. We also quantified noise levels in the frequency range of their communication (100 Hz third octave) to understand the change in active space whales may be experiencing. We measured noise levels from 90 dB re 1 µPa to 111 dB re 1 µPa (5th and 95th percentile), a 21 dB fluctuation that results in an order-of-magnitude decrease in active space area. We identified sources of high noise at or above the 75th percentile as predominately blue and humpback whale calls (occurring in 71.6% of total sampled minutes) and ship noise (occurring in 69.4% of total sampled minutes). Ship noise was responsible for outliers in excess of 140 dB re 1 µPa. In a population as diminished as ESPSRW, such disruptions of their communication range could result in significant barriers to maintaining contact with conspecifics. Passive acoustic monitoring is a powerful tool for monitoring populations as rarely sighted as ESPSRW. Understanding trends in presence and behavior as well as potential sources of disruption of their calling behavior is vital to determining conservation measures that will be most effective toward helping this critically endangered population.
    Description: Support from a private foundation in Chile, Fundacion MERI
    Keywords: Eastern South Pacific southern right whales ; Marine bioacoustics ; Chile ; Diel patterns ; Upsweep calls ; Marine conservation
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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