Cerchio, S.,Willson, A.,Leroy, E.C.,Muirhead, C.,Al Harthi, S.,baldwin, R,Cholewiak, D.,Collins, T.,Minton, Gianna,Rasoloarijao, T.,Rogers, T.,Sarrouf Willson, M.
A new blue whale song-type described for the Arabian Sea and Western Indian Ocean Technical Report
no. 513, 2020.
Abstract | Links | BibTeX | Tags: acoustic detection, Arabian Sea, balaenoptera musculus, behaviour, Blue whale, breeding grounds, Oman, Passive acoustic detection, song
@techreport{,
title = {A new blue whale song-type described for the Arabian Sea and Western Indian Ocean },
author = {Cerchio, S.,Willson, A.,Leroy, E.C.,Muirhead, C.,Al Harthi, S.,baldwin, R,Cholewiak, D.,Collins, T.,Minton, Gianna,Rasoloarijao, T.,Rogers, T.,Sarrouf Willson, M.},
url = {https://arabianseawhalenetwork.org/wp-content/uploads/2020/06/sc_68b_info_28_-new-blue-whale-call-from-oman-2.pdf},
year = {2020},
date = {2020-01-01},
journal = {Report Presented to the Scientific Committee meeting of the International Whaling Commission},
number = {513},
publisher = {IWC},
abstract = {Blue whales in the Indian Ocean (IO) are currently thought to represent two or three subspecies (Balaenoptera musculus intermedia, B. m. brevicauda, B. m. indica), and are structured into four populations with diagnostic song-types. Here we describe a previously unreported song-type that implies the existence of a population that has been undetected or conflated with another population. The song-type was recorded off Oman in the northern IO/Arabian Sea, off the western Chagos Archipelago in the equatorial central IO, and off Madagascar in the southwestern IO. As this is the only blue whale song that has been identified in the western Arabian Sea, we label it the “Oman” song-type to distinguish it from other regionally classified song-types. Spatiotemporal variation at the three sites suggested a distribution west of 70°E, with potential affinity for the northern IO/Arabian Sea, and only minor presence in the southwestern IO. Timing of presence off Oman suggests that intensive illegal Soviet whaling that took 1,294 blue whales in the 1960s likely targeted this population, as opposed to the more widely spread “Sri Lanka” acoustic population as previously assumed. Based upon geographic distribution and potential aseasonal reproduction found in the Soviet catch data, we suggest that if there is a northern Indian Ocean subspecies (B. m. c.f. indica), it is likely this population. Moreover, the potentially restricted range, intensive historic whaling, and the fact that the song-type has been previously undetected, suggests a small population that is in critical need of status assessment and conservation action. },
keywords = {acoustic detection, Arabian Sea, balaenoptera musculus, behaviour, Blue whale, breeding grounds, Oman, Passive acoustic detection, song},
pubstate = {published},
tppubtype = {techreport}
}
Blue whales in the Indian Ocean (IO) are currently thought to represent two or three subspecies (Balaenoptera musculus intermedia, B. m. brevicauda, B. m. indica), and are structured into four populations with diagnostic song-types. Here we describe a previously unreported song-type that implies the existence of a population that has been undetected or conflated with another population. The song-type was recorded off Oman in the northern IO/Arabian Sea, off the western Chagos Archipelago in the equatorial central IO, and off Madagascar in the southwestern IO. As this is the only blue whale song that has been identified in the western Arabian Sea, we label it the “Oman” song-type to distinguish it from other regionally classified song-types. Spatiotemporal variation at the three sites suggested a distribution west of 70°E, with potential affinity for the northern IO/Arabian Sea, and only minor presence in the southwestern IO. Timing of presence off Oman suggests that intensive illegal Soviet whaling that took 1,294 blue whales in the 1960s likely targeted this population, as opposed to the more widely spread “Sri Lanka” acoustic population as previously assumed. Based upon geographic distribution and potential aseasonal reproduction found in the Soviet catch data, we suggest that if there is a northern Indian Ocean subspecies (B. m. c.f. indica), it is likely this population. Moreover, the potentially restricted range, intensive historic whaling, and the fact that the song-type has been previously undetected, suggests a small population that is in critical need of status assessment and conservation action.
Cerchio, S,Willson, A.,Muirhead, C.,Minton, G.,Collins, T.,Baldwin, R.,Sarrouf Willson, M.,Al Harthi, S.
Preliminary Report on Long-term Detection of Arabian Sea Humpback Whale Vocalizations off Oman Technical Report
no. 343, 2016.
Abstract | BibTeX | Tags: acoustic detection, Arabian Sea, behaviour, breeding grounds, Humpback Whale, megaptera novaeangliae, Oman, Passive acoustic detection, song
@techreport{,
title = {Preliminary Report on Long-term Detection of Arabian Sea Humpback Whale Vocalizations off Oman},
author = {Cerchio, S,Willson, A.,Muirhead, C.,Minton, G.,Collins, T.,Baldwin, R.,Sarrouf Willson, M.,Al Harthi, S.},
year = {2016},
date = {2016-01-01},
journal = {Report Presented to the Scientific Committee meeting of the International Whaling Commission},
number = {343},
publisher = {IWC},
abstract = {This report presents an overview of the progress to date on the humpback whale detection
component of the Arabian Sea Humpback Whale Acoustic Research program off Oman. Three
archival acoustic recorders were deployed at sites in two regions for approximately one year each,
in Hallaniyats Bay during 2011/2012, and the Gulf of Masirah during 2012/2013. Performance of
recorders varied among deployments, but despite some challenges due to equipment failures we
succeeded in documenting spatiotemporal patterns in the presence of humpback whales in a large
dataset. Several key findings broaden our understanding of the Arabian Sea humpback whale
population off Oman. There appears a strong seasonal component to the use of song by this
population, primarily from November through May, which is congruent with the Northern
Hemisphere breeding cycle and singing season. Throughout this period, singing was heard in both
Hallaniyats Bay and the Gulf of Masirah, separated by approximately 400km, indicating that the
population utilizes both of these regions. However, there was a much stronger presence in
Hallaniyats Bay, with song heard nearly 24 hours/day during the peak months, and song detected
simultaneously at multiple sites across the Bay. Previous boat-based survey data indicated similar
trends, however, given limitation in the duration of this fieldwork the current acoustic dataset
provides a more reliable indication of this population’s breeding related activity. This suggests that
the Hallaniyats Bay might serve as a more important habitat for breeding activity than the
monitored region of the Gulf of Masirah. There also appeared to be a subtle northward shift in
distribution of detections as the singing season progressed, both within Hallaniyats Bay, and from
Hallaniyats Bay to the Gulf of Masirah, suggesting a seasonal shift in distribution for singing males.
During the summer and autumn months, very little song was detected, however sparse detections
indicate that whales are present in both regions during at least some of this period. It is
recommended that similar acoustic monitoring be conducted in all range states of the population to
elucidate spatiotemporal distribution throughout the Arabian Sea.},
keywords = {acoustic detection, Arabian Sea, behaviour, breeding grounds, Humpback Whale, megaptera novaeangliae, Oman, Passive acoustic detection, song},
pubstate = {published},
tppubtype = {techreport}
}
This report presents an overview of the progress to date on the humpback whale detection
component of the Arabian Sea Humpback Whale Acoustic Research program off Oman. Three
archival acoustic recorders were deployed at sites in two regions for approximately one year each,
in Hallaniyats Bay during 2011/2012, and the Gulf of Masirah during 2012/2013. Performance of
recorders varied among deployments, but despite some challenges due to equipment failures we
succeeded in documenting spatiotemporal patterns in the presence of humpback whales in a large
dataset. Several key findings broaden our understanding of the Arabian Sea humpback whale
population off Oman. There appears a strong seasonal component to the use of song by this
population, primarily from November through May, which is congruent with the Northern
Hemisphere breeding cycle and singing season. Throughout this period, singing was heard in both
Hallaniyats Bay and the Gulf of Masirah, separated by approximately 400km, indicating that the
population utilizes both of these regions. However, there was a much stronger presence in
Hallaniyats Bay, with song heard nearly 24 hours/day during the peak months, and song detected
simultaneously at multiple sites across the Bay. Previous boat-based survey data indicated similar
trends, however, given limitation in the duration of this fieldwork the current acoustic dataset
provides a more reliable indication of this population’s breeding related activity. This suggests that
the Hallaniyats Bay might serve as a more important habitat for breeding activity than the
monitored region of the Gulf of Masirah. There also appeared to be a subtle northward shift in
distribution of detections as the singing season progressed, both within Hallaniyats Bay, and from
Hallaniyats Bay to the Gulf of Masirah, suggesting a seasonal shift in distribution for singing males.
During the summer and autumn months, very little song was detected, however sparse detections
indicate that whales are present in both regions during at least some of this period. It is
recommended that similar acoustic monitoring be conducted in all range states of the population to
elucidate spatiotemporal distribution throughout the Arabian Sea.
component of the Arabian Sea Humpback Whale Acoustic Research program off Oman. Three
archival acoustic recorders were deployed at sites in two regions for approximately one year each,
in Hallaniyats Bay during 2011/2012, and the Gulf of Masirah during 2012/2013. Performance of
recorders varied among deployments, but despite some challenges due to equipment failures we
succeeded in documenting spatiotemporal patterns in the presence of humpback whales in a large
dataset. Several key findings broaden our understanding of the Arabian Sea humpback whale
population off Oman. There appears a strong seasonal component to the use of song by this
population, primarily from November through May, which is congruent with the Northern
Hemisphere breeding cycle and singing season. Throughout this period, singing was heard in both
Hallaniyats Bay and the Gulf of Masirah, separated by approximately 400km, indicating that the
population utilizes both of these regions. However, there was a much stronger presence in
Hallaniyats Bay, with song heard nearly 24 hours/day during the peak months, and song detected
simultaneously at multiple sites across the Bay. Previous boat-based survey data indicated similar
trends, however, given limitation in the duration of this fieldwork the current acoustic dataset
provides a more reliable indication of this population’s breeding related activity. This suggests that
the Hallaniyats Bay might serve as a more important habitat for breeding activity than the
monitored region of the Gulf of Masirah. There also appeared to be a subtle northward shift in
distribution of detections as the singing season progressed, both within Hallaniyats Bay, and from
Hallaniyats Bay to the Gulf of Masirah, suggesting a seasonal shift in distribution for singing males.
During the summer and autumn months, very little song was detected, however sparse detections
indicate that whales are present in both regions during at least some of this period. It is
recommended that similar acoustic monitoring be conducted in all range states of the population to
elucidate spatiotemporal distribution throughout the Arabian Sea.