A new blue whale song-type described for the Arabian Sea and Western Indian Ocean

Blue whales Balaenoptera musculus in the Indian Ocean (IO) are currently thought to represent 2 or 3 subspecies (B. m. intermedia, B. m. brevicauda, B. m. indica), and believed to be structured into 4 populations, each with a diagnostic song-type. Here we describe a previously unreported song-type that implies the probable existence of a population that has been undetected or conflated with another population. The novel 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 ‘Northwest Indian Ocean’ song-type to distinguish it from other regional song-types. Spatiotemporal variation 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 suggested that intensive illegal Soviet whaling that took 1294 blue whales in the 1960s likely targeted this population, as opposed to the more widely distributed ‘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 IO subspecies (B. m. 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.

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First occurrence of the moray eel Gymnothorax prolatus Sasaki & Amaoka, 1991 (Teleostei: Anguilliformes: Muraenidae) from the northern Indian Ocean

Marine Biodiversity Records ◽

10.1017/s1755267215000834 ◽

2015 ◽

Vol 8 ◽

Cited By ~ 1

Author(s):

Anil Mohapatra ◽

Dipanjan Ray ◽

David G. Smith

Keyword(s):

Indian Ocean ◽

Arabian Sea ◽

Western Indian Ocean ◽

Northern Indian Ocean ◽

The North ◽

First Occurrence ◽

The Indian Ocean ◽

First Time ◽

North Western ◽

Moray Eel

Gymnothorax prolatusis recorded for the first time from the Indian Ocean on the basis of four specimens collected in the Bay of Bengal off India and one from the Arabian Sea off Pakistan. These records extend the range of the species from Taiwan to the north-western Indian Ocean.

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South Georgia blue whales five decades after the end of whaling

Endangered Species Research ◽

10.3354/esr01077 ◽

2020 ◽

Vol 43 ◽

pp. 359-373

Author(s):

SV Calderan ◽

A Black ◽

TA Branch ◽

MA Collins ◽

N Kelly ◽

...

Keyword(s):

Frequency Analysis ◽

Current Distribution ◽

Line Transect ◽

Blue Whale ◽

South Georgia ◽

Photo Identification ◽

Time Period ◽

Acoustic Surveys ◽

The 1960S ◽

Blue Whales

Blue whales Balaenoptera musculus at South Georgia were heavily exploited during 20th century industrial whaling, to the point of local near-extirpation. Although legal whaling for blue whales ceased in the 1960s, and there were indications of blue whale recovery across the wider Southern Ocean area, blue whales were seldom seen in South Georgia waters in subsequent years. We collated 30 yr of data comprising opportunistic sightings, systematic visual and acoustic surveys and photo-identification to assess the current distribution of blue whales in the waters surrounding South Georgia. Over 34000 km of systematic survey data between 1998 and 2018 resulted in only a single blue whale sighting, although opportunistic sightings were reported over that time period. However, since 2018 there have been increases in both sightings of blue whales and detections of their vocalisations. A survey in 2020 comprising visual line transect surveys and directional frequency analysis and recording (DIFAR) sonobuoy deployments resulted in 58 blue whale sightings from 2430 km of visual effort, including the photo-identification of 23 individual blue whales. Blue whale vocalisations were detected on all 31 sonobuoys deployed (114 h). In total, 41 blue whales were photo-identified from South Georgia between 2011 and 2020, none of which matched the 517 whales in the current Antarctic catalogue. These recent data suggest that blue whales have started to return to South Georgia waters, but continued visual and acoustic surveys are required to monitor any future changes in their distribution and abundance.

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RADseq analyses reveal concordant Indian Ocean biogeographic and phylogeographic boundaries in the reef fish Dascyllus trimaculatus

Royal Society Open Science ◽

10.1098/rsos.172413 ◽

2019 ◽

Vol 6 (5) ◽

pp. 172413 ◽

Cited By ~ 2

Author(s):

E. M. Salas ◽

G. Bernardi ◽

M. L. Berumen ◽

M. R. Gaither ◽

L. A. Rocha

Keyword(s):

Indian Ocean ◽

Red Sea ◽

Arabian Sea ◽

Population Level ◽

Western Indian Ocean ◽

Genetic Connectivity ◽

Nucleotide Polymorphisms ◽

Population Genetic Analysis ◽

Outlier Loci ◽

Biogeographic Provinces

Population genetic analysis is an important tool for estimating the degree of evolutionary connectivity in marine organisms. Here, we investigate the population structure of the three-spot damselfish Dascyllus trimaculatus in the Red Sea, Arabian Sea and Western Indian Ocean, using 1174 single nucleotide polymorphisms (SNPs). Neutral loci revealed a signature of weak genetic differentiation between the Northwestern (Red Sea and Arabian Sea) and Western Indian Ocean biogeographic provinces. Loci potentially under selection (outlier loci) revealed a similar pattern but with a much stronger signal of genetic structure between regions. The Oman population appears to be genetically distinct from all other populations included in the analysis. While we could not clearly identify the mechanisms driving these patterns (isolation, adaptation or both), the datasets indicate that population-level divergences are largely concordant with biogeographic boundaries based on species composition. Our data can be used along with genetic connectivity of other species to identify the common genetic breaks that need to be considered for the conservation of biodiversity and evolutionary processes in the poorly studied Western Indian Ocean region.

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Air mass motion, temperature, and humidity over the Arabian Sea and western Indian Ocean during the INDOEX intensive phase, as obtained from a set of superpressure drifting balloons

Journal of Geophysical Research Atmospheres ◽

10.1029/2001jd001120 ◽

2002 ◽

Vol 107 (D19) ◽

Cited By ~ 13

Author(s):

Christian Ethé

Keyword(s):

Indian Ocean ◽

Arabian Sea ◽

Western Indian Ocean ◽

Mass Motion ◽

Intensive Phase ◽

Air Mass ◽

Temperature And Humidity

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Multiple pygmy blue whale acoustic populations in the Indian Ocean: whale song identifies a possible new population

Scientific Reports ◽

10.1038/s41598-021-88062-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Emmanuelle C. Leroy ◽

Jean-Yves Royer ◽

Abigail Alling ◽

Ben Maslen ◽

Tracey L. Rogers

Keyword(s):

Indian Ocean ◽

Southern Hemisphere ◽

Tropical Indian Ocean ◽

Blue Whale ◽

The North ◽

Central Indian Ocean ◽

Commercial Whaling ◽

The Indian Ocean ◽

And Migration ◽

Blue Whales

AbstractBlue whales were brought to the edge of extinction by commercial whaling in the twentieth century and their recovery rate in the Southern Hemisphere has been slow; they remain endangered. Blue whales, although the largest animals on Earth, are difficult to study in the Southern Hemisphere, thus their population structure, distribution and migration remain poorly known. Fortunately, blue whales produce powerful and stereotyped songs, which prove an effective clue for monitoring their different ‘acoustic populations.’ The DGD-Chagos song has been previously reported in the central Indian Ocean. A comparison of this song with the pygmy blue and Omura’s whale songs shows that the Chagos song are likely produced by a distinct previously unknown pygmy blue whale population. These songs are a large part of the underwater soundscape in the tropical Indian Ocean and have been so for nearly two decades. Seasonal differences in song detections among our six recording sites suggest that the Chagos whales migrate from the eastern to western central Indian Ocean, around the Chagos Archipelago, then further east, up to the north of Western Australia, and possibly further north, as far as Sri Lanka. The Indian Ocean holds a greater diversity of blue whale populations than thought previously.

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Seasonal Occurrence of Sympatric Blue Whale Subspecies: the Chilean and Southeast Indian Ocean Pygmy Blue Whales With the Antarctic Blue Whale

Frontiers in Marine Science ◽

10.3389/fmars.2021.671145 ◽

2021 ◽

Vol 8 ◽

Author(s):

Gary Truong ◽

Tracey L. Rogers

Keyword(s):

Indian Ocean ◽

Southern Hemisphere ◽

Lower Latitude ◽

Seasonal Patterns ◽

Austral Winter ◽

Blue Whale ◽

Acoustic Data ◽

The Pacific ◽

The Antarctic ◽

Blue Whales

There are multiple blue whale acoustic populations found across the Southern Hemisphere. The different subspecies of blue whales feed in separate areas, but during their migration to lower-latitude breeding areas each year, Antarctic blue whales become sympatric with pygmy and Chilean blue whales. Few studies have compared the degree of this overlap of the Southern Hemisphere blue whale subspecies across ocean basins during their migration. Using up to 16 years of acoustic data, this study compares the broad seasonal presence of Antarctic blue whales, Chilean blue whales, and Southeast Indian Ocean (SEIO) pygmy blue whales across the Pacific and Indian Oceans. Antarctic blue whales were sympatric with the other two blue whale subspecies during the migrating season of every year. Despite this overlap, Chilean and pygmy blue whale detections peaked earlier during the austral autumn (April–May) while Antarctic blue whale detections peaked later during the austral winter (June). Chilean (Pacific Ocean) and SEIO (Indian Ocean) pygmy blue whales showed similar seasonal patterns in detections despite occurring in different ocean basins. Though we have shown that Antarctic blue whales have the potential to encounter other blue whale subspecies during the breeding season, these distinct groups have remained acoustically stable through time. Further understanding of where these whales migrate will enable a better insight as to how these subspecies continue to remain separate.

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The status of Pteropus livingstonii in the Comores

Oryx ◽

10.1017/s0030605300028404 ◽

1994 ◽

Vol 28 (2) ◽

pp. 107-114 ◽

Cited By ~ 6

Author(s):

P. F. Reason ◽

W. J. Trewhella

Keyword(s):

Indian Ocean ◽

Captive Breeding ◽

Action Plan ◽

Western Indian Ocean ◽

Small Population ◽

Fruit Bats ◽

Major Threat ◽

The Status ◽

Comoro Islands ◽

Population Numbers

Pteropus livingstonii is one of the world's most endangered fruit bats, with a small population limited to two of the Comoro Islands (western Indian Ocean), Surveys carried out in 1992 and 1993 suggest that the population numbers around 150 individuals. Loss of habitat through deforestation is the major threat to this species. Old World Fruit Bats: An Action Plan for their Conservation recommends captive-breeding of this species as one of 20 priority projects. The FFPS helped fund both the preparation of the Action Plan and the field projects described in this paper.

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