Omura's whale Balaenoptera omurai stranding on Qeshm Island, Iran, Persian Gulf:Further Evidence for a Wide (Sub) Tropical Distribution

Ranjbar, Sharif; Dakhteh, Seyed Mohammad Hashem; Waerebeek, Koen Van

doi:10.4172/2324-8661.1000161

Cited by 6 publications

(3 citation statements)

References 4 publications

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“…Western North Indian Ocean (see Figure 5 for Detail) Iran Based on direct external examination and photographs of a stranded specimen from Qeshm Island, Strait of Hormuz, Iran, Ranjbar et al (2016) identified a 3.97 m calf rorqual as an Omura's whale, however, no specimens were preserved from this whale. Omura's whales may not be common in this region as none were found nearby among 18 specimens from Oman that were genetically identified as either B. edeni edeni or B. edeni brydei (Kershaw et al, 2013).…”

Section: France/new Caledoniamentioning

confidence: 99%

Global Distribution of Omura’s Whales (Balaenoptera omurai) and Assessment of Range-Wide Threats

2019

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When the Omura's whale (Balaenoptera omurai) was first described in 2003, it was known from only three locations: the southern Sea of Japan, and the vicinities of the Cocos (Keeling) Islands and Solomon Islands. Work over the following decade suggested a range limited to the eastern Indo-Pacific, but more recent discoveries in the western Indian Ocean and Atlantic Ocean suggested a more widespread range than previously thought. Here we use all available sources of information, including published papers, unpublished reports, and internet-based accounts, substantiated through genetic, morphological, photographic and acoustic documentation, to compile accounts of Omura's whales globally. Reports increased precipitously since 2015 after publication of the first detailed external description of the species, reflecting the impact of the recently elevated awareness of the species. We report 161 accounts from 95 locales in the waters of 21 range states, and found that the species is widely distributed in primarily tropical and warm-temperate locations. Currently it is known from all ocean basins with the exception of the central and eastern Pacific. The majority of accounts remain in the eastern Indo-Pacific suggesting a potentially recent range expansion from this region. There is a strong tendency toward a coastal and neritic distribution, although there are also several pelagic records. A predominantly near-coastal distribution places Omura's whale at risk from anthropogenic activities throughout its range, and its tropical distribution in often remote and poorly monitored areas makes adequately documenting and assessing threats challenging. We assess documented threats in light of the reported species' range, and found threats from, at minimum, ship strikes, fisheries bycatch and entanglement, local directed hunting, petroleum exploration (seismic surveys), and coastal industrial development. Current evidence indicates that at least some populations are non-migratory with local, potentially restricted ranges. Furthermore, there is low genetic diversity documented throughout its global distribution. Given the species may be characterized by small local populations, it may be particularly vulnerable to impacts from existing regional anthropogenic threats. We recommend that focused work be conducted to locate and study local populations, assess potential population isolation, and determine conservation status and specific anthropogenic threats across the species' range.

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Section: France/new Caledoniamentioning

confidence: 99%

Global Distribution of Omura’s Whales (Balaenoptera omurai) and Assessment of Range-Wide Threats

2019

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“…This in turn may explain similarities in pigmentation patterns such as those we observed and which at first sight appeared to differ from those of a few individuals from other areas where pigmentation patterns were partly visible (Western Australia, Persian Gulf) 10,11 . However, the skin of the Western Australian specimen had likely undergone post-mortem darkening 10 and the skin of the Persian Gulf specimen presented cuts, scratches and abrasions on part of its surface (we ascribe these injuries to a collision with a ship), erasing part of the pigmentation 11 . The fact that a similar three-dark chevrons pattern also characterized an individual documented from off Komodo island 1 and another one from off southern Sri Lanka 5 suggests that it is, at least, a pattern frequently encountered in Omura's whales from the Indian-Ocean.…”

Section: Resultsmentioning

confidence: 99%

A feeding aggregation of Omura‘s whale Balaenoptera omurai off Nosy Be, Mozambique Channel

Laboute

Borsa

2018

Preprint

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A feeding aggregation of Omura’s whales Balaenoptera omurai was documented off Nosy Be Island at the northeastern entrance of Mozambique Channel in November 1994. Underwater photographs of live individuals illustrated sub-surface skimming as main feeding behaviour, with small crustaceans, small jellyfish, and other gelatinous micronecton identified as prey. A precise description of the whales’ pigmentation patterns completes previous descriptions from the recent literature.

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“…Sightings of Omura's whale B. omurai have not yet been reported in the Arabian Sea and appear not to be among sightings of balaenopterids off Oman (Minton et al 2010), although a stranding has been reported off Iran (Ranjbar et al 2016). Omura's whale song has now been described for several locations from the mid-equatorial Atlantic to the Western Indian Ocean to the northwest coast of Australia, with consistent features across this range that are stereotyped and distinctly different from the novel songtype we describe here (Cerchio et al 2015, 2019.…”

Section: Species Attributionmentioning

confidence: 99%

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

Cerchio

Willson

Leroy

et al. 2020

Endang. Species. Res.

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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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Omura's whale Balaenoptera omurai stranding on Qeshm Island, Iran, Persian Gulf:Further Evidence for a Wide (Sub) Tropical Distribution

Cited by 6 publications

References 4 publications

Global Distribution of Omura’s Whales (Balaenoptera omurai) and Assessment of Range-Wide Threats

Global Distribution of Omura’s Whales (Balaenoptera omurai) and Assessment of Range-Wide Threats

A feeding aggregation of Omura‘s whale Balaenoptera omurai off Nosy Be, Mozambique Channel

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

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