Bryde’s whales (Balaenoptera edeni) sighting
In recent news from the region, two baleen whales were spotted by fishermen; Mr. Meysam Sajadi Far and Amir Jamshidiat from Kangan, at two different locations in the Persian* Gulf on the 20th and 21st of June 2023. The fishermen shared photos and videos of the sightings with ASWN members, Plan4theLand, who, in turn, shared photos with ASWN members with particular expertise in identifying baleen whales. It was agreed that the whales are very likely to be Bryde’s whales (Balaenoptera edeni) based upon some discernible features and elimination of other candidate species.
Caption: Locations of two Bryde’s whale sightings reported by fishers to ASWN Partners in Iran, Plan4theLand.
Sightings of Bryde’s whales are fairly common throughout the Northern Indian Ocean, including in the Persian* Gulf. ASWN members have reported many sightings over the years, and the ASWN Google Group email list has proven a good forum for sharing these sightings and confirming species’ identifications. The region hosts two 2 genetically recognized, but poorly studied subspecies of Bryde’s whale: the larger, offshore form, Balaenoptera edeni brydei, and the smaller, coastal form, Balaenoptera edeni edeni (Kershaw et al. 2013). Furthermore, researchers are always on the lookout for the more rarely documented Omura’s whale (Balaenotera omura) (Cerchio et al. 2019), which is similar in general size and warm-water range, and is known to occur in the region, based on a confirmed stranding record from Qeshm, Iran (Ranjbar et al. 2016). In the recent observations of these two baleen whales, photographic evidence clearly indicates that they are not Omura’s whales, leaving Bryde’s whale as the most likely alternative since other small to medium size balaenopterid (rorquals) whales are absent from the Gulf.
Reports from fishing communities and recreational vessels or other ‘citizen scientists’ are very helpful in learning more about the distribution of these whales in the region. This information plays a vital role in regional research and conservation efforts. During the 2023 IWC Scientific Committee meeting, the Committee discussed the importance of further investigations to better understand the drivers of the distribution and relative abundance of Bryde’s whales in the Arabian region.
Recent acoustic data from southern oman (Cerchio et al. 2023) indicated the consistent presence throughout the year of a vocalisation likely to be from Bryde’s whale, and the results of boat-based surveys (Minton et al. 2023) reflected an inverse relationship between detections of Bryde’s whales and humpback whales, with authors speculating that both species’ relative abundance may vary in relation to oceanographic conditions that favour one type of prey over another. There were several recommendations to continue this work and, when possible, combine observational and acoustic datasets within the Arabian Sea to advance our understanding of whale habitat use and distribution in the region. The sub-committee recommended regional collaboration to continue to collect information, and to conduct more dedicated research to better address the status of this species. The ASWN hopes to foster this regional collaboration and to support members in their efforts to foster effective reporting networks that will facilitate the contribution of more valuable sightings like this most recent one from Iran.
- Cerchio, S., Willson, A., Cholewiak, D., Sackett, M., Al Harthi, S., Baldwin, R., Collins, T., Minton, G., Sarrouf Willson, M., 2023. Acoustic monitoring for baleen whale vocalizations off southern Oman, 2020 to 2022. Document presented to the Scientific Committee of the International Whaling Commission SC/69A/CMP/12/Rev1, 18.
- Cerchio S, Yamada TK and Brownell RL Jr (2019) Global Distribution of Omura’s Whales (Balaenoptera omurai) and Assessment of Range-Wide Threats. Front. Mar. Sci. 6:67. doi: 10.3389/fmars.2019.00067
- Kershaw, F., Leslie, M.S., Collins, T., Mansur, R.M., Smith, B.D., Minton, G., Baldwin, R., LeDuc, R.G., Anderson, R.C., Brownell, R.L., 2013. Population differentiation of 2 forms of Bryde’s Whales in the Indian and Pacific Oceans. Journal of Heredity 104, 755-764.
- Minton, G., Willson, A., Christiansen, F., Al Jabri, A., Al Lawati, R., Al Aamri, A., Baldwin, R., Collins, T., Cerchio, S., Willson, M.S., 2023. Cetacean surveys in Oman November 2019- November 2022. Docment presented to the Scientific Committee of the International Whaling Commission SC/69A/CMP/07, 19.
- Ranjbar, S., Dakhteh, S. M. H., and Van Waerebeek, K. (2016). Omura’s whale Balaenoptera omurai stranding on Qeshm Island, Iran, Persian Gulf: further evidence for a wide (sub)tropical distribution. J. Mar. Biol. Oceanogr. 5:3. doi: 10.4172/2324-8661.1000161