Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam
The uniqueness of the Bay of Brunei makes it an ideal place to be inhabited by Irrawaddy dolphins. However, the increasing potential impacts of anthropogenic factors and environmental changes on the dolphins are alarming. The objectives of this study were to determine the seasonal occurrence and dis...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Penerbit Universiti Kebangsaan Malaysia
2021
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| Online Access: | http://journalarticle.ukm.my/18289/ http://journalarticle.ukm.my/18289/1/1.pdf |
| _version_ | 1848814532622811136 |
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| author | Farah Dayana Haji Ismail, Nurlisa Azizul, Saifullah Arifin Jaaman, Azmi Marzuki Muda, Mohd Vol Momin, Bohari Abdullah, Zhang, Xuelei Hairul Masrini Muhamad, |
| author_facet | Farah Dayana Haji Ismail, Nurlisa Azizul, Saifullah Arifin Jaaman, Azmi Marzuki Muda, Mohd Vol Momin, Bohari Abdullah, Zhang, Xuelei Hairul Masrini Muhamad, |
| author_sort | Farah Dayana Haji Ismail, |
| building | UKM Institutional Repository |
| collection | Online Access |
| description | The uniqueness of the Bay of Brunei makes it an ideal place to be inhabited by Irrawaddy dolphins. However, the increasing potential impacts of anthropogenic factors and environmental changes on the dolphins are alarming. The objectives of this study were to determine the seasonal occurrence and distribution, and to estimate the group size of Irrawaddy dolphins in the Bay of Brunei. Surveys were conducted between January 2016 and April 2018. The total distance surveyed was 2,439.2 km in 189.13 h (survey effort = 13,081.93 km.h). Forty-nine groups of Irrawaddy dolphins were recorded with a sighting rate of 0.37 per 100 km.h. Thirteen of the groups were observed with calves. Overall, the group size ranged between 1 and 15 individuals with a mean of 4.5 individuals (SD = 3.3). There was no statistical significance in the number of dolphin sightings between four different monsoon seasons (Northeast, Southwest, April Inter-monsoon, and October Inter-monsoon) (χ2 = 5.66, df = 3, p > 0.05). The number of sightings and number of individuals suggest that Irrawaddy dolphins are residents of the Bay of Brunei and are in need of a conservation management plan. |
| first_indexed | 2025-11-15T00:35:35Z |
| format | Article |
| id | oai:generic.eprints.org:18289 |
| institution | Universiti Kebangasaan Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-15T00:35:35Z |
| publishDate | 2021 |
| publisher | Penerbit Universiti Kebangsaan Malaysia |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | oai:generic.eprints.org:182892022-04-06T05:27:41Z http://journalarticle.ukm.my/18289/ Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam Farah Dayana Haji Ismail, Nurlisa Azizul, Saifullah Arifin Jaaman, Azmi Marzuki Muda, Mohd Vol Momin, Bohari Abdullah, Zhang, Xuelei Hairul Masrini Muhamad, The uniqueness of the Bay of Brunei makes it an ideal place to be inhabited by Irrawaddy dolphins. However, the increasing potential impacts of anthropogenic factors and environmental changes on the dolphins are alarming. The objectives of this study were to determine the seasonal occurrence and distribution, and to estimate the group size of Irrawaddy dolphins in the Bay of Brunei. Surveys were conducted between January 2016 and April 2018. The total distance surveyed was 2,439.2 km in 189.13 h (survey effort = 13,081.93 km.h). Forty-nine groups of Irrawaddy dolphins were recorded with a sighting rate of 0.37 per 100 km.h. Thirteen of the groups were observed with calves. Overall, the group size ranged between 1 and 15 individuals with a mean of 4.5 individuals (SD = 3.3). There was no statistical significance in the number of dolphin sightings between four different monsoon seasons (Northeast, Southwest, April Inter-monsoon, and October Inter-monsoon) (χ2 = 5.66, df = 3, p > 0.05). The number of sightings and number of individuals suggest that Irrawaddy dolphins are residents of the Bay of Brunei and are in need of a conservation management plan. Penerbit Universiti Kebangsaan Malaysia 2021-11 Article PeerReviewed application/pdf en http://journalarticle.ukm.my/18289/1/1.pdf Farah Dayana Haji Ismail, and Nurlisa Azizul, and Saifullah Arifin Jaaman, and Azmi Marzuki Muda, and Mohd Vol Momin, and Bohari Abdullah, and Zhang, Xuelei and Hairul Masrini Muhamad, (2021) Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam. Sains Malaysiana, 50 (11). pp. 3159-3169. ISSN 0126-6039 https://www.ukm.my/jsm/malay_journals/jilid50bil11_2021/KandunganJilid50Bil11_2021.html |
| spellingShingle | Farah Dayana Haji Ismail, Nurlisa Azizul, Saifullah Arifin Jaaman, Azmi Marzuki Muda, Mohd Vol Momin, Bohari Abdullah, Zhang, Xuelei Hairul Masrini Muhamad, Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam |
| title | Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam |
| title_full | Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam |
| title_fullStr | Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam |
| title_full_unstemmed | Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam |
| title_short | Seasonal occurrence, distribution and group size of Irrawaddy dolphins (Orcaella brevirostris) in the bay of Brunei, Brunei Darussalam |
| title_sort | seasonal occurrence, distribution and group size of irrawaddy dolphins (orcaella brevirostris) in the bay of brunei, brunei darussalam |
| url | http://journalarticle.ukm.my/18289/ http://journalarticle.ukm.my/18289/ http://journalarticle.ukm.my/18289/1/1.pdf |