Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia

The Irrawaddy dolphin (Orcaella brevirostris) is the most common cetacean species inhabiting the coastal waters of the main estuaries of Sarawak. Their habitats are highly overlapping with the areas of intensive use by human activities, which have evolved potential threats to their very survival. Th...

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Main Author:	James Anak Bali
Format:	Thesis
Language:	English English
Published:	2016
Subjects:	QL605-739.8 Chordates Vertebrates
Online Access:	https://eprints.ums.edu.my/id/eprint/39313/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/39313/2/FULLTEXT.pdf
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id	my-ums-ep.39313
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spelling	my-ums-ep.393132024-07-31T03:55:57Z Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia 2016 James Anak Bali QL605-739.8 Chordates. Vertebrates The Irrawaddy dolphin (Orcaella brevirostris) is the most common cetacean species inhabiting the coastal waters of the main estuaries of Sarawak. Their habitats are highly overlapping with the areas of intensive use by human activities, which have evolved potential threats to their very survival. The study was conducted in Rajang and Saribas rivers, Sarawak with the objectives to determine their spatial and temporal occurrence and distribution, density and abundance patterns, their association with environmental water parameters, and to identify their ‘hot spot’ area. Data collection was carried out from April 2009 to October 2010. Surveys were conducted using modified boat strip-transect technique, with the width of the river as the strip width for each transects and each river was divided into segments. Irrawaddy dolphins were found in all segments of both Rajang and Saribas rivers but they were not distributed evenly. Higher mean sighting frequency, mean number of individual sighted per survey, sighting rate, probability of sighting, density and abundance of Irrawaddy dolphins were recorded at the lower river segment of Rajang and Saribas rivers. Probability of sighting was highly significant between the Kuala Rajang-Sarikei and Sarikei-Sibu segments (McNemar:  =38.726, df=1, p=0.000). Probability of sighting was highly significant between the Kuala Saribas and and Pusa-Sebemban segments in Saribas River (McNemar:  =37.770, df=1, p=0.000). The density (Mann-Whitney: U=28.0, n=9 and 7, p=0.758) and abundance (Mann-Whitney: U=24.0, n= 9 and 7, p=0.470) of animals between the river segments in Rajang River are not statistically different. There is no statistically significicant different on density (Mann-Whitney: U=24.0, n=12 and 8, p=0.069) and abundance (Mann-Whitney: U=23.0, n=12 and 8, p=0.57) of animals between the river segments in Saribas River. The probability of sighting between the seasons in both Rajang and Saribas rivers was not statistical significant difference. The abundance of O. brevirostris was not statistically different between seasons for both in Rajang River (Kruskall-Wallis: H=2.768, df=2, p=0.251) and Saribas River (Kruskall-Wallis: H=0.323, df=2, p=0.851). Distribution of O. brevirostris in Rajang River is significantly associated with salinity with weak correlation, while in Saribas River their distribution is significantly associated with turbidity, surface water temperature and salinity with water temperature has strong negative correlation. The ‘hot spot’ of O. brevirostris in Rajang River was identified between Sungai Sebubal to Sungai Barong while in Saribas River, the area is situated between the waters of Kampung Sepinang-Kampung Beladin Hilir. The conservation and protection of O. brevirostris and their habitats in the two river systems need to be managed holistictically with specific recommendations on conservation education to raise public awareness about the importance of protecting the new identified ‘hot spot’ areas, developed the the newly identified ‘hot spots’ as new eco-tourism tousim site for dolphin watching and continue carry out more detail researches to overcome the knowledge gaps that required to produce a ‘Species Conservation Management Plan’ for O. brevirostris in these areas. 2016 Thesis https://eprints.ums.edu.my/id/eprint/39313/ https://eprints.ums.edu.my/id/eprint/39313/1/24%20PAGES.pdf text en public https://eprints.ums.edu.my/id/eprint/39313/2/FULLTEXT.pdf text en validuser masters Universiti Malaysia Sabah Institut Penyelidikan Marin Borneo
institution	Universiti Malaysia Sabah
collection	UMS Institutional Repository
language	English English
topic	QL605-739.8 Chordates Vertebrates
spellingShingle	QL605-739.8 Chordates Vertebrates James Anak Bali Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia
description	The Irrawaddy dolphin (Orcaella brevirostris) is the most common cetacean species inhabiting the coastal waters of the main estuaries of Sarawak. Their habitats are highly overlapping with the areas of intensive use by human activities, which have evolved potential threats to their very survival. The study was conducted in Rajang and Saribas rivers, Sarawak with the objectives to determine their spatial and temporal occurrence and distribution, density and abundance patterns, their association with environmental water parameters, and to identify their ‘hot spot’ area. Data collection was carried out from April 2009 to October 2010. Surveys were conducted using modified boat strip-transect technique, with the width of the river as the strip width for each transects and each river was divided into segments. Irrawaddy dolphins were found in all segments of both Rajang and Saribas rivers but they were not distributed evenly. Higher mean sighting frequency, mean number of individual sighted per survey, sighting rate, probability of sighting, density and abundance of Irrawaddy dolphins were recorded at the lower river segment of Rajang and Saribas rivers. Probability of sighting was highly significant between the Kuala Rajang-Sarikei and Sarikei-Sibu segments (McNemar:  =38.726, df=1, p=0.000). Probability of sighting was highly significant between the Kuala Saribas and and Pusa-Sebemban segments in Saribas River (McNemar:  =37.770, df=1, p=0.000). The density (Mann-Whitney: U=28.0, n=9 and 7, p=0.758) and abundance (Mann-Whitney: U=24.0, n= 9 and 7, p=0.470) of animals between the river segments in Rajang River are not statistically different. There is no statistically significicant different on density (Mann-Whitney: U=24.0, n=12 and 8, p=0.069) and abundance (Mann-Whitney: U=23.0, n=12 and 8, p=0.57) of animals between the river segments in Saribas River. The probability of sighting between the seasons in both Rajang and Saribas rivers was not statistical significant difference. The abundance of O. brevirostris was not statistically different between seasons for both in Rajang River (Kruskall-Wallis: H=2.768, df=2, p=0.251) and Saribas River (Kruskall-Wallis: H=0.323, df=2, p=0.851). Distribution of O. brevirostris in Rajang River is significantly associated with salinity with weak correlation, while in Saribas River their distribution is significantly associated with turbidity, surface water temperature and salinity with water temperature has strong negative correlation. The ‘hot spot’ of O. brevirostris in Rajang River was identified between Sungai Sebubal to Sungai Barong while in Saribas River, the area is situated between the waters of Kampung Sepinang-Kampung Beladin Hilir. The conservation and protection of O. brevirostris and their habitats in the two river systems need to be managed holistictically with specific recommendations on conservation education to raise public awareness about the importance of protecting the new identified ‘hot spot’ areas, developed the the newly identified ‘hot spots’ as new eco-tourism tousim site for dolphin watching and continue carry out more detail researches to overcome the knowledge gaps that required to produce a ‘Species Conservation Management Plan’ for O. brevirostris in these areas.
format	Thesis
qualification_level	Master's degree
author	James Anak Bali
author_facet	James Anak Bali
author_sort	James Anak Bali
title	Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia
title_short	Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia
title_full	Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia
title_fullStr	Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia
title_full_unstemmed	Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia
title_sort	population ecology of irrawaddy dolphin (orcaella brevirostris) in rajang and saribas rivers, sarawak, malaysia
granting_institution	Universiti Malaysia Sabah
granting_department	Institut Penyelidikan Marin Borneo
publishDate	2016
url	https://eprints.ums.edu.my/id/eprint/39313/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/39313/2/FULLTEXT.pdf
_version_	1811770500478664704

Population ecology of irrawaddy dolphin (Orcaella brevirostris) in Rajang and Saribas Rivers, Sarawak, Malaysia

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