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Brian D Smith - One of the best experts on this subject based on the ideXlab platform.
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clicking in shallow rivers short range echolocation of irrawaddy and ganges river dolphins in a shallow acoustically complex habitat
PLOS ONE, 2013Co-Authors: Frants H Jensen, Alice Rocco, Rubaiyat M Mansur, Brian D Smith, Vincent M Janik, Peter T MadsenAbstract:Toothed whales (Cetacea, odontoceti) use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica) and Irrawaddy dolphins (Orcaella brevirostris) within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB) re 1 µPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191) re 1 µPapp. These source levels are 1–2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehead may help achieve a higher directionality than expected using clicks nearly an octave lower than similar sized odontocetes.
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catch composition and conservation management of a human dolphin cooperative cast net fishery in the ayeyarwady river myanmar
Biological Conservation, 2009Co-Authors: Brian D Smith, Mya Than Tun, Aung Myo Chit, Han Win, Thida MoeAbstract:Abstract A study of the catch composition of a cooperative fishery practiced between cast-net fishermen and Irrawaddy dolphins (Orcaella brevirostris) in the Ayeyarwady River, Myanmar, was conducted at fishing grounds near Myay Zun, Indown, The‘ Kyun and Hsithe during November and December 2006 and 2007. A total of 4139 fish from 42 species and five crustaceans from a single species were recorded in 1099 net casts made during 33 fishing sessions. Sufficient data were only available to conduct in-depth analyses of catches obtained from Myay Zun (776 net casts, 41.2% while cooperating with dolphins). These analyses indicated that catch per cast, defined by the number of fish, their weight and economic value, was higher (Mann–Whitney P
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habitat selection of freshwater dependent cetaceans and the potential effects of declining freshwater flows and sea level rise in waterways of the sundarbans mangrove forest bangladesh
Aquatic Conservation-marine and Freshwater Ecosystems, 2009Co-Authors: Brian D Smith, Gill T Braulik, Samantha Strindberg, R Mansur, M A A Diyan, Benazir AhmedAbstract:1. Generalized additive models of sighting data for cetaceans collected during two surveys of waterways in the Sundarbans mangrove forest of Bangladesh indicated that Ganges River dolphin Platanista gangetica gangetica distribution was conditionally dependent (P<0.05) on low salinity, high turbidity, and moderate depth during both low and high freshwater flow; and Irrawaddy dolphin Orcaella brevirostris distribution was conditionally dependent (P<0.05) on low salinity during high freshwater flow, high and moderate depths during low and high freshwater flow, respectively; low and high-low extremes of turbidity during low and high freshwater flow, respectively; and high temperature and increasing numbers of large–small channel confluences during low freshwater flow. 2. According to sighting data collected over a 3-year period by the captains of three nature tourism vessels, there were significant differences between the actual and expected frequencies of Ganges River dolphin sightings and individuals according to various channel types (chi-square=64.22, P<0.0001 and chi-square=134.14, P<0.0001, respectively, df=6) and of Irrawaddy dolphin sightings and individuals (chi-square=15.28, P=0.0182, and chi-square=29.42, P<0.0001, respectively, df=6), with shared preferences for wide sinuous channels with at least two small confluences or one large confluence. 3. The dependency exhibited by both species for environmental characteristics associated with abundant freshwater flow, including low salinity and the availability of confluences, make them particularly vulnerable to habitat loss due to upstream water abstraction and sea-level rise. 4. Although the results of this study may not affect plans for construction in India of large-scale, inter-basin water transfer projects that will result in further declines in freshwater flows, or decisions within the international community about CO2 emissions affecting global sea levels, they can be used to prioritize locations where protective measures could be employed to benefit the long-term conservation of both species. Copyright © 2008 John Wiley & Sons, Ltd.
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Irrawaddy Dolphin: Orcaella brevirostris
Encyclopedia of Marine Mammals, 2009Co-Authors: Brian D SmithAbstract:Publisher Summary This chapter discusses the characteristics, taxonomy, distribution, abundance, and ecology of the Irrawaddy dolphin or Orcaella brevirostris. Orcaella has been placed in the monotypic family Orcellidae, the family Delphinapteridae along with the beluga, Delphinapterus leucas, and in the family Monodontidae that includes both the beluga and narwhal, Monodon monoceros. Concordant evidence from cladistic analysis of morphology and genetics places the genus decisively in the family Delphinidae. The species Orcaella brevirostris was recently split into two species based on concordant character differences in external features, osteology, and genetics between the dolphins occurring in five freshwater systems and nearshore waters of Southeast Asia extending west across the Bay of Bengal and south along the east coast of India to Vishakhapatnam and those occurring in the coastal waters of northern Australia and southern Papua New Guinea. Freshwater populations occur in three river systems: the Ayeyarwady of Myanmar, Mahakam of Indonesia, and Mekong of Cambodia, Lao PDR, and Vietnam. They also inhabit two partially isolated freshwater/brackish lakes or lagoons: Chilika of India and Songkhla of Thailand. All five freshwater populations are believed to be demographically isolated from members of the species occurring in marine waters.
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abundance of irrawaddy dolphins Orcaella brevirostris and ganges river dolphins platanista gangetica gangetica estimated using concurrent counts made by independent teams in waterways of the sundarbans mangrove forest in bangladesh
Marine Mammal Science, 2006Co-Authors: Brian D Smith, Gill T Braulik, Samantha Strindberg, Benazir Ahmed, Rubaiyat M MansurAbstract:Independent observer teams made concurrent counts of Irrawaddy dolphins Orcaella brevirostris and Ganges River dolphins Platanista gangetica gangetica in mangrove channels of the Sundarbans Delta in Bangladesh. These counts were corrected for missed groups using mark-recapture models. For Irrawaddy dolphins, a stratified Lincoln-Petersen model, which incorporated group size and sighting conditions as covariates, and a Huggins conditional likelihood model, which averaged models that individually incorporated group size, sighting conditions, and channel width as covariates, generated abundance estimates of 397 individuals (CV = 10.2%) and 451 individuals (CV = 9.6%), respectively. For Ganges River dolphins, a stratified Lincoln-Petersen model, which incorporated group size as a covariate, and a Huggins conditional likelihood model, which averaged the same models described above, generated abundance estimates of 196 individuals (CV = 12.7%) and 225 individuals (CV = 12.6%), respectively. Although the estimates for both models were relatively close, the analytical advantages of the Huggins models probably outweigh those of the Lincoln-Petersen models. However, the latter should be considered appropriate when simplicity is a priority. This study found that waterways of the Sundarbans support significant numbers of Irrawaddy and Ganges River dolphins, especially compared to other areas where the species have been surveyed.
Daniëlle Kreb - One of the best experts on this subject based on the ideXlab platform.
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kelimpahan dan sebaran populasi pesut mahakam Orcaella brevirostris gray 1866 di sungai mahakam kalimantan timur
Jurnal Penelitian Hutan dan Konservasi Alam, 2013Co-Authors: Ivan Yusfi Noor, Sambas Basuni, Agus Priyono Kartono, Daniëlle KrebAbstract:Pesut mahakam ( Orcaella brevirostris Gray, 1866) berstatus kritis, sehingga mendapat prioritas konservasi. Untuk mendukung upaya konservasinya diperlukan data dan informasi tentang populasinya. Penelitian ini bertujuan untuk mendapatkan informasi tentang jumlah individu, angka kematian dan kelahiran pesut mahakam; pemetaan sebaran serta memperoleh informasi jarak jelajah hariannya. Pendugaan jumlah individu pesut mahakam dilakukan dengan menggunakan metode capture-mark-and recapture berdasarkan identifikasi foto sirip punggung. Angka kematian dan kelahiran pesut dikumpulkan melalui pengamatan langsung di lapangan dan wawacara. Jarak jelajah harian pesut dihitung berdasarkan trayek pergerakan focal group yang diikuti selama 8-11 jam. Hasil penelitian yaitu jumlah individu pesut pada tahun 2012 sebanyak 92 individu.Jumlah kematian sebesar enam individu, sedangkan jumlah kelahirannya adalah lima individu. Jarak jelajah rata-rata harian pesut adalah 27,3 km. Penelitian ini juga menemukan bahwa telah terjadi perubahan sebaran pesut di Sungai Mahakam. Pesut mahakam tidak lagi mendiami wilayah Muara Pahu-Penyinggahan yang sebelumnya merupakan habitat intinya. Saat ini, pesut-pesut terkonsentrasi di lokasi lain yakni Pela-Muara Kaman.
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kelimpahan dan sebaran populasi pesut mahakam Orcaella brevirostris gray 1866 di sungai mahakam kalimantan timur abundance and distribution of mahakam irrawaddy dolphin Orcaella brevirostris gray 1866 in mahakam river east kalimantan
Jurnal Penelitian Hutan dan Konservasi Alam, 2013Co-Authors: Ivan Yusfi Noor, Sambas Basuni, Agus Priyono Kartono, Daniëlle KrebAbstract:Pesut mahakam ( Orcaella brevirostris Gray, 1866) berstatus kritis, sehingga mendapat prioritas konservasi. Untuk mendukung upaya konservasinya diperlukan data dan informasi tentang populasinya. Penelitian ini bertujuan untuk mendapatkan informasi tentang jumlah individu, angka kematian dan kelahiran pesut mahakam; pemetaan sebaran serta memperoleh informasi jarak jelajah hariannya. Pendugaan jumlah individu pesut mahakam dilakukan dengan menggunakan metode capture-mark-and recapture berdasarkan identifikasi foto sirip punggung. Angka kematian dan kelahiran pesut dikumpulkan melalui pengamatan langsung di lapangan dan wawacara. Jarak jelajah harian pesut dihitung berdasarkan trayek pergerakan focal group yang diikuti selama 8-11 jam. Hasil penelitian yaitu jumlah individu pesut pada tahun 2012 sebanyak 92 individu.Jumlah kematian sebesar enam individu, sedangkan jumlah kelahirannya adalah lima individu. Jarak jelajah rata-rata harian pesut adalah 27,3 km. Penelitian ini juga menemukan bahwa telah terjadi perubahan sebaran pesut di Sungai Mahakam. Pesut mahakam tidak lagi mendiami wilayah Muara Pahu-Penyinggahan yang sebelumnya merupakan habitat intinya. Saat ini, pesut-pesut terkonsentrasi di lokasi lain yakni Pela-Muara Kaman.
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Development and deployment of the long-term in-situ observation system of the Irrawaddy dolphins (Orcaella brevirostris) in Borneo
2013 IEEE International Underwater Technology Symposium (UT), 2013Co-Authors: Harumi Sugimatsu, Junichi Kojima, Rajendar Bahl, Sandeep Behera, Sabro Tomuro, Shizuko Hiryu, Ajit Pattnaik, Idris Mandan, Daniëlle KrebAbstract:Irrawaddy dolphins are wildly distributed in Asian rivers, lakes and coastal areas. Unfortunately, their population is drastically reducing especially in river areas. Approximately 70-80 Irrawaddy dolphins divided into groups inhabit a 180km stretch of the up-river district of the Mahakam river in Borneo. For understanding the trend of some dolphin groups' migration pattern from Semayang Lake to up/down stream of the river and their echolocation strategy, the stationary observatory using an existing floating house was developed in December 2011 and its first long-term in-situ monitoring was conducted for 3 months in 2012. Taking advantage of the floating house observation platform on the river, one SBL system which consists of a three-piece set of SSBL units with environmental sensors were used for the recording system. In the Mahakam river, boat traffic is steadily increasing. Not only for understanding the trend of the dolphin's migration but also for evaluation of increasing boat noise effect on their echolocation ability, basic acoustic characteristics of the dolphin's echolocation clicks and two typical types of boat noise pulses (type A and type B) were revealed to classify dolphin clicks accurately from boat noise.
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Long-term in-situ monitoring of the Irrawaddy Dolphins (Orcaella brevirostris) in Borneo
2013 Ocean Electronics (SYMPOL), 2013Co-Authors: Harumi Sugimatsu, Junichi Kojima, Rajendar Bahl, Tamaki Ura, A. K. Pattnaik, Sandeep Behera, Sabro Tomuro, Daniëlle KrebAbstract:In Borneo, to monitor the dolphin's groups that migrate from the Semayang Lake to the Mahakam river at Pela village, the annual long-term in-situ monitoring using a stationary observatory deployed from an existing floating house was started in June 2012. Taking advantage of the floating house observation platform on the river, one SBL (Short Base Line) system which consists of a three-piece set of SSBL (Super Short Base Line) units with environmental sensors was used for the recording system. In the Mahakam river, boat traffic has been steadily increasing. Not only for understanding the trend of the dolphin's migration but also for evaluation of increasing boat noise on their echolocation ability, basic acoustic characteristics of the dolphin's echolocation clicks and two typical types of boat noise pulses (type A and type B) were revealed to distinguish dolphin clicks accurately from boat noise.
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Conservation management of small core areas: Key to survival of a Critically Endangered population of Irrawaddy river dolphins Orcaella brevirostris in Indonesia
ORYX, 2005Co-Authors: Daniëlle KrebAbstract:Indonesia's only freshwater dolphin is the facultative Irrawaddy river dolphin Orcaella brevirostris in the Mahakam River in East Kalimantan, Borneo. To clarify the status of this Critically Endangered subpopulation we carried out a series of surveys from early 1999 until mid 2002 on abundance, habitat use, population dynamics and threats. Our estimates of total population size were 3355 dolphins (95% confidence limits 3176) based on direct counts, strip-transect analysis, and Petersen and Jolly-Seber mark-recapture analyses of photo-identified individuals. Mean minimum annual birth and mortality rates were similar, i.e. 13.6 and 11.4%, and no changes in abundance >8% were detected over 2.5 years. Dolphins died mainly from entanglement in gill-nets (73% of deaths). The dolphins' main habitat includes confluence areas between the main river and tributaries or lakes. Dolphins make intensive daily use of these confluences, moving up and downstream over an average length of 10 km of river and within a 1.1 km2 area. These areas are also important fishing grounds and subject to intensive motorized boat traffic. Sixty-four percent of deaths (19952001) with known location (n = 36) occurred in these areas. Interviews with local residents revealed a generally positive attitude towards the establishment of protected areas for this subpopulation. Because of the dolphins' dependence on areas that are also used intensively by people, primary conservation strategies should be to increase local awareness and introduce alternative fishing techniques.
Peter T Madsen - One of the best experts on this subject based on the ideXlab platform.
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Clicking in Shallow Rivers: Short-Range Echolocation of Irrawaddy and Ganges River Dolphins in a Shallow, Acoustically Complex Habitat
2016Co-Authors: Frants H Jensen, Peter T MadsenAbstract:Toothed whales (Cetacea, odontoceti) use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica) and Irrawaddy dolphins (Orcaella brevirostris) within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB) re 1 mPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191) re 1 mPapp. These source levels are 1–2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehea
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clicking in shallow rivers short range echolocation of irrawaddy and ganges river dolphins in a shallow acoustically complex habitat
PLOS ONE, 2013Co-Authors: Frants H Jensen, Alice Rocco, Rubaiyat M Mansur, Brian D Smith, Vincent M Janik, Peter T MadsenAbstract:Toothed whales (Cetacea, odontoceti) use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica) and Irrawaddy dolphins (Orcaella brevirostris) within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB) re 1 µPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191) re 1 µPapp. These source levels are 1–2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehead may help achieve a higher directionality than expected using clicks nearly an octave lower than similar sized odontocetes.
Dharmadi Dharmadi - One of the best experts on this subject based on the ideXlab platform.
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keberadaan pesut Orcaella brevirostris di sungai mahakam kalimantan timur
BAWAL Widya Riset Perikanan Tangkap, 2017Co-Authors: Dian Oktaviani, Syahroma Husni Nasution, Dharmadi DharmadiAbstract:Pesut atau dalam bahasa Inggris dikenal dengan sebutan Irrawaddy dolphin dengan nama ilmiah (Orcaella brevirotris) adalah spesies mamalia air tawar yang dilindungi baik secara nasional maupun internasional. Sungai Mahakam yang berada di Propinsi Kalimantan merupakan salah satu habitat pesut di Indonesia, dan sampai dengan saat ini dapat dilihat keberadaan. Populasi pesut yang semakin turun sehingga memerlukan perhatian dalam upaya mempertahankan keberadaan. Upaya tersebut memerlukan koordinasi yang baik antara pemerintah dan masyarakat dalam menjaga kualitas habitat dan pesut.
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pemantauan status populasi pesut Orcaella brevirostris di sungai pella daerah aliran sungai mahakam kalimantan timur
BAWAL Widya Riset Perikanan Tangkap, 2017Co-Authors: Dian Oktaviani, Aisyah Aisyah, Dharmadi DharmadiAbstract:Populasi pesut (Orcaella brevirostris) saat ini dikatakan mengalami penurunan setiap tahun dan dalam status terancam kepunahan. Sungai Pella merupakan sungai yang menghubungkan antara Danau Semayang dengan Sungai Mahakam dan dikenal sebagai tempat pesut beraktivitas seperti mencari makan dan bermain. Penelitian mengenai status monitoring populasi pesut dilakukan pada bulan September 2004 dan Oktober 2005. Metodologi yang digunakan yaitu purposif untuk penentuan lokasi dan penghitungan langsung populasi dengan analisis secara deskriptif. Lokasi penelitian di Sungai Pella terletak pada posisi 116°33’03,0" BT 00°14’09,9" LS-116°33’55,2" BT 00°14’25,2" LS. Hasil penelitian menunjukkan populasi pesut yang muncul di Sungai Pella antara 2 sampai dengan 12 ekor. Status populasi pesut di Sungai Pella adalah tetap dibandingkan dengan penghitungan pada tahun 1999 dan 2002.
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kondisi kualitas air habitat pesut mahakam Orcaella brevirostris di wilayah daerah aliran sungai mahakam kalimantan timur
Jurnal Penelitian Perikanan Indonesia, 2017Co-Authors: Aisyah Aisyah, Dharmadi Dharmadi, Dian Oktaviani, Syahroma Husni Nasution, Dede Irving HartotoAbstract:Sungai Mahakam merupakan sungai terpanjang dan terbesar di Propinsi Kalimantan Timur dan menjadi habitat dari pesut (Orcaella brevirostris). Kondisi habitat diduga berkaitan dengan kecendrungan menurunnya populasi pesut, untuk itu perlu dilakukan penelitian mengenai kondisi kualitas air habitat pesut. Penelitian dilakukan di wilayah daerah aliran Sungai Mahakam, Kalimantan Timur pada bulan Oktober 2004 dan Oktober 2005 yang mewakili musim kemarau (air rendah) serta bulan Desember 2005 yang mewakili musim hujan (air tinggi) di 5 stasiun. Parameter kualitas air terdiri atas parameter fisika dan kimia yang dikompositkan dari lapisan bawah sampai dengan permukaan menggunakan water quality checker Horiba U-10. Secara umum, tipe perairan tergolong eutrofik dengan kondisi kualitas air yang tergolong aman diperuntukkan bagi habitat pesut. Mahakam River is one of the longest and biggest river in East Kalimantan Province and becoming the habitat for Irrawady Dolphin, locally refers as Pesut (Orcaella brevirostris). It is important to understand about the condition of water quality that support the pesut habitat which has degradated. The sampling was conducted three times in Oktober 2004 and, October and December 2005 when it represented the low water and the high water condition’s respectivelly. At each sampling station physical and chemical parameters were analysed. Water samples were taken from each station as a composit samples taken from the bottom and surface layers and analysis was conducted using water quality checker Horiba U-10. In general, the locations of sampling station were classified as eutrophic water with most of the water quality would still meet the requirement for Irrawady Dolphin habitat.
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distribusi spasial status pemanfaatan dan upaya konservasi pesut mahakam Orcaella brevirostris di kalimantan timur
Jurnal Penelitian Perikanan Indonesia, 2017Co-Authors: Dharmadi Dharmadi, Syahroma Husni Nasution, Dede Irving Hartoto, Dian OktavianiAbstract:Penelitian dilakukan pada tahun 2004 - 2006 di Danau Semayang dan Muara Kaman (bagian dari Sungai Mahakam), Kalimantan Timur, melalui survei lapangan dan wawancara langsung dengan nelayan, masyarakat, dan Dinas Perikanan, Dinas Perlindungan Hutan dan Pelestarian Alam. Tujuan penelitian ini adalah untuk mengetahui penyebaran secara spasial, status pemanfaatan, dan upaya konservasi pesut Mahakam (Orcaella brevirostris). Hasil pengamatan menunjukkan bahwa distribusi pesut Mahakam secara spasial terdapat di Muara Kaman, Muara Sungai Pela Kecil, muara Sungai Pela Besar, Danau Semayang, dan Danau Melintang. Pada saat ini, pesut Mahakam di Sungai Mahakam digunakan sebagai wisata air bagi turis domestik maupun luar negeri. Upaya konservasi pesut Mahakan dapat dilakukan melalui perlindungan habitat dari pencemaran dan pendangkalan, perlindungan suaka perikanan yang berfungsi untuk penyedia makanan alami serta meningkatkan peran aktif masyarakat agar turut menjaga kelestarian pesut. This study was conducted during 2004 to 2006 in Semayang and Melintang Lakes, Mahakam segment around Muara Kaman River of East Kalimantan, through field survey methods, and directly interview to respective respondens of fishers, local people, Fisheries Regency Departement and Forest Protection and Natural Resources Conservation. The objective of the study was to elucidate the distribution spasial, utilization status, and conservation effort of freshwater dolphin (Orcaella brevirostris). Results show that the spasial distributions of freshwater dolphin were found in Kaman, Pela Kecil, Bank of Pela Besar Rivers, Semayang, and Melintang Lakes. Freshwater dolphines was used as echotourism for local and foreign tourisms. There are some efforts to conserve of freshwater dolphin in the East Kalimantan, namely habitat protection from pollution and sedimentation, fisheries area protection for providing natural food and to increase local people role in conserving the existence of these animals.
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kemunculan dan tingkah laku pesut Orcaella brevirostris owen in gray 1866 sebagaimamaliaterancamlangka di perairankubu rayadankayongutarakalimantan barat
BAWAL Widya Riset Perikanan Tangkap, 2015Co-Authors: Regi Fiji Anggawangsa, Dharmadi Dharmadi, Nunik SulistyowatiAbstract:Pesut atau Irrawaddy dolphin (Orcaella brevirostris) merupakan salah satu spesies mamalia air yang populasinya semakin terancam. Sedikitnya informasi keberadaan pesut di Kalimantan Barat, menyebabkan upaya konservasi dan pengelolaannya belum optimal. Tulisan ini bertujuan untuk mengetahui keberadaan dan tingkah laku pesut yang terdapat di perairan Kubu Raya dan Kayong Utara, Kalimantan Barat. Kegiatan pengamatan menggunakan metode jelajah dengan bantuan teropong binokuler dilaksanakan pada bulan April 2013. Selama pengamatan hanya diketahui terdapat satu kelompok pesut sebanyak 4-6 individu yang terdiri dari pesut muda dan dewasa. Kelompokan itu dijumpai di muara Sungai Bumbun pada kedalamanan perairan 11 meter. Tingkah laku yang teramati menunjukkan gerombolan pesut umumnya memburu kelompokan ikan dan sesekali menyemburkan air dari blowhole nya. Berdasarkan ciri-ciri morfologi dan tingkah laku yang teramati serta kondisi lingkungan perairan setempat maka perairan di Kabupaten Kubu Raya dan Kabupaten Kayong Utara yang terletak di Provinsi Kalimantan Barat diduga merupakan perairan yang potensial sebagai habitat pesut (Orcaella brevirostris). Irrawaddy dolphins (Orcaella brevirostris (Owen in Gray 1866)) is one of aquatic mammals species who populations are increasingly threatened. The lack information about population of Irrawaddy dolphins in West Kalimantan waters makes the conservation of this species and its management were still not optimized yet. This research aims to identify the characteristics and behavior of dolphins found in Kubu Raya and Kayong Utara waters of West Kalimantan. The observation was held on April 2013, exploring coastal waters and estuaries which are expected to be the habitats of Irrawaddy dolphins using binoculars. There are 4-6 individuals of Irrawaddy dolphin found at the mouth of Bumbun River. A group consist of young and adults dolphins at the depth of 11 meters. The observed behavior is chasing schooling fish and occasionally spitting water from his blowhole. Based on morphological character and fish behavior observed, and environmental condition parameters, indicated that the water surrounding of Kubu Raya and Kayong Utara District were potential habitat for Irrawaddy dolphins.
Rubaiyat M Mansur - One of the best experts on this subject based on the ideXlab platform.
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clicking in shallow rivers short range echolocation of irrawaddy and ganges river dolphins in a shallow acoustically complex habitat
PLOS ONE, 2013Co-Authors: Frants H Jensen, Alice Rocco, Rubaiyat M Mansur, Brian D Smith, Vincent M Janik, Peter T MadsenAbstract:Toothed whales (Cetacea, odontoceti) use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica) and Irrawaddy dolphins (Orcaella brevirostris) within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB) re 1 µPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191) re 1 µPapp. These source levels are 1–2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehead may help achieve a higher directionality than expected using clicks nearly an octave lower than similar sized odontocetes.
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abundance of irrawaddy dolphins Orcaella brevirostris and ganges river dolphins platanista gangetica gangetica estimated using concurrent counts made by independent teams in waterways of the sundarbans mangrove forest in bangladesh
Marine Mammal Science, 2006Co-Authors: Brian D Smith, Gill T Braulik, Samantha Strindberg, Benazir Ahmed, Rubaiyat M MansurAbstract:Independent observer teams made concurrent counts of Irrawaddy dolphins Orcaella brevirostris and Ganges River dolphins Platanista gangetica gangetica in mangrove channels of the Sundarbans Delta in Bangladesh. These counts were corrected for missed groups using mark-recapture models. For Irrawaddy dolphins, a stratified Lincoln-Petersen model, which incorporated group size and sighting conditions as covariates, and a Huggins conditional likelihood model, which averaged models that individually incorporated group size, sighting conditions, and channel width as covariates, generated abundance estimates of 397 individuals (CV = 10.2%) and 451 individuals (CV = 9.6%), respectively. For Ganges River dolphins, a stratified Lincoln-Petersen model, which incorporated group size as a covariate, and a Huggins conditional likelihood model, which averaged the same models described above, generated abundance estimates of 196 individuals (CV = 12.7%) and 225 individuals (CV = 12.6%), respectively. Although the estimates for both models were relatively close, the analytical advantages of the Huggins models probably outweigh those of the Lincoln-Petersen models. However, the latter should be considered appropriate when simplicity is a priority. This study found that waterways of the Sundarbans support significant numbers of Irrawaddy and Ganges River dolphins, especially compared to other areas where the species have been surveyed.