Abundance estimates of Irrawaddy dolphins in Chilika Lagoon, India, using photo‐identification based mark‐recapture methods

Sutaria, Dipani; Marsh, Helene

doi:10.1111/j.1748-7692.2011.00471.x

Cited by 22 publications

(21 citation statements)

References 19 publications

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“…The photo-identification surveys were realized in Bangladesh, Malaysia andIndia between 2004 and (Table 1) following the methods described in Smith et al (2006), Minton et al (2011Minton et al ( , 2013 and Sutaria & Marsh (2011). Dolphins were photo graph ed with digital SLR cameras equipped with 70 to 400 mm zoom lenses, at distances ranging from a few to several hundreds of meters.…”

Section: Photo-identification Surveys and Study Areasmentioning

confidence: 99%

“…Whenever possible, both sides of the dorsal fin were photographed during the surveys, and each dolphin was assigned a single ID number (Sutaria & Marsh 2011). Adults or sub-adults (distinguished by relative size) closely accompanying calves and juveniles were assumed to be females (Sutaria 2009).…”

Section: Malaysiamentioning

confidence: 99%

“…It is separated from the Bay of Bengal by an approximately 1.5 km wide and 60 km long sandy ridge. Surveys were carried out twice a month in the outer channel, in the central and southern sectors and in a dredged channel in the northern sector.Whenever possible, both sides of the dorsal fin were photographed during the surveys, and each dolphin was assigned a single ID number (Sutaria & Marsh 2011). Adults or sub-adults (distinguished by relative size) closely accompanying calves and juveniles were assumed to be females (Sutaria 2009).…”

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confidence: 99%

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Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations

Bressem¹,

Minton²,

Sutaria³

et al. 2014

Dis. Aquat. Org.

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The presence of cutaneous nodules is reported in vulnerable populations of Irrawaddy dolphins Orcaella brevirostris from Malaysia (Kuching, Bintulu-Similajau, KinabatanganSegama and Penang Island), India (Chilika Lagoon) and Bangladesh (Sundarbans). Approximately 5700 images taken for photo-identification studies in 2004 to 2013 were examined for skin disorders. Nodules were detected in 6 populations. They appeared as circumscribed elevations of the skin and varied in size from 2 to > 30 mm, were sparse or numerous and occurred on all visible body areas. In 8 photo-identified (PI) dolphins from India and Malaysia, the lesions remained stable (N = 2) or progressed (N = 6) over months but did not regress. The 2 most severely affected individuals were seen in Kuching and the Chilika Lagoon. Their fate is unknown. Cutaneous nodules were sampled in a female that died in a gillnet in Kuching in 2012. Histologically, the lesions consisted of thick collagen bundles covered by a moderately hyperplasic epithelium and were diagnosed as fibropapillomas. Whether the nodules observed in the other O. brevirostris were also fibropapillomas remains to be investigated. Disease prevalence ranged from 2.2% (N = 46; Bintulu-Similajau) to 13.9% (N = 72; Chilika) in 4 populations from Malaysia and India. It was not significantly different in 3 study areas in eastern Malaysia. In Chilika, prevalence was significantly higher (p = 0. well et al. 1975, Kiszka et al. 2009, Reif et al. 2009, Van Bressem et al. 2009b. In some small communities of inshore and estuarine populations, these pathologies are highly prevalent, may progress to cover extensive body areas and have been associated with the death or disappearance of severely affected individuals, including calves (Simões-Lopes et al. 1993, Van Bressem et al. 2007a, Kiszka et al. 2009, Daura-Jorge & Simões-Lopes 2011. However, their impact on the long-term viability of affected communities is still vastly unknown. The fungi Lacazia loboi, Fusarium spp., Paracoccidioides brasiliensis and Trichophyton spp. have been identified as the aetiological agents of some nodular disorders (Caldwell et al. 1975, Frasca et al. 1996, Van Bressem et al. 2007a, Esperón et al. 2012, Tanaka et al. 2012). Immune dysfunction is also known to play a role in the pathogenesis of L. loboi disease in coastal common bottlenose dolphins Tursiops truncatus from Florida, USA (Reif et al. 2009, Murdoch et al. 2010.Irrawaddy dolphins Orcaella brevirostris occur in large rivers and marine appended lakes in South Asia, as well as in the coastal waters of the Indo-Pacific Ocean (Smith 2009). Estuarine and nearshore populations are distributed in tropical and subtropical waters of the Indo-Pacific Ocean, from eastern India to the Philippines (Dolar et al. 2002, Minton et al. 2011. Riverine populations have been documented in 3 major river systems: the Mahakam (Indonesia), the Ayeyarwady (Myanmar) and the Mekong (Laos, Cambodia and Vietnam) (Smith 2009). Their habitat preference exposes them to multiple anthropog...

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Section: Photo-identification Surveys and Study Areasmentioning

confidence: 99%

Section: Malaysiamentioning

confidence: 99%

mentioning

confidence: 99%

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Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations

Bressem¹,

Minton²,

Sutaria³

et al. 2014

Dis. Aquat. Org.

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“…The population of Irrawaddy dolphins at Chilika lagoon is likely ''critically endangered'' and decreasing (Sutaria and Marsh 2011). In addition, a small gill-net fishery occasionally operates in the lagoon, sometimes resulting in dolphin bycatch mortality.…”

Section: Conservation Implications Of This Study For Irrawaddy Dolphimentioning

confidence: 99%

“…In the lagoon, both dolphins and local fishers overlap in their use of space and resources. The Irrawaddy dolphin, is a globally vulnerable species (IUCN 2012); at Chilika, the population comprises approximately 150 individuals and likely meets the criteria for listing as ''critically endangered'' (Sutaria and Marsh 2011). Dolphin foraging overlaps closely in the lagoon with areas that fishers use to deploy their gear, as the animals track much of the same fish and invertebrate resources as local fishers.…”

Section: Introductionmentioning

confidence: 99%

Positive Interactions Between Irrawaddy Dolphins and Artisanal Fishers in the Chilika Lagoon of Eastern India are Driven by Ecology, Socioeconomics, and Culture

D’Lima

Marsh

Hamann

et al. 2013

AMBIO

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In human-dominated landscapes, interactions and perceptions towards wildlife are influenced by multidimensional drivers. Understanding these drivers could prove useful for wildlife conservation. We surveyed the attitudes and perceptions of fishers towards threatened Irrawaddy dolphins (Orcaella brevirostris) at Chilika Lagoon India. To validate the drivers of fisher perceptions, we : (1) observed dolphin foraging behavior at stake nets, and (2) compared catch per unit effort (CPUE) and catch income of fishers from stake nets in the presence and absence of foraging dolphins. We found that fishers were mostly positive towards dolphins, believing that dolphins augmented their fish catch and using culture to express their perceptions. Foraging dolphins were observed spending half their time at stake nets and were associated with significantly higher catch income and CPUE of mullet (Liza sp.), a locally preferred food fish species. Wildlife conservation efforts should use the multidimensional drivers of human-wildlife interactions to involve local stakeholders in management.

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Abundance estimates of three cetacean species in the coastal waters of Matang, Perak, Peninsular Malaysia

Kuit

Ponnampalam²,

Hammond

et al. 2021

Aquatic Conservation

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1. The paucity of baseline data on coastal cetaceans due to a lack of research in developing countries frequently precludes assessment of their status and informed management actions for conservation.2. This study provides the first abundance estimates of Indo-Pacific humpback dolphins, Irrawaddy dolphins, and Indo-Pacific finless porpoises in the coastal waters of Matang, Peninsular Malaysia. 3. Boat-based surveys covering 1,152 km 2 of coastal waters with 4,108 km of survey effort were conducted between 2013 and 2016 to collect data for line transect analysis of Irrawaddy dolphins and finless porpoises. Photo-identification data of humpback dolphins were concurrently collected for mark-recapture analysis. 4. Estimates of abundance from four sampling strata totalled 763 Irrawaddy dolphins (CV = 13%, 95% confidence interval (CI) [588, 990]) and 600 Indo-Pacific finless porpoises (CV = 27%, 95% CI [354, 1,016]). 5. The annual abundance estimates of humpback dolphins ranged between 171 (95% CI [148, 208]) in 2014-2015 and 81 (95% CI [67, 98]) in 2015-2016, likely due to the presence of offshore individuals that moved in and out of the study area. The estuarine strata were inhabited by 68 (95% CI [63, 73]) inshore humpback dolphins in 2013-2014 to 87 (95% CI [78, 97]) dolphins in 2014-2015. 6. As an International Union for Conservation of Nature important marine mammal area, the productive coastal waters of Matang are shown to support a high density of small coastal cetaceans, and the results serve as an important baseline for future studies to identify population trends for conservation management plans.

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Abundance estimates of Irrawaddy dolphins in Chilika Lagoon, India, using photo‐identification based mark‐recapture methods

Cited by 22 publications

References 19 publications

Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations

Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations

Positive Interactions Between Irrawaddy Dolphins and Artisanal Fishers in the Chilika Lagoon of Eastern India are Driven by Ecology, Socioeconomics, and Culture

Abundance estimates of three cetacean species in the coastal waters of Matang, Perak, Peninsular Malaysia

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