Status assessment of the Indus River dolphin, Platanista gangetica minor, March–April 2001

Braulik, Gill

doi:10.1016/j.biocon.2005.11.026

Cited by 34 publications

(53 citation statements)

References 11 publications

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“…), the Amazon River dolphin (Inia geoffrensis), the Irrawaddy dolphin (Orcaella brevirostris) and the tucuxi (Sotalia fluviatilis), also face comparable challenges of long-term survival (Reeves et al, 1991;Reeves and Chaudhry, 1998;Smith and Smith, 1998;Smith et al, 2001;Martin et al, 2004;Braulik, 2006), but demographic data for these species are still extremely limited. Although specific threats facing these freshwater cetaceans may vary geographically in their importance, common threats include substantial loss of effective habitat (Reeves et al, 1991;Braulik, 2006), increasing concentrations of persistent organic pollutants in cetacean tissue (Senthilkumar et al, 1999), and incidental fisheries by-catch (Martin et al, 2004). The drastic decline of the Yangtze finless porpoise in two decades as a result of rapid industrial and economic growth reveals how uncontrolled environmental deterioration threatens the future of freshwater cetaceans despite the potential for the massive scale of the Yangtze system to buffer anthropogenic impacts.…”

Section: Immediate Acts For Conservationmentioning

confidence: 99%

Accelerating population decline of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)

Mei

Huang

Hao

et al. 2012

Biological Conservation

105

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Section: Immediate Acts For Conservationmentioning

confidence: 99%

Accelerating population decline of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)

Mei

Huang

Hao

et al. 2012

Biological Conservation

105

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“…A thalweg transect survey unavoidably samples unrepresentative habitat as it passes through areas with higher densities, and in addition the animals are unlikely to be uniformly distributed in the surveyed strips. Other less significant challenges to distance sampling in this environment include measuring perpendicular sighting distances when surveying moving objects from a sharply curving path (Hiby & Krishna 2001), frequent constrictions in the river channel that cut off the potential detection width causing a narrowing or unusual shoulder in the detection function (Dawson et al 2008), and the presence of a downstream population density gradient (Braulik 2006) that complicates extrapolation of data from one area to another.…”

Section: Methodological Challenges To Surveyingmentioning

confidence: 99%

“…The Indus dolphin persists within this system, but its range has declined by 80%, its population is fragmented by barrages, and its habitat is degraded due to water diversion. In 2001, dolphins were recorded within around 1000 km of the Indus mainstem in 5 subpopulations separated by barrages, and the metapopulation was estimated as approximately 1200 (Braulik 2006). A sixth very small dolphin subpopulation, located more than 600 km from all the others, was recently discovered in the Beas River, India (Behera et al 2008).…”

Section: Status Of the Indus Dolphinmentioning

confidence: 99%

Robust abundance estimate for endangered river dolphin subspecies in South Asia

Braulik¹,

Bhatti²,

Ehsan³

et al. 2012

Endang. Species. Res.

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Robust estimates of absolute abundance are vital for management of threatened species, but these have rarely been generated for endangered South Asian river dolphins due to methodological challenges. An estimate of abundance for the Indus River dolphin in 2006 was generated by conducting tandem vessel-based direct counts; conditional likelihood capture-recapture models were then used to correct for missed animals. Group size and sighting conditions were included as covariates, and abundances of the 3 largest subpopulations were estimated as 101 (coefficient of variation, CV = 44.1%) between Chashma and Taunsa barrages, 52 (CV = 14.9%) between Taunsa barrage and Ghazi Ghat, and 1289 (CV = 33.4%) between Guddu and Sukkur barrages. A total of 75.3% of groups were seen by both independent survey teams, and single animals were almost 5 times more likely to be missed than groups of 3 or more. Providing groups can be matched with minimal error, this survey method shows good potential for abundance estimation of dolphins in confined habitat and the shallow rivers of South Asia. Dolphin encounter rates within the Guddu-Sukkur subpopulation (10.35 km −1 ) are the highest reported for any river dolphin. Direct counts conducted over a 35 yr period, suggest that this subpopulation may have been increasing in abundance, probably due to the cessation of hunting and possible immigration from other subpopulations. The future of South Asian river dolphins is intimately tied to water security in the region, and escalating and competing demands for freshwater mean that the long-term future of South Asia's river dolphins is uncertain.

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“…It is my goal to summarize the techniques frequently used to solve the population trend and status/risk assessment in many cetaceans. This summarization could be helpful for the conservation of cetaceans for forming sound conservation actions, especial for the species inhabiting freshwater habitats and coastal waters under intensive anthropogenic threats [10][11][12][13][14][15][16][17] in developing countries.…”

Section: Introductionmentioning

confidence: 99%

Assessing Population Trend and Risk of Extinction for Cetaceans Lacking Long- Term Census Baselines

Huang¹

2013

J Biodivers Endanger Species

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Assessment of population trend and risk of extinction, essential for informed conservation, needs baselines including percentage of population decline, extent of occurrence, population size, population structure and probabilities of extinction. Construction of these baselines usually claims long-term census efforts that are often insufficient or even lacking for many cetaceans, especially for those nearby rapidly developing countries. Restricted to variation from current census techniques, however, the approach based on long-term census database is unlikely to detect early or recent sign of population decline. Here, I propose an integrative perspective, the systematic demographic analysis, to solve life history and demographic parameters essential for status and risk assessment for the cetacean populations. Transect technique with the aid of GPS records and environmental characteristics can be used to estimate population abundance and figure the extent of occurrence and critical habitat, information essential for sound habitat protection. Capturemark-recapture technique based on the database from individual photo-ID histories can be used to estimate population size, apparent survival rate and life history parameters. Collections of stranded and by caught carcasses can be used to solve life history parameters, age-specific survivorships or mortality rates and population genetic diversity indirectly relating to population size. Applications of population viability analysis to above parameters such as VORTEX model or other individual-based stage/age matrix model that factors the stochasticity and uncertainty can be used to solve the likely range of rate of decline and extinction risk of threatened population. Finally, I emphasize the need to integrate the histories of long-term land use and landscape change when formulating habitat management programme for the rare and/or endangered populations to avoid skipping the low-sighting habitat from intense anthropogenic impacts.

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Status assessment of the Indus River dolphin, Platanista gangetica minor, March–April 2001

Cited by 34 publications

References 11 publications

Accelerating population decline of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)

Accelerating population decline of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)

Robust abundance estimate for endangered river dolphin subspecies in South Asia

Assessing Population Trend and Risk of Extinction for Cetaceans Lacking Long- Term Census Baselines

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