Demography and population trends of the largest population of Indo-Pacific humpback dolphins

Huang, Shuqiang; Karczmarski, Leszek; Chen, Jialin; Zhou, Rongyan; Lin, Wenzhi; Zhang, Haifei; Li, Haiyan; Wu, Yuping

doi:10.1016/j.biocon.2012.01.004

Cited by 109 publications

(126 citation statements)

References 68 publications

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“…Furthermore, the age-at-death data in our study span more than 10 years, reducing the likelihood of potential deviations in any single year (Stolen and Barlow, 2003). This method has previously been employed for bottlenose dolphins (Tursiops truncatus) (Stolen and Barlow, 2003), harbor porpoises (Phocoena phocoena) (Moore and Read, 2008), and humpback dolphins (Sousa chinensis) from the Pearl River Estuary (Huang et al, 2012b), as well as for several terrestrial mammals (Barlow and Boveng, 1991).…”

Section: Life Tables and Demographymentioning

confidence: 99%

“…We simulated future changes of abundance for the Yangtze finless porpoise population, N(t), at year t using an individual-based Leslie matrix model that also factors the effects of demographic stochasticity and parameter uncertainty (Slooten et al, 2000;Currey et al, 2009a;Huang et al, 2012b). In this approach, N(t) was modelled by the following process:…”

Section: Population Trend Modelling and Status Assessmentmentioning

confidence: 99%

“…Cetacean population decline rates can be estimated directly by using historical abundance estimates (Stevick et al, 2003;George, 2004;Zerbini et al, 2006;Zhao et al, 2008), or by demographic approaches (Fujiwara and Caswell, 2001;Stolen and Barlow, 2003;Moore and Read, 2008;Currey et al, 2009a,b;Huang et al, 2012b) such as life table analysis (Caswell et al, 1998;Dans et al, 2003;Stolen and Barlow, 2003;Moore and Read, 2008;Huang et al, 2012b). However, direct detection of population trends, either increases or declines, usually requires decades of field investigations, and the target population may have declined substantially before a change in abundance is detectable (Gerrodette, 1987;Taylor and Gerrodette, 1993;Thompson et al, 2000;Taylor et al, 2007;Wilson et al, 2011;Huang et al, 2012a).…”

Section: Introductionmentioning

confidence: 99%

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

Mei

Huang

Hao

et al. 2012

Biological Conservation

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106

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Section: Life Tables and Demographymentioning

confidence: 99%

Section: Population Trend Modelling and Status Assessmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Mei

Huang

Hao

et al. 2012

Biological Conservation

Self Cite

106

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“…This restricted inshore distri bution exposes humpback dolphins to various anthropogenic impacts, such as incidental mortality in fishing gear (bycatch), vessel collisions, resource de pletion, bioaccumulation of harmful pollutants and habitat destruction through direct human activities (Jefferson & Karczmarski 2001, Reeves et al 2008, Jefferson et al 2009, Ross et al 2010, Huang et al 2013, Slooten et al 2013. The long-term survival of humpback dolphin populations has received remarkable conservation attention in recent years, especially in areas neighboring intense human urbanization, industrialization and coastal land exploitation (Reeves et al 2008, Jefferson et al 2009, Ross et al 2010, Huang et al 2012b. The current IUCN Red List of Threatened Species classifies humpback dolphins globally as Near Threatened (NT) (Reeves et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Population trends and vulnerability of humpback dolphins Sousa chinensis off the west coast of Taiwan

Huang¹,

Chang²,

Karczmarski³

2014

Endang. Species. Res.

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Predictive modeling of population trends can indicate the rate of population decline and risk of extinction, providing quantitative means of assessing conservation status and threats. Our study tests the rate of population change and risk of extinction of the Indo-Pacific humpback dolphin Sousa chinensis off the west coast of Taiwan, the only humpback dolphin population classified as Critically Endangered (CR) by the IUCN Red List of Threatened Species. Under the most optimistic assumptions, almost 60% of simulations (out of 250 replications × 5000 iterations) predicted that population decline will exceed 80% within 3 generations, while the mean estimate of population decline within 1 generation was > 50% of the current population numbers. Status classification performed using IUCN Red List Categories and Criteria Version 3.1 supported previous CR classification, while risk assessment models that factored in anthropogenic impacts further increased the estimated extinction risk. At an adult survival rate of 0.95, a modeled increment of annual bycatch rate by 1% of population size increased the probability of extinction within 100 yr by 7.5%; this increase was lower at a higher adult survival rate. The estimated extinction risk was greatest under the impact of habitat loss, reaching a hazardous level when habitat carrying capacity dropped to less than 50%, indicating that habitat fragmentation and alteration of coastal environments pose the greatest threats to this population, even if the cumulative sum of fragmented patches of habitat may superficially appear to be large.

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“…The only analysis of population viability for S. chinensis to date has been for the animals of the Pearl River Estuary, including Hong Kong's waters (Huang et al 2012). This analysis was performed using demographic information obtained from carcasses found stranded on the shores or floating at sea.…”

Section: Introductionmentioning

confidence: 99%

Viability of the Critically Endangered eastern Taiwan Strait population of Indo-Pacific humpback dolphins Sousa chinensis

Araújo¹,

Wang²,

Hung³

et al. 2014

Endang. Species. Res.

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The population of humpback dolphins Sousa chinensis that resides in the eastern Taiwan Strait (ETS) is geographically and genetically isolated from populations inhabiting the coastal waters of mainland China and appears to be facing unsustainable levels of human threats. Using VORTEX 9.99b, we modeled the viability of this Critically Endangered population under the present conditions as well as under realistic additional threat scenarios. We examined 6 different levels of bycatch mortality, 3 scenarios of habitat loss/degradation, and scenarios in which these threats were experienced together. Under the baseline (present) scenario, the population exhibited a decreasing growth rate and was predicted to be smaller than the initial population size in more than 76% of all model runs. In all scenarios with additional threats, the proportion of model runs in which population size was smaller than the initial size varied from 77.1 to 92.6%. Over the short term, fisheries-related mortality appears to have a more obvious impact on the population's trajectory than habitat loss/degradation. Even minimal increases in mortality from the current baseline levels will increase the probability of extinction of this population. Due to the fragile situation of ETS humpback dolphins, mitigation actions to reduce the current threats to this population are needed immediately.

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Demography and population trends of the largest population of Indo-Pacific humpback dolphins

Cited by 109 publications

References 68 publications

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

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

Population trends and vulnerability of humpback dolphins Sousa chinensis off the west coast of Taiwan

Viability of the Critically Endangered eastern Taiwan Strait population of Indo-Pacific humpback dolphins Sousa chinensis

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