Integrating multiple lines of evidence to better understand the evolutionary divergence of humpback dolphins along their entire distribution range: a new dolphin species in Australian waters?

Mendez, Martín; Jefferson, Thomas A.; Kolokotronis, Sergios‐Orestis; Krützen, Michael; Parra, Guido J.; Collins, Tim; Minton, Giana; Baldwin, R.M.; Berggren, Per; Särnblad, Anna; Amir, Omar; Peddemors, Victor M.; Karczmarski, Leszek; Guissamulo, Almeida; Smith, Brian D.; Sutaria, Dipani; Amato, George; Rosenbaum, Howard C.

doi:10.1111/mec.12535

Cited by 67 publications

(88 citation statements)

References 72 publications

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“…The Indo-Pacific humpback dolphin Sousa chinensis inhabits coastal waters of the Indian and western Pacific Oceans (Jefferson & Karczmarski 2001, Reeves et al 2008 and is found predominantly close inshore in waters less than 20 m deep (Karczmarski 1999, 2000, Jefferson & Karcz marski 2001, Reeves et al 2008, Ross et al 2010, Mendez et al 2013). 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.…”

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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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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“…However, dramatic declines along the urban coast of Queensland are evident from catch per unit effort data in shark nets for bather protection along the Queensland coast from 1962 to 1999, and dugongs are impacted by multiple threats including incidental bycatch in fishing nets, loss of seagrass, vessel strike, illegal poaching, and legal indigenous hunting in northern Australian waters (104). Two inshore dolphins, the Australian snubfin dolphin, Orcaella heinsohni, and Australian humpback dolphin, Sousa sahulensis, also face a similar range of threats from fisheries bycatch, habitat degradation, vessel strike, pollution, and acoustic disturbances (6,7). For Australia's marine mammals, our review concluded that six species are threatened, with a further five species Near Threatened, but a much higher proportion (60%) are Data Deficient.…”

Section: Significancementioning

confidence: 99%

“…Australia's terrestrial mammal fauna is the most distinctive in the world (5), including ancient lineages of monotremes, very diverse marsupials, and a wide range of eutherians: 87% of Australia's 316 terrestrial mammal species are endemic. The Australian marine mammal fauna is also diverse (58 species) but has a lower rate of endemism: one pinniped species and two near-endemic cetacean species (6)(7)(8).…”

mentioning

confidence: 99%

Ongoing unraveling of a continental fauna: Decline and extinction of Australian mammals since European settlement

Woinarski

Burbidge

Harrison

2015

Proc. Natl. Acad. Sci. U.S.A.

748

634

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The highly distinctive and mostly endemic Australian land mammal fauna has suffered an extraordinary rate of extinction (>10% of the 273 endemic terrestrial species) over the last ∼200 y: in comparison, only one native land mammal from continental North America became extinct since European settlement. A further 21% of Australian endemic land mammal species are now assessed to be threatened, indicating that the rate of loss (of one to two extinctions per decade) is likely to continue. Australia's marine mammals have fared better overall, but status assessment for them is seriously impeded by lack of information. Much of the loss of Australian land mammal fauna (particularly in the vast deserts and tropical savannas) has been in areas that are remote from human population centers and recognized as relatively unmodified at global scale. In contrast to general patterns of extinction on other continents where the main cause is habitat loss, hunting, and impacts of human development, particularly in areas of high and increasing human population pressures, the loss of Australian land mammals is most likely due primarily to predation by introduced species, particularly the feral cat, Felis catus, and European red fox, Vulpes vulpes, and changed fire regimes.conservation | biodiversity | marsupial | predation | feral animal

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“…There are now increasing prospects and proposals for development in coastal waters of northern Australia, and, consequently, there are concerns about the conservation of the following three species of coastal dolphins occurring in these waters Allen et al 2012;Bejder et al 2012;Cagnazzi et al 2013;Palmer et al 2014): the Australian snubfin, Orcaella heinsohni (hereafter snubfin), a new as-yet-unnamed species of humpback dolphin, Sousa sp. (Frère et al 2011;Mendez et al 2013), and the bottlenose dolphins, Tursiops sp.…”

Section: Introductionmentioning

confidence: 99%

Estimates of abundance and apparent survival of coastal dolphins in Port Essington harbour, Northern Territory, Australia

et al. 2014

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Abstract, and grey shading in the table). The errors were due to transcription error and in no way affect the outcome and conclusions of the study. AbstractKey results. Abundance estimates for the three species varied across the sampling periods, with the estimated number of Australian snubfin dolphins ranging from 136 (s.e. 62) to 222 (s.e. 48); from 48 (s.e. 17) to 207 (s.e. 65) for the Australian humpback dolphin; and 34 (s.e. 16) to 75 (s.e. 26) for the bottlenose dolphin. AbstractContext. Three dolphin species occur in coastal waters of monsoonal northern Australia: the Australian snubfin (Orcaella heinsohni), humpback (Sousa sp.) and the bottlenose (Tursiops sp.). Their overall population size and trends are poorly known, and their conservation status has been difficult to resolve, but can be expected to deteriorate with likely increased development pressures.Aims. We sought to provide an estimate of abundance, and apparent survival, of the three dolphin species at the largely undeveloped harbour of Port Essington (325 km 2 ), Northern Territory, with repeated sampling over a 2.9-year period. Given increasing obligations to undertake population assessments for impact studies at proposed development sites, we assess the strengths and limitations of a systematic sampling program.Methods. We used photo-identification data collected during systematic boat-based transect surveys undertaken from 2008 to 2010 and Pollock's robust capture-recapture design model. Key results. Total abundance estimates for the three species were variable across different sampling periods. The estimated number of individuals in the sampled area varied per sampling episode from 136 (s.e. 62) to 222 (s.e. 48) for snubfin, from 48 (s.e. 7) to 207 (s.e. 14) for humpbacks and from 34 (s.e. 6) to 75 (s.e. 9) for bottlenose dolphins. Apparent survival was estimated for snubfin at 0.81 (s.e. 0.11), humpbacks at 0.59 (s.e. 0.12) and bottlenose at 0.51 (s.e. 0.17) per annum.Key conclusions.(1) The values derived here provide some of the only estimates of local population size for these species across monsoonal northern Australia; (2) population-size estimates varied considerably among seasons or sampling episodes; (3) the low apparent survival probabilities indicated that many individuals may move at scales larger than the study area; (4) density of snubfin and humpback dolphins in the present study area exceeded the few other estimates available for these species elsewhere in Australia.Implications. The present study provided the first baseline estimates of abundance and apparent survival for three coastal dolphin species in monsoonal northern Australia. Such information is becoming increasingly important as development pressures intensify in coastal areas. Sampling protocols for future monitoring and impact assessment need an enhanced consideration of seasonality and scale issues.

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Integrating multiple lines of evidence to better understand the evolutionary divergence of humpback dolphins along their entire distribution range: a new dolphin species in Australian waters?

Cited by 67 publications

References 72 publications

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

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

Ongoing unraveling of a continental fauna: Decline and extinction of Australian mammals since European settlement

Estimates of abundance and apparent survival of coastal dolphins in Port Essington harbour, Northern Territory, Australia

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