Braulik, G.,Natoli, A.,Kiszka, J,Parra, G.,Plon, S.,Smith, B.D.
Tursiops aduncus Journal Article
In: IUCN Red List of Threatened Species, vol. Downloaded on 20 April 2020, no. 50, 2019.
Abstract | Links | BibTeX | Tags: conservation status, indo-Pacific bottlenose dolphin, IUCN, Red List, tursiops aduncus
@article{,
title = {Tursiops aduncus},
author = {Braulik, G.,Natoli, A.,Kiszka, J,Parra, G.,Plon, S.,Smith, B.D.},
url = {https://www.iucnredlist.org/species/41714/50381127},
doi = {https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T41714A50381127.en},
year = {2019},
date = {2019-01-01},
journal = {IUCN Red List of Threatened Species},
volume = {Downloaded on 20 April 2020},
number = {50},
abstract = {Near-threatened: Justification: Indo-Pacific Bottlenose Dolphins generally occur in shallow coastal waters of the Indian Ocean,
Southeast Asia and Australia. They are among the more commonly studied cetaceans in the Indian
Ocean, especially in Shark Bay, Western Australia. However, information on distribution, population size,
and trends in abundance and mortality from much of the species’ range is still very limited. As they are
primarily coastal, Indo-Pacific Bottlenose Dolphins often co-occur with fisheries, and bycatch is a major
cause of concern for this species. Indo-Pacific Bottlenose Dolphins are also at risk from high levels of
noise and chemical pollution, industrial activity such as oil and gas development, and habitat reduction
caused by land reclamation and coastal development (Curry and Smith 1997, Wells and Scott 1999,
Reeves et al. 2003, Kiszka et al. 2008). Furthermore, survey data suggest that Indo-Pacific Bottlenose
Dolphins occur in relatively small populations or communities with limited geographic ranges, especially
where they reside close to islands (Krützen et al. 2004, Natoli et al. 2008, Fury et al. 2008, Särnblad et al.
2011, Kiszka et al. 2012, Gray et al. 2018), which can exacerbate the impact of human activities and
demographic stochasticity on this species. Estimates of abundance from populations for which
information on bycatch is also available indicate that human-caused mortality is frequently
unsustainable (Cockcroft et al. 1992, Shirakihara and Shirakihara 2012, Preen 2004). Based on the sum
of existing abundance estimates, the total population size for the species over its entire range is likely
well in excess of 40,000 individuals. Large parts of the range have never been surveyed (e.g. much of the
Arabian Sea, Arabian/Persian Gulf, Pakistan, India, Red Sea, Somalia, Yemen, Mozambique, Indonesia,
Philippines). The Indo-Pacific Bottlenose Dolphin was classified as Data Deficient in 2008. The species
distribution overlaps the range of several other coastal cetacean species that are red-listed as
Endangered (Irrawaddy Dolphin Orcaella brevirostris and Indian Ocean Humpback Dolphin Sousa
plumbea) or Vulnerable (Indo-Pacific Humpback Dolphin Sousa chinensis and Australian Humpback
Dolphin Sousa sahulensis, Australian Snubfin Dolphin Orcaella heinsohni and the Indo-Pacific Finless
Porpoise Neophocaena phocaenoides) and are subject to the same anthropogenic threats. However,
compared to these other species, the Indo-Pacific Bottlenose Dolphin is assumed to be under less
immediate threat because it has a wider geographic range and probably larger numbers, greater
behavioural plasticity and broader habitat preferences. Data are insufficient to present a robust case for
listing the Indo-Pacific Bottlenose Dolphin in a threatened category (CR, EN, or VU). However, its coastal
distribution, inferred local declines, and intensity of threats throughout its range lead to the conclusion
that Least Concern is not an appropriate category. The Red List Guidelines (version 11, 2014) state that
“the category Near Threatened is applied to taxa that do not qualify as threatened now, but may be
close to qualifying as threatened, and to taxa that do not currently meet the criteria for a threatened
category, but are likely to do so if ongoing conservation actions abate or cease.” Also, to qualify for Near
Threatened, the taxon “should be close to qualifying for the Vulnerable category; estimates of
population size or habitat should be close to the Vulnerable thresholds, especially when there is a high
degree of uncertainty, or possibly meet some of the subcriteria; and this may be combined with
biological susceptibility and threat.” Considering the above, the Indo-Pacific Bottlenose Dolphin is listed
as Near Threatened because: 1) it occurs in a relatively small and restricted near-shore range, 2) it is
highly vulnerable to entanglement in fishing gear and its range overlaps with intensive fisheries known
to entangle and kill dolphins, 3) its near-shore habitat is subject to increasing anthropogenic threats
resulting in habitat loss and degradation, and 4) it is experiencing mortality rates that are likely to be
causing population declines in several areas. The species therefore comes close to meeting criterion A4
for Vulnerable. Population size is inferred and suspected to have declined by close to 30% throughout
the range of the species, over three generations and in a time period encompassing the past, present
and future. The causes of the reduction (gillnet entanglement and coastal habitat degradation) have not
ceased. Generation length for Indo-Pacific Bottlenose Dolphins, according to Taylor et al. (2007), is 21.1
years, therefore three generations is 63.3 years. Thus, an annual decline of around 0.5% would result in
exceeding the 30% decline in 3 generations. Gillnet fisheries and coastal development are increasing
throughout the range of the species and bycatch is anticipated to remain stable or to increase in the
future without urgent and intensive efforts which are unlikely to be forthcoming. It is important to
emphasize that numerous isolated populations of this species would likely qualify as threatened
subpopulations, particularly those found around island groups in the Indian Ocean.},
keywords = {conservation status, indo-Pacific bottlenose dolphin, IUCN, Red List, tursiops aduncus},
pubstate = {published},
tppubtype = {article}
}
Near-threatened: Justification: Indo-Pacific Bottlenose Dolphins generally occur in shallow coastal waters of the Indian Ocean,
Southeast Asia and Australia. They are among the more commonly studied cetaceans in the Indian
Ocean, especially in Shark Bay, Western Australia. However, information on distribution, population size,
and trends in abundance and mortality from much of the species’ range is still very limited. As they are
primarily coastal, Indo-Pacific Bottlenose Dolphins often co-occur with fisheries, and bycatch is a major
cause of concern for this species. Indo-Pacific Bottlenose Dolphins are also at risk from high levels of
noise and chemical pollution, industrial activity such as oil and gas development, and habitat reduction
caused by land reclamation and coastal development (Curry and Smith 1997, Wells and Scott 1999,
Reeves et al. 2003, Kiszka et al. 2008). Furthermore, survey data suggest that Indo-Pacific Bottlenose
Dolphins occur in relatively small populations or communities with limited geographic ranges, especially
where they reside close to islands (Krützen et al. 2004, Natoli et al. 2008, Fury et al. 2008, Särnblad et al.
2011, Kiszka et al. 2012, Gray et al. 2018), which can exacerbate the impact of human activities and
demographic stochasticity on this species. Estimates of abundance from populations for which
information on bycatch is also available indicate that human-caused mortality is frequently
unsustainable (Cockcroft et al. 1992, Shirakihara and Shirakihara 2012, Preen 2004). Based on the sum
of existing abundance estimates, the total population size for the species over its entire range is likely
well in excess of 40,000 individuals. Large parts of the range have never been surveyed (e.g. much of the
Arabian Sea, Arabian/Persian Gulf, Pakistan, India, Red Sea, Somalia, Yemen, Mozambique, Indonesia,
Philippines). The Indo-Pacific Bottlenose Dolphin was classified as Data Deficient in 2008. The species
distribution overlaps the range of several other coastal cetacean species that are red-listed as
Endangered (Irrawaddy Dolphin Orcaella brevirostris and Indian Ocean Humpback Dolphin Sousa
plumbea) or Vulnerable (Indo-Pacific Humpback Dolphin Sousa chinensis and Australian Humpback
Dolphin Sousa sahulensis, Australian Snubfin Dolphin Orcaella heinsohni and the Indo-Pacific Finless
Porpoise Neophocaena phocaenoides) and are subject to the same anthropogenic threats. However,
compared to these other species, the Indo-Pacific Bottlenose Dolphin is assumed to be under less
immediate threat because it has a wider geographic range and probably larger numbers, greater
behavioural plasticity and broader habitat preferences. Data are insufficient to present a robust case for
listing the Indo-Pacific Bottlenose Dolphin in a threatened category (CR, EN, or VU). However, its coastal
distribution, inferred local declines, and intensity of threats throughout its range lead to the conclusion
that Least Concern is not an appropriate category. The Red List Guidelines (version 11, 2014) state that
“the category Near Threatened is applied to taxa that do not qualify as threatened now, but may be
close to qualifying as threatened, and to taxa that do not currently meet the criteria for a threatened
category, but are likely to do so if ongoing conservation actions abate or cease.” Also, to qualify for Near
Threatened, the taxon “should be close to qualifying for the Vulnerable category; estimates of
population size or habitat should be close to the Vulnerable thresholds, especially when there is a high
degree of uncertainty, or possibly meet some of the subcriteria; and this may be combined with
biological susceptibility and threat.” Considering the above, the Indo-Pacific Bottlenose Dolphin is listed
as Near Threatened because: 1) it occurs in a relatively small and restricted near-shore range, 2) it is
highly vulnerable to entanglement in fishing gear and its range overlaps with intensive fisheries known
to entangle and kill dolphins, 3) its near-shore habitat is subject to increasing anthropogenic threats
resulting in habitat loss and degradation, and 4) it is experiencing mortality rates that are likely to be
causing population declines in several areas. The species therefore comes close to meeting criterion A4
for Vulnerable. Population size is inferred and suspected to have declined by close to 30% throughout
the range of the species, over three generations and in a time period encompassing the past, present
and future. The causes of the reduction (gillnet entanglement and coastal habitat degradation) have not
ceased. Generation length for Indo-Pacific Bottlenose Dolphins, according to Taylor et al. (2007), is 21.1
years, therefore three generations is 63.3 years. Thus, an annual decline of around 0.5% would result in
exceeding the 30% decline in 3 generations. Gillnet fisheries and coastal development are increasing
throughout the range of the species and bycatch is anticipated to remain stable or to increase in the
future without urgent and intensive efforts which are unlikely to be forthcoming. It is important to
emphasize that numerous isolated populations of this species would likely qualify as threatened
subpopulations, particularly those found around island groups in the Indian Ocean.
Southeast Asia and Australia. They are among the more commonly studied cetaceans in the Indian
Ocean, especially in Shark Bay, Western Australia. However, information on distribution, population size,
and trends in abundance and mortality from much of the species’ range is still very limited. As they are
primarily coastal, Indo-Pacific Bottlenose Dolphins often co-occur with fisheries, and bycatch is a major
cause of concern for this species. Indo-Pacific Bottlenose Dolphins are also at risk from high levels of
noise and chemical pollution, industrial activity such as oil and gas development, and habitat reduction
caused by land reclamation and coastal development (Curry and Smith 1997, Wells and Scott 1999,
Reeves et al. 2003, Kiszka et al. 2008). Furthermore, survey data suggest that Indo-Pacific Bottlenose
Dolphins occur in relatively small populations or communities with limited geographic ranges, especially
where they reside close to islands (Krützen et al. 2004, Natoli et al. 2008, Fury et al. 2008, Särnblad et al.
2011, Kiszka et al. 2012, Gray et al. 2018), which can exacerbate the impact of human activities and
demographic stochasticity on this species. Estimates of abundance from populations for which
information on bycatch is also available indicate that human-caused mortality is frequently
unsustainable (Cockcroft et al. 1992, Shirakihara and Shirakihara 2012, Preen 2004). Based on the sum
of existing abundance estimates, the total population size for the species over its entire range is likely
well in excess of 40,000 individuals. Large parts of the range have never been surveyed (e.g. much of the
Arabian Sea, Arabian/Persian Gulf, Pakistan, India, Red Sea, Somalia, Yemen, Mozambique, Indonesia,
Philippines). The Indo-Pacific Bottlenose Dolphin was classified as Data Deficient in 2008. The species
distribution overlaps the range of several other coastal cetacean species that are red-listed as
Endangered (Irrawaddy Dolphin Orcaella brevirostris and Indian Ocean Humpback Dolphin Sousa
plumbea) or Vulnerable (Indo-Pacific Humpback Dolphin Sousa chinensis and Australian Humpback
Dolphin Sousa sahulensis, Australian Snubfin Dolphin Orcaella heinsohni and the Indo-Pacific Finless
Porpoise Neophocaena phocaenoides) and are subject to the same anthropogenic threats. However,
compared to these other species, the Indo-Pacific Bottlenose Dolphin is assumed to be under less
immediate threat because it has a wider geographic range and probably larger numbers, greater
behavioural plasticity and broader habitat preferences. Data are insufficient to present a robust case for
listing the Indo-Pacific Bottlenose Dolphin in a threatened category (CR, EN, or VU). However, its coastal
distribution, inferred local declines, and intensity of threats throughout its range lead to the conclusion
that Least Concern is not an appropriate category. The Red List Guidelines (version 11, 2014) state that
“the category Near Threatened is applied to taxa that do not qualify as threatened now, but may be
close to qualifying as threatened, and to taxa that do not currently meet the criteria for a threatened
category, but are likely to do so if ongoing conservation actions abate or cease.” Also, to qualify for Near
Threatened, the taxon “should be close to qualifying for the Vulnerable category; estimates of
population size or habitat should be close to the Vulnerable thresholds, especially when there is a high
degree of uncertainty, or possibly meet some of the subcriteria; and this may be combined with
biological susceptibility and threat.” Considering the above, the Indo-Pacific Bottlenose Dolphin is listed
as Near Threatened because: 1) it occurs in a relatively small and restricted near-shore range, 2) it is
highly vulnerable to entanglement in fishing gear and its range overlaps with intensive fisheries known
to entangle and kill dolphins, 3) its near-shore habitat is subject to increasing anthropogenic threats
resulting in habitat loss and degradation, and 4) it is experiencing mortality rates that are likely to be
causing population declines in several areas. The species therefore comes close to meeting criterion A4
for Vulnerable. Population size is inferred and suspected to have declined by close to 30% throughout
the range of the species, over three generations and in a time period encompassing the past, present
and future. The causes of the reduction (gillnet entanglement and coastal habitat degradation) have not
ceased. Generation length for Indo-Pacific Bottlenose Dolphins, according to Taylor et al. (2007), is 21.1
years, therefore three generations is 63.3 years. Thus, an annual decline of around 0.5% would result in
exceeding the 30% decline in 3 generations. Gillnet fisheries and coastal development are increasing
throughout the range of the species and bycatch is anticipated to remain stable or to increase in the
future without urgent and intensive efforts which are unlikely to be forthcoming. It is important to
emphasize that numerous isolated populations of this species would likely qualify as threatened
subpopulations, particularly those found around island groups in the Indian Ocean.
Gray, H. W. I.,Nishida, S.,Welch, A. J.,Moura, A. E.,Tanabe, S.,Kiani, M. S.,Culloch, R.,Möller, L.,Natoli, A.,Ponnampalam, L. S.,Minton, G.,Gore, M.,Collins, T.,Willson, A.,Baldwin, R.,Hoelzel, A. R.
Cryptic Lineage Differentiation Among Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in the Northwest Indian Ocean Journal Article
In: Molecular Phylogenetics and Evolution, no. 381, 2017, ISBN: 1055-7903.
Abstract | Links | BibTeX | Tags: bottlenose dolphin, conservation, Indian Ocean, Phylogeography, Pleistocene, taxonomy, tursiops aduncus
@article{,
title = {Cryptic Lineage Differentiation Among Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in the Northwest Indian Ocean},
author = {Gray, H. W. I.,Nishida, S.,Welch, A. J.,Moura, A. E.,Tanabe, S.,Kiani, M. S.,Culloch, R.,Möller, L.,Natoli, A.,Ponnampalam, L. S.,Minton, G.,Gore, M.,Collins, T.,Willson, A.,Baldwin, R.,Hoelzel, A. R.},
url = {https://www.sciencedirect.com/science/article/pii/S1055790317300635},
issn = {1055-7903},
year = {2017},
date = {2017-01-01},
journal = {Molecular Phylogenetics and Evolution},
number = {381},
abstract = {Phylogeography can provide insight into the potential for speciation and identify geographic regions and evolutionary processes associated with species richness and evolutionary endemism. In the marine environment, highly mobile species sometimes show structured patterns of diversity, but the processes isolating populations and promoting differentiation are often unclear. The Delphinidae (oceanic dolphins) are a striking case in point and, in particular, bottlenose dolphins (Tursiops spp.). Understanding the radiation of species in this genus is likely to provide broader inference about the processes that determine patterns of biogeography and speciation, because both fine-scale structure over a range of kilometers and relative panmixia over an oceanic range are known for Tursiops populations. In our study, novel Tursiops spp. sequences from the northwest Indian Ocean (including mitogenomes and two nuDNA loci) are included in a worldwide Tursiops spp. phylogeographic analysis. We discover a new ‘aduncus’ type lineage in the Arabian Sea (off India, Pakistan and Oman) that diverged from the Australasian lineage },
keywords = {bottlenose dolphin, conservation, Indian Ocean, Phylogeography, Pleistocene, taxonomy, tursiops aduncus},
pubstate = {published},
tppubtype = {article}
}
Phylogeography can provide insight into the potential for speciation and identify geographic regions and evolutionary processes associated with species richness and evolutionary endemism. In the marine environment, highly mobile species sometimes show structured patterns of diversity, but the processes isolating populations and promoting differentiation are often unclear. The Delphinidae (oceanic dolphins) are a striking case in point and, in particular, bottlenose dolphins (Tursiops spp.). Understanding the radiation of species in this genus is likely to provide broader inference about the processes that determine patterns of biogeography and speciation, because both fine-scale structure over a range of kilometers and relative panmixia over an oceanic range are known for Tursiops populations. In our study, novel Tursiops spp. sequences from the northwest Indian Ocean (including mitogenomes and two nuDNA loci) are included in a worldwide Tursiops spp. phylogeographic analysis. We discover a new ‘aduncus’ type lineage in the Arabian Sea (off India, Pakistan and Oman) that diverged from the Australasian lineage
Reeves, R.R.,Brownell Jr, R.L.
Indo-Pacific bottlenose dolphin assessment workshop report: Solomon Islands case study of Journal Article
In: Occasional Paper of the Species Survival Commission, IUCN, Gland, vol. 40, no. 203, pp. 53, 2009.
Abstract | BibTeX | Tags: bottlenose dolphin, captive dolphin trade, Live capture, solomon islands, tursiops aduncus
@article{,
title = {Indo-Pacific bottlenose dolphin assessment workshop report: Solomon Islands case study of },
author = {Reeves, R.R.,Brownell Jr, R.L.},
year = {2009},
date = {2009-01-01},
journal = {Occasional Paper of the Species Survival Commission, IUCN, Gland},
volume = {40},
number = {203},
pages = {53},
abstract = {A workshop on the assessment of Indo-Pacific bottlenose dolphins (Tursiops aduncus), with the Solomon Islands as a case study, took place from 21-23 August 2008 in Apia, Samoa. It was planned and organized under the auspices of the Cetacean Specialist Group and attended by 19 invited participants from eight countries. Financial support was provided by WWF (International), The Ocean Conservancy, Animal Welfare Institute, Humane Society of the United States, Whale and Dolphin Conservation Society, U.S. Marine Mammal Commission and U.S. National Oceanic and Atmospheric Administration. The workshop was hosted by the Secretariat of the Pacific Regional Environment Programme (SPREP).
Live-capture, holding in captivity and export of Indo-Pacific bottlenose dolphins from the Solomon Islands began in 2003. These activities stimulated global interest and generated concern about the potential conservation implications. The IUCN Global Plan of Action for the Conservation of Cetaceans had stated that as a general principle, small cetaceans should not be captured or removed from a wild population unless that specific population has been assessed and shown capable of sustaining the removals. A principal goal of the present workshop was to elaborate on the elements of an assessment that would meet this standard. Participants noted that an assessment involving delineation of stock boundaries, abundance, reproductive potential, mortality and trend cannot necessarily be achieved quickly or inexpensively.
Specific topics covered by the workshop included management goals and assessment options, general biology and life history of bottlenose dolphins, forms of direct removal of dolphins from the wild, other threat factors, defining units to conserve, methods for estimating population size and assessment algorithms (e.g. population viability analysis). A framework for assessment was outlined, suggestions for genetic sampling and analyses were developed, and cultural and other local considerations for researchers working in the Pacific Islands region were summarised.
There is a need to determine the conservation status of Indo-Pacific bottlenose dolphin populations around islands where human-caused mortality or removal (direct or incidental catch) is known to be occurring. The species has a limited coastal range throughout much of the Indo-Pacific Ocean except in areas with wide continental shelves. Its near-shore distribution makes it particularly vulnerable to exploitation and other anthropogenic threats. In some regions where these dolphins have been studied, the populations have been found to be small compared to nearby open-ocean populations of common bottlenose dolphins (T. truncatus) and other species. The only known large concentrations (> ca. 1,000) are in regions with large shallow-water areas, e.g. Shark Bay on the western coast of Australia, North Stradbroke Island on the eastern coast of Australia and the Arabian Gulf. Given the restricted areas of potentially suitable habitat, populations of T. aduncus in the South Pacific islands are likely small, i.e. in the hundreds.
The government of the Solomon Islands had issued a permit for export of up to 80 dolphins per year (CITES Secretariat document AC 23 Doc.8.5) and it was reported at the workshop that the annual allowable export level was being increased to 100 dolphins of any species, but most likely to be only T. aduncus. If an international standard rule allowing 1% or 2% of a population to be removed annually (per IWC, ASCOBANS etc.) were applied in this instance, the local T. aduncus population would have to be at least 5,000 or 10,000 to sustain the permitted level of exports.
Based on the current state of knowledge of Indo-Pacific bottlenose dolphins throughout their range, as well as the information on this species in the Solomon Islands reviewed at the workshop, abundance in the area of recent live-captures appears to be well below 5,000. By the time of the workshop, an ongoing photo-identification study around Guadalcanal Island had catalogued only somewhat more than 100 individuals. Population assessment efforts need to be expanded if live-capture activities are to continue. It was concluded that the best approach to assess abundance and delineate populations would be a combination of mark-recapture analyses of photo-identification data and genetic analyses of tissue samples. It is assumed that Indo-Pacific bottlenose dolphins are not taken in the drive hunt in the Solomon Islands, but if they are, then both types of removal – live-capture and hunting – would need to be considered in any assessment of population status.},
keywords = {bottlenose dolphin, captive dolphin trade, Live capture, solomon islands, tursiops aduncus},
pubstate = {published},
tppubtype = {article}
}
A workshop on the assessment of Indo-Pacific bottlenose dolphins (Tursiops aduncus), with the Solomon Islands as a case study, took place from 21-23 August 2008 in Apia, Samoa. It was planned and organized under the auspices of the Cetacean Specialist Group and attended by 19 invited participants from eight countries. Financial support was provided by WWF (International), The Ocean Conservancy, Animal Welfare Institute, Humane Society of the United States, Whale and Dolphin Conservation Society, U.S. Marine Mammal Commission and U.S. National Oceanic and Atmospheric Administration. The workshop was hosted by the Secretariat of the Pacific Regional Environment Programme (SPREP).
Live-capture, holding in captivity and export of Indo-Pacific bottlenose dolphins from the Solomon Islands began in 2003. These activities stimulated global interest and generated concern about the potential conservation implications. The IUCN Global Plan of Action for the Conservation of Cetaceans had stated that as a general principle, small cetaceans should not be captured or removed from a wild population unless that specific population has been assessed and shown capable of sustaining the removals. A principal goal of the present workshop was to elaborate on the elements of an assessment that would meet this standard. Participants noted that an assessment involving delineation of stock boundaries, abundance, reproductive potential, mortality and trend cannot necessarily be achieved quickly or inexpensively.
Specific topics covered by the workshop included management goals and assessment options, general biology and life history of bottlenose dolphins, forms of direct removal of dolphins from the wild, other threat factors, defining units to conserve, methods for estimating population size and assessment algorithms (e.g. population viability analysis). A framework for assessment was outlined, suggestions for genetic sampling and analyses were developed, and cultural and other local considerations for researchers working in the Pacific Islands region were summarised.
There is a need to determine the conservation status of Indo-Pacific bottlenose dolphin populations around islands where human-caused mortality or removal (direct or incidental catch) is known to be occurring. The species has a limited coastal range throughout much of the Indo-Pacific Ocean except in areas with wide continental shelves. Its near-shore distribution makes it particularly vulnerable to exploitation and other anthropogenic threats. In some regions where these dolphins have been studied, the populations have been found to be small compared to nearby open-ocean populations of common bottlenose dolphins (T. truncatus) and other species. The only known large concentrations (> ca. 1,000) are in regions with large shallow-water areas, e.g. Shark Bay on the western coast of Australia, North Stradbroke Island on the eastern coast of Australia and the Arabian Gulf. Given the restricted areas of potentially suitable habitat, populations of T. aduncus in the South Pacific islands are likely small, i.e. in the hundreds.
The government of the Solomon Islands had issued a permit for export of up to 80 dolphins per year (CITES Secretariat document AC 23 Doc.8.5) and it was reported at the workshop that the annual allowable export level was being increased to 100 dolphins of any species, but most likely to be only T. aduncus. If an international standard rule allowing 1% or 2% of a population to be removed annually (per IWC, ASCOBANS etc.) were applied in this instance, the local T. aduncus population would have to be at least 5,000 or 10,000 to sustain the permitted level of exports.
Based on the current state of knowledge of Indo-Pacific bottlenose dolphins throughout their range, as well as the information on this species in the Solomon Islands reviewed at the workshop, abundance in the area of recent live-captures appears to be well below 5,000. By the time of the workshop, an ongoing photo-identification study around Guadalcanal Island had catalogued only somewhat more than 100 individuals. Population assessment efforts need to be expanded if live-capture activities are to continue. It was concluded that the best approach to assess abundance and delineate populations would be a combination of mark-recapture analyses of photo-identification data and genetic analyses of tissue samples. It is assumed that Indo-Pacific bottlenose dolphins are not taken in the drive hunt in the Solomon Islands, but if they are, then both types of removal – live-capture and hunting – would need to be considered in any assessment of population status.
Live-capture, holding in captivity and export of Indo-Pacific bottlenose dolphins from the Solomon Islands began in 2003. These activities stimulated global interest and generated concern about the potential conservation implications. The IUCN Global Plan of Action for the Conservation of Cetaceans had stated that as a general principle, small cetaceans should not be captured or removed from a wild population unless that specific population has been assessed and shown capable of sustaining the removals. A principal goal of the present workshop was to elaborate on the elements of an assessment that would meet this standard. Participants noted that an assessment involving delineation of stock boundaries, abundance, reproductive potential, mortality and trend cannot necessarily be achieved quickly or inexpensively.
Specific topics covered by the workshop included management goals and assessment options, general biology and life history of bottlenose dolphins, forms of direct removal of dolphins from the wild, other threat factors, defining units to conserve, methods for estimating population size and assessment algorithms (e.g. population viability analysis). A framework for assessment was outlined, suggestions for genetic sampling and analyses were developed, and cultural and other local considerations for researchers working in the Pacific Islands region were summarised.
There is a need to determine the conservation status of Indo-Pacific bottlenose dolphin populations around islands where human-caused mortality or removal (direct or incidental catch) is known to be occurring. The species has a limited coastal range throughout much of the Indo-Pacific Ocean except in areas with wide continental shelves. Its near-shore distribution makes it particularly vulnerable to exploitation and other anthropogenic threats. In some regions where these dolphins have been studied, the populations have been found to be small compared to nearby open-ocean populations of common bottlenose dolphins (T. truncatus) and other species. The only known large concentrations (> ca. 1,000) are in regions with large shallow-water areas, e.g. Shark Bay on the western coast of Australia, North Stradbroke Island on the eastern coast of Australia and the Arabian Gulf. Given the restricted areas of potentially suitable habitat, populations of T. aduncus in the South Pacific islands are likely small, i.e. in the hundreds.
The government of the Solomon Islands had issued a permit for export of up to 80 dolphins per year (CITES Secretariat document AC 23 Doc.8.5) and it was reported at the workshop that the annual allowable export level was being increased to 100 dolphins of any species, but most likely to be only T. aduncus. If an international standard rule allowing 1% or 2% of a population to be removed annually (per IWC, ASCOBANS etc.) were applied in this instance, the local T. aduncus population would have to be at least 5,000 or 10,000 to sustain the permitted level of exports.
Based on the current state of knowledge of Indo-Pacific bottlenose dolphins throughout their range, as well as the information on this species in the Solomon Islands reviewed at the workshop, abundance in the area of recent live-captures appears to be well below 5,000. By the time of the workshop, an ongoing photo-identification study around Guadalcanal Island had catalogued only somewhat more than 100 individuals. Population assessment efforts need to be expanded if live-capture activities are to continue. It was concluded that the best approach to assess abundance and delineate populations would be a combination of mark-recapture analyses of photo-identification data and genetic analyses of tissue samples. It is assumed that Indo-Pacific bottlenose dolphins are not taken in the drive hunt in the Solomon Islands, but if they are, then both types of removal – live-capture and hunting – would need to be considered in any assessment of population status.
Jayasankar, P.,Anoop, B.,Vivekanandan, E.,Rajagopalan, M.,Yousuf, K.M.M.,Reynolds, P.,Krishnakumar, P.K.,Kumaran, PL.,Afsal, V.V.,Krishnan, A.A.
Molecular identification of delphinids and finless porpoise (Cetacea) from the Arabian Sea and Bay of Bengal Journal Article
In: Zootaxa, vol. 1853, no. 125, pp. 57-67, 2008.
Abstract | BibTeX | Tags: bottlenose dolphin, Common dolphin, D.capensis, DNA, Finless Porpoise, India, Neophocaena phocaenoides, sousa, species identification, Spinner dolphin, Stenella longirostris, taxonomy, tursiops aduncus
@article{,
title = {Molecular identification of delphinids and finless porpoise (Cetacea) from the Arabian Sea and Bay of Bengal},
author = {Jayasankar, P.,Anoop, B.,Vivekanandan, E.,Rajagopalan, M.,Yousuf, K.M.M.,Reynolds, P.,Krishnakumar, P.K.,Kumaran, PL.,Afsal, V.V.,Krishnan, A.A.},
year = {2008},
date = {2008-01-01},
journal = {Zootaxa},
volume = {1853},
number = {125},
pages = {57-67},
abstract = {The exact number of extant delphinid species from seas around India is still debated and the lack of adequate field keys
and reliable inventory has resulted in misidentification of several species. As a part of a project to develop a molecular
taxonomy of cetaceans from this region, partial sequences of mtDNA cytochrome b were generated from accidentally
caught/stranded delphinids and finless porpoise. Species were identified by phylogenetic reconstruction of sample
sequences with the reference sequences available in portals GenBank (NCBI) and the web-based program DNA Surveillance.
A comparison was made with the homologous sequences of corresponding species from other seas of the world.
Our molecular investigations allowed us to identify five species of cetaceans from Indian coasts, including Delphinus
capensis, previously reported as D. delphis. We detected unique haplotypes in Indo pacific humpbacked dolphin (Sousa
chinensis; n = 2) and finless porpoise (Neophocaena phocaenoides; n = 12) from Indian coast. On the other hand, some
haplotypes were shared with other regional populations in spinner dolphin (Stenella longirostris; n = 16) and bottlenose
dolphin (Tursiops aduncus; n = 3). Common dolphins (Delphinus capensis; n = 2) had both unique and shared haplotypes
including one highly divergent sequence.},
keywords = {bottlenose dolphin, Common dolphin, D.capensis, DNA, Finless Porpoise, India, Neophocaena phocaenoides, sousa, species identification, Spinner dolphin, Stenella longirostris, taxonomy, tursiops aduncus},
pubstate = {published},
tppubtype = {article}
}
The exact number of extant delphinid species from seas around India is still debated and the lack of adequate field keys
and reliable inventory has resulted in misidentification of several species. As a part of a project to develop a molecular
taxonomy of cetaceans from this region, partial sequences of mtDNA cytochrome b were generated from accidentally
caught/stranded delphinids and finless porpoise. Species were identified by phylogenetic reconstruction of sample
sequences with the reference sequences available in portals GenBank (NCBI) and the web-based program DNA Surveillance.
A comparison was made with the homologous sequences of corresponding species from other seas of the world.
Our molecular investigations allowed us to identify five species of cetaceans from Indian coasts, including Delphinus
capensis, previously reported as D. delphis. We detected unique haplotypes in Indo pacific humpbacked dolphin (Sousa
chinensis; n = 2) and finless porpoise (Neophocaena phocaenoides; n = 12) from Indian coast. On the other hand, some
haplotypes were shared with other regional populations in spinner dolphin (Stenella longirostris; n = 16) and bottlenose
dolphin (Tursiops aduncus; n = 3). Common dolphins (Delphinus capensis; n = 2) had both unique and shared haplotypes
including one highly divergent sequence.
and reliable inventory has resulted in misidentification of several species. As a part of a project to develop a molecular
taxonomy of cetaceans from this region, partial sequences of mtDNA cytochrome b were generated from accidentally
caught/stranded delphinids and finless porpoise. Species were identified by phylogenetic reconstruction of sample
sequences with the reference sequences available in portals GenBank (NCBI) and the web-based program DNA Surveillance.
A comparison was made with the homologous sequences of corresponding species from other seas of the world.
Our molecular investigations allowed us to identify five species of cetaceans from Indian coasts, including Delphinus
capensis, previously reported as D. delphis. We detected unique haplotypes in Indo pacific humpbacked dolphin (Sousa
chinensis; n = 2) and finless porpoise (Neophocaena phocaenoides; n = 12) from Indian coast. On the other hand, some
haplotypes were shared with other regional populations in spinner dolphin (Stenella longirostris; n = 16) and bottlenose
dolphin (Tursiops aduncus; n = 3). Common dolphins (Delphinus capensis; n = 2) had both unique and shared haplotypes
including one highly divergent sequence.