Díaz López, Bruno,Grandcourt, Edwin,Methion, Séverine,Das, Himansu,Bugla, Ibrahim,Al Hameli, Maitha,Al Ameri, Hind,Abdulla, Mohamed,Al Blooshi, Ayesha,Al Dhaheri, Shaikha
The distribution, abundance and group dynamics of Indian Ocean humpback dolphins ( Journal Article
In: Journal of the Marine Biological Association of the United Kingdom, no. 88, pp. 1-9, 2017, ISBN: 0025-3154.
Abstract | Links | BibTeX | Tags: abundance, Arabian Gulf, coastal environment, conservation, Indian Ocean humpback dolphins, Persian Gulf, photo-identification, sousa
@article{,
title = {The distribution, abundance and group dynamics of Indian Ocean humpback dolphins (},
author = {Díaz López, Bruno,Grandcourt, Edwin,Methion, Séverine,Das, Himansu,Bugla, Ibrahim,Al Hameli, Maitha,Al Ameri, Hind,Abdulla, Mohamed,Al Blooshi, Ayesha,Al Dhaheri, Shaikha},
url = {https://www.cambridge.org/core/article/distribution-abundance-and-group-dynamics-of-indian-ocean-humpback-dolphins-sousa-plumbea-in-the-emirate-of-abu-dhabi-uae/9FB6BE811A329C1A0BA57F0BDFC65AB3},
issn = {0025-3154},
year = {2017},
date = {2017-01-01},
journal = {Journal of the Marine Biological Association of the United Kingdom},
number = {88},
pages = {1-9},
publisher = {Cambridge University Press},
abstract = {The Arabian Gulf is one of the most heavily impacted water bodies raising serious concerns about the conservation status of many marine species. A limited coastal range and near-shore distribution make Indian Ocean humpback dolphins particularly vulnerable to mortality and traumatic injuries from heavy maritime traffic and gill-netting practices. Prior to the present study, no research had focused on the ecology of this species in the Arabian Gulf, despite the potential for human impacts. The mark–recapture method of photo-identification, undertaken during 55 boat-based surveys conducted between 2014 and 2015, was used to assess the occurrence, abundance and use of habitat of this endangered species along the coast of the Emirate of Abu Dhabi (UAE). In all, 368 h and 6703 km of observation were carried out over a period of 5 months, and 54 encounters were made with humpback dolphins. The group size ranged from 1 to 24 individuals and group composition showed that 79% of the observed dolphins were adults. Abundance estimates were calculated and fitted with open population models. A review of all available data indicates that the studied population is the largest reported in the world with 701 (95% CI = 473–845) individuals. While their occurrence within Abu Dhabi near-shore waters is frequent, the survey area appears to be only a part of a much larger home range for this humpback dolphin population. The observation of multiple threats derived from anthropogenic activities increases our concerns regarding the conservation of this important dolphin population.},
keywords = {abundance, Arabian Gulf, coastal environment, conservation, Indian Ocean humpback dolphins, Persian Gulf, photo-identification, sousa},
pubstate = {published},
tppubtype = {article}
}
The Arabian Gulf is one of the most heavily impacted water bodies raising serious concerns about the conservation status of many marine species. A limited coastal range and near-shore distribution make Indian Ocean humpback dolphins particularly vulnerable to mortality and traumatic injuries from heavy maritime traffic and gill-netting practices. Prior to the present study, no research had focused on the ecology of this species in the Arabian Gulf, despite the potential for human impacts. The mark–recapture method of photo-identification, undertaken during 55 boat-based surveys conducted between 2014 and 2015, was used to assess the occurrence, abundance and use of habitat of this endangered species along the coast of the Emirate of Abu Dhabi (UAE). In all, 368 h and 6703 km of observation were carried out over a period of 5 months, and 54 encounters were made with humpback dolphins. The group size ranged from 1 to 24 individuals and group composition showed that 79% of the observed dolphins were adults. Abundance estimates were calculated and fitted with open population models. A review of all available data indicates that the studied population is the largest reported in the world with 701 (95% CI = 473–845) individuals. While their occurrence within Abu Dhabi near-shore waters is frequent, the survey area appears to be only a part of a much larger home range for this humpback dolphin population. The observation of multiple threats derived from anthropogenic activities increases our concerns regarding the conservation of this important dolphin population.
Braulik,G.,Ranjbar,S.,Owfi,F.,Aminrad,T.,Dakhteh,S.M.H.,Kamrani,E.,Mohsenizadeh,F.
Marine Mammal Records from Iran Journal Article
In: Journal of Cetacean Research and Management, vol. 11, no. 334, pp. 49-63, 2010.
Abstract | BibTeX | Tags: abundance, bottlenose dolphin, Bryde's whale, Common dolphin, conservation, Distribution, dolphin, dugong, fin whale, Finless Porpoise, fishing gear, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, killer whale, location, mammals, management, marine, marine mammal, Marine mammals, mortality, mysticete, mysticetes, Oman, Porpoise, Risso's dolphin, rough-toothed dolphin, Spinner dolphin, whale, whales
@article{,
title = {Marine Mammal Records from Iran},
author = {Braulik,G.,Ranjbar,S.,Owfi,F.,Aminrad,T.,Dakhteh,S.M.H.,Kamrani,E.,Mohsenizadeh,F.},
year = {2010},
date = {2010-01-01},
journal = {Journal of Cetacean Research and Management},
volume = {11},
number = {334},
pages = {49-63},
abstract = {A total of 114 marine mammal records of 14 species were compiled from Iranian coastalwaters of the Persian Gulf and Gulf of Oman. Eighty-one were from the Persian Gulf, 23from the Gulf of Oman and 10 were of unknown location. Records of finless porpoise(Neophocaena phocaenoides) (24), Indo-pacific humpback dolphin (Sousa chinensis) (22)and Indo-pacific bottlenose dolphin (Tursiops aduncus) (21) were by far the most numerousa probable reflection of their inshore distribution and local abundance. Other speciesrecorded were common dolphin (Delphinus capensis tropicalis), rough-toothed dolphin(Steno bredanensis), striped dolphin (Stenella coeruleoalba), spinner dolphin (Stenellalongirostris), Risso's dolphin (Grampus griseus), false killer whale (Pseudorca crassidens),sperm whale (Physeter macrocephalus) and dugong (Dugong dugon). Records of 24Mysticetes were compiled, 11 of which were tentatively identified as Bryde's whales(Balaenoptera edeni), three as Fin whales (Balaenoptera physalus), three as Humpbackwhales (Megaptera novaeangliae) and the remainder were unidentified. The largest threat tomarine mammals in Iran is likely to be incidental capture in fishing gear. Nine finlessporpoises were recorded as bycatch and this and other coastal species may be declining dueto unsustainable mortality rates. Other threats to the marine environment are discussed andrecommended marine mammal conservation and management small projects are described.},
keywords = {abundance, bottlenose dolphin, Bryde's whale, Common dolphin, conservation, Distribution, dolphin, dugong, fin whale, Finless Porpoise, fishing gear, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, killer whale, location, mammals, management, marine, marine mammal, Marine mammals, mortality, mysticete, mysticetes, Oman, Porpoise, Risso's dolphin, rough-toothed dolphin, Spinner dolphin, whale, whales},
pubstate = {published},
tppubtype = {article}
}
A total of 114 marine mammal records of 14 species were compiled from Iranian coastalwaters of the Persian Gulf and Gulf of Oman. Eighty-one were from the Persian Gulf, 23from the Gulf of Oman and 10 were of unknown location. Records of finless porpoise(Neophocaena phocaenoides) (24), Indo-pacific humpback dolphin (Sousa chinensis) (22)and Indo-pacific bottlenose dolphin (Tursiops aduncus) (21) were by far the most numerousa probable reflection of their inshore distribution and local abundance. Other speciesrecorded were common dolphin (Delphinus capensis tropicalis), rough-toothed dolphin(Steno bredanensis), striped dolphin (Stenella coeruleoalba), spinner dolphin (Stenellalongirostris), Risso's dolphin (Grampus griseus), false killer whale (Pseudorca crassidens),sperm whale (Physeter macrocephalus) and dugong (Dugong dugon). Records of 24Mysticetes were compiled, 11 of which were tentatively identified as Bryde's whales(Balaenoptera edeni), three as Fin whales (Balaenoptera physalus), three as Humpbackwhales (Megaptera novaeangliae) and the remainder were unidentified. The largest threat tomarine mammals in Iran is likely to be incidental capture in fishing gear. Nine finlessporpoises were recorded as bycatch and this and other coastal species may be declining dueto unsustainable mortality rates. Other threats to the marine environment are discussed andrecommended marine mammal conservation and management small projects are described.
Cockcroft, V.,Guissamulo, A.,Findlay, K.
Dugongs (Dugong dugon) of the Bazaruto Archipelago, Mozambique Technical Report
no. 72, 2008, ISBN: Final Report to SASOL Mozambique.
Abstract | BibTeX | Tags: abundance, Distribution, dugong, East Africa, Mozambique
@techreport{,
title = {Dugongs (Dugong dugon) of the Bazaruto Archipelago, Mozambique},
author = {Cockcroft, V.,Guissamulo, A.,Findlay, K.},
issn = {Final Report to SASOL Mozambique},
year = {2008},
date = {2008-01-01},
number = {72},
pages = {1-84},
abstract = {Historically, dugongs occurred in almost all coastal areas from southern Mozambique in the
west to Australia in the east, including many of the island States in the Indian and Pacific
Oceans between. However, through much of this range, dugongs have all but disappeared
and where they occur, are represented by relict populations. This is especially true for
Eastern Africa and the Indian Ocean and Mascerine Islands. In most areas dugongs have
been extirpated and only in southern, central Mozambique, the Bazaruto Archipelago, does a
relatively large number still survive.
Between April 2006 and December 2007 a series of 27 aerial surveys was flown over the
Bazaruto Bay region, from Cabo Sao Sebastio in the south to north of the Save River Mouth
in the north and between the coast and the 30 m isobath (extending to eastwards of the
Bazaruto Archipelago islands in the south). A total of 9052 nautical miles of survey was flown
during the 27 surveys. During these, 355 sightings of an estimated 760 dugongs were made.
Two core areas of distribution were apparent; a northern core region, between the Save River
Mouth and 21°24’ S, and a southern core region aligned with the shallow sandbanks to the
north and south of Santa Carolina Island. The mean group size of dugongs encountered was
2.22 and comparable to mean group sizes observed elsewhere. However, the maximum
group size observed was considerably smaller than those observed in other areas of dugong
abundance. Likewise, calculated dugong densities were substantially lower in the Bazaruto
area than they are in the Arabian Gulf or Australia. There was no evidence of any seasonal
variation in occurrence, group size, density or proportion of calves. The proportion of calves
was similar to that in other areas surveyed for dugongs.
Statistical manipulation of the data from aerial surveys suggests that the dugong population
inhabiting the area surveyed is around 250 animals.
The extent of dugong habitat was gauged by mapping seagrass occurrence, diversity and
distribution. Mapping was accomplished through extensive dive sampling of 982 stations
within the surveyed area, within 5m to about 25 m depth. Five species of seagrass were
identified within the area. These covered some 4.68 % of the area and occurred generally in
the north and close to the shore in waters less than 8 m deep. In the north, the areas of
greatest seagrass abundance and diversity coincide with the areas of greatest dugong
abundance. However, in the area to the north and south of Santa Carolina, seagresses were
almost absent, suggesting that this area is used by dugongs for reasons other than feeding.
Population Viability Analysis (PVA) modelling was used to assess the viability of the dugong
population in the Bazaruto Archipelago under various scenarios. PVA is a statistical method
of understanding the influence of a species’ natural history, in combination with demographic,
environmental, and random genetic (stochastic) events, on the dynamics of its future. The
species’ population dynamics is modelled as a set of discrete, sequential events (e.g., births,
deaths, catastrophes, etc.), which occur according to defined probabilities. Population
dynamics models provide a predictive tool, where the impacts of variables (threats), in this
instance – environmental threats (cyclones, floods); hydrocarbon exploration and incidental
fishing catch, can be theoretically modelled.
Overall, the PVA models suggest strongly that the dugongs inhabiting Bazaruto Bay are in a
precarious position and face extirpation. The models suggest that dugongs are particularly
susceptible to long term stressors that might reduce overall reproductive success. Further, the
analyses clearly show that regular deaths, from anthropogenic sources, are the major cause
of dugong decline.
A number of scenarios, covering options for hydrocarbon exploration and exploitation, are
presented and discussed, in terms of their potential impacts on the dugongs inhabiting the
Bazaruto area.},
keywords = {abundance, Distribution, dugong, East Africa, Mozambique},
pubstate = {published},
tppubtype = {techreport}
}
Historically, dugongs occurred in almost all coastal areas from southern Mozambique in the
west to Australia in the east, including many of the island States in the Indian and Pacific
Oceans between. However, through much of this range, dugongs have all but disappeared
and where they occur, are represented by relict populations. This is especially true for
Eastern Africa and the Indian Ocean and Mascerine Islands. In most areas dugongs have
been extirpated and only in southern, central Mozambique, the Bazaruto Archipelago, does a
relatively large number still survive.
Between April 2006 and December 2007 a series of 27 aerial surveys was flown over the
Bazaruto Bay region, from Cabo Sao Sebastio in the south to north of the Save River Mouth
in the north and between the coast and the 30 m isobath (extending to eastwards of the
Bazaruto Archipelago islands in the south). A total of 9052 nautical miles of survey was flown
during the 27 surveys. During these, 355 sightings of an estimated 760 dugongs were made.
Two core areas of distribution were apparent; a northern core region, between the Save River
Mouth and 21°24’ S, and a southern core region aligned with the shallow sandbanks to the
north and south of Santa Carolina Island. The mean group size of dugongs encountered was
2.22 and comparable to mean group sizes observed elsewhere. However, the maximum
group size observed was considerably smaller than those observed in other areas of dugong
abundance. Likewise, calculated dugong densities were substantially lower in the Bazaruto
area than they are in the Arabian Gulf or Australia. There was no evidence of any seasonal
variation in occurrence, group size, density or proportion of calves. The proportion of calves
was similar to that in other areas surveyed for dugongs.
Statistical manipulation of the data from aerial surveys suggests that the dugong population
inhabiting the area surveyed is around 250 animals.
The extent of dugong habitat was gauged by mapping seagrass occurrence, diversity and
distribution. Mapping was accomplished through extensive dive sampling of 982 stations
within the surveyed area, within 5m to about 25 m depth. Five species of seagrass were
identified within the area. These covered some 4.68 % of the area and occurred generally in
the north and close to the shore in waters less than 8 m deep. In the north, the areas of
greatest seagrass abundance and diversity coincide with the areas of greatest dugong
abundance. However, in the area to the north and south of Santa Carolina, seagresses were
almost absent, suggesting that this area is used by dugongs for reasons other than feeding.
Population Viability Analysis (PVA) modelling was used to assess the viability of the dugong
population in the Bazaruto Archipelago under various scenarios. PVA is a statistical method
of understanding the influence of a species’ natural history, in combination with demographic,
environmental, and random genetic (stochastic) events, on the dynamics of its future. The
species’ population dynamics is modelled as a set of discrete, sequential events (e.g., births,
deaths, catastrophes, etc.), which occur according to defined probabilities. Population
dynamics models provide a predictive tool, where the impacts of variables (threats), in this
instance – environmental threats (cyclones, floods); hydrocarbon exploration and incidental
fishing catch, can be theoretically modelled.
Overall, the PVA models suggest strongly that the dugongs inhabiting Bazaruto Bay are in a
precarious position and face extirpation. The models suggest that dugongs are particularly
susceptible to long term stressors that might reduce overall reproductive success. Further, the
analyses clearly show that regular deaths, from anthropogenic sources, are the major cause
of dugong decline.
A number of scenarios, covering options for hydrocarbon exploration and exploitation, are
presented and discussed, in terms of their potential impacts on the dugongs inhabiting the
Bazaruto area.
west to Australia in the east, including many of the island States in the Indian and Pacific
Oceans between. However, through much of this range, dugongs have all but disappeared
and where they occur, are represented by relict populations. This is especially true for
Eastern Africa and the Indian Ocean and Mascerine Islands. In most areas dugongs have
been extirpated and only in southern, central Mozambique, the Bazaruto Archipelago, does a
relatively large number still survive.
Between April 2006 and December 2007 a series of 27 aerial surveys was flown over the
Bazaruto Bay region, from Cabo Sao Sebastio in the south to north of the Save River Mouth
in the north and between the coast and the 30 m isobath (extending to eastwards of the
Bazaruto Archipelago islands in the south). A total of 9052 nautical miles of survey was flown
during the 27 surveys. During these, 355 sightings of an estimated 760 dugongs were made.
Two core areas of distribution were apparent; a northern core region, between the Save River
Mouth and 21°24’ S, and a southern core region aligned with the shallow sandbanks to the
north and south of Santa Carolina Island. The mean group size of dugongs encountered was
2.22 and comparable to mean group sizes observed elsewhere. However, the maximum
group size observed was considerably smaller than those observed in other areas of dugong
abundance. Likewise, calculated dugong densities were substantially lower in the Bazaruto
area than they are in the Arabian Gulf or Australia. There was no evidence of any seasonal
variation in occurrence, group size, density or proportion of calves. The proportion of calves
was similar to that in other areas surveyed for dugongs.
Statistical manipulation of the data from aerial surveys suggests that the dugong population
inhabiting the area surveyed is around 250 animals.
The extent of dugong habitat was gauged by mapping seagrass occurrence, diversity and
distribution. Mapping was accomplished through extensive dive sampling of 982 stations
within the surveyed area, within 5m to about 25 m depth. Five species of seagrass were
identified within the area. These covered some 4.68 % of the area and occurred generally in
the north and close to the shore in waters less than 8 m deep. In the north, the areas of
greatest seagrass abundance and diversity coincide with the areas of greatest dugong
abundance. However, in the area to the north and south of Santa Carolina, seagresses were
almost absent, suggesting that this area is used by dugongs for reasons other than feeding.
Population Viability Analysis (PVA) modelling was used to assess the viability of the dugong
population in the Bazaruto Archipelago under various scenarios. PVA is a statistical method
of understanding the influence of a species’ natural history, in combination with demographic,
environmental, and random genetic (stochastic) events, on the dynamics of its future. The
species’ population dynamics is modelled as a set of discrete, sequential events (e.g., births,
deaths, catastrophes, etc.), which occur according to defined probabilities. Population
dynamics models provide a predictive tool, where the impacts of variables (threats), in this
instance – environmental threats (cyclones, floods); hydrocarbon exploration and incidental
fishing catch, can be theoretically modelled.
Overall, the PVA models suggest strongly that the dugongs inhabiting Bazaruto Bay are in a
precarious position and face extirpation. The models suggest that dugongs are particularly
susceptible to long term stressors that might reduce overall reproductive success. Further, the
analyses clearly show that regular deaths, from anthropogenic sources, are the major cause
of dugong decline.
A number of scenarios, covering options for hydrocarbon exploration and exploitation, are
presented and discussed, in terms of their potential impacts on the dugongs inhabiting the
Bazaruto area.
IWC
Report of the workshop on the comprehensive assessment of Southern Hemisphere humpback whales Technical Report
no. 392, 2006.
Abstract | BibTeX | Tags: abundance, Arabian Sea, Australia, Distribution, Humpback Whale, humpback whales, Indian Ocean, Movements, Oman, population, populations, Southern Hemisphere, survey, whale, whales, whaling
@techreport{,
title = {Report of the workshop on the comprehensive assessment of Southern Hemisphere humpback whales},
author = {IWC},
year = {2006},
date = {2006-01-01},
journal = {Report presented to the 58th meeting of the International Whaling Commission},
volume = {SC/58/Rep5},
number = {392},
pages = {1-77},
abstract = {This report summarises all the data for SH humpback whales. Specific recommendations for Pop X (Arabian Sea/Oman) include: Given that the humpback whales of Region X represent an isolated population that has a very low estimate ofabundance, it is strongly recommended that further research be undertaken that will aid in protection of thisstock.There are whales in unsampled areas between Oman and other study areas in Africa and Western Australia. TheWorkshop recommended that studies should be conducted in these areas.It was recommended that further genetic sampling and analysis be completed to more conclusively determinethe degree of differentiation for humpback whales of Region X and the timing of its separation from otherhumpback whale populations.Distribution of whales in Region X clearly occurs throughout areas of the Arabian Sea but surveys conducted todate have been limited to the coast of Oman. The Workshop encourages more survey effort in other areas toevaluate movements and relationships with whales off the coast of Oman.Given the seasonal limitations in survey effort and an unresolved degree of movement and connectivity withother concentrations of humpback whales in the Indian Ocean, the Workshop suggests that satellite telemetrystudies be initiated.},
keywords = {abundance, Arabian Sea, Australia, Distribution, Humpback Whale, humpback whales, Indian Ocean, Movements, Oman, population, populations, Southern Hemisphere, survey, whale, whales, whaling},
pubstate = {published},
tppubtype = {techreport}
}
This report summarises all the data for SH humpback whales. Specific recommendations for Pop X (Arabian Sea/Oman) include: Given that the humpback whales of Region X represent an isolated population that has a very low estimate ofabundance, it is strongly recommended that further research be undertaken that will aid in protection of thisstock.There are whales in unsampled areas between Oman and other study areas in Africa and Western Australia. TheWorkshop recommended that studies should be conducted in these areas.It was recommended that further genetic sampling and analysis be completed to more conclusively determinethe degree of differentiation for humpback whales of Region X and the timing of its separation from otherhumpback whale populations.Distribution of whales in Region X clearly occurs throughout areas of the Arabian Sea but surveys conducted todate have been limited to the coast of Oman. The Workshop encourages more survey effort in other areas toevaluate movements and relationships with whales off the coast of Oman.Given the seasonal limitations in survey effort and an unresolved degree of movement and connectivity withother concentrations of humpback whales in the Indian Ocean, the Workshop suggests that satellite telemetrystudies be initiated.
Baldwin,R.M.,Collins,T.J.Q.,Van Waerebeek,K.,Minton,G.
The Indo-Pacific humpback dolphin of the Arabian region: a status review Journal Article
In: Aquatic Mammals, vol. 30, no. 319, pp. 111-124, 2004.
Abstract | Links | BibTeX | Tags: abundance, Arabian Gulf, Arabian region, Arabian Sea, associations, behaviour, Boat traffic, cetacean, cetaceans, conservation, development, Distribution, dolphin, dolphins, ecology, Fisheries, Gulf of Aden, Gulf of Oman, humpback dolphins, incidental capture, military, museum specimens, nets, Oman, pollution, population, populations, Red Sea, status, Stock identity, Strandings, tursiops
@article{,
title = {The Indo-Pacific humpback dolphin of the Arabian region: a status review},
author = {Baldwin,R.M.,Collins,T.J.Q.,Van Waerebeek,K.,Minton,G.},
url = {https://www.aquaticmammalsjournal.org/index.php?option=com_content&view=article&id=247:the-indo-pacific-humpback-dolphin-of-the-arabian-region-a-status-review&catid=13&Itemid=157},
year = {2004},
date = {2004-01-01},
journal = {Aquatic Mammals},
volume = {30},
number = {319},
pages = {111-124},
abstract = {Records of Indo-Pacific humpback dolphin sightings, strandings, and museum specimens in the Arabian region were compiled and used to review the distribution and status of this species. Nominal usage of Sousa chinensis (Osbeck, 1765) has been retained as a pragmatic measure, although the species present in the region resembles Sousa plumbea (G. Cuvier, 1828). Little is known about the ecology of this species in the region. Most available information on S. chinensis in the region originates from the Sultanate of Oman, where this species is among the most commonly recorded cetaceans. However, there is no absolute measure of abundance for anywhere in the region and the status of the species is unknown. Distribution is described for the region to include much of the Arabian (Persian) Gulf, Arabian Sea, Gulf of Aden, and Red Sea, but notably excludes the Gulf of Oman. This discontinuous distribution suggests the possible presence of discrete populations within the region. Beach-cast/dead individuals represent nearly two-thirds of all records (n=303) of this species in Oman. Live sightings indicate unusually large group sizes (up to 100 individuals) in the Arabian Sea and Arabian Gulf. Occasional associations with Tursiops sp. and Delphinus capensis tropicalis were documented. Mating behaviour and the presence of calves were recorded in the months of April and May and calves are also reported in June, October, November and December. Threats to humpback dolphins in the Arabian region include incidental capture in fishing nets, coastal and offshore development (e.g. land reclamation, dredging, port and harbour construction), pollution, boat traffic, oil and gas exploration (including seismic surveying), military exercises and biotoxins associated with red tide events. Evidence for historic and current directed catches of S. chinensis is limited, but opportunistic hunting may occur. Intraspecific variation in cranial measurements of individuals from the Arabian Sea coast of Oman fall within relative values found in individuals from the Saudi Arabian Gulf coast. Cranial abnormalities were few. Recommendations are made for conservation management-oriented research focusing on stock identity and status assessments, as well as for monitoring of fisheries bycatch, clearer definition of other threats, continued specimen and sample collection and training of local scientists.},
keywords = {abundance, Arabian Gulf, Arabian region, Arabian Sea, associations, behaviour, Boat traffic, cetacean, cetaceans, conservation, development, Distribution, dolphin, dolphins, ecology, Fisheries, Gulf of Aden, Gulf of Oman, humpback dolphins, incidental capture, military, museum specimens, nets, Oman, pollution, population, populations, Red Sea, status, Stock identity, Strandings, tursiops},
pubstate = {published},
tppubtype = {article}
}
Records of Indo-Pacific humpback dolphin sightings, strandings, and museum specimens in the Arabian region were compiled and used to review the distribution and status of this species. Nominal usage of Sousa chinensis (Osbeck, 1765) has been retained as a pragmatic measure, although the species present in the region resembles Sousa plumbea (G. Cuvier, 1828). Little is known about the ecology of this species in the region. Most available information on S. chinensis in the region originates from the Sultanate of Oman, where this species is among the most commonly recorded cetaceans. However, there is no absolute measure of abundance for anywhere in the region and the status of the species is unknown. Distribution is described for the region to include much of the Arabian (Persian) Gulf, Arabian Sea, Gulf of Aden, and Red Sea, but notably excludes the Gulf of Oman. This discontinuous distribution suggests the possible presence of discrete populations within the region. Beach-cast/dead individuals represent nearly two-thirds of all records (n=303) of this species in Oman. Live sightings indicate unusually large group sizes (up to 100 individuals) in the Arabian Sea and Arabian Gulf. Occasional associations with Tursiops sp. and Delphinus capensis tropicalis were documented. Mating behaviour and the presence of calves were recorded in the months of April and May and calves are also reported in June, October, November and December. Threats to humpback dolphins in the Arabian region include incidental capture in fishing nets, coastal and offshore development (e.g. land reclamation, dredging, port and harbour construction), pollution, boat traffic, oil and gas exploration (including seismic surveying), military exercises and biotoxins associated with red tide events. Evidence for historic and current directed catches of S. chinensis is limited, but opportunistic hunting may occur. Intraspecific variation in cranial measurements of individuals from the Arabian Sea coast of Oman fall within relative values found in individuals from the Saudi Arabian Gulf coast. Cranial abnormalities were few. Recommendations are made for conservation management-oriented research focusing on stock identity and status assessments, as well as for monitoring of fisheries bycatch, clearer definition of other threats, continued specimen and sample collection and training of local scientists.
Koppelman,R.,Fabian,H.,Weikert,H.
Temporal variability of deep-sea zooplankton in the Arabian Sea Journal Article
In: Marine Biology, vol. 142, no. 138, pp. 959-970, 2003.
Abstract | BibTeX | Tags: abundance, Arabian Sea, depth, Distribution, zooplankton
@article{,
title = {Temporal variability of deep-sea zooplankton in the Arabian Sea},
author = {Koppelman,R.,Fabian,H.,Weikert,H.},
year = {2003},
date = {2003-01-01},
journal = {Marine Biology},
volume = {142},
number = {138},
pages = {959-970},
abstract = {Mesozooplankton samples from two stations in the Arabian Sea (W AST, 4,050 in, 16 degrees 15'N, 60 degrees 20'E; CAST, 3,950 in, 14 degrees 30'N, 64 degrees 30'E) were collected from the surface down to 20 in above bottom during three monsoon periods: the autumn inter-monsoon in October 1995, the spring inter-monsoon in April 1997 , and the NE monsoon in February 1998. The main goal of this study is to enhance our knowledge on the effect of spatial and temporal differences in primary production and particle flux rates on the abundance and distribution of mesozooplankton, with special attention to the deep sea. Literature data indicate episodically high rates of primary production and particle flux in the region during the sw monsoon and the autumn intermonsoon. Set in this context, the zooplankton showed an in-phase coupling in biomass and abundance with the primary production in the surface 150 in. In the mesopelagic realm (150-1,050 in), the seasonal coupling was less clear. In the bathypelagic zone, below 1 ,050 m, there was no evidence of in-phase coupling, though temporal differences in the distribution of zooplankton abundance and biomass with depth between seasons could be shown by an analysis of covariance and an a posteriori test. The results suggest that the bathypelagic community responds to increased particle flux rates, but with longer time gaps than in the epipelagic zone. This is probably due to longer development and response times of zooplankton in the cold, deep-water environment independent of possible lateral advection processes.},
keywords = {abundance, Arabian Sea, depth, Distribution, zooplankton},
pubstate = {published},
tppubtype = {article}
}
Mesozooplankton samples from two stations in the Arabian Sea (W AST, 4,050 in, 16 degrees 15'N, 60 degrees 20'E; CAST, 3,950 in, 14 degrees 30'N, 64 degrees 30'E) were collected from the surface down to 20 in above bottom during three monsoon periods: the autumn inter-monsoon in October 1995, the spring inter-monsoon in April 1997 , and the NE monsoon in February 1998. The main goal of this study is to enhance our knowledge on the effect of spatial and temporal differences in primary production and particle flux rates on the abundance and distribution of mesozooplankton, with special attention to the deep sea. Literature data indicate episodically high rates of primary production and particle flux in the region during the sw monsoon and the autumn intermonsoon. Set in this context, the zooplankton showed an in-phase coupling in biomass and abundance with the primary production in the surface 150 in. In the mesopelagic realm (150-1,050 in), the seasonal coupling was less clear. In the bathypelagic zone, below 1 ,050 m, there was no evidence of in-phase coupling, though temporal differences in the distribution of zooplankton abundance and biomass with depth between seasons could be shown by an analysis of covariance and an a posteriori test. The results suggest that the bathypelagic community responds to increased particle flux rates, but with longer time gaps than in the epipelagic zone. This is probably due to longer development and response times of zooplankton in the cold, deep-water environment independent of possible lateral advection processes.
Minton,G.,Collins,T.J.Q.,Findlay,K.P.,Baldwin,R.,Rosenbaum,H.C.,Kennedy,F.D.,Cockcroft,V.
Preliminary investigations of humpback whale Technical Report
no. 414, 2002, ISBN: SC/54/H3.
Abstract | BibTeX | Tags: abundance, Arabian Sea, Distribution, habitat use, Humpback Whale, humpback whales, megaptera novaeangliae, Northern Hemisphere, occurrence, Oman, population, relative abundance, sex-ratio, song, survey, whale, whales, whaling
@techreport{,
title = {Preliminary investigations of humpback whale },
author = {Minton,G.,Collins,T.J.Q.,Findlay,K.P.,Baldwin,R.,Rosenbaum,H.C.,Kennedy,F.D.,Cockcroft,V.},
issn = {SC/54/H3},
year = {2002},
date = {2002-01-01},
journal = {Document presented to the 54th meeting of the International Whaling Commission},
volume = {SC/54/H3},
number = {414},
pages = {1-19},
abstract = {Previously published data on the occurrence of humpback whales (Megaptera novaeangliae) in the Arabian Sea suggest that the region hosts a non-migratory population that adheres to a Northern Hemisphere breeding cycle. Six small boat surveys and one shore-based survey were conducted at three locations off the coast of Oman between February 2000 and February 2002. Encounter rates varied between surveys from 0.0 whales/hour to 0.545 whales per hour. Two of 36 photo-identified whales were re-sighted between surveys. Sex ratios in October were near parity while all whales sampled in February were male. Song was detected frequently in the Kuria Muria Bay in February, but records of mother-calf pairs are sparse and competitive groups were absent. Feeding was infrequently observed in both October and February. Implications for relative abundance and habitat use are discussed. Additional questions are raised and recommendations for further research are made.},
keywords = {abundance, Arabian Sea, Distribution, habitat use, Humpback Whale, humpback whales, megaptera novaeangliae, Northern Hemisphere, occurrence, Oman, population, relative abundance, sex-ratio, song, survey, whale, whales, whaling},
pubstate = {published},
tppubtype = {techreport}
}
Previously published data on the occurrence of humpback whales (Megaptera novaeangliae) in the Arabian Sea suggest that the region hosts a non-migratory population that adheres to a Northern Hemisphere breeding cycle. Six small boat surveys and one shore-based survey were conducted at three locations off the coast of Oman between February 2000 and February 2002. Encounter rates varied between surveys from 0.0 whales/hour to 0.545 whales per hour. Two of 36 photo-identified whales were re-sighted between surveys. Sex ratios in October were near parity while all whales sampled in February were male. Song was detected frequently in the Kuria Muria Bay in February, but records of mother-calf pairs are sparse and competitive groups were absent. Feeding was infrequently observed in both October and February. Implications for relative abundance and habitat use are discussed. Additional questions are raised and recommendations for further research are made.
Barber,R.T.,Marra,J.,Bidigare,R.C.,Codispoti,L.A.,Halpern,D.,Johnson,Z.,Latasa,M.,Goericke,R.,Smith,S.L.
Primary productivity and its regulation in the Arabian Sea during 1995 Journal Article
In: Deep-Sea Research Part II, vol. 48, no. 323, pp. 1127-1172, 2001.
Abstract | BibTeX | Tags: abundance, Arabian Sea, Atlantic, location, North Atlantic, Oman, Pacific Ocean, performance, productivity, Upwelling
@article{,
title = {Primary productivity and its regulation in the Arabian Sea during 1995},
author = {Barber,R.T.,Marra,J.,Bidigare,R.C.,Codispoti,L.A.,Halpern,D.,Johnson,Z.,Latasa,M.,Goericke,R.,Smith,S.L.},
year = {2001},
date = {2001-01-01},
journal = {Deep-Sea Research Part II},
volume = {48},
number = {323},
pages = {1127-1172},
abstract = {The annual cycle of monsoon-driven variability in primary productivity was studied in 1995 during the Arabian Sea Expedition as part of the United States Joint Global Ocean Flux Studies (US JGOFS). This paper describes the seasonal progression of productivity and its regulation on a section which ran from the coast of Oman to about 1000km offshore in the centralArabian Sea at 65§E. During the SW Monsoon (June-mid-September), the coolest water and highest nutrient concentrations were close to the coast, although they extended offshore to about 800 km; during the January NE Monsoon, deep convective mixing provided nutrients to the mixed layer in the region 400 - 1000km o!shore. As expected, the SW Monsoon was the most productive season (123ñ9mmolC m-2d-1) along the southern US JGOFS section from the coast to 1000km offshore, but productivity in the NE Monsoon was surprisingly high (112ñ7mmol C m-2d-1). There was no onshore/offshore gradient in primary productivity from 150 to 1000km o! the Omani coast in 1995, and there was no evidence of light limitation of either primary productivity or photosynthetic performance (PBopt) from deep convective mixing during the NE Monsoon, deep wind mixing during the SW Monsoon or offshore Ekman downwelling during the SW Monsoon. Productivity during the Spring Intermonsoon (86ñ6mmolC m-2d-1) was much higher than in oligotrophic regions such as the tropical Pacific Ocean (29ñ2 mmolC m-2 d-1) or the North Pacific gyre region (32ñ8 mmolC m-2 d-1). The 1995 annual mean productivity (111ñ11mmolC m-2 d-1) along this section from the Omani coast to the central Arabian Sea was about equal to the spring bloom maximum (107ñ23mmolC m-2 d-1) during the 1989 North Atlantic Bloom Experiment (NABE) and the equatorial, 1§N-1§S wave guide maximum (95ñ6mmolC m-2 d-1) in the Pacific Ocean during the 1992 EqPac study. The 1995 SW Monsoon primary productivity was similar to the mean value observed in the same region in 1994 by the Arabesque Expedition (127ñ14mmolC m-2 d-1) and in 1964 by the ANTON BRUUN Expedition (115ñ27 mmol C m-2 d-1). During the 1995 SW Monsoon, strong, narrow and meandering current filaments extended from the region of coastal upwelling to about 700km offshore; these filaments had levels of biomass, primary productivity, chlorophyll-specific productivity and diatom abundance that were elevated relative to other locations during the SW Monsoon. The SW Monsoon was the most productive period, but SW Monsoon primary productivity values were lower than predicted because effcient grazing by mesozooplankton kept diatoms from accumulating the biomass necessary for achieving the high levels of primary productivity characteristic of other coastal upwelling regions. The high rates of chlorophyll-specific productivity (PBopt>10mmolC mg Chl-1 d-1) observed in the 1995 SW Monsoon, together with the observed dust flux and iron concentrations, indicate that the Arabian Sea was more iron replete than the equatorial Pacific Ocean or the Southern Ocean },
keywords = {abundance, Arabian Sea, Atlantic, location, North Atlantic, Oman, Pacific Ocean, performance, productivity, Upwelling},
pubstate = {published},
tppubtype = {article}
}
The annual cycle of monsoon-driven variability in primary productivity was studied in 1995 during the Arabian Sea Expedition as part of the United States Joint Global Ocean Flux Studies (US JGOFS). This paper describes the seasonal progression of productivity and its regulation on a section which ran from the coast of Oman to about 1000km offshore in the centralArabian Sea at 65§E. During the SW Monsoon (June-mid-September), the coolest water and highest nutrient concentrations were close to the coast, although they extended offshore to about 800 km; during the January NE Monsoon, deep convective mixing provided nutrients to the mixed layer in the region 400 - 1000km o!shore. As expected, the SW Monsoon was the most productive season (123ñ9mmolC m-2d-1) along the southern US JGOFS section from the coast to 1000km offshore, but productivity in the NE Monsoon was surprisingly high (112ñ7mmol C m-2d-1). There was no onshore/offshore gradient in primary productivity from 150 to 1000km o! the Omani coast in 1995, and there was no evidence of light limitation of either primary productivity or photosynthetic performance (PBopt) from deep convective mixing during the NE Monsoon, deep wind mixing during the SW Monsoon or offshore Ekman downwelling during the SW Monsoon. Productivity during the Spring Intermonsoon (86ñ6mmolC m-2d-1) was much higher than in oligotrophic regions such as the tropical Pacific Ocean (29ñ2 mmolC m-2 d-1) or the North Pacific gyre region (32ñ8 mmolC m-2 d-1). The 1995 annual mean productivity (111ñ11mmolC m-2 d-1) along this section from the Omani coast to the central Arabian Sea was about equal to the spring bloom maximum (107ñ23mmolC m-2 d-1) during the 1989 North Atlantic Bloom Experiment (NABE) and the equatorial, 1§N-1§S wave guide maximum (95ñ6mmolC m-2 d-1) in the Pacific Ocean during the 1992 EqPac study. The 1995 SW Monsoon primary productivity was similar to the mean value observed in the same region in 1994 by the Arabesque Expedition (127ñ14mmolC m-2 d-1) and in 1964 by the ANTON BRUUN Expedition (115ñ27 mmol C m-2 d-1). During the 1995 SW Monsoon, strong, narrow and meandering current filaments extended from the region of coastal upwelling to about 700km offshore; these filaments had levels of biomass, primary productivity, chlorophyll-specific productivity and diatom abundance that were elevated relative to other locations during the SW Monsoon. The SW Monsoon was the most productive period, but SW Monsoon primary productivity values were lower than predicted because effcient grazing by mesozooplankton kept diatoms from accumulating the biomass necessary for achieving the high levels of primary productivity characteristic of other coastal upwelling regions. The high rates of chlorophyll-specific productivity (PBopt>10mmolC mg Chl-1 d-1) observed in the 1995 SW Monsoon, together with the observed dust flux and iron concentrations, indicate that the Arabian Sea was more iron replete than the equatorial Pacific Ocean or the Southern Ocean
Butler,M.,Bollens,S.M.,Burghalter,B.,Madin,L.P.,Horgan,E.
Mesopelagic fishes of the Arabian Sea: distribution, abundance and diet of Journal Article
In: Deep-Sea Research Part II, vol. 48, no. 61, pp. 1369-1383, 2001.
Abstract | BibTeX | Tags: abundance, Arabian Sea, diel, diet, diets, Distribution, ecology, feeding, migration, oxygen minimum, population, populations, predation, south
@article{,
title = {Mesopelagic fishes of the Arabian Sea: distribution, abundance and diet of },
author = {Butler,M.,Bollens,S.M.,Burghalter,B.,Madin,L.P.,Horgan,E.},
year = {2001},
date = {2001-01-01},
journal = {Deep-Sea Research Part II},
volume = {48},
number = {61},
pages = {1369-1383},
abstract = {Four species of predatory fishes - Chauliodus pammelas, Chauliodus sloani, Stomias afffnis and Stomias nebulosus - were collected on two cruises to the Arabian Sea during 1995. We present data on the abundances, horizontal and vertical distributions, and diet of these fishes. We also discuss briefly the importance of the oxygen minimum zone and predation on myctophid fishes to the ecology of these mesopelagic predators. Chauliodus pammelas and C. sloani appear to have only partially overlapping horizontal distributions in the Arabian Sea, with C. pammelas more common to the north and C. sloani more common to the south. Our data support previous results suggesting that diel vertical migration is the norm for these species, with smaller individuals usually nearer to the surface and larger individuals tending to stay deeper. In contrast to Chauliodus, Stomias affinis and S. nebulosus appear to have largely overlapping horizontal distributions in the Arabian Sea. However, they may have slightly di!erent vertical distributions, with S. affinis living slightly shallower (especially at night) than S. nebulosus. All four species spend most of their time in the oxygen minimum zone, entering the surface oxygenated waters (100-150 m) only at night (if at all). The diets of C. pammelas, C. sloani, and S. affinis consisted mainly of lantern fishes, Myctophidae, and other fishes. In contrast, S. nebulosus, the smaller of the two Stomias species, ate mostly copepods and other crustaceans. This differential feeding may allow the two Stomias species to co-occur. Three of these four stomiids appear to play an important role in predation on myctophid fish populations in the Arabian Sea.},
keywords = {abundance, Arabian Sea, diel, diet, diets, Distribution, ecology, feeding, migration, oxygen minimum, population, populations, predation, south},
pubstate = {published},
tppubtype = {article}
}
Four species of predatory fishes - Chauliodus pammelas, Chauliodus sloani, Stomias afffnis and Stomias nebulosus - were collected on two cruises to the Arabian Sea during 1995. We present data on the abundances, horizontal and vertical distributions, and diet of these fishes. We also discuss briefly the importance of the oxygen minimum zone and predation on myctophid fishes to the ecology of these mesopelagic predators. Chauliodus pammelas and C. sloani appear to have only partially overlapping horizontal distributions in the Arabian Sea, with C. pammelas more common to the north and C. sloani more common to the south. Our data support previous results suggesting that diel vertical migration is the norm for these species, with smaller individuals usually nearer to the surface and larger individuals tending to stay deeper. In contrast to Chauliodus, Stomias affinis and S. nebulosus appear to have largely overlapping horizontal distributions in the Arabian Sea. However, they may have slightly di!erent vertical distributions, with S. affinis living slightly shallower (especially at night) than S. nebulosus. All four species spend most of their time in the oxygen minimum zone, entering the surface oxygenated waters (100-150 m) only at night (if at all). The diets of C. pammelas, C. sloani, and S. affinis consisted mainly of lantern fishes, Myctophidae, and other fishes. In contrast, S. nebulosus, the smaller of the two Stomias species, ate mostly copepods and other crustaceans. This differential feeding may allow the two Stomias species to co-occur. Three of these four stomiids appear to play an important role in predation on myctophid fish populations in the Arabian Sea.
Ducklow,H.W.,Smith,D.C.,Campbell,L.,Landry,M.R.,Quinby,H.L.,Steward,G.F.,Azam,F.
Heterotrophic bacterioplankton in the Arabian Sea: Basinwide response to year-round high primary productivity Journal Article
In: Deep-Sea Research Part II, vol. 48, no. 90, pp. 1303-1323, 2001.
Abstract | BibTeX | Tags: abundance, Arabian Sea, Distribution, population, populations, productivity, Upwelling
@article{,
title = {Heterotrophic bacterioplankton in the Arabian Sea: Basinwide response to year-round high primary productivity},
author = {Ducklow,H.W.,Smith,D.C.,Campbell,L.,Landry,M.R.,Quinby,H.L.,Steward,G.F.,Azam,F.},
year = {2001},
date = {2001-01-01},
journal = {Deep-Sea Research Part II},
volume = {48},
number = {90},
pages = {1303-1323},
abstract = {Heterotrophic bacterial abundance and productivity were measured during five and four cruises, respectively, in the northwest Arabian Sea as part of the US JGOFS Process Study, which provided a new view of seasonal bacterial dynamics in that part of the basin influenced by monsoonal forcing. In this paper, surface layer data are used to address two questions concerning the influence of the monsoon cycle on bacterial dynamics: (1) Is there a bacterial bloom in the SW Monsoon? and (2) Is bacterial production low during the oligotrophic Spring Intermonsoon? An extensive comparison of epifluorescence microscopy and flow cytometry, unprecedented at this scale, detected essentially the same heterotrophic bacterial populations and distributions, with some between-cruise di!erences. Use of the two methods allowed us to extend our observations in space and time. Bacterial productivity, both in the surface layer and integrated over the euphotic zone, was elevated less than 2-fold during the Southwest Monsoon. Levels of bacterial abundance and production were low during the Northeast Monsoon, then increased in March during the Spring Intermonsoon. There was some stimulation of abundance or production inshore in response to coastal upwelling. In general, the basin was enriched in bacterial biomass >5 ' 108 cells l-1 throughout the year, relative to other tropical regimes, presumably in response to overall high PP and DOC levels. Seasonally uniform DOC levels may be regulated in part by intense bacterial utilization rates, but also reflect seasonal consistency in PP.},
keywords = {abundance, Arabian Sea, Distribution, population, populations, productivity, Upwelling},
pubstate = {published},
tppubtype = {article}
}
Heterotrophic bacterial abundance and productivity were measured during five and four cruises, respectively, in the northwest Arabian Sea as part of the US JGOFS Process Study, which provided a new view of seasonal bacterial dynamics in that part of the basin influenced by monsoonal forcing. In this paper, surface layer data are used to address two questions concerning the influence of the monsoon cycle on bacterial dynamics: (1) Is there a bacterial bloom in the SW Monsoon? and (2) Is bacterial production low during the oligotrophic Spring Intermonsoon? An extensive comparison of epifluorescence microscopy and flow cytometry, unprecedented at this scale, detected essentially the same heterotrophic bacterial populations and distributions, with some between-cruise di!erences. Use of the two methods allowed us to extend our observations in space and time. Bacterial productivity, both in the surface layer and integrated over the euphotic zone, was elevated less than 2-fold during the Southwest Monsoon. Levels of bacterial abundance and production were low during the Northeast Monsoon, then increased in March during the Spring Intermonsoon. There was some stimulation of abundance or production inshore in response to coastal upwelling. In general, the basin was enriched in bacterial biomass >5 ' 108 cells l-1 throughout the year, relative to other tropical regimes, presumably in response to overall high PP and DOC levels. Seasonally uniform DOC levels may be regulated in part by intense bacterial utilization rates, but also reflect seasonal consistency in PP.
Shalapyonok,A.,Olson,R.J.,Shalapyonok,L.S.
Arabian Sea phytoplankton during Southwest and Northeast Monsoons 1995: composition, size structure and biomass from individual cell properties measured by flow cytometry Journal Article
In: Deep-Sea Research Part II, vol. 48 , no. 221, pp. 1231-1261, 2001.
Abstract | BibTeX | Tags: abundance, Arabian Sea, diel, Distribution, location, surface temperature, temperature, Upwelling
@article{,
title = {Arabian Sea phytoplankton during Southwest and Northeast Monsoons 1995: composition, size structure and biomass from individual cell properties measured by flow cytometry},
author = {Shalapyonok,A.,Olson,R.J.,Shalapyonok,L.S.},
year = {2001},
date = {2001-01-01},
journal = {Deep-Sea Research Part II},
volume = {48 },
number = {221},
pages = {1231-1261},
abstract = {As part of the US JGOFS Arabian Sea Process Study, we determined the abundance, size distributions and carbon biomass of autotrophic phytoplankton in the Arabian Sea during summer Southwest and fall Northeast Monsoon seasons of 1995 (R/V Thomas G. Thompson cruises TN 049 and TN 053). Flowcytometry of 60-ml samples was used to enumerate and determine scattering and fluorescence properties of Prochlorococcus sp., Synechococcus sp., and eukaryotic phytoplankton with cell equivalent spherical diameter up to 40 æm. Cellular forward light scattering was calibrated against Coulter size using 22 phytoplankton cultures spanning the size range 0.8-40 æm, grown exponentially in natural sunlight. The phytoplankton community structure was strongly linked to water-mass characteristics, and was affected by both intense monsoon-related environmental forcing and widespread and dynamic mesoscale structures; the magnitude of spatial variability was similar to that between seasons for all three phytoplankton groups. Prochlorococcus was numerically dominant in the more oligotrophic, stratified areas with surface nitrate concentrations below 0.1 æM and surface temperatures above 27§C. Its abundance was significantly greater during the NE Monsoon and was inversely correlated with the abundance of the two other groups. Synechococcus and eukaryotic phytoplankton cell concentrations covaried at most locations, were highest in areas of intense, monsoon-related mixing, and changed less between seasons than Prochlorococcus. The bulk of biomass of all three groups was located within the mixed layer. Only eukaryotes formed notable subsurface maxima at several offshore locations where Prochlorococcus dominated the mixed layer. Dramatically elevated eukaryotic phytoplankton concentrations in the nutrient-rich upwelling areas were due to the blooming of smaller (<3 æm) cells. Surprisingly, stratified, offshore, nutrient-depleted areas had concentrations of 10-40 æm phytoplankton cells similar to or even higher than upwelling areas. Thus, the mean eukaryotic cell size and the relative contribution of large nanoeukaryotes to the phytoplankton biomass were highest in offshore waters. Eukaryotes accounted for most of the phytoplankton carbon biomass - from about 50 to 80% on average during both seasons. Both Prochlorococcus and large (10 æm) nanoeukaryotes reached their greatest biomass contributions - up to 40% each - in the offshore oligotrophic locations. For the SW and NE Monsoon cruises, flow cytometrically-measured phytoplankton was estimated at 1.1 and 2.2 gCm-2 on average and comprised 33 and 38% of POC, respectively. Diel variability in cellular carbon content accounted for 52% of the observed variability in cellular carbon content for Prochlorococcus, 26% for Synechococcus, and 14% for eukaryotic phytoplankton cells at the surface.},
keywords = {abundance, Arabian Sea, diel, Distribution, location, surface temperature, temperature, Upwelling},
pubstate = {published},
tppubtype = {article}
}
As part of the US JGOFS Arabian Sea Process Study, we determined the abundance, size distributions and carbon biomass of autotrophic phytoplankton in the Arabian Sea during summer Southwest and fall Northeast Monsoon seasons of 1995 (R/V Thomas G. Thompson cruises TN 049 and TN 053). Flowcytometry of 60-ml samples was used to enumerate and determine scattering and fluorescence properties of Prochlorococcus sp., Synechococcus sp., and eukaryotic phytoplankton with cell equivalent spherical diameter up to 40 æm. Cellular forward light scattering was calibrated against Coulter size using 22 phytoplankton cultures spanning the size range 0.8-40 æm, grown exponentially in natural sunlight. The phytoplankton community structure was strongly linked to water-mass characteristics, and was affected by both intense monsoon-related environmental forcing and widespread and dynamic mesoscale structures; the magnitude of spatial variability was similar to that between seasons for all three phytoplankton groups. Prochlorococcus was numerically dominant in the more oligotrophic, stratified areas with surface nitrate concentrations below 0.1 æM and surface temperatures above 27§C. Its abundance was significantly greater during the NE Monsoon and was inversely correlated with the abundance of the two other groups. Synechococcus and eukaryotic phytoplankton cell concentrations covaried at most locations, were highest in areas of intense, monsoon-related mixing, and changed less between seasons than Prochlorococcus. The bulk of biomass of all three groups was located within the mixed layer. Only eukaryotes formed notable subsurface maxima at several offshore locations where Prochlorococcus dominated the mixed layer. Dramatically elevated eukaryotic phytoplankton concentrations in the nutrient-rich upwelling areas were due to the blooming of smaller (<3 æm) cells. Surprisingly, stratified, offshore, nutrient-depleted areas had concentrations of 10-40 æm phytoplankton cells similar to or even higher than upwelling areas. Thus, the mean eukaryotic cell size and the relative contribution of large nanoeukaryotes to the phytoplankton biomass were highest in offshore waters. Eukaryotes accounted for most of the phytoplankton carbon biomass - from about 50 to 80% on average during both seasons. Both Prochlorococcus and large (10 æm) nanoeukaryotes reached their greatest biomass contributions - up to 40% each - in the offshore oligotrophic locations. For the SW and NE Monsoon cruises, flow cytometrically-measured phytoplankton was estimated at 1.1 and 2.2 gCm-2 on average and comprised 33 and 38% of POC, respectively. Diel variability in cellular carbon content accounted for 52% of the observed variability in cellular carbon content for Prochlorococcus, 26% for Synechococcus, and 14% for eukaryotic phytoplankton cells at the surface.
Sherry,N.D.,Wood,A.M.
Phycoerythrin-containing picocyanobacteria in the Arabian Sea in February 1995: diel patterns, spatial variability, and growth rates Journal Article
In: Deep-Sea Research Part II, vol. 48 , no. 225, pp. 1263-1283, 2001.
Abstract | BibTeX | Tags: abundance, Arabian Sea, depth, diel, growth, length, population, survey
@article{,
title = {Phycoerythrin-containing picocyanobacteria in the Arabian Sea in February 1995: diel patterns, spatial variability, and growth rates},
author = {Sherry,N.D.,Wood,A.M.},
year = {2001},
date = {2001-01-01},
journal = {Deep-Sea Research Part II},
volume = {48 },
number = {225},
pages = {1263-1283},
abstract = {The abundance of phycoerythrin-containing picocyanobacteria in the surface mixed layer was measured both along-shore and offshore between 8 and 23 February 1995 in the Northwestern Arabian Sea. Water samples from 3m depth were taken at 2-h intervals and picocyanobacterial abundance and frequency of dividing cells were determined by epifluorescence microscopy. Cell counts showed an average diel change from a mid-day minimum of ~50'103 cells ml-1 to an evening maximum of ~180'103 cells ml-1. The diel change was greater than the differences observed between physically and spatially discrete water masses. By counting the frequency of dividing cells (FDC) and using a novel approach to estimating the length of time required to complete cell division, growth and loss rates were both estimated to be ~2.9 d-1 with daily turnover being 140% of the mean standing stock. If differences in the intrinsic population growth rate (æ) and the net rate of change in cell number (r) are assumed to be due to grazing, then grazing occurred throughout the day at a relatively constant rate (reflecting phytoplankton loss rates of ~0.12 h-1). Cell division rates peaked in the late afternoon and early evening. FDC decreased throughout the night, suggesting that dark-inhibition of cell division is weak or nonexistent in the picocyanobacteria we studied. While all cell types included in this study would be identified as Synechococcus by flow cytometry because they were small unicells with bright phycoerythrin fluorescence, morphological variability suggests that the community was actually taxonomically diverse and included cells other than Synechococcus, including Synechocystis. Despite this diversity, the strong diel patterns we observed persisted throughout the study region, suggesting that great care should be taken when interpreting picocyanobacterial survey data and experimental results that do not account for the e!ects of time-of-day.},
keywords = {abundance, Arabian Sea, depth, diel, growth, length, population, survey},
pubstate = {published},
tppubtype = {article}
}
The abundance of phycoerythrin-containing picocyanobacteria in the surface mixed layer was measured both along-shore and offshore between 8 and 23 February 1995 in the Northwestern Arabian Sea. Water samples from 3m depth were taken at 2-h intervals and picocyanobacterial abundance and frequency of dividing cells were determined by epifluorescence microscopy. Cell counts showed an average diel change from a mid-day minimum of ~50'103 cells ml-1 to an evening maximum of ~180'103 cells ml-1. The diel change was greater than the differences observed between physically and spatially discrete water masses. By counting the frequency of dividing cells (FDC) and using a novel approach to estimating the length of time required to complete cell division, growth and loss rates were both estimated to be ~2.9 d-1 with daily turnover being 140% of the mean standing stock. If differences in the intrinsic population growth rate (æ) and the net rate of change in cell number (r) are assumed to be due to grazing, then grazing occurred throughout the day at a relatively constant rate (reflecting phytoplankton loss rates of ~0.12 h-1). Cell division rates peaked in the late afternoon and early evening. FDC decreased throughout the night, suggesting that dark-inhibition of cell division is weak or nonexistent in the picocyanobacteria we studied. While all cell types included in this study would be identified as Synechococcus by flow cytometry because they were small unicells with bright phycoerythrin fluorescence, morphological variability suggests that the community was actually taxonomically diverse and included cells other than Synechococcus, including Synechocystis. Despite this diversity, the strong diel patterns we observed persisted throughout the study region, suggesting that great care should be taken when interpreting picocyanobacterial survey data and experimental results that do not account for the e!ects of time-of-day.
Balch,W.M.,Drapeau,D.T.,Fritz,J.J.
Monsoonal forcing of calcification in the Arabian Sea Journal Article
In: Deep-Sea Research Part II, vol. 47, no. 18, pp. 1301-1337, 2000.
Abstract | BibTeX | Tags: abundance, Arabian Sea, stocks, trap
@article{,
title = {Monsoonal forcing of calcification in the Arabian Sea},
author = {Balch,W.M.,Drapeau,D.T.,Fritz,J.J.},
year = {2000},
date = {2000-01-01},
journal = {Deep-Sea Research Part II},
volume = {47},
number = {18},
pages = {1301-1337},
abstract = {This paper summarizes our results on the changes in pelagic calcification and the standing stock of calcium carbonate associated with the SW Monsoon and NE Monsoon (cruises TN049 and TN053 of the U.S. JGOFS study, respectively) in the northern portion of the Arabian Sea. Mean calcification was~3X greater during the SW Monsoon than during the NE Monsoon. Calcification per coccolithophore was 7-10X higher, and the ratio of calcification to photosynthesis (C/P) was 40-45% higher during the SW Monsoon. The turnover time of PIC was not statistically different between the two cruises (~4.5 d averaged over the euphotic zone). Turnover time of POC increased significantly between TN049 and TN053 (from ~3 to 6 d over the euphotic zone). We discuss vertical sections of coccolithophore abundance, carbon standing stocks and carbon fixation. Coccolithophore calcification was usually about 1-5% of community photosynthesis. The ratio of calcification to photosynthesis spanned almost 2 orders of magnitude, and was not significantly di!erent from the ratio of the PIC and POC standing stocks. We compare surface PIC and POC production rates to sediment trap fluxes from the same region.},
keywords = {abundance, Arabian Sea, stocks, trap},
pubstate = {published},
tppubtype = {article}
}
This paper summarizes our results on the changes in pelagic calcification and the standing stock of calcium carbonate associated with the SW Monsoon and NE Monsoon (cruises TN049 and TN053 of the U.S. JGOFS study, respectively) in the northern portion of the Arabian Sea. Mean calcification was~3X greater during the SW Monsoon than during the NE Monsoon. Calcification per coccolithophore was 7-10X higher, and the ratio of calcification to photosynthesis (C/P) was 40-45% higher during the SW Monsoon. The turnover time of PIC was not statistically different between the two cruises (~4.5 d averaged over the euphotic zone). Turnover time of POC increased significantly between TN049 and TN053 (from ~3 to 6 d over the euphotic zone). We discuss vertical sections of coccolithophore abundance, carbon standing stocks and carbon fixation. Coccolithophore calcification was usually about 1-5% of community photosynthesis. The ratio of calcification to photosynthesis spanned almost 2 orders of magnitude, and was not significantly di!erent from the ratio of the PIC and POC standing stocks. We compare surface PIC and POC production rates to sediment trap fluxes from the same region.
Baldwin,R.M.
Oman's humpback whales (Megaptera novaeangliae) Journal Article
In: The Journal of Oman Studies, vol. 11 , no. 316, pp. 11-18, 2000.
Abstract | BibTeX | Tags: abundance, Arabian Sea, behaviour, conservation, Distribution, ecology, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, megaptera novaeangliae, mortality, occurrence, Oman, population, population identity, status, survey, whale, whales
@article{,
title = {Oman's humpback whales (Megaptera novaeangliae) },
author = {Baldwin,R.M.},
year = {2000},
date = {2000-01-01},
journal = {The Journal of Oman Studies},
volume = {11 },
number = {316},
pages = {11-18},
abstract = {Data are presented on the general distribution and abundance of humpback whales off the coast of the Sultanate of Oman, with particular reference to observations made during an offshore seismic survey in the Arabian Sea in November 1997. Additional information is presented on seasonal occurrence, ecology and behaviour, external appearance, conservation, mortality, incidental capture, population status and identity of Oman's humpback whales. The data generally support the notion of year-round residency of humpback whales off the coast of Oman, but indicate the need for further research to establish whether the low frequency of positive records during summer months is a true reflection of seasonal distribution. Other research on humpback whales in the region is recommended.},
keywords = {abundance, Arabian Sea, behaviour, conservation, Distribution, ecology, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, megaptera novaeangliae, mortality, occurrence, Oman, population, population identity, status, survey, whale, whales},
pubstate = {published},
tppubtype = {article}
}
Data are presented on the general distribution and abundance of humpback whales off the coast of the Sultanate of Oman, with particular reference to observations made during an offshore seismic survey in the Arabian Sea in November 1997. Additional information is presented on seasonal occurrence, ecology and behaviour, external appearance, conservation, mortality, incidental capture, population status and identity of Oman's humpback whales. The data generally support the notion of year-round residency of humpback whales off the coast of Oman, but indicate the need for further research to establish whether the low frequency of positive records during summer months is a true reflection of seasonal distribution. Other research on humpback whales in the region is recommended.
Mincks,S.L.,Bollens,S.M.,Madin,L.P.,Horgan,E.,Butler,M.,Kremer,P.M.,Craddock,J.E.
Distribution, abundance, and feeding ecology of decapods in the Arabian Sea, with implications for vertical flux Journal Article
In: Deep-Sea Research Part II, vol. 47, no. 158, pp. 1475-1516, 2000.
Abstract | BibTeX | Tags: abundance, Arabian Sea, depth, Distribution, ecology, feeding ecology, migration, oxygen minimum, population, zooplankton
@article{,
title = {Distribution, abundance, and feeding ecology of decapods in the Arabian Sea, with implications for vertical flux},
author = {Mincks,S.L.,Bollens,S.M.,Madin,L.P.,Horgan,E.,Butler,M.,Kremer,P.M.,Craddock,J.E.},
year = {2000},
date = {2000-01-01},
journal = {Deep-Sea Research Part II},
volume = {47},
number = {158},
pages = {1475-1516},
abstract = {Macrozooplankton and micronekton samples were collected on two cruises in the Arabian Sea conducted during the Spring Intermonsoon period (May) and the SW Monsoon period (August) of 1995. Discrete depth samples were collected down to depths of 1000-1500 m. Quantitative gut content analyses were performed on four species of decapod shrimps, Gennadas sordidus, Sergia filictum, Sergia creber, and Eupasiphae gilesii, as well as on the pelagic crab Charybdis smithii. Of the shrimps, only S. filictum and S. creber increased significantly in abundance between the Spring Intermonsoon and SW Monsoon seasons. These four species were found at all depths sampled, and most did not appear to be strong vertical migrators. G. sordidus and S. filictum did appear to spread upward at night, especially during the SW Monsoon, but this movement did not include the entire population. S. creber showed signs of diel vertical migration only in some areas. All four shrimp species except, to some degree, S. creber lived almost exclusively within the oxygen minimum zone(150-1000 m), and are likely to have respiratory adaptations that allow them to persist under such conditions. Feeding occurred at all depths throughout these species' ranges, but only modest feeding occurred in the surface layer (0-150 m). G. sordidus appeared to feed continuously throughout the day and night. Estimated contribution of fecal material to vertical flux ranged from < 0.01-2.1% of particulate flux at 1000 m for the shrimps and 1.8-3.0% for C. smithii. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. .},
keywords = {abundance, Arabian Sea, depth, Distribution, ecology, feeding ecology, migration, oxygen minimum, population, zooplankton},
pubstate = {published},
tppubtype = {article}
}
Macrozooplankton and micronekton samples were collected on two cruises in the Arabian Sea conducted during the Spring Intermonsoon period (May) and the SW Monsoon period (August) of 1995. Discrete depth samples were collected down to depths of 1000-1500 m. Quantitative gut content analyses were performed on four species of decapod shrimps, Gennadas sordidus, Sergia filictum, Sergia creber, and Eupasiphae gilesii, as well as on the pelagic crab Charybdis smithii. Of the shrimps, only S. filictum and S. creber increased significantly in abundance between the Spring Intermonsoon and SW Monsoon seasons. These four species were found at all depths sampled, and most did not appear to be strong vertical migrators. G. sordidus and S. filictum did appear to spread upward at night, especially during the SW Monsoon, but this movement did not include the entire population. S. creber showed signs of diel vertical migration only in some areas. All four shrimp species except, to some degree, S. creber lived almost exclusively within the oxygen minimum zone(150-1000 m), and are likely to have respiratory adaptations that allow them to persist under such conditions. Feeding occurred at all depths throughout these species' ranges, but only modest feeding occurred in the surface layer (0-150 m). G. sordidus appeared to feed continuously throughout the day and night. Estimated contribution of fecal material to vertical flux ranged from < 0.01-2.1% of particulate flux at 1000 m for the shrimps and 1.8-3.0% for C. smithii. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. .
Roman,M.,Smith,S.,Wishner,K.,Gowing,M.,Zhang,X.S.
Mezozooplankton production and grazing the Arabian Sea Journal Article
In: Deep-Sea Research Part II, vol. 47, no. 452, pp. 1423-1450, 2000.
Abstract | BibTeX | Tags: abundance, Arabian Sea, ecology, marine, mortality, multivariate, temperature, zooplankton
@article{,
title = {Mezozooplankton production and grazing the Arabian Sea},
author = {Roman,M.,Smith,S.,Wishner,K.,Gowing,M.,Zhang,X.S.},
year = {2000},
date = {2000-01-01},
journal = {Deep-Sea Research Part II},
volume = {47},
number = {452},
pages = {1423-1450},
abstract = {Growth rates, grazing and fecal pellet production by mesozooplankton size classes in the surface 200 m are compared over two inshore/offshore transects in the Northern Arabian Sea during different monsoon seasons. We derived these rate parameters from measured biomass and several empirical models that estimate copepod production from temperature, body weight and food availability. The multivariate regression published by Hirst and Sheader (1997, Marine Ecology Progress Series, 154, 155-165) gave the most reasonable rate estimates when compared to direct grazing measurements as well as published data on copepod ingestion and growth rates. In general, zooplankton rate estimates were highest at the inshore stations where phytoplankton production and zooplankton biomass were maximum. Overall cruise means of zooplankton biomass and rate estimates during the early and late NE Monsoon, Spring Inter-monsoon and SW Monsoon were not significantly different. The estimated zooplankton community (all size fractions) growth rate averaged 0.12d(-I) over all stations during the different monsoon seasons. Although smaller zooplankton size fractions grew faster, slower growing > 2 mm zooplankton dominated the zooplankton biomass of the Arabian Sea and this resulted in a lower overall community growth rate. Estimated total carbon (phytoplankton, protozoa and detritus) ingestion averaged 44 mM C m(-2) d(-I), which was approximately 40% of primary production, Expressed as a percentage ofbiomass, we found that zooplankton ingested approximately 400/0 of their body carbon d( -1 ). Zooplankton fecal pellet production averaged 13 mM C m(-2) d(-I) or roughly 12% of primary production. This estimated fecal pellet production was greater than measurements of the export flux during the NE Monsoon and Spring Intermonsoon. However, estimated fecal pellet production was less than measured export flux during the SW Monsoon when sinking phytoplankton likely contributed directly to the export flux. Our data suggest that relative to other ocean basins, the grazing impact of mesozooplankton is significant in the Arabian Sea as a consequence of the high zooplankton biomass, abundance of diatoms, and warm temperatures, which result in high zooplankton metabolic demands and growth rates. The observation that the average zooplankton biomass ( 110 mM C m( -2¯) did not change significantly over the monsoon seasons suggests that zooplankton production (13 mM C m(-2) d(-I)) and zooplankton mortality were similar over the study interval. (C) 2000 Elsevier Science Ltd. All rights reserved.},
keywords = {abundance, Arabian Sea, ecology, marine, mortality, multivariate, temperature, zooplankton},
pubstate = {published},
tppubtype = {article}
}
Growth rates, grazing and fecal pellet production by mesozooplankton size classes in the surface 200 m are compared over two inshore/offshore transects in the Northern Arabian Sea during different monsoon seasons. We derived these rate parameters from measured biomass and several empirical models that estimate copepod production from temperature, body weight and food availability. The multivariate regression published by Hirst and Sheader (1997, Marine Ecology Progress Series, 154, 155-165) gave the most reasonable rate estimates when compared to direct grazing measurements as well as published data on copepod ingestion and growth rates. In general, zooplankton rate estimates were highest at the inshore stations where phytoplankton production and zooplankton biomass were maximum. Overall cruise means of zooplankton biomass and rate estimates during the early and late NE Monsoon, Spring Inter-monsoon and SW Monsoon were not significantly different. The estimated zooplankton community (all size fractions) growth rate averaged 0.12d(-I) over all stations during the different monsoon seasons. Although smaller zooplankton size fractions grew faster, slower growing > 2 mm zooplankton dominated the zooplankton biomass of the Arabian Sea and this resulted in a lower overall community growth rate. Estimated total carbon (phytoplankton, protozoa and detritus) ingestion averaged 44 mM C m(-2) d(-I), which was approximately 40% of primary production, Expressed as a percentage ofbiomass, we found that zooplankton ingested approximately 400/0 of their body carbon d( -1 ). Zooplankton fecal pellet production averaged 13 mM C m(-2) d(-I) or roughly 12% of primary production. This estimated fecal pellet production was greater than measurements of the export flux during the NE Monsoon and Spring Intermonsoon. However, estimated fecal pellet production was less than measured export flux during the SW Monsoon when sinking phytoplankton likely contributed directly to the export flux. Our data suggest that relative to other ocean basins, the grazing impact of mesozooplankton is significant in the Arabian Sea as a consequence of the high zooplankton biomass, abundance of diatoms, and warm temperatures, which result in high zooplankton metabolic demands and growth rates. The observation that the average zooplankton biomass ( 110 mM C m( -2¯) did not change significantly over the monsoon seasons suggests that zooplankton production (13 mM C m(-2) d(-I)) and zooplankton mortality were similar over the study interval. (C) 2000 Elsevier Science Ltd. All rights reserved.
Phillip Clapham, Sharon Young, Robert L. Brownell Jr
Baleen whales: conservation issues and the status of the most endangered populations Journal Article
In: Mammal Review, vol. 29 , no. 69, pp. 35-60, 1999.
Abstract | Links | BibTeX | Tags: abundance, Arabian Sea, Arctic, Balaena mysticetus, baleen whale, baleen whales, Blue whale, bowhead whale, bowhead whales, conservation, contaminants, disease, endangered, Entanglement, Eubalaena glacialis, fishing gear, gray whales, habitat degradation, Humpback Whale, humpback whales, mortality, Okhotsk Sea, population, populations, right whale, right whales, ship-strike, southern right whales, status, stocks, whale, whales, whaling
@article{,
title = {Baleen whales: conservation issues and the status of the most endangered populations },
author = {Phillip Clapham, Sharon Young, Robert L. Brownell Jr},
doi = {https://doi.org/10.1046/j.1365-2907.1999.00035.x},
year = {1999},
date = {1999-01-01},
urldate = {1999-01-01},
journal = {Mammal Review},
volume = {29 },
number = {69},
pages = {35-60},
abstract = {Most species of baleen whales were subject to intensive overexploitation by commercial whaling in this and previous centuries, and many populations were reduced to small fractions of their original sizes. Here, we review the status of baleen whale stocks, with an emphasis on those that are known or thought to be critically endangered. Current data suggest that, of the various threats potentially affecting baleen whales, only entanglement in fishing gear and ship strikes may be significant at the population level, and then only in those populations which are already at critically low abundance. The impact of some problems (vessel harassment, and commercial or aboriginal whaling) is at present probably minor. For others (contaminants, habitat degradation, disease), existing data either indicate no immediate cause for concern, or are insufficient to permit an assessment. While the prospect for many baleen whales appears good, there are notable exceptions: populations that are of greatest concern are those suffering from low abundance and associated problems, including (in some cases) anthropogenic mortality. These include: all Northern Right N hales Eubalaena glacialis. Bowhead Whales Balaena mysticetus of the Okhotsk Sea and various eastern Arctic populations. western Gray Whales Eschrichtius robustus, and probably many Blue Whale Balaenoptera musculus populations. We review the status of these populations and. where known, the issues potentially affecting their recovery. Although Humpback Whales Megaptera novaeangliae and Southern Right Whales Eubalaena australis were also heavily exploited by whaling. existing data indicate strong recovery in most studied populations of these species.},
keywords = {abundance, Arabian Sea, Arctic, Balaena mysticetus, baleen whale, baleen whales, Blue whale, bowhead whale, bowhead whales, conservation, contaminants, disease, endangered, Entanglement, Eubalaena glacialis, fishing gear, gray whales, habitat degradation, Humpback Whale, humpback whales, mortality, Okhotsk Sea, population, populations, right whale, right whales, ship-strike, southern right whales, status, stocks, whale, whales, whaling},
pubstate = {published},
tppubtype = {article}
}
Most species of baleen whales were subject to intensive overexploitation by commercial whaling in this and previous centuries, and many populations were reduced to small fractions of their original sizes. Here, we review the status of baleen whale stocks, with an emphasis on those that are known or thought to be critically endangered. Current data suggest that, of the various threats potentially affecting baleen whales, only entanglement in fishing gear and ship strikes may be significant at the population level, and then only in those populations which are already at critically low abundance. The impact of some problems (vessel harassment, and commercial or aboriginal whaling) is at present probably minor. For others (contaminants, habitat degradation, disease), existing data either indicate no immediate cause for concern, or are insufficient to permit an assessment. While the prospect for many baleen whales appears good, there are notable exceptions: populations that are of greatest concern are those suffering from low abundance and associated problems, including (in some cases) anthropogenic mortality. These include: all Northern Right N hales Eubalaena glacialis. Bowhead Whales Balaena mysticetus of the Okhotsk Sea and various eastern Arctic populations. western Gray Whales Eschrichtius robustus, and probably many Blue Whale Balaenoptera musculus populations. We review the status of these populations and. where known, the issues potentially affecting their recovery. Although Humpback Whales Megaptera novaeangliae and Southern Right Whales Eubalaena australis were also heavily exploited by whaling. existing data indicate strong recovery in most studied populations of these species.
Corkeron,P.J.,Connor,R.C.
Why do baleen whales migrate? Journal Article
In: Marine Mammal Science, vol. 15, no. 76, pp. 1228-1245, 1999.
Abstract | BibTeX | Tags: abundance, Distribution, killer whale, killer whales, migration, mysticetes, Orca, predation
@article{,
title = {Why do baleen whales migrate?},
author = {Corkeron,P.J.,Connor,R.C.},
year = {1999},
date = {1999-01-01},
journal = {Marine Mammal Science},
volume = {15},
number = {76},
pages = {1228-1245},
abstract = {The annual migrations of baleen whales are a conspicuous, but unexplained feature of their behavioural repertoire. Some hypotheses offered to explain whale migration focus on direct benefits to the calf (thermoregulation, calm water) and some do not (resource tracking, and the "evolutionary holdover" hypothesis). Here we suggest that a major selective advantage to migrating pregnant female baleen whales is a reduced risk of killer whale predation on their newborn calves in low-latitude waters. Killer whale abundance in high latitudes is substantially greater than that in lower latitudes, and most killer whales do not appear to migrate with baleen whales. We suggest that the distribution of killer whales is determined more by their primary marine mammal prey, pinnipeds, and that following the baleen whale migrations would remove them from their pinnipeds prey. There are problems with all current hypotheses, most of which stem from a lack of directed research. We explore variation in migratory habits between species, populations, and individuals that may provide a "natural laboratory" for discriminating among the competing hypotheses. The authors specifically recommend more detailed study of non-migrating populations, such as the Arabian Sea population of humpback whales.},
keywords = {abundance, Distribution, killer whale, killer whales, migration, mysticetes, Orca, predation},
pubstate = {published},
tppubtype = {article}
}
The annual migrations of baleen whales are a conspicuous, but unexplained feature of their behavioural repertoire. Some hypotheses offered to explain whale migration focus on direct benefits to the calf (thermoregulation, calm water) and some do not (resource tracking, and the "evolutionary holdover" hypothesis). Here we suggest that a major selective advantage to migrating pregnant female baleen whales is a reduced risk of killer whale predation on their newborn calves in low-latitude waters. Killer whale abundance in high latitudes is substantially greater than that in lower latitudes, and most killer whales do not appear to migrate with baleen whales. We suggest that the distribution of killer whales is determined more by their primary marine mammal prey, pinnipeds, and that following the baleen whale migrations would remove them from their pinnipeds prey. There are problems with all current hypotheses, most of which stem from a lack of directed research. We explore variation in migratory habits between species, populations, and individuals that may provide a "natural laboratory" for discriminating among the competing hypotheses. The authors specifically recommend more detailed study of non-migrating populations, such as the Arabian Sea population of humpback whales.
Dennett,M.R.,Caron,D.A.,Murzov,S.A.,Polikarpov,I.G.,Gavrilova,N.A.,Georgieva,L.V.,Kuzmenko,L.V.
Abundance and biomass of nano- and microplankton during the 1995 Northeast Monsoon and Spring Intermonsoon in the Arabian Sea Journal Article
In: Deep-Sea Research Part II, vol. 46, no. 87, pp. 1691-1717, 1999.
Abstract | BibTeX | Tags: abundance, Arabian Sea, ecosystem, Oceanic, oxygen minimum, plankton
@article{,
title = {Abundance and biomass of nano- and microplankton during the 1995 Northeast Monsoon and Spring Intermonsoon in the Arabian Sea},
author = {Dennett,M.R.,Caron,D.A.,Murzov,S.A.,Polikarpov,I.G.,Gavrilova,N.A.,Georgieva,L.V.,Kuzmenko,L.V.},
year = {1999},
date = {1999-01-01},
journal = {Deep-Sea Research Part II},
volume = {46},
number = {87},
pages = {1691-1717},
abstract = {Phototrophic and heterotrophic nanoplankton (PNAN, HNAN; 2-20 æm protists) and microplankton (PMIC, HMIC; 20-200 æm protists and micrometazoa) are major components of the producer and consumer assemblages in oceanic plankton communities. Abundances and biomasses of these microorganisms were determined from samples collected along two transects during the Northeast Monsoon and Spring Intermonsoon process cruises of the US JGOFS Arabian Sea Program in 1995. Vertical profiles of these assemblages were strongly affected by the presence of a subsurface oxygen minimum layer. Abundances of all four assemblages decreased dramatically below the top of this layer. Depth-integrated (0-160 m) abundances and biomasses of nanoplankton and microplankton were of similar magnitude for most samples. Exceptions to this rule were primarily due to PMIC (mostly diatom) species which dominated phytoplankton assemblages at a few stations during each season. Depth-integrated biomasses for the combined nano- and microplankton averaged over all stations for each cruise were surprisingly similar for the Northeast Monsoon and Spring Intermonsoon seasons in this ecosystem (2.0 and 1.8 g C m-2 [170 and 150 m moles C m-2] for the two seasons, respectively). Nano- and microplankton biomass for these two time periods constituted a significant portion of the total amount of the particulate organic carbon (POC) in the water column. Summed over all stations, these assemblages constituted approximately 25-35% of the POC in the top 160 m of the northern Arabian Sea.},
keywords = {abundance, Arabian Sea, ecosystem, Oceanic, oxygen minimum, plankton},
pubstate = {published},
tppubtype = {article}
}
Phototrophic and heterotrophic nanoplankton (PNAN, HNAN; 2-20 æm protists) and microplankton (PMIC, HMIC; 20-200 æm protists and micrometazoa) are major components of the producer and consumer assemblages in oceanic plankton communities. Abundances and biomasses of these microorganisms were determined from samples collected along two transects during the Northeast Monsoon and Spring Intermonsoon process cruises of the US JGOFS Arabian Sea Program in 1995. Vertical profiles of these assemblages were strongly affected by the presence of a subsurface oxygen minimum layer. Abundances of all four assemblages decreased dramatically below the top of this layer. Depth-integrated (0-160 m) abundances and biomasses of nanoplankton and microplankton were of similar magnitude for most samples. Exceptions to this rule were primarily due to PMIC (mostly diatom) species which dominated phytoplankton assemblages at a few stations during each season. Depth-integrated biomasses for the combined nano- and microplankton averaged over all stations for each cruise were surprisingly similar for the Northeast Monsoon and Spring Intermonsoon seasons in this ecosystem (2.0 and 1.8 g C m-2 [170 and 150 m moles C m-2] for the two seasons, respectively). Nano- and microplankton biomass for these two time periods constituted a significant portion of the total amount of the particulate organic carbon (POC) in the water column. Summed over all stations, these assemblages constituted approximately 25-35% of the POC in the top 160 m of the northern Arabian Sea.
Baldwin,R.
Humpback whales Technical Report
no. 19, 1998.
Abstract | BibTeX | Tags: abundance, Arabian Sea, behaviour, conservation, Distribution, ecology, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, megaptera novaeangliae, mortality, occurrence, Oman, population, population identity, status, survey, whale, whales
@techreport{,
title = {Humpback whales },
author = {Baldwin,R.},
year = {1998},
date = {1998-01-01},
volume = {SC/50/CAWS21},
number = {19},
pages = {1-6},
abstract = {Data are presented on the general distribution and abundance of humpback whales off the coast of the Sultanate of Oman, with particular reference to observations made during an offshore seismic survey in the Arabian Sea in November 1997. Additional information is presented on seasonal occurrence, ecology and behaviour, external appearance, conservation, mortality, incidental capture and population status and identity of Oman's humpback whales. The data generally support the notion of year-round residency of humpback whales off the coast of Oman, but indicate the need for further research to establish whether the low frequency of positive records during summer months is a true reflection of seasonal distribution. Other research on humpback whales in the region is recommended.},
keywords = {abundance, Arabian Sea, behaviour, conservation, Distribution, ecology, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, megaptera novaeangliae, mortality, occurrence, Oman, population, population identity, status, survey, whale, whales},
pubstate = {published},
tppubtype = {techreport}
}
Data are presented on the general distribution and abundance of humpback whales off the coast of the Sultanate of Oman, with particular reference to observations made during an offshore seismic survey in the Arabian Sea in November 1997. Additional information is presented on seasonal occurrence, ecology and behaviour, external appearance, conservation, mortality, incidental capture and population status and identity of Oman's humpback whales. The data generally support the notion of year-round residency of humpback whales off the coast of Oman, but indicate the need for further research to establish whether the low frequency of positive records during summer months is a true reflection of seasonal distribution. Other research on humpback whales in the region is recommended.
Baldwin,R.,Van Waerebeek,K.,Gallagher,M.
A review of small cetaceans from waters off the Arabian Peninsula Technical Report
no. 27, 1998.
Abstract | BibTeX | Tags: abundance, cetacean, cetaceans, Distribution, ecology, migration, Movements, status, Stock identity, whaling
@techreport{,
title = {A review of small cetaceans from waters off the Arabian Peninsula},
author = {Baldwin,R.,Van Waerebeek,K.,Gallagher,M.},
year = {1998},
date = {1998-01-01},
journal = {Document presented at the 50th meeting of the Scientific Committee of the International Whaling Commission},
volume = {SC/50/SM6},
number = {27},
pages = {1-26},
abstract = {Available data on small cetacean species in coastal and offshore waters off peninsula Arabia are reviewed. Species accounts are presented for a total of 16 small cetaceans, including information on the date and source of first records in the region, distribution, stock identity, abundance, external appearance, migrations or local movements, status, incidental takes, directed catches and other threats, ecology, life history and disease/parasites. In addition the origin and present location of all curated specimens are listed. Anecdotal information, such as that obtained from local fishermen and other observers, is also presented.},
keywords = {abundance, cetacean, cetaceans, Distribution, ecology, migration, Movements, status, Stock identity, whaling},
pubstate = {published},
tppubtype = {techreport}
}
Available data on small cetacean species in coastal and offshore waters off peninsula Arabia are reviewed. Species accounts are presented for a total of 16 small cetaceans, including information on the date and source of first records in the region, distribution, stock identity, abundance, external appearance, migrations or local movements, status, incidental takes, directed catches and other threats, ecology, life history and disease/parasites. In addition the origin and present location of all curated specimens are listed. Anecdotal information, such as that obtained from local fishermen and other observers, is also presented.
Baldwin,R.M.
Humpback whales (Megaptera novaeangliae) of the Sultanate of Oman Technical Report
no. 315, 1998.
Abstract | BibTeX | Tags: abundance, Arabian Sea, behaviour, conservation, Distribution, ecology, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, megaptera novaeangliae, mortality, occurrence, Oman, population, population identity, status, survey, whale, whales
@techreport{,
title = {Humpback whales (Megaptera novaeangliae) of the Sultanate of Oman },
author = {Baldwin,R.M.},
year = {1998},
date = {1998-01-01},
journal = {Report presented to the Scientific Committee of the International Whaling Commission},
volume = {SC/50/CAWS21 },
number = {315},
pages = {1-6},
abstract = {Data are presented on the general distribution and abundance of humpback whales off the coast of the Sultanate of Oman, with particular reference to observations made during an offshore seismic survey in the Arabian Sea in November 1997. Additional information is presented on seasonal occurrence, ecology and behaviour, external appearance, conservation, mortality, incidental capture and population status and identity of Oman's humpback whales. The data generally support the notion of year-round residency of humpback whales off the coast of Oman, but indicate the need for further research to establish whether the low frequency of positive records during summer months is a true reflection of seasonal distribution. Other research on humpback whales in the region is recommended.},
keywords = {abundance, Arabian Sea, behaviour, conservation, Distribution, ecology, Gulf of Oman, Humpback Whale, humpback whales, incidental capture, megaptera novaeangliae, mortality, occurrence, Oman, population, population identity, status, survey, whale, whales},
pubstate = {published},
tppubtype = {techreport}
}
Data are presented on the general distribution and abundance of humpback whales off the coast of the Sultanate of Oman, with particular reference to observations made during an offshore seismic survey in the Arabian Sea in November 1997. Additional information is presented on seasonal occurrence, ecology and behaviour, external appearance, conservation, mortality, incidental capture and population status and identity of Oman's humpback whales. The data generally support the notion of year-round residency of humpback whales off the coast of Oman, but indicate the need for further research to establish whether the low frequency of positive records during summer months is a true reflection of seasonal distribution. Other research on humpback whales in the region is recommended.
Ballance,L.T,Pitman,R.L.
Cetaceans of the Western Tropical Indian Ocean: Distribution, Relative Abundance, and comparisons with Cetacean Communities of Two other Tropical Ecosystems Journal Article
In: Marine Mammal Science, vol. 14, no. 321, pp. 429-459, 1998.
Abstract | BibTeX | Tags: abundance, cetacean, cetaceans, Distribution, dolphin, dolphins, Gulf of Mexico, habitat preference, Indian Ocean, Maldives, Mexico, Oman, relative abundance, seabirds, survey, whale
@article{,
title = {Cetaceans of the Western Tropical Indian Ocean: Distribution, Relative Abundance, and comparisons with Cetacean Communities of Two other Tropical Ecosystems},
author = {Ballance,L.T,Pitman,R.L.},
year = {1998},
date = {1998-01-01},
journal = {Marine Mammal Science},
volume = {14},
number = {321},
pages = {429-459},
abstract = {We conducted a cetacean survey in the pelagic western tropical Indian Ocean (WTIO) aboard an 85-m research vessel from March to July 1995, covering 9,784 linear km. Using 25x binoculars and line-transect methods, we recorded 589 sightings of 21 species. Stenella longirostris was the most abundant cetacean, in terms of number of individuals sighted, by an order of magnitude above any other species, while Physeter macrocephalus was the most frequently sighted, in terms of number of schools. Twelve species were widespread, seven were rare, and two were localized; our sightings include new distributional records for 12 species. Significant observations included the following: (1) Delphinus cf. tropicalis was abundant off the coast of Oman (16 sightings) and readily distinguishable in the field from D. delphis and D. capensis, (2) Balaenoptera musculus was fairly common and localized in the area of the Maldives (17 sightings), and (3) three sightings were made of an unidentified bottlenose whale tentatively referred to as Indopacetus (i.e., Mesoplodon) pacificus. We recorded 26 mixed-species cetacean schools, 43 schools with which seabirds associated, and 17 schools associated with tuna. Notable among these were mixed aggregations of Stenella attenuata, S. longirostris, yellowfin tuna, and seabirds. The cetacean community of the WTIO was similar to that of the eastern tropical Pacific (ETP) and the Gulf of Mexico (GM) in several respects. First, differences in abundance rank of individual species were small, with the result that common species were common and rare species were rare, regardless of ocean. Second, these differences in abundance were due primarily to differences in encounter rate, which varied with ocean by as much as 3,000%, and less so to school size, which generally varied less than 100%. Third, regardless of ocean, three species comprised the majority of cetaceans in the community, Stenella attenuata, S. longirostris, and S. coeruleoalba, representing 62%-82% of all individuals for all species. However, the rank order of abundance for these three species differed with ocean. Most notably, S. attenuata was abundant in the ETP and GM (abundance rank = 2 and 1, respectively) but much less common in the WTIO (abundance rank = 6). Although habitat preferences for S. attenuata appear to overlap considerably with those of S. longirostris in the ETP, our results suggest there may actually be significant differences between these two species. Detailed analysis of oceanographic correlates of distribution will be necessary in order to understand fully the habitat requirements of these pelagic dolphins, often the most conspicuous elements of tropical cetacean communities around the world.},
keywords = {abundance, cetacean, cetaceans, Distribution, dolphin, dolphins, Gulf of Mexico, habitat preference, Indian Ocean, Maldives, Mexico, Oman, relative abundance, seabirds, survey, whale},
pubstate = {published},
tppubtype = {article}
}
We conducted a cetacean survey in the pelagic western tropical Indian Ocean (WTIO) aboard an 85-m research vessel from March to July 1995, covering 9,784 linear km. Using 25x binoculars and line-transect methods, we recorded 589 sightings of 21 species. Stenella longirostris was the most abundant cetacean, in terms of number of individuals sighted, by an order of magnitude above any other species, while Physeter macrocephalus was the most frequently sighted, in terms of number of schools. Twelve species were widespread, seven were rare, and two were localized; our sightings include new distributional records for 12 species. Significant observations included the following: (1) Delphinus cf. tropicalis was abundant off the coast of Oman (16 sightings) and readily distinguishable in the field from D. delphis and D. capensis, (2) Balaenoptera musculus was fairly common and localized in the area of the Maldives (17 sightings), and (3) three sightings were made of an unidentified bottlenose whale tentatively referred to as Indopacetus (i.e., Mesoplodon) pacificus. We recorded 26 mixed-species cetacean schools, 43 schools with which seabirds associated, and 17 schools associated with tuna. Notable among these were mixed aggregations of Stenella attenuata, S. longirostris, yellowfin tuna, and seabirds. The cetacean community of the WTIO was similar to that of the eastern tropical Pacific (ETP) and the Gulf of Mexico (GM) in several respects. First, differences in abundance rank of individual species were small, with the result that common species were common and rare species were rare, regardless of ocean. Second, these differences in abundance were due primarily to differences in encounter rate, which varied with ocean by as much as 3,000%, and less so to school size, which generally varied less than 100%. Third, regardless of ocean, three species comprised the majority of cetaceans in the community, Stenella attenuata, S. longirostris, and S. coeruleoalba, representing 62%-82% of all individuals for all species. However, the rank order of abundance for these three species differed with ocean. Most notably, S. attenuata was abundant in the ETP and GM (abundance rank = 2 and 1, respectively) but much less common in the WTIO (abundance rank = 6). Although habitat preferences for S. attenuata appear to overlap considerably with those of S. longirostris in the ETP, our results suggest there may actually be significant differences between these two species. Detailed analysis of oceanographic correlates of distribution will be necessary in order to understand fully the habitat requirements of these pelagic dolphins, often the most conspicuous elements of tropical cetacean communities around the world.
Gowing,M.M.,Wishner,K.F.
Feeding ecology of the copepod Journal Article
In: Deep-Sea Research Part II, vol. 45 , no. 105, pp. 2433, 1998.
Abstract | BibTeX | Tags: abundance, Arabian Sea, depth, eastern tropical Pacific, ecology, feeding ecology, oxygen minimum, population, populations, zooplankton
@article{,
title = {Feeding ecology of the copepod},
author = {Gowing,M.M.,Wishner,K.F.},
year = {1998},
date = {1998-01-01},
journal = {Deep-Sea Research Part II},
volume = {45 },
number = {105},
pages = {2433},
abstract = {Feeding ecology of the calanoid copepod Lucicutia aff. L. grandis collected in the Arabian Sea at one station during the Spring Intermonsoon and during the Southwest Monsoon of 1995 was studied with transmission electron microscopy of gut-contents. Highest abundances of these animals occurred from 400 to 1100 m, near the lower interface of the oxygen minimum zone and at the inflection point where oxygen starts to increase. We expected that their gut-contents would include particles and cells that had sunk relatively undegraded from surface waters as well as those from within the oxygen minimum zone, and that gut-contents would differ between the Spring Intermonsoon and the more productive SW Monsoon. Overall, in both seasons Lucicutia aff. L. grandis was omnivorous, and consumed a variety of detrital particles, prokaryotic and eukaryotic autotrophs, gram-negative bacteria including metal-precipitating bacteria, aggregates of probable gram-positive bacteria, microheterotrophs, virus-like particles and large virus-like particles, as well as cuticle and cnidarian tissue. Few significant differences in types of food consumed were seen among life stages within or among various depth zones. Amorphous, unidentifiable material was significantly more abundant in guts during the Spring Intermonsoon than during the late SW Monsoon, and recognizable cells made up a significantly higher portion of gut-contents during the late SW Monsoon. This is consistent with the Intermonsoon as a time when organic material is considerably re-worked by the surface water microbial loop before leaving the euphotic zone. In both seasons Lucicutia aff. L. grandis had consumed what appeared to be aggregates of probable gram-positive bacteria, similar to those we had previously found in gut-contents of several species of zooplankton from the oxygen minimum zone in the eastern tropical Pacific. By intercepting sinking material, populations of Lucicutia aff. L. grandis act as a filter for carbon sinking to the sea floor. They also},
keywords = {abundance, Arabian Sea, depth, eastern tropical Pacific, ecology, feeding ecology, oxygen minimum, population, populations, zooplankton},
pubstate = {published},
tppubtype = {article}
}
Feeding ecology of the calanoid copepod Lucicutia aff. L. grandis collected in the Arabian Sea at one station during the Spring Intermonsoon and during the Southwest Monsoon of 1995 was studied with transmission electron microscopy of gut-contents. Highest abundances of these animals occurred from 400 to 1100 m, near the lower interface of the oxygen minimum zone and at the inflection point where oxygen starts to increase. We expected that their gut-contents would include particles and cells that had sunk relatively undegraded from surface waters as well as those from within the oxygen minimum zone, and that gut-contents would differ between the Spring Intermonsoon and the more productive SW Monsoon. Overall, in both seasons Lucicutia aff. L. grandis was omnivorous, and consumed a variety of detrital particles, prokaryotic and eukaryotic autotrophs, gram-negative bacteria including metal-precipitating bacteria, aggregates of probable gram-positive bacteria, microheterotrophs, virus-like particles and large virus-like particles, as well as cuticle and cnidarian tissue. Few significant differences in types of food consumed were seen among life stages within or among various depth zones. Amorphous, unidentifiable material was significantly more abundant in guts during the Spring Intermonsoon than during the late SW Monsoon, and recognizable cells made up a significantly higher portion of gut-contents during the late SW Monsoon. This is consistent with the Intermonsoon as a time when organic material is considerably re-worked by the surface water microbial loop before leaving the euphotic zone. In both seasons Lucicutia aff. L. grandis had consumed what appeared to be aggregates of probable gram-positive bacteria, similar to those we had previously found in gut-contents of several species of zooplankton from the oxygen minimum zone in the eastern tropical Pacific. By intercepting sinking material, populations of Lucicutia aff. L. grandis act as a filter for carbon sinking to the sea floor. They also
Best,P.B.
Increase rates in severely depleted stocks of baleen whales Journal Article
In: ICES Journal of Marine Science, vol. 50, no. 43, pp. 169-186, 1993.
Abstract | BibTeX | Tags: abundance, Arabian Sea, baleen whales, historical whaling, population estimates, Stock identity, whaling
@article{,
title = {Increase rates in severely depleted stocks of baleen whales},
author = {Best,P.B.},
year = {1993},
date = {1993-01-01},
journal = {ICES Journal of Marine Science},
volume = {50},
number = {43},
pages = {169-186},
abstract = {The paper tries to examine the status of all known stocks of baleen whales that were depleted to an estimated 10% of their original abundance. Of 44 such stocks, 18 are classified as not feasible to monitor (including Arabian Sea humpbacks), 12 have been or are being monitored (at the time of writing), and increase rates have been demonstrated for 10 of those. The author concludes that more depleted stocks show higher rates of increase than less depleted stocks, and that most populations are reaching a size which would allow harvesting (a minimum of 60% of their pre-exploitation numbers according to the IWC). The paper points out some interesting problems with the use of historical whaling data and mark-recapture in estimating fecundity rates. It also suggests that population increases were not detected in the years immediately following protection for two reasons: 1) commercial catches were underreported and initial post-whaling population estimates were too high, 2) following population decreases, whales may condense their ranges, leaving some historical feeding or breeding sites to form concentration areas, some of which were only recently discovered.},
keywords = {abundance, Arabian Sea, baleen whales, historical whaling, population estimates, Stock identity, whaling},
pubstate = {published},
tppubtype = {article}
}
The paper tries to examine the status of all known stocks of baleen whales that were depleted to an estimated 10% of their original abundance. Of 44 such stocks, 18 are classified as not feasible to monitor (including Arabian Sea humpbacks), 12 have been or are being monitored (at the time of writing), and increase rates have been demonstrated for 10 of those. The author concludes that more depleted stocks show higher rates of increase than less depleted stocks, and that most populations are reaching a size which would allow harvesting (a minimum of 60% of their pre-exploitation numbers according to the IWC). The paper points out some interesting problems with the use of historical whaling data and mark-recapture in estimating fecundity rates. It also suggests that population increases were not detected in the years immediately following protection for two reasons: 1) commercial catches were underreported and initial post-whaling population estimates were too high, 2) following population decreases, whales may condense their ranges, leaving some historical feeding or breeding sites to form concentration areas, some of which were only recently discovered.
Matthew,K.J.,Naomi,T.S.,Antony,G.,Scariah,K.S.
Proceedings of the first workshop on scientific results of FORV Sagar Sampada, 5-7 June, 1989. Cochin. Conference
no. 150, Central Marine Fisheries Research Institute, 1990.
Abstract | BibTeX | Tags: abundance, Arabian Sea, density, Distribution, Euphausiid
@conference{,
title = {Proceedings of the first workshop on scientific results of FORV Sagar Sampada, 5-7 June, 1989. Cochin.},
author = {Matthew,K.J.,Naomi,T.S.,Antony,G.,Scariah,K.S.},
year = {1990},
date = {1990-01-01},
number = {150},
pages = {121-127},
publisher = {Central Marine Fisheries Research Institute},
abstract = {The Euphausiacea collected from 1,086 stations during the cruises 1-44 of FORV Sagar Sampada in the eastern Arabian Sea and the Bay of Bengal from 1985-'88 were studied for their spatial, seasonal and day and night abundance. The average density of euphausiids in the entire area investigated was estimated to be 3,214 per 1000 m super(3) ofwater. With regard to spatial distribution, more euphausiids were present in the eastern Arabian Sea (3,680/1000 m super(3)) than in the Bay of Bengal (2,517/1000 m super(3)). The observed percentage of increase for the eastern Arabian Sea over the Bay of Bengal worked out to 92.42. When an attempt was made to understand the seasonal variation, it was found that off the west coast, more number of euphausiids was present (the rate being 5,272/1000 m super(3)) during the south west monsoon season. Least abundance of2,505 was noticed during the premonsoon season. The day time abundance ofeuphausiids in the upper 150 m of water column was at a rate of2,282 while the same during the night was 4,651, thus indicating 103.81% of increase in the night samples.},
keywords = {abundance, Arabian Sea, density, Distribution, Euphausiid},
pubstate = {published},
tppubtype = {conference}
}
The Euphausiacea collected from 1,086 stations during the cruises 1-44 of FORV Sagar Sampada in the eastern Arabian Sea and the Bay of Bengal from 1985-'88 were studied for their spatial, seasonal and day and night abundance. The average density of euphausiids in the entire area investigated was estimated to be 3,214 per 1000 m super(3) ofwater. With regard to spatial distribution, more euphausiids were present in the eastern Arabian Sea (3,680/1000 m super(3)) than in the Bay of Bengal (2,517/1000 m super(3)). The observed percentage of increase for the eastern Arabian Sea over the Bay of Bengal worked out to 92.42. When an attempt was made to understand the seasonal variation, it was found that off the west coast, more number of euphausiids was present (the rate being 5,272/1000 m super(3)) during the south west monsoon season. Least abundance of2,505 was noticed during the premonsoon season. The day time abundance ofeuphausiids in the upper 150 m of water column was at a rate of2,282 while the same during the night was 4,651, thus indicating 103.81% of increase in the night samples.
Silas,E.G.,Matthew,K.J.
Spatial distribution of Euphausiacea (Crustacea) in the southeastern Arabian Sea Journal Article
In: Journal of the Marine Biological Association of India, vol. 28, no. 230, pp. 1-21, 1986.
Abstract | BibTeX | Tags: abundance, Arabian Sea, Distribution, Euphausiid, India, Oceanic, zooplankton
@article{,
title = {Spatial distribution of Euphausiacea (Crustacea) in the southeastern Arabian Sea},
author = {Silas,E.G.,Matthew,K.J.},
year = {1986},
date = {1986-01-01},
journal = {Journal of the Marine Biological Association of India},
volume = {28},
number = {230},
pages = {1-21},
abstract = {Spatial distribution of euphausiids of the southeastern Arabian Sea (west coast of India including the Lakshadweep Sea) was studied. The Arabian Sea and the Bay of Bengal, closed at their northern parts, present special hydrographical features which influence the distribution and abundance of zooplankton in these areas. Here the l0 degree N latitude is thought to be an effective barrier against he penetration of several oceanic species of euphausiids northwards. This is because of the significant changes in the water quality of N of 10 degree N being influenced by the discharge from major river systems of the Indian sub-continent. The species Thysanopoda monacantha, T. tricuspidata and Stylocheiron maximum, which were believed to be restricted to areas south of 10 degrees N are distributed even further northwards.},
keywords = {abundance, Arabian Sea, Distribution, Euphausiid, India, Oceanic, zooplankton},
pubstate = {published},
tppubtype = {article}
}
Spatial distribution of euphausiids of the southeastern Arabian Sea (west coast of India including the Lakshadweep Sea) was studied. The Arabian Sea and the Bay of Bengal, closed at their northern parts, present special hydrographical features which influence the distribution and abundance of zooplankton in these areas. Here the l0 degree N latitude is thought to be an effective barrier against he penetration of several oceanic species of euphausiids northwards. This is because of the significant changes in the water quality of N of 10 degree N being influenced by the discharge from major river systems of the Indian sub-continent. The species Thysanopoda monacantha, T. tricuspidata and Stylocheiron maximum, which were believed to be restricted to areas south of 10 degrees N are distributed even further northwards.