Ponnampalam,L.,Collins,T.J.Q.,Minton,G.,Baldwin,R
Feeding ecology of small cetaceans in the Sultanate of Oman Journal Article
In: Poster presented at the 17th meeting of the Society for Marine Mammals in Cape Town, no. 433, 2007.
Abstract | BibTeX | Tags: bottlenose dolphin, bottlenose dolphins, cephalopod, cetacean, cetaceans, conservation, diet, Distribution, dolphin, dolphins, ecology, feeding, feeding ecology, fish, habitat, humpback dolphins, occurrence, Oman, prey, Spinner dolphin, Stenella longirostris, stomach contents, survey, tursiops
@article{,
title = {Feeding ecology of small cetaceans in the Sultanate of Oman},
author = {Ponnampalam,L.,Collins,T.J.Q.,Minton,G.,Baldwin,R},
year = {2007},
date = {2007-01-01},
journal = {Poster presented at the 17th meeting of the Society for Marine Mammals in Cape Town},
number = {433},
abstract = {Beach surveys were conducted along the coast of Oman between 2000 and 2006 to locate and examine cetacean remains. This study examines the stomach contents of 11 bottlenose dolphins (Tursiops sp.), 5 Indo-Pacific humpback dolphins (Sousa chinensis) and 2 spinner dolphins (Stenella longirostris) that were found beach-cast along the Omani coastline. Across the three species examined, a total of 4796 fish otoliths and 214 cephalopod beaks were found, representing 36 species in 23 families. No crustacean remains were found. Prey item importance was calculated using the percentage by number (%N), and percentage by frequency of occurrence (%FO) methods, and a modified index of relative importance (IRI). Percentage similarity was also calculated to examine interspecific and intraspecific dietary overlap. All three species of dolphins examined here ate mainly fish. The fish families Apogonidae and Carangidae were the most numerically important prey in the diet of bottlenose dolphins. Sciaenidae was the most numerically important fish family for humpback dolphins. Mesopelagic fishes comprised the diet of spinner dolphins, with the myctophid Benthosema pterotum forming the bulk of the prey items. The cephalopod preys found in the stomach samples were represented by the families Sepiidae, Loliginidae and Onychoteuthidae. The frequency distribution of prey items indicate that the bottlenose dolphins fed in a wide variety of habitats, and may reflect the occurrence of at least two species or ecotypes of Tursiops in Oman. The humpback dolphin prey items indicate feeding in coastal, nearshore areas with soft substrate. Spinner dolphins appeared to feed in the upper 200m of the water column on nocturnal vertically migrating prey. Although most of the prey species do not appear to be of commercial importance, the findings of this study indicated that all three species of dolphins were feeding in areas where fishing occurs and this is likely to have conservation implications. },
keywords = {bottlenose dolphin, bottlenose dolphins, cephalopod, cetacean, cetaceans, conservation, diet, Distribution, dolphin, dolphins, ecology, feeding, feeding ecology, fish, habitat, humpback dolphins, occurrence, Oman, prey, Spinner dolphin, Stenella longirostris, stomach contents, survey, tursiops},
pubstate = {published},
tppubtype = {article}
}
Beach surveys were conducted along the coast of Oman between 2000 and 2006 to locate and examine cetacean remains. This study examines the stomach contents of 11 bottlenose dolphins (Tursiops sp.), 5 Indo-Pacific humpback dolphins (Sousa chinensis) and 2 spinner dolphins (Stenella longirostris) that were found beach-cast along the Omani coastline. Across the three species examined, a total of 4796 fish otoliths and 214 cephalopod beaks were found, representing 36 species in 23 families. No crustacean remains were found. Prey item importance was calculated using the percentage by number (%N), and percentage by frequency of occurrence (%FO) methods, and a modified index of relative importance (IRI). Percentage similarity was also calculated to examine interspecific and intraspecific dietary overlap. All three species of dolphins examined here ate mainly fish. The fish families Apogonidae and Carangidae were the most numerically important prey in the diet of bottlenose dolphins. Sciaenidae was the most numerically important fish family for humpback dolphins. Mesopelagic fishes comprised the diet of spinner dolphins, with the myctophid Benthosema pterotum forming the bulk of the prey items. The cephalopod preys found in the stomach samples were represented by the families Sepiidae, Loliginidae and Onychoteuthidae. The frequency distribution of prey items indicate that the bottlenose dolphins fed in a wide variety of habitats, and may reflect the occurrence of at least two species or ecotypes of Tursiops in Oman. The humpback dolphin prey items indicate feeding in coastal, nearshore areas with soft substrate. Spinner dolphins appeared to feed in the upper 200m of the water column on nocturnal vertically migrating prey. Although most of the prey species do not appear to be of commercial importance, the findings of this study indicated that all three species of dolphins were feeding in areas where fishing occurs and this is likely to have conservation implications.
Luo,J.,Ortner,P.B.,Forcucci,D.,Cummings,S.R.
Diel vertical migration of zooplankton and mesopelagic fish in the Arabian Sea Journal Article
In: Deep-Sea Research Part II, vol. 47 , no. 145, pp. 1451-1473, 2000.
Abstract | BibTeX | Tags: acoustic, Arabian Sea, depth, diel, displacement, fish, migration, oxygen minimum, sonar, temperature, zooplankton
@article{,
title = {Diel vertical migration of zooplankton and mesopelagic fish in the Arabian Sea},
author = {Luo,J.,Ortner,P.B.,Forcucci,D.,Cummings,S.R.},
year = {2000},
date = {2000-01-01},
journal = {Deep-Sea Research Part II},
volume = {47 },
number = {145},
pages = {1451-1473},
abstract = {Acoustic (153 kHz ADCP and 12 kHz hull-mounted transducers) data and MOCNESS (MOC01 and MOC10) net tow samples collected in the Arabian Sea during the Spring Intermonsoon (April/May) and Southwest Monsoon (August) in 1995 documented substantial diel migrations of fish and zooplankton despite the year-round presence of an oxygen minimum ((0.2 ml l-1 at 125-150 m). Fish and zooplankton layers were distinguished by comparing 12 kHz sonar and 153 kHz ADCP backscatter data, which indicated that the strongly migrating layers were predominantly composed of fishes. Fish vertical migration speeds were independently estimated from the slopes of the volume scattering layers and from the vertical velocity components of the ADCP, yielding average speeds of 4 and 3 cm s-1 and maximum speeds of 13 and 10 cm s-1, respectively. A few migrating zooplankton layers were identified with an average speed of about 2 cm s-1 and maximum speeds as high as 8 cm s-1. Migration depths for both zooplankton and fish differed somewhat amongst stations and appeared to be related to local hydrographic conditions (principally the vertical gradients in DO and water temperature). Zooplankton displacement volumes at individual sites suggested that zooplankton biomass during the Southwest Monsoon could be as much as fivefold greater than during the Spring Intermonsoon. This observation was confirmed for the region in general by first deriving a relationship between ADCP backscatter intensity and daytime zooplankton biomass and then comparing the latter between cruises using daytime ADCP data taken along a 1500 km transect that extended from the coast of Somalia to the center of the northern basin.},
keywords = {acoustic, Arabian Sea, depth, diel, displacement, fish, migration, oxygen minimum, sonar, temperature, zooplankton},
pubstate = {published},
tppubtype = {article}
}
Acoustic (153 kHz ADCP and 12 kHz hull-mounted transducers) data and MOCNESS (MOC01 and MOC10) net tow samples collected in the Arabian Sea during the Spring Intermonsoon (April/May) and Southwest Monsoon (August) in 1995 documented substantial diel migrations of fish and zooplankton despite the year-round presence of an oxygen minimum ((0.2 ml l-1 at 125-150 m). Fish and zooplankton layers were distinguished by comparing 12 kHz sonar and 153 kHz ADCP backscatter data, which indicated that the strongly migrating layers were predominantly composed of fishes. Fish vertical migration speeds were independently estimated from the slopes of the volume scattering layers and from the vertical velocity components of the ADCP, yielding average speeds of 4 and 3 cm s-1 and maximum speeds of 13 and 10 cm s-1, respectively. A few migrating zooplankton layers were identified with an average speed of about 2 cm s-1 and maximum speeds as high as 8 cm s-1. Migration depths for both zooplankton and fish differed somewhat amongst stations and appeared to be related to local hydrographic conditions (principally the vertical gradients in DO and water temperature). Zooplankton displacement volumes at individual sites suggested that zooplankton biomass during the Southwest Monsoon could be as much as fivefold greater than during the Spring Intermonsoon. This observation was confirmed for the region in general by first deriving a relationship between ADCP backscatter intensity and daytime zooplankton biomass and then comparing the latter between cruises using daytime ADCP data taken along a 1500 km transect that extended from the coast of Somalia to the center of the northern basin.