bluuebunny/crossref_metadata_2025 huggingface dataset:
NO EVIDENCE OF ACCOMMODATION IN THE EYES OF THE BOTTLENOSE DOLPHIN, TURSIOPS TRUNCATUS
Authors: Litwiler Tricia L. , Cronin Thomas W.
Published: August 2006

Abstract

Bottlenose dolphins (Tursiops truncatus) are aquatic mammals that must come to the surface to breathe. As a result, it might be expected that their eyes are adapted for both aerial and underwater vision. Earlier studies suggest that dolphins are emmetropic (i. e., focused at infinity) in water, and in some cases, emmetropic in air, although the mechanisms that permit these animals to see well in both media are not well understood. Nor is it known whether they can accommodate to focus sharply on objects at different distances. We employed video photoretinoscopy to investigate the possibility of an active accommodative mechanism in the eyes of the bottlenose dolphin in water. Measurements of the refractive state in water indicated near emmetropia for two individuals and slight myopia (nearsightedness) for the third individual. No clear cases of accommodation were observed underwater in any of the subjects examined. Vision underwater may be used to supplement echolocation. If so, such a role might not require an accommodative mechanism.
INTERACTIONS OF SINGING HUMPBACK WHALES WITH OTHER MALES
Authors: Darling James D. , Bérubé Martine
Published: August 2006

Abstract

Two non‐mutually exclusive hypotheses on the function of the humpback whale song are: (1) it attracts females to the male singer; (2) it is a male‐male display, that may order status. To evaluate these, from 24 January‐13 April 1997 off Maui, Hawaii, 42 singers were located, audio‐recorded, photo‐identified and monitored for interactions with other whales. Whales that joined singers were biopsy sampled for molecular determination of sex. In 76% (32 of 42) of the interactions, a lone non‐singing adult joined the singer. In the remainder, singers stopped singing and joined a nearby group or accompanied other whales. In 81% (26 of 32) instances where a lone adult joined a singer, the pair split again within minutes; otherwise a group formed. In one such group the pair became a trio and eventually joined a competitive group. Behavior in joining/splitting interactions ranged from a single pass‐by, to surface activity such as tail lobs and breaches. The sex of 22 joiners was determined: 14 genetically and eight behaviorally. All were males. Humpback whale song preceded, and at times followed, male‐male interactions of variable duration and agonistic level in and around the breeding season. If considered within the context of a proposed dominance polygyny mating system, these observations appear to support speculation that the song may function in male social ordering.
BEHAVIOR AND ECOLOGY OF THE ATLANTIC WHITE‐SIDED DOLPHIN (LAGENORHYNCHUS ACUTUS) IN COASTAL NEW ENGLAND WATERS
Authors: Weinrich Mason T. , Belt Cynthia R. , Morin David
Published: August 2006

Abstract

Atlantic white‐sided dolphins (Lagenorhynchus acutus) are among the most abundant, and least studied, cetaceans in coastal New England. Between April and October 1984 through 1997 we sighted 1,231 groups of Atlantic white‐sided dolphins, primarily on Stellwagen Bank and Jeffreys Ledge (two shallow glacial deposits along the coasts of Massachusetts, New Hampshire, and Maine). Mean group size was 52 (≥90.9), and was significantly larger from August through October (71.9 ± 111.4) than April through June (35.0 ± 45.4). Calf sightings were uncommon until June and July, after which they were present in over 50% of groups. Combined with observations of apparent newborn calves, this confirms that early summer is an important calving period. The presence of calves did not, however, solely account for the increase in group size. Boat interaction (bow‐ and stern‐wake riding) was the most commonly recorded behavior (47.4% of sightings), followed by traveling (31.4%), interactions with other cetacean species (27.6%), social interaction (15.5%), and feeding (9.5%). While feeding was uncommon, one observation of apparently coordinated “ball” feeding was seen with sand lance (Ammodytesspp.) as the visible prey. Aerial behavior showed a positive correlation with group size, although it was often impossible to tell whether the same dolphins were leaping repeatedly. Eighty‐eight dolphins were photo‐identified using either unusual body pigment or a distinctive dorsal fin. While several individuals were reidentified between years and between areas, no reidentifications were made within a year in the same area. Unusually pigmented individuals were much more likely to be reidentified than those with distinctive dorsal fins, most likely due to higher visibility. We suggest that Atlantic white‐sided dolphins are generally using the study area as transients in what appears to be a large home range.
COASTAL BOTTLENOSE DOLPHINS FROM SOUTHEASTERN AUSTRALIA ARE TURSIOPS ADUNCUS ACCORDING TO SEQUENCES OF THE MITOCHONDRIAL DNA CONTROL REGION
Authors: Möller Luciana M. , Beheregaray Luciano B.
Published: August 2006

Abstract

Sequence analysis of the mitochondrial DNA control region was used to clarify the taxonomic status of two coastal bottlenose dolphin populations from southeastern Australia currently classified as Tursiops truncatus. A 368‐bp segment of the control region of 57 biopsy‐sampled, photo‐identified dolphins of Jervis Bay and Port Stephens was compared to published sequences of T. truncatus and T. aduncus from different oceanic regions. Sequence divergence between haplotypes from southeastern Australia and T. aduncus was much lower than that from T. truncatus. Analyses using two different methods of phylogenetic reconstruction unambiguously placed all haplotypes from southeastern Australia in a group composed exclusively of T. aduncus. The results strongly indicated that these two bottlenose dolphin populations belong to T. aduncus, extending the range of the species to subtropical waters of the Western South Pacific Ocean.
GEOGRAPHICAL VARIATION OF THE PARASITE, PHYLLOBOTHRIUM DELPHINI (CESTODA), IN BALL'S PORPOISE, PHOCOENOIDES DALLI, IN THE NORTHERN NORTH PACIFIC, BERING SEA, AND SEA OF OKHOTSK
Authors: Walker William A.
Published: August 2006

Abstract

Prevalence of the larval cestode, Phyllobothrium delphini, was estimated from 2,445 Dall's porpoise, Phocoenoides dalli, from the incidental take of the Japanese high seas salmon drift‐net fishery in the northwestern North Pacific Ocean, Bering Sea, and a local hand harpoon fishery in the southern Sea of Okhotsk. Prevalence of P. delphini was 22.7% in the northwestern North Pacific Ocean and 1.4% in the Bering Sea. This parasite was not found in the southern Sea of Okhotsk. Geographical differences in the prevalence of P. delphini may be due, at least in part, to regional differences in abundance of elasmobranchs known to feed on marine mammals and suspected as hosts of the parasite. Estimated intensity of infection of individual porpoises by P. delphini was low (estimated mean intensity of 3.5 plerocercoids per animal). This is a low intensity of infection compared to other species of small cetaceans studied and may be due to both differences in regional abundance of elasmobranchs and the comparatively short life span of P. dalli.
CORRECTING AERIAL SURVEY COUNTS OF HARBOR SEALS (PHOCA VITULINA RICHARDSI) IN WASHINGTON AND OREGON
Authors: Huber Harriet R. , Jeffries Steven J. , Brown Robin F. , Delong Robert L. , Vanblaricom Glenn
Published: August 2006

Abstract

Aerial surveys of harbor seals on land produce only a minimum assessment of the population; a correction factor to account for the missing animals is necessary to estimate total abundance. In 1991 and 1992, VHF radio tags were deployed on harbor seals (n= 124) at six sites in Washington and Oregon. During aerial surveys a correction factor to account for seals in the water was determined from the proportion of radio‐tagged seals on shore during the pupping season. This proportion ranged from 0.54 to 0.74. Among the six sites there was no significant difference in the proportion of animals on shore nor was there a difference in age/sex categories of seals on shore between sites. The pooled correction factor for determining total population abundance was 1.53. An additional 32 seals were radio tagged in 1993 at one of the sites used in 1991. Comparing data from the two years, we found no interannual variation. Aerial surveys of all known harbor seal haul‐out sites in Washington (n= 319) and Oregon (n= 68) were flown during the peak of the pupping season, 1991–1993. The Washington and Oregon harbor seal population was divided into two stocks based on pupping phenology, morphometics, and genetics. Mean counts for the Washington inland stock were 8,710 in 1991, 9,018 in 1992, and 10,092 in 1993. Oregon and Washington coastal stock mean counts were 18,363 in 1991, 18,556 in 1992, and 17,762 in 1993. Multiplying the annual count by the correction factor yielded estimates of harbor seal abundance in the Washington inland stock of 13,326 (95% CI = 11,637–15,259) for 1991, 13,798 (95% CI = 11,980–15,890) for 1992, and 15,440 (95% CI = 13,382–17,814) for 1993. In the Oregon and Washington coastal stock the corrected estimate of harbor seal abundance was 28,094 (95% CI = 24,697–31,960) in 1991, 28,391 (95% CI = 24,847–32,440) for 1992, and 27,175 (95% CI = 23,879–30,926) for 1993.
CHARACTERIZATION OF BEAKED WHALE (ZIPHIIDAE) AND SPERM WHALE (PHYSETER MACROCEPHALUS) SUMMER HABITAT IN SHELF‐EDGE AND DEEPER WATERS OFF THE NORTHEAST U. S.
Authors: Waring G. T. , Hamazaki T. , Sheehan Daniel , Wood Grayson , Baker Sheekela
Published: August 2006

Abstract

Sperm whales (Physeter macrocephalus) and beaked whales (Mesoplodonspp. andZiphius cavirostris) are deep‐diving cetaceans that frequent shelf‐edge and Gulf Stream waters off the northeast U. S. coast. Sighting data collected during seven summer (1990, 1991, 1993, and 1995–1998) shipboard surveys were analyzed using a geographic information system to determine habitat use based on bathymetric and oceanographic features. Although sighting rates were lower for beaked whales, both taxa occupied similar habitats. Beaked whales were concentrated at the colder shelf edge, whereas sperm whales were associated with warmer off‐shelf water. Mean sighting rates for both taxa were higher in canyon features, but only beaked whale sighting rates were significantly different between canyon and non‐canyon habitat (Wilcoxon signed rank testP= 0.007). Within the shared habitat, the two taxa were separated at fine‐scale based on oceanographic features.
MORPHOLOGY OF THE EYE AND SURROUNDING STRUCTURES OF THE BOWHEAD WHALE, BALAENA MYSTICETUS
Authors: Zhu Qian , Hillmann Daniel J. , Henk William G.
Published: August 2006

Abstract

Observations were made on eyes from 46 bowhead whales, Balaena mysticetus, taken in the subsistence harvest near Barrow, Point Hope, Savoonga, and Kaktovik, Alaska. Data reported here include palpebral, eyeball, corneal, scleral, pupillary, and lens dimensions. These quantitative data have allowed us to compare structures relative to one another and sometimes to compare them with similar structures in other species. We found, for example, that the cornea is almost three times as thick at its periphery as at its center; that when the ratio of scleral thickness and eyeball size are compared, the ratio, in the bowhead whale, is twice that of any other cetacean for which data were available; and that the corneal and pupillary width to height ratios indicate a less elongated cornea and pupil than has been reported in other cetaceans. We also found a strong correlation between body length and eyeball size indicating that within the species, unlike what is seen between species, larger animals have larger eyes. Novel observations include the presence of three periorbital fatty layers, 112 ciliary processes, the presence of scleral canals, the absence of an obvious fovea or macular region in the retina, a holangiotic pattern of fundic vessels, the presence of zonular fibers and a lens sheath, and the absence of an obvious pupillary operculum. Anatomical features like the wide angle of divergence and the palpebral dimensions suggest the absence of binocular vision while features like the size of the palpebral sac, abundant conjuctival fat, and the prominence of the retractor bulbi muscle suggest mechanisms for the protrusion and retraction of the eyeball.
SEAL RESPONSES TO AIRGUN SOUNDS DURING SUMMER SEISMIC SURVEYS IN THE ALASKAN BEAUFORT SEA
Authors: Harris Ross E. , Miller Gary W. , Richardson W. John
Published: August 2006

Abstract

Numbers, sighting distances, and behavior of seals were studied during a nearshore seismic program off northern Alaska in July‐September 1996. We observed from the seismic vessel for 885.6 h, including all periods (day and night) when airguns operated and many periods without airguns. Of 422 seals seen, 421 were seen in daylight; 91‐8% were ringed seals, 7.3% were bearded seals, and 0.9% were spotted seals. About 79% were first seen within 250 m of the seismic boat, and sighting rate declined rapidly at lateral distances > 50 m. During daylight, seals were seen at nearly identical rates (0.60‐0.63/ h) during periods with no airguns firing, one airgun, and a “full‐array” of 8‐11 120‐in3 airguns. However, seals tended to be farther away (P < 0.0001) during full‐array seismic. There was partial avoidance of the zone <150 m from the boat during full‐array seismic, but seals apparently did not move much beyond 250 m. “Swimming away” was more common during full‐array than no‐airgun periods, but relative frequencies of five behaviors did not differ significantly among distance categories. Airgun operations were interrupted 112 times when seals were sighted within safety radii (150–250 m). The National Marine Fisheries Service specified these radii in the Incidental Harassment Authorization issued for the project; they are based on a 190 dB re 1 μPa (rms) criterion for broadband received level. Methods for estimating numbers of seals potentially affected by the seismic program are described, and effectiveness of monitoring and mitigation is discussed. There is an urgent need for more data on effects of strong seismic pulses on seals.
ONTOGENETIC AND SEASONAL VARIATION IN BLOOD PARAMETERS IN SOUTHERN ELEPHANT SEALS
Authors: Lewis Mirtha , Campagna Claudio , Uhart Marcela , Ortiz Charles Leo
Published: August 2006

Abstract

Blood samples were collected from 156 free‐ranging southern elephant seals (Mirounga leonina) from Peninsula Valdes to study the variation in blood parameters related to ontogeny and the annual cycle. Samples ranged from newborn pups to adults. Interactions between age and sex showed different trends in ontogenetic changes of blood parameters (MANOVA, Wilkis' Lamb‐da12,243= 0.75,P< 0.01). The hematocrit (HCT) and hemoglobin concentration (HB) reached adult levels early in life. Weanlings had 14 % higher HCT than pups, and similar levels to juveniles and adults (HCT range = 46%‐62 %). HB of males were below those of females from weaning (18.4vs. 20.3 g/dl) to adulthood (19.8vs. 22.3 g/dl). Red blood cell counts (RBC) did not change significantly from pups to juveniles (2.8–3.2 106/μl), but varied for adults at different times of the annual cycle. Breeding females had higher RBC than molting females (3.1vs.2.4 106/μl). Changes in blood parameters are related to the development of diving capabilities from pups to juveniles. Changes in adults were associated with different stages of the annual cycle, and these may be the result of the requirements imposed by pregnancy and fasting duration.
DIET OF RINGED SEALS (PHOCA HISPIDA) ON THE EAST AND WEST SIDES OF THE NORTH WATER POLYNYA, NORTHERN BAFFIN BAY
Authors: Holst Meike , Stirling Ian , Hobson Keith A.
Published: August 2006

Abstract

In conjunction with the International North Water Polynya Study (NOW) in northern Baffin Bay, we examined the diets of ringed seals (Phoca hispida)1on the west (Grise Fiord, Nunavut) and east (Qaanaaq, Greenland) sides of the polynya, using conventional stomach content analysis, as well as inferences from stable isotope ratios in seal muscle. Between May and July 1998, stomach and muscle tissue samples were collected from 99 ringed seals taken near Grise Fiord and 100 taken near Qaanaaq. The amphipodThemisto libellulawas the dominant prey type in the diet of immature ringed seals from Grise Fiord, whereas arctic cod (Boreogadus saida) and polar cod (Arctogadus glacialis) predominated in the diet of adults. Both immature and adult seals collected near Qaanaaq fed predominantly on arctic cod. Overall, seals collected near Grise Fiord had significantly higher δ13C values than those collected near Qaanaaq (P< 0.001), but there was no statistical separation in δ15N values between the two samples (P= 0.06). Differences in diets of ringed seals from the east and west sides of the North Water Polynya may be due to differences in prey distribution and/or differences in biological productivity and fish biomass within the polynya.
A RESIDENT POPULATION OF INDO‐PACIFIC BOTTLENOSE DOLPHINS (TURSIOPS ADUNCUS) IN AMAKUSA, WESTERN KYUSHU, JAPAN
Authors: Shirakihara Miki , Shirakihara Kunio , Tomonaga Jyunji , Takatsuki Megumi
Published: August 2006

Abstract

Residency patterns and population size were examined for Indo‐Pacific bottlenose dolphins (Tursiops aduncus) in the coastal waters of Amakusa‐Shimoshima Island, western Kyushu, Japan, from summer 1994 to fall 1998. A total of 203 individuals were identified. The number of newly identified individuals barely increased after the first 1.5 yr. The identified individuals in one season were frequently resighted with percentages of mostly over 60% during the subsequent seasons. Most of the dolphins off Amakusa were yearround residents, although the total range of their habitat was unknown. The population size estimated by the mark‐recapture technique was 218 individuals with a CV of 5.41% in 1995–1997. The group commonly consisted of more than 100 individuals. The large group size was thought to be a response to feeding on schooling fishes.
GRAY WHALE CALF PRODUCTION 1994–2000: ARE OBSERVED FLUCTUATIONS RELATED TO CHANGES IN SEASONAL ICE COVER?
Authors: Perryman Wayne L. , Donahue Meghan A. , Perkins Peter C. , Reilly Stephen B.
Published: August 2006

Abstract

We conducted shore‐based sighting surveys to estimate the number of northbound migrating gray whale calves passing Piedras Blancas, California, for seven consecutive years (1994–2000). In addition, we conducted aerial surveys to determine offshore distribution of the migration in 1994 and 1995, measured day/night migration rates with thermal sensors in 1994–1996, and maintained concurrent replicate watches near the peak of each migration to estimate the proportion of the cow/calf pairs missed by the standard watch team. During good weather, we counted 325, 194, 407, 501, 440, 141, and 96 calves during 1994–2000, respectively. Correcting these counts for periods not on watch and for calves missed, produced final estimates of 945 calves (SE = 68.21) for 1994, 619 calves (SE = 67.19) for 1995, 1,146 calves (SE = 70.67) for 1996, 1,431 calves (SE = 82.02) for 1997, 1,388 calves (SE = 91.84) for 1998, 427 calves (SE = 41.10) for 1999, and 279 calves (SE = 34.79) for 2000. Calf production indices (calf estimate/total population estimate) are 4.2%, 2.7%, 4.8%, 5.8%, 5.5%, 1.7%, and 1.1% for the years 1994–2000, respectively. Fluctuations in calf production over this time period were positively correlated with the length of time that primary feeding habitat was free of seasonal ice during the previous year.
DIET‐TISSUE FRACTIONATION OF STABLE CARBON AND NITROGEN ISOTOPES IN PHOCID SEALS
Authors: Lesage VÉRONIQUE , Hammill Mike O. , Kovacs Kit M.
Published: August 2006

Abstract

Diet‐tissue isotopic fractionation of carbon (C) and nitrogen (N) isotopes in short‐ and longer‐term diet integrators of diet (i. e., blood serum and red cells), that involve non‐invasive sampling techniques was examined using three species of phocid seals (harbor seals, gray seals, and harp seals) fed a known diet. Variability in diet‐tissue fractionation values within and between species was also scrutinized to determine the legitimacy of using values obtained from one species to explore trophic positions and diets of other related species. All captive seals raised on a constant diet had tissues enriched in 13C and 15N relative to their diet. Diet‐tissue isotopic fractionation values were generally consistent among conspecifics and among phocid species for a given tissue. Trophic isotopic enrichment in 13C was significantly higher in red blood cells (+1.5%±) than in blood serum (+0.8%±), whereas the reverse was observed for nitrogen isotopes (+1.7%± in red cells vs. +3.1%± in serum). However, 13C‐depleted lipids were not extracted from blood tissues in this study. This results in a downward bias in the diet‐tissue fractionation factors for carbon for both red cells and blood serum, particularly the latter because of their significantly higher lipid contents (x̄± SD = 14.6 ± 2.3%; n= 20; red blood cells 3.8 ± 0.9%±; n= 50, muscle 7.7 ± 2.0; n= 21) in marine mammals.
HAUL‐OUT SELECTION BY PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDII): ISOLATION AND PERCEIVED PREDATION RISK
Authors: Nordstrom Chad A.
Published: August 2006

Abstract

The potential for non‐aquatic predators to influence habitat use by harbor seals (Phoca vitulina) in a nearshore marine environment was studied by examining haul‐out site use and through an experimental approach. Distance from shore, distance to possible foraging depths, peripheral water depth, and haul‐out areas were quantified for each haul‐out. There was a positive relationship between the number of seals hauled out and the distance from shore for eight known haul‐out sites. The hypothesis that harbor seals increasingly hauled out farther offshore to reduce predation risk was tested experimentally by measuring their response to a model of a potential terrestrial predator in comparison to a control object, and to disturbance by a human at one of the study sites. Harbor seals abandoned the haul‐out in the presence of the predator model, but showed little response to the controls, suggesting they possess a threat image for terrestrial predators and avoid hauling out when it is perceived. These results support the hypothesis that harbor seals select isolated sites to reduce exposure to terrestrial carnivores.
AIRCRAFT SOUND AND DISTURBANCE TO BOWHEAD AND BELUGA WHALES DURING SPRING MIGRATION IN THE ALASKAN BEAUFORT SEA
Authors: Patenaude Nathalie J. , Richardson W. John , Smultea Mari A. , Koski William R. , Miller Gary W. , Würsig Bernd , GReene Charles R.
Published: August 2006

Abstract

Short‐term behavioral responses of bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas) to a Bell 212 helicopter and Twin Otter fixed‐wing aircraft were observed opportunistically during four spring seasons (1989–1991 and 1994). Behaviors classified as reactions consisted of short surfacings, immediate dives or turns, changes in behavior state, vigorous swimming, and breaching.

The helicopter elicited fewer detectable responses by bowheads (14% of 63 groups) than by belugas (38% of 40). Most observed reactions by bowheads (63%) and belugas (86%) occurred when the helicopter was at altitudes ≤150 m and lateral distances ≤250 m. Belugas reacted significantly more frequently during overflights at lateral distances ≤250 m than at longer lateral distances (P= 0.004). When the helicopter was on the ice with engines running, 7 of 14 groups of belugas reacted, up to 320 m away, sometimes with small‐scale (≤100 m) diversion; only 1 of 8 groups of bowheads reacted.

For the fixed‐wing aircraft, few bowheads (2.2%) or belugas (3.2%) were observed to react to overflights at altitudes 60–460 m. Most observed reactions by bowheads (73%) and belugas (70%) occurred when the fixed‐wing aircraft was at altitudes ≤182 m and lateral distances ≤250 m. However, the proportions reacting, especially to low‐altitude flights (e. g., ≤182 m), were underestimated for both species because observation opportunities were brief. Even so, reactions were more common when the aircraft was low (≤182 m): P= 0.009 for belugas, P= 0.06 for bowheads. There was little if any reaction by bowheads when the aircraft circled at altitude 460 m and radius 1 km.

Aircraft sounds measured underwater at depths 3 m and 18 m showed that a Bell 212 helicopter was 7–17.5 dB noisier than a Twin Otter (10–500 Hz band). Bell 212 sound consisted mainly of main rotor tones ahead of the helicopter and tail rotor tones behind it. Twin Otter sound contained fewer prominent tones. Peak sound level as received underwater was inversely related to aircraft altitude, and received levels at 3 m depth averaged 2.5 dB higher than at 18 m depth. The dominant low‐frequency components of aircraft sound are presumed to be readily audible to bowheads. For belugas, these components may be inaudible, or at most only weakly audible. Mid‐frequency sound components, visual cues, or both, are probably important in eliciting beluga reactions to aircraft.
BEHAVIORAL EVIDENCE OF THERMAL STRESS FROM OVERHEATING IN UK BREEDING GRAY SEALS
Authors: Twiss S. D. , Wright N. C. , Dunstone N. , Redman P. , Moss S. , Pomeroy P. P.
Published: August 2006

Abstract

Gray seals (Halichoerus grypus) in the UK exhibit clear preferences for pupping close to pools of water on inland breeding sites. The reasons for this are unclear as seals are thought to derive all their water requirements from the metabolism of fat. Likewise, the prospect of seals overheating during the UK's cool, damp, autumnal breeding seasons, has seemed unlikely, but has not been previously explored. Here, we provide preliminary behavioral evidence of thermal stress in female gray seals breeding on the island of North Rona, Scotland. Video footage provided measures of proximity to, and the proportion of animals bathing in, pools in relation to meteorological data (temperature, mean sea‐level pressure, rainfall, wind speed and direction) on four dates spread through a single breeding season. The proportion of females close to pools increased with pressure (warmer, drier conditions) and decreased on wetter days. In addition, analyses of colony‐wide patterns of seal dispersion showed that females tended to be closer to pools of water at higher pressures and temperatures and at lower wind‐speeds. These results provide the first evidence of thermal stress and behavioral thermoregulation through access to pools of water in a phocid breeding in temperate autumnal conditions.
USE OF MIDAZOLAM/PETHIDINE AND TILETAMINE/ZOLAZEPAM COMBINATIONS FOR THE CHEMICAL RESTRAINT OF LEOPARD SEALS (HYDRURGA LEPTONYX)
Authors: Higgins Damien P. , Rogers Tracey L. , Irvine Andrew D. , Hall‐Aspland Sophie A.
Published: August 2006

Abstract

We immobilized 200–550‐kg leopard seals (Hydrurga leptonyx) on sea ice in Prydz Bay, Antarctica (68°25′S, 77°10′E) between November 1997 and February 2000. Midazolam (0.18–0.27 mg/kg)/ pethidine (1.0–1.5 mg/kg) was administered by dart to 16 leopard seals. Unpredictable immobilization, poor airway maintenance, and our inability to fully assess the suitability of flumazenil (0.003–0.01 mg/kg), naloxone (0.01–0.013 mg/kg), and naltrexone (0.05–0.12 mg/kg) as reversal agents limited suitability of midazolam/pethidine. Tiletamine/zolazepam 1:1 (0.5–1.5 mg/kg) was, therefore, administered to 19 leopard seals. It produced faster induction (19 ± 3 min), more effective and reliable response to dose (rank correlation: rs= 0.88, n= 18), and better pulmonary ventilation and faster return of cognitive function upon recovery, in comparison to midazolam/pethidine. Best results were achieved with tiletamine/zolazepam (1.2–1.4 mg/kg) which safely immobilized seven of nine seals for 20–30 min. Entry to the water upon darting was minimized, but not eliminated, by the use of lightweight air‐pressurized darts and a thorough knowledge of leopard seal behavior.
COST OF TRANSPORT IN STELLER SEA LIONS, EUMETOPIAS JUBATUS
Authors: Rosen David A. S. , Trites Andrew W.
Published: August 2006

Abstract

The cost of swimming is a key component in the energy budgets of marine mammals. Unfortunately, data to derive predictive allometric equations are limited, and estimates exist for only one other species of otariid. Our study measured the oxygen consumption of three juvenile Steller sea lions (Eumetopias jubatus) swimming in a flume tank at velocities up to 2.2 m sec−1. Minimum measured cost of transport ranged from 3.5–5.3 J kg−1 m−1, and was reached at swimming speeds of 1.7–2.1 m s−1. These cost‐of‐transport values are higher than those reported for other marine mammals. However, once differences in stationary metabolic rate were accounted for, the locomotor costs (LC) for the Steller sea lions were commensurate with those of other marine mammals. Locomotor costs (LC in J m−1) appeared to be directly proportional to body mass (M in kg) such that LC = 1.651M1.01. These estimates for the cost of locomotion can be incorporated into bioenergetic models and used to determine the energetic consequences of observed swimming behavior in wild marine mammals.
A NEW SPECIES OF BEAKED WHALE MESOPLODON PERRINI SP. N. (CETACEA: ZIPHIIDAE) DISCOVERED THROUGH PHYLOGENETIC ANALYSES OF MITOCHONDRIAL DNA SEQUENCES
Authors: Dalebout Merel L. , Mead James G. , Baker C. Scott , Baker Alan N. , van Helden Anton L.
Published: August 2006

Abstract

Mesoplodon perrini, a new species of beaked whale is described on the basis of five animals stranded on the coast of California (between 32°55′N, 117°15′W and 36°37′N, 121°55′W) from May 1975 to September 1997. Four of these animals were initially identified as Hector's beaked whales M. hectori based on cranial morphology (Mead 1981). A fifth specimen was initially identified as a neonate Cuvier's beaked whale Ziphius cavirostris based on external features. These specimens were first recognized as representatives of an undescribed species through phylogenetic analysis of mitochondrial (mt) DNA control region and cytochrome b sequence data. Although similar morphologically, the genetic data do not support a close evolutionary relationship between M. perrini and M. hectori. Instead, these data suggest a possible sister species relationship with the lesser beaked whale M. peruvianus. Sightings of two small beaked whales off California in the 1970s which were tentatively identified as M. hectori are also likely to be M. perrini. We suggest that M. hectori is confined to the Southern Hemisphere, while M. perrini is known to date only from the North Pacific.
RESURRECTION OFMESOPLODON TRAVERSII(GRAY, 1874), SENIOR SYNONYM OFM. BAHAMONDIREYES, VAN WAEREBEEK, CÁRDENAS AND YÁÑEZ, 1995 (CETACEA: ZIPHIIDAE)
Authors: van Helden Anton L. , Baker Alan N. , Dalebout Merel L. , Reyes Julio C. , Waerebeek Koen Van , Baker C. Scott
Published: August 2006

Abstract

Mesoplodon traversii(Gray, 1874) is shown to be a senior synonym of the recently described beaked whaleMesoplodon hahamondiReyeset al., 1995 on the basis of a phylogenetic analysis of mitochondrial DNA control region sequences. The mandible and teeth ofM. traversii, first reported in 1873 by Hector asDolichodon layardii. are redescribed. The species can be distinguished by features of the calvaria; including the large jugal, broad rostrum, and small distance between premaxillary foramina. The male teeth, which are large and spade‐shaped with a strong terminal denticle, are also diagnostic.M. traversiiis known only from Pitt Island and White Island, New Zealand and Robinson Crusoe Island, Juan Fernandez Archipelago, Chile.
ATOC AND OTHER FACTORS AFFECTING THE DISTRIBUTION AND ABUNDANCE OF HUMPBACK WHALES (MEGAPTERA NOVAEANGLIAE) OFF THE NORTH SHORE OF KAUAI
Authors: Frankel Adam S. , Clark Christopher W.
Published: August 2006

Abstract

Humpback whale diving behavior changes subtly when exposed to signals transmitted from the Acoustic Thermometry of Ocean Climate (ATOC) sound projector located 14 km offshore the island of Kauai. This study considered whether such responses would lead to changes in distribution and abundance. A land‐based shore station measured humpback whale locations (scan samples) for both nearshore (<5 km) and offshore (5–10 km) areas. Control observations were made in 1994 and 1998. In 1998 multipleday blocks with ATOC transmissions were interspersed with multiple‐day control blocks without transmissions. Sighting rates were higher in 1998 (ATOC) than in 1994 (control year), probably due to better sighting conditions, but may reflect increased population size. Sighting rates did not differ between control and ATOC conditions in 1998. A seasonal sighting peak was observed in both years. No vessel effect on sighting rate was detected in 1998.

There was no effect of ATOC on the distance from the shore station to whales, or the depth of water where pods were located. However, the distribution of whales shifted slightly eastward during the ATOC blocks and the mean distance between the ATOC source and pods was greater during transmissions. Nonetheless, more whales were found close to the source when it was on, suggesting a more variable response rather than simple avoidance, with whales found both closer to, and farther away from, the source during transmissions.
DIETS OF FIN, SEI, AND SPERM WHALES IN BRITISH COLUMBIA: AN ANALYSIS OF COMMERCIAL WHALING RECORDS, 1963–1967
Authors: Flinn Rowenna D. , Trites Andrew W. , Gregr Edward J. , Perry R. Ian
Published: August 2006

Abstract

Diets of fin (Balaenoptera physalus), sei (Balaenoptera borealis), and sperm whales (Physeter macrocephalus) were estimated from the stomach contents of individuals killed along the British Columbia coast from 1963 to 1967. The dominant prey types of fin whales were euphausiids, with minor contributions from copepods and fish. Sei whale stomachs contained primarily copepods in three years, whereas euphausiids or a variety of fish dominated the diet in the other two years. Sperm whales consumed primarily North Pacific giant squid (Moroteuthis robusta), but secondary prey differed between males and females. Female sperm whales frequently consumed ragfish (Icosteusspp.) and other fish, whereas the male diet also contained rockfish (Sebastesspp.). The high abundance of euphausiids along the British Columbia coast likely contributed to the presence of a summer resident population of fin whales. The high abundance of large copepods farther north probably influenced the migration of sei whales through the offshore waters of British Columbia. Sperm whale stomach contents differed by sex reflecting location and possibly breeding behaviors.
MONITORING THE PREY‐FIELD OF MARINE PREDATORS: COMBINING DIGITAL IMAGING WITH DATALOGGING TAGS
Authors: Hooker Sascha K. , Boyd Ian L. , Jessopp Mark , Cox Oliver , Blackwell John , Boveng Peter L. , Bengtson John L.
Published: August 2006

Abstract

There is increasing interest in the diving behavior of marine mammals. However, identifying foraging among recorded dives often requires several assumptions. The simultaneous acquisition of images of the prey encountered, together with records of diving behavior will allow researchers to more fully investigate the nature of subsurface behavior. We tested a novel digital camera linked to a time‐depth recorder on Antarctic fur seals (Arctocephalus gazella). During the austral summer 2000–2001, this system was deployed on six lactating female fur seals at Bird Island, South Georgia, each for a single foraging trip. The camera was triggered at depths greater than 10 m. Five deployments recorded still images (640 × 480 pixels) at 3‐sec intervals (total 8,288 images), the other recorded movie images at 0.2‐sec intervals (total 7,598 frames). Memory limitation (64 MB) restricted sampling to approximately 1.5 d of 5–7 d foraging trips. An average of 8.5% of still pictures (2.4%‐11.6%) showed krill (Euphausia sulperba) distinctly, while at least half the images in each deployment were empty, the remainder containing blurred or indistinct prey. In one deployment krill images were recorded within 2.5 h (16 km, assuming 1.8 m/sec travel speed) of leaving the beach. Five of the six deployments also showed other fur seals foraging in conjunction with the study animal. This system is likely to generate exciting new avenues for interpretation of diving behavior.
ESTIMATING STRUCK AND LOSS RATES FOR HARP SEALS (PAGOPHILUS GROENLANDICUS) IN THE NORTHWEST ATLANTIC
Authors: Sjare B. , Stenson G. B.
Published: August 2006

Abstract

One of the major sources of unreported mortality during the commercial harp seal (Pagophilus groenlandicus) hunt in the Northwest Atlantic is the number of animals that are killed but not recovered or reported, commonly referred to as struck and lost. With the significant expansion of the hunt in Canada and in Greenland during the mid‐1990s, there is a concern that the number of seals lost may have reached a level that is not sustainable relative to current harvest levels. To address this problem a study examining struck and loss rates was initiated in 1998 and 1999. Loss rates for young seals taken on the ice varied from 0% to 1.9% and from 0% to 10.0% when taken in the water. Seals greater than one year of age had loss rates of 0%–4.9% when taken on the ice and 13.8%‐50.0% when taken in the water. These estimates are lower than those recently reported for Northwest Atlantic harp seals.
DIET OF SOUTH AMERICAN FUR SEALS (ARCTOCEPHALUS AUSTRALIS) IN ISLA DE LOBOS, URUGUAY
Authors: Naya Daniel E. , Arim Matías , Vargas Rodrigo
Published: August 2006

Abstract

The diet of Arctocephalus australis was studied through fecal analysis, from September of 1995 to May of 1998, in Isla de Lobos (35°01′50″S‐54°53′00″W), Uruguay. A total of 539 scats analyzed indicated that the weakfish (Cynoscion guatucupa), the cutlasfish (Trichiurus lepturus), the anchoveta (Engraulis anchoita), the anchovy (Anchoa marinii), and cephalopods were the main prey consumed by these fur seals. Prey richness was higher during January. The diet of A. australis varied between years, apparently related to changes in prey availability. C. guatucupa and E. anchoita decreased while T. lepturus and cephalopods increased from 1996 to 1998. South American fur seals fed on fish ranging in length from 5.4 to 104.8 cm and from 0.7 to 629.9 g in wet mass. However, the mean mass of the main items was never more than 200 g. Observations suggests that A. australis is a trophic generalist with the potential to prey on a wide range of species, although most of the diet is comprised of relatively few species. Fur seals and artisan fisheries both took C. guatucupa, with fur seals taking younger individuals (1–2 yr) than artisan fisheries (> 3 yr).
THE TAXONOMIC STATUS OF THE NOMINAL DOLPHIN SPECIES DELPHINUS TROPICALIS VAN BREE, 1971
Authors: Jefferson Thomas A. , Waerebeek Koen Van
Published: August 2006

Abstract

The taxonomic status of common dolphins in the Atlantic and Pacific oceans has been clarified in recent years, with the discovery that there appear to be two species, a short‐beaked (Delphinus delphis) and a long‐beaked (D. capensis) species. However, the taxonomy of common dolphins in the Indian Ocean and southeast Asia is still unclear. A nominal third species, Delphinus tropicalis van Bree, 1971, has been described from this area, but its validity is controversial. We reviewed records and literature on common dolphins from South Africa east to Australia and Japan, and measured 206 skulls of common dolphins from the Indo‐Pacific and southern California. Other than southern Australia, we found no evidence for Delphinus delphis in the Indo‐Pacific (South African specimens appear to be D. capensis). Previous reports of short‐beaked common dolphins in the Indo‐Pacific appear to have been cases of misidentification. The tropicalis‐form has an exceptionally long and narrow rostrum with high tooth counts, but otherwise appears to resemble D. capensis, in both skeletal and external morphology. From an examination of 86 Delphinus skulls from the reported range of tropicalis (Middle East to China), we found that both tooth counts and rostral length/zygomatic width ratios were higher than for 94 D. capensis specimens from southern Japan, South Africa, and California. These measurements were greatest in the central Indian Ocean (around India). However, there was evidence of clinal variation, with both decreasing as one moves east or west from India, towards South Africa in the west or Japan in the east. We suggest that the tropicalis‐form is actually a long‐beaked subspecies of D. capensis, which may hybridize or intergrade with the standard capensis‐form in southeast Asia and possibly along the east coast of Africa. The appropriate name is Delphinus capensis tropicalis (van Bree, 1971), and a formal description of the subspecies is provided.
RESIDENCE PATTERNS OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN THE STONO RIVER ESTUARY, CHARLESTON COUNTY, SOUTH CAROLINA, U.S.A.
Authors: Zolman Eric Samuel
Published: August 2006

Abstract

Residence patterns of inshore bottlenose dolphins (Tursiops truncatus) in the Stono River estuary, Charleston County, South Carolina were investigated as part of a larger effort to better understand stock structure of these dolphins along the east coast of the United States. Eighty‐seven small‐boat surveys for bottlenose dolphins were conducted from October 1994 through January 1996. Dolphins were sighted during all surveys. Approximately 304 h were spent surveying the study area; 64% (n= 196 h) of this time was spent observing and videotaping dolphins. A catalog, containing 112 individually identified dolphins was compiled. Thirty‐two percent (n= 36) of identified dolphins were sighted once, while 28% (n= 31) were sighted five or more times. Nineteen percent (n= 21) of identified dolphins were determined to be year‐round residents; eight percent (n= 9) seasonal residents. The majority (64%, n= 72) of identified dolphins were sighted in the study area during a single season or in two consecutive seasons and were classified as transients. This study documents the northernmost known site of a resident bottlenose dolphin community on the east coast of the United States, suggesting a complex bottlenose dolphin stock structure.
SPATIOTEMPORAL PREDICTION MODELS OF CETACEAN HABITATS IN THE MID‐WESTERN NORTH ATLANTIC OCEAN (FROM CAPE HATTERAS, NORTH CAROLINA, U.S.A. TO NOVA SCOTIA, CANADA)
Authors: Hamazaki Toshihide
Published: August 2006

Abstract

Habitat prediction models were developed for 13 cetacean species of the mid‐western North Atlantic Ocean: beaked whale, fin whale, humpback whale, minke whale, pilot whale, sperm whale, bottlenose dolphin, common dolphin, Risso's dolphin, spotted dolphin, whitesided dolphin, and harbor porpoise. Using the multiple logistic regression, sightings of cetaceans during the 1990–1996 summer (June‐September) surveys were modeled with oceanographic (sea surface temperature, monthly probability of front occurrence) and topographic (depth, slope) variables for the same period. Predicted habitat maps for June and August were created for each species using a Geographical Information System. The predicted habitat locations matched with current and historic cetacean sighting locations. The model also predicted habitat shifts for some species associated with oceanographic changes. The correct classification rate of the prediction models with 1997–1998 summer survey data ranged from 44% to 70%, of which most of the misclassifications were caused by false positives (i.e., absence of sightings at locations where the models predicted).
THERMAL FUNCTION OF PHOCID SEAL FUR
Authors: Kvadsheim P. H. , Aarseth J. J.
Published: August 2006

Abstract

In phocid seals, blubber serves as the main thermal insulation instead of fur. The thermal function of fur, at least in adult phocid seals, has therefore been questioned. We measured the relative contribution of fur to the combined thermal resistance (insulation) offered by blubber, skin, and fur in newborn and adult harp (Pagophilus groenlandicus) and hooded (Cystophora cristata) seals, in air and water, to elucidate the role of fur as insulation in phocid seals. In air the fur contributed 90% of the combined thermal resistance of blubber, skin, and fur in newborn harp seal pups and 29% in adulrs, whereas in hooded seals the fur contributed 73% in newborn pups and 34% in adults. When submerged the thermal resistance of the fur was reduced by 84%‐92%, and contributed 65% to the total insulation in newborn harp seal pups and 3% in adults, and 26% in newborn hooded seal pups and 5% in adults. We conclude that in air the fur of phocid seals makes an important contribution to the insulation of pups, and also contributes considerably to the insulation of adult animals. In water, even though the thermal resistance of the fur is dramatically reduced, the fur still contributes substantially to the insulation of pups, but its contribution in adults is negligible.
COMPARATIVE FEEDING ECOLOGY OF SPINNER DOLPHINS (STENELLA LONGIROSTRIS) AND FRASER'S DOLPHINS (LAGENODELPHIS HOSEI) IN THE SULU SEA
Authors: Dolar M. Louella L. , Walker William A. , Kooyman Gerald L. , Perrin William F.
Published: August 2006

Abstract

Fraser's and spinner dolphins are known to feed on mesopelagic prey, bur their diets and feeding ecologies have not been compared in areas where they are observed together. In this study we examined the stomach contents of both species caught incidentally in a driftnet fishery for tuna in the eastern Sulu Sea. Importance of prey items was determined using the percent occurrence, percent number, and volumetric methods. Mesopelagic fishes, particularly myctophids (mainly Ceratoscopelus warmingi, Diaphus spp. and Myctophum asperum), were the most important component in the diet of spinner dolphins, whereas in Eraser's dolphins, mesopelagic cephalopods (Abraliopsis, Onychoteuthis, Histioteuthis, and Chiroteuthis), and crustaceans (Notostomos elegans, Acanthephyra quadrispinosa, and Acanthephyra carinata) appeared to be equally important as the myctophid species. Fraser's dolphins appeared to feed preferentially on larger prey and had more diversified prey (Shannon's diversity index = 1.2) than spinner dolphins (diversity index = 0.9). Vertical distributions of the prey items summarized from published literature indicate that spinner dolphins forage in the upper 200 m and probably occasionally to as deep as 400 m, whereas Fraser's dolphins have a wider vertical foraging range, from near the surface to probably as deep as 600 m.
ABUNDANCE OF BOTTLENOSE DOLPHINS IN THE BAYS, SOUNDS, AND ESTUARIES OF NORTH CAROLINA
Authors: Read Andrew J. , Urian Kim W. , Wilson Ben , Waples Danielle M.
Published: August 2006

Abstract

We conducted a mark‐recapture survey of bottlenose dolphins Tursiops truncatus in the bays, sounds, and estuaries of North Carolina during July 2000, using photographic identification techniques. During this survey we took 7,682 photographs of dolphins and, of these, 3,457 images were of sufficient quality for analysis. We identified 306 dolphins from distinctive nicks and notches on their dorsal fins. Eighry‐six dolphins were photographed on more than one occasion during the course of the survey; one dolphin was photographed on four separate days. We then applied the results of our photographic analyses to several mark‐recapture models and examined potential violations of the assumptions of these models, including an unexpected correlation between photo quality and mark distinctiveness. Our analysis suggests that our results are robusr to possible violations of these assumptions. The resulting estimates were then scaled to account for the proportion (0.46) of unmarked dolphins in the population. Our best estimate of the number of dolphins present in the inshore waters of North Carolina during July 2000 is 1,033 with a 95% Confidence Interval of 860–1,266 (CV = 0.099). Most dolphins were found in the northern part of the study area, which includes the second largest estuarine system in the United States.