bluuebunny/crossref_metadata_2025_split huggingface dataset:
GRAY WHALE (ESCHRICHTIUS ROBUSTUS) HABITAT UTILIZATION AND PREY SPECIES OFF VANCOUVER ISLAND, B. C.
Authors: Darling James D. , Keogh Kathleen E. , Steeves Tammy E. 
Published: August 2006

AbstractHabitat utilization and prey species of Vancouver Island gray whales were investigated by (1) summarizing 26 yr of distribution and feeding data and (2) conducting intensive observations in Clayoquot Sound, Vancouver Island, from 1989 to 1996. Whale distribution and movements were monitored from March to November through systematic boat surveys and whale‐watch sighting programs. Prey species were collected by suction hose and plankton net or determined through analysis of fecal samples. Gray whales utilized virtually all of the southern west coast of Vancouver Island over the 26‐yr observation period. Distribution, prey species, and feeding behavior showed marked variability during any one season and between years. Some feeding areas were used on an annual basis, others with >10‐yr intervals between use. Feeding occurred in shallow sand or mud bays, eel grass beds, kelp beds, in the open water column, and at the surface. Young whales appeared to utilize habitat and prey species differently than adults. Main prey species included herring eggs/larvae (Clupea harengus pallasi), crab larvae (Cancer magistermegalops,Pachycbelesspp. zoea), mysids (Holmesimysis sculpta, Neomysis rayii, Acanthomysisspp.), amphipods (Ampeliscaspp.,Atylus borealis), and ghost shrimp (Callianassa californiensis). The definition and relative importance of specific feeding grounds and the study of human impacts on this population are complicated by its broad and variable use of habitat and prey species.
MITOCHONDRIAL DNA VARIATION AND MATERNAL GENE FLOW AMONG HUMPBACK WHALES OF THE SOUTHERN HEMISPHERE
Authors: Baker C. S. , Flórez‐González L. , Abernethy B. , Rosenbaum H. C. , Slade R. W. , Capella J. , Bannister J. L. 
Published: August 2006

AbstractSamples of skin tissue were collected by biopsy darting from humpback whales (Megaptera novaeangliae) in six seasonal habitats representing three stocks and four regions: Groups IV (western Australia), V western component (eastern Australia), V eastern component (New Zealand and Tonga) and VI (the Antarctic Peninsula and Gorgona Island, Colombia, South America) of the Southern Hemisphere. A variable section of the mitochondrial DNA control region was amplified and sequenced from 84 of these individuals, distinguishing a total of 48 unique sequences (i. e., mtDNA nucleotypes). Phylogenetic reconstructions suggested that these nucleotypes form three clades, corresponding to those previously described in a world‐wide survey of humpback whale mtDNA variation, although bootstrap support for two of the clades was relatively low (<50%). An analysis of variance adapted for molecular information showed significant differentiation of nucleotypes among the three Groups (Stocks) and heterogeneity of haplotype diversity among the four regions. A pattern of interchange within and between oceanic basins was demonstrated by the presence of shared identical nucleotypes among humpback whales in regions of the Southern and Northern Hemispheres.
RESPONSE OF PACIFIC WALRUSES TO DISTURBANCES FROM CAPTURE AND HANDLING ACTIVITIES AT A HAUL‐OUT IN BRISTOL BAY, ALASKA
Authors: Jay Chadwick V. , Olson Tamara L. , Garner Gerald W. , Ballachey Brenda E. 
Published: August 2006

AbstractObservations were made on herds of the Pacific walrus (Odobenus rosmarus divergens) to study their response during the capturing and handling of adult males in summer 1995 at a haul‐out at Cape Peirce in southwestern Alaska. Three behaviors (alertness, displacement, and dispersal) were quantified from 16 capture sessions. Herd sizes ranged from 622 to 5,289 walruses. Handling of an immobilized walrus consisted of attempts to attach telemetry devices to the tusks and collect various biological samples. Handling activities resulted in an average of about 10‐fold or greater levels of behavior in alertness, displacement, and dispersal than during precapture and darting periods. High levels of behavior usually occurred within the first 45 min of handling. In 8 of 10 capture sessions, walruses returned to predisturbance levels of behavior within 40 min of cessation of the handling disturbance. Alertness and displacement were moderately and negatively correlated with herd size during the handling period, which may reflect an effect of a threshold distance from the point of disturbance to responding individuals. Observations of walruses tagged with VHF radio transmitters indicated that the activities from a given capture session did not preclude tagged walruses from using the haul‐out over a subsequent 11 ‐wk monitoring period. Moreover, non‐tagged walruses continued to extensively use the haul‐out during and after the period in which capture sessions were conducted.
THE EFFECT OF VESSEL NOISE ON THE VOCAL BEHAVIOR OF BELUGAS IN THE ST. LAWRENCE RIVER ESTUARY, CANADA
Authors: Lesage Véronique , Barrette Cyrille , Kingsley Michael C. S. , Sjare Becky 
Published: August 2006

AbstractDuring June‐July 1991, we monitored the vocal behavior of belugas before, during, and after exposure to noise from a small motorboat and a ferry to determine if there were any consistent patterns in their vocal behavior when exposed to these two familiar, but different sources of potential disturbance. Vocal responses were observed in all trials and were more persistent when whales were exposed to the ferry than to the small boat. These included (1) a progressive reduction in calling rate from 3.4–10.5 calls/whale/min to 0.0 or <1.0 calls/whale/min while vessels were approaching; (2) brief increases in the emission of falling tonal calls and the theree pulsed‐tone call types; (3) at distances <1 km, an increase in the repetition of specific calls, and (4) a shift in frequency bands used by vocalizing animals from a mean frequency of 3.6 kHz prior to exposure to noise to frequencies of 5.2‐8.8 kHz when vessels were close to the whales.
COUNTS OF CALIFORNIA SEA LION (ZALOPHUS CALIFORNIANUS) PUPS FROM AERIAL COLOR PHOTOGRAPHS AND FROM THE GROUND: A COMPARISON OF TWO METHODS
Authors: Lowry Mark S. 
Published: August 2006

AbstractPups on San Nicolas Island were counted by two methods; counts by observers on the ground were compared to counts from aerial photographs taken with a 126‐mm‐format camera with image motion compensation. No difference was detected between photographic counts and ground counts (P= 0.367) when ground counters had unobstructed views. However, ground counts were significantly lower when areas with obstructed views were included in the analysis (P < 0.001). For areas with unobstructed viewing conditions, no difference was detected between counts by the two methods for rock substrates (P= 0.140), sand substrates (P= 0.468), or mixed rock‐and‐sand substrates (P= 0.968). No differences were found among three replicate aerial photographic censuses (P= 0.432), but a significant difference was found between two replicate ground censuses (P= 0.037). Total counts obtained from the aerial photographs were more precise (CV = 0.042) than counts obtained on the ground (CV = 0.078). Less variability in counts was found between photographic counters than for ground counters.
FEMALE REPRODUCTIVE PATTERNS AND FETAL GROWTH OF ATLANTIC WALRUSES (ODOBENUS ROSMARUS ROSMARUS) IN FOXE BASIN, NORTHWEST TERRITORIES, CANADA
Authors: Garlich‐Miller J. L. , Stewart R. E. A. 
Published: August 2006

AbstractWe examined the reproductive tracts of 79 female Arlantic walruses (Odohenus rosmarus rosmarus) caught in July and August by Inuit hunters in northern Foxe Basin, NWT, Canada. We found no evidence of past or present ovulation in animals less than 5 yr old, but the poor representation of juvenile and adolescent animals precluded statistical analysis of the average age of maturity. The ovulation frequency of 64 mature females (0.52) indicated biennial ovulation, while the pregnancy rate (0.33) and birth rate (0.30) suggested that females gave birth once every three years. The sex ratio of 17 fetuses was not significantly different from 1:1. Fetuses increased 2.9 mm d‐1in crown‐rump length and 0.12 g1/3d‐1in mass over the range of collection dates. Based on the inverse regressions of fetal growth, implantation occurred in late June early July.
AGE, GROWTH, AND REPRODUCTIVE PATTERNS OF DALL'S PORPOISE (PHOCOENOIDES DALLI) IN THE CENTRAL NORTH PACIFIC OCEAN
Authors: Ferrero Richard C. , Walker William A. 
Published: August 2006

AbstractLife history parameters were estimated for Dall's porpoise, Phocoenoides dalli, from biological specimens collected in the western Aleutian Islands, during 1981–1987. Of 2,033 males and 3,566 females examined, reproductive data were available for 1,941 males and 1,906 females; ages were determined for 813 males and 1,297 females. Female sexual maturity was based on the presence of one or more corpus on either ovary; 845 were sexually immature and 1,061 were sexually mature. Two estimates of female average age at sexual maturity (ASM) were 3.8 and 4.4 yr; average length at sexual maturity (LSM) was 172 cm. Males were considered sexually mature when evidence of spermatogenesis was detected; 1,136 were sexually immature and 805 were sexually mature. Two estimates of male ASM were 4.5 and 5.0 yr; LSM was 179.7 cm. Physical maturity was assessed for 246 males and 446 females by examining the degree of fusion in thoracic vertebral epiphyses. For both sexes, the average age at physical maturity was 7.2 yr. Average length at physical maturity was 202.6 cm for males and 192.7 cm for females. Average lengths of physically mature males (x̄= 198.1 cm, SE = 0.8566) and females (x̄= 189.7 cm, SE = 0.4002) were significantly different(P < 0.0001). Early postnatal growth was rapid in both sexes. A secondary growth spurt in both mass and length was characteristic for both sexes; the increase in length preceded the mass increase by 1–2 yr. Average length at birth (LOB) was approximately 100 cm; birth mass averaged 11.3 kg (SE = 0.0772). By the time the umbilicus had healed (<2 mo), the average length and mass had increased to 114.1 cm and 23.8 kg, respectively. Gestation period based on projections using LOB was 12 mo, but this was considered an overestimate. Calving was modal, centered in early July; an annual reproductive interval was indicated. Among the sexually mature females, 120 were pregnant, 55 were pregnant and lactating, 321 were pregnant with colostrum, and 33 were “resting.” By 3 July (95% CI =x̄ 1 d), 50% of births had occurred, during each of the seven years sampled. The ovulation rate was estimated at 0.914 ovulations per average reproductive year. Enlarged follicles and recent ovulations were observed in postpartum females in late July.
THE DIETS OF MODERN AND HISTORIC BOTTLENOSE DOLPHIN POPULATIONS REFLECTED THROUGH STABLE ISOTOPES
Authors: Walker Jane L. , Potter Charles W. , Macko Stephen A. 
Published: August 2006

AbstractThe δ13C and δ15N compositions of teeth used in combination with existing data provide dietary information for different populations of western North Atlantic bottlenose dolphins (Tursiops truncatus). The dental isotopic signatures of bottlenose dolphins collected during the 1980s significantly differ for coastal and offshore ecotypes and are consistent with reports that coastal forms feed primarily on fish whereas offshore individuals consume more squid. In a second study, the isotopic compositions of teeth from bottlenose dolphins that span a 100‐yr period and data from published stomach content analyses as well as field observations made during the past 100 yr provide evidence that coastal bottlenose dolphins from the 1880s, 1920s, and 1980s had similar diets.
DIEL VARIATION IN MIGRATION RATES OF EASTERN PACIFIC GRAY WHALES MEASURED WITH THERMAL IMAGING SENSORS
Authors: Perryman Wayne L. , Donahue Meghan A. , Laake Jeffrey L. , Martin Thomas E. 
Published: August 2006

AbstractWe recorded the blows of gray whales during their southbound migration past central California in January 1994, 1995, and 1996, using thermal imaging sensors. For our sampling purposes, we defined day (0730–1630) and night (1630–0730) to coincide with the on/off effort periods of the visual counts being conducted concurrently. We pooled data across the three years of sampling and tested for diel variation in surfacing interval, pod size, offshore distance, migration rate, and swimming speed by comparing paired day/night means for samples collected within the respective 24‐h period. We performed these tests using data from the entire migration period and then repeated the tests for samples collected prior to and after the approximate median migration date (15 January). Over the entire migration period we observed larger diurnal pod sizes (x̄day= 1.75 ± 0.280, x̄night= 1.63 ± 0.232) and greater diurnal offshore distances (x̄day= 2.30 ± 0.328 km, x̄night= 2.03 ± 0.356 km) but found no diel variation in surfacing interval. For the entire migration period, the nocturnal migration rate (average number of whales passing per hour) was higher than the diurnal rate. During the first half of the migration we detected no diel variation in pod size or surfacing interval, but diurnal offshore distances were larger than at night (x̄day= 2.28 ± 0.273 km, x̄night= 1.96 ± 0.318 km). Diurnal and nocturnal migration rates prior to 15 January were not different. During the second half of the migration, there was no diel variation in surfacing interval, pod size, or distance offshore, but the nocturnal migration rate was higher (28%, SE = 11.6%) than the diurnal rate. We found no diel variation in swimming speed in any comparison. We propose that later migrants socialize more during the day, which effectively slows their diurnal rate of migration relative to nocturnal rates.
STELLER SEA LION STATUS AND TREND IN SOUTHEAST ALASKA: 1979–1997
Authors: Calkins D. G. , Mallister D. C. , Pitcher K. W. , Pendleton G. W. 
Published: August 2006

AbstractSteller sea lion (Eumetopias jubatus) numbers in the United States declined by about 75% over the past 20+ yr. They are classified, under the U. S. Endangered Species Act, as “threatened” in the eastern portion of their range and as “endangered” in the western portion. We analyzed trends in numbers of pup and non‐pup Steller sea lions counted in Southeast Alaska between 1979 and 1997. Sea lion numbers, based on counts of pups on rookeries, increased by an average of 5.9% per year between 1979 and 1997. However, numbers of pups increased at a much slower rate (+ 1.7% per year) between 1989 and 1997. For counts of non‐pup Steller sea lions we used models that controlled for the effects of date, time, and tide at the time of the survey to analyze trends. This technique reduced bias and increased precision of the resulting trend estimates. Numbers of sea lions were stable (+0.5%) between 1989 and 1996, based on counts of non‐pups. We estimated the Southeast Alaska breeding population of Steller sea lions at about 19,000 animals of all ages in 1997, a level that is probably near the highest in recorded history.
DISTRIBUTION AND POPULATION SIZE OF THE SOUTHERN SEA LION (OTARIA FLAVESCENS) IN CENTRAL AND SOUTHERN CHUBUT, PATAGONIA, ARGENTINA
Authors: Reyes Laura M. , Crespo Enrique A. , Szapkievich Valeria 
Published: August 2006

AbstractPopulation size and distribution of Otaria flavescens in central and southern Chubut, Patagonia were determined by aerial censuses conducted during the breeding season in 1989 and 1995 and outside the season. Pup numbers were corrected by means of a linear regression between pup and adult male (AM) numbers obtained from terrestrial censuses carried out in 1994 and 1996. During the 1989 breeding season, 10,557 sea lions occurred at 29 locations; 2,800 (26.3%) were pups. During the 1995 breeding season, 14,887 animals were censused at 32 sites; 3,311 (22.2%) were pups. The corrected pup number increased to 4,852, indicating that around 32% is lost when counting from photographs. The corrected total number increased to 16,483; this fell to less than one half between breeding seasons (November 1990 and 1995). The 1995 breeding season census represents the highest number since 1972 (8,800) and the widest historical dispersion (37 sites year round contrasting with 13 in the late 1940s and 1972). However, the present number is about one half of the 33,000 censused about 50 yr ago. Using a correction factor developed for the north Paragonian population (1.8 × censused number) the present population size in the area can be estimated at around 29,669 individuals.
RESPONSES BY HECTOR'S DOLPHINS TO BOATS AND SWIMMERS IN PORPOISE BAY, NEW ZEALAND
Authors: Bejder Lars , Dawson Stephen M. , Harraway John A. 
Published: August 2006

AbstractTheodolite tracking (61 d; 251 h) was used to quantify dolphin reactions to boats and swimmers in the austral summers of 1995‐1996 and 1996‐1997. Dolphins were accompanied by swimmers (within 200 m) for 11.2% of the total observation time, whereas boats accounted for an additional 12.4%. Dolphins were not displaced by either of these activities. Swimmers caused only weak, non‐significant effects, perhaps because dolphins could very easily avoid them. Reactions to the dolphin‐watching boat were stronger. Analyses of relative orientation indicate that dolphins tended to approach the vessel in the initial stages of an encounter but became less interested as the encounter progressed. By 70 min into an encounter dolphins were either actively avoiding the boat or equivocal towards it, approaching significantly less often than would be expected by chance. Analyses of group dispersion indicate that dolphins were significantly more tightly bunched when a boat was in the bay.
ADRENAL FUNCTION IN WILD AND REHABILITATED PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDII) AND IN SEALS WITH PHOCINE HERPESVIRUS‐ASSOCIATED ADRENAL NECROSIS
Authors: Gulland F. M. D. , Haulena M. , Lowenstine L. J. , Munro C. , Graham P. A. , Bauman J. , Harvey J. 
Published: August 2006

AbstractAdrenal function in harbor seals (Phoca vitulina richardii) was evaluated using adrenocorticotrophic hormone (ACTH) stimulation tests and fecal cortisol levels. The effect of ACTH administration on plasma cortisol and aldosterone levels in five free‐living and 14 rehabilitated harbor seal pups was determined using enzyme immunoassay and radioimmunoassay, respectively. In free‐living seals, injection of ACTH caused a significant increase in mean plasma cortisol but not of mean aldosterone levels 60 min postinjection. In these seals, mean initial plasma aldosterone was significantly higher than initial levels in rehabilitated seals, while initial cortisol levels were similar. Of the rehabilitated seals, eight died with adrenal cortical necrosis associated with herpesvirus inclusions, while six lived to be released. In the seals that were released, both mean initial cortisol levels and response to ACTH decreased through rehabilitation. In the seals that died, mean initial cortisol and response to ACTH increased through rehabilitation. The differences between initial cortisol levels in seals that lived and those that died were significant at weeks two and four of rehabilitation but not at the week of admission. There was considerable individual variation in initial plasma aldosterone levels and responses to ACTH, although initial aldosterone levels were significantly higher in rehabilitated seals that died than in seals that lived. Seals with adrenal necrosis associated with herpesvirus infection did not have decreased adrenal hormone responses to ACTH. Differences between initial hormone levels and responses to ACTH in different groups of seals may be associated with differing stress levels. Fecal cortisol assays were not a useful method of assessing adrenal function in these seals, as measured levels did not correlate with plasma cortisol levels.
LONG DISTANCE OFFSHORE MOVEMENTS OF BOTTLENOSE DOLPHINS1
Authors: Wells Randall S. , Rhinehart Howard L. , Cunningham Petra , Whaley Joanne , Baran Melody , Koberna Chris , Costa Daniel P. 
Published: August 2006

AbstractDespite recent progress defining the morphological and genetic characteristics of forms of the bottlenose dolphin inhabiting offshore waters, little is known of their behavior or ranging patterns. Reports suggest that an “offshore form” exists between the 200‐ and 2,000‐m isobaths in distinct Gulf of Mexico and western North Atlantic stocks, while one or more coastal forms inhabit the waters inshore. Two opportunities to track rehabilitated adult male bottlenose dolphins with satellite‐linked transmitters occurred in 1997. “Rudy” stranded in NW Florida and was released in the Gulf of Mexico off central west Florida. He moved around Florida and northward to off Cape Hatteras, NC, covering 2,050 km in 43 d. “Gulliver” stranded near St. Augustine and was released off Cape Canaveral, FL. He moved 4,200 km in 47 d to a location northeast of the Virgin Islands. Gulliver swam through 5,000‐m‐deep waters 300 km offshore of the northern Caribbean islands, against the North Equatorial Current. These records expand the range and habitat previously reported for the offshore stock of bottlenose dolphins inhabiting the waters off the southeastern United States, underscore the difficulties of defining pelagic stocks, illustrate the success of rehabilitation efforts, indicate the value of follow‐up monitoring of rehabilitated and released cetaceans, and expand our understanding of the long‐range movement capabilities of a dolphin species more commonly thought of as a resident in coastal waters.
SPERM WHALE SURFACE ACTIVITY FROM TRACKING BY RADIO AND SATELLITE TAGS1
Authors: Watkins William A. , Daher Mary Ann , Dimarzio Nancy A. , Samuels Amy , Wartzok Douglas , Fristrup Kurt M. , Gannon Damon P. , Howey Paul W. , Maiefski Romaine R. , Spradlin Trevor R. 
Published: August 2006

AbstractThree 12‐m sperm whales (Physeter catodon) were tagged and tracked west of Dominica in the southeast Caribbean to follow the surfacing patterns and movements of these presumed subadult males. Whale N was tagged in April 1993 with a 30‐MHz radio tag and tracked for two days. Whale H was tagged in April 1995 with a 30‐MHz radio tag and tracked for 4.6 d. Whale A was tagged in April 1995 with a satellite‐monitored tag tracked by ARGOS for 21.5 d, the first four of which were concurrent with the tracking of Whale H, an associate. The tagged whales remained west of Dominica for at least 2, 5, and 13 d, respectively. Whales N and A then moved southward to waters off Martinique. There were no apparent effects on the whales by tagging or the presence of the tags. The whales averaged speeds of 2.6‐3.5 km/h. Surfacings, indicated by tag signals, were of two types: short surfacings apparently primarily for respiration, averaging 7‐10.5 min between repeated longer dives, occurring day and night; and extended surfacings seemingly for rest and social interactions with conspecifics, occurring mostly in daylight. Whales were near the surface for 20.4%–22.6% of the total time (26.6%–27.1% during the day and 14.9%–17.1% at night). Delayed blowing was observed as Whale N surfaced for 8.3 min between 47‐ and 45‐min dives but delayed the first of its 31 blows for 1.5 min after surfacing.