bluuebunny/crossref_metadata_2025 huggingface dataset:
A PROTRACTED FORAGING AND ATTENDANCE CYCLE IN FEMALE JUAN FERNÁNDEZ FUR SEALS
Authors: Francis John , Boness Daryl , Ochoa‐Acuña Hugo
Published: August 2006

Abstract

Previous studies of fur seals suggest that the attendance patterns and consequent temporal patterning of energy transfer from mother to pup follows a latitudinal cline. While data from subpolar, tropical, and some temperate latitude species support the postulated cline, data for the temperate latitude Juan Fernández fur seal do not. Maternal foraging trips and associated visits ashore were the longest of all otariids studied to date. The first foraging trip postpartum averaged 10.2 d (n= 51 females, range 1–22.5), foraging trips combined averaged 12.3 d (n= 100, range 1.0‐25.0), and visits ashore averaged 5.3 d (n= 91, range 0.3‐15.8) over the three seasons of study. Only duration of lactation was intermediate between subpolar and tropical strategies as predicted. Dive records suggest that these females feed almost exclusively at night at depths of less than 10 m and at distances of more than 500 km offshore. The prey species of this fur seal, primarily myctophids and squid, migrate to the surface at night and are patchily distributed. Foraging trip length varied between years in conjunction with shifts in seasurface temperature and type of prey consumed. We suggest that distribution of prey, irrespective of latitude, dictates foraging patterns of fur seals and leads to the exceptionally long foraging trips and visits ashore observed in this species.
INCREASED VIGILANCE TOWARD UNFAMILIAR HUMANS BY HARBOR (PHOCA VITULINA) AND GRAY (HALICHOERUS GRYPUS) SEALS
Authors: Taylor Allison A. , Davis Hank , Boyle Glenn J.
Published: August 2006

Abstract

Two pairs of harbor (Phoca vitulina) and three pairs of gray (Halicboeruls grypus) seals were exposed to one of three human handlers for 15 min, twice a day, for a total of six sessions. Following habituation to the familiar handler, animals were then exposed to a novel human for 7 min, and then retested for 7 min with the familiar human. In all cases, animals responded to the unfamiliar human with increased vigilant behavior, i. e., they spent more time oriented towards the unfamiliar handler during the first 2 min of the test session than during the same interval of either the final habituation session or the retest with the familiar human (P= 0.03 in all cases). There was also a tendency for seals to contact the familiar handler with their noses more rapidly than the novel human (P= 0.06). These results support the hypothesis that phocid seals are capable of discriminating between individual humans in their environment, setting the stage for human‐based Pavlovian conditioning.
ABUNDANCE OF SOUTHERN CALIFORNIA COASTAL BOTTLENOSE DOLPHINS ESTIMATED FROM TANDEM AERIAL SURVEYS
Authors: Carretta J. V. , Forney K. A. , Laake J. L.
Published: August 2006

Abstract

We describe a tandem aerial survey method for bottlenose dolphins (Tursiops truncatus) that uses two aircraft and independent observer teams to conduct consecutive surveys of the same coastal strip one hour apart. Alternatively, one aircraft with one observer team surveys the same coastal strip twice over several hours. Using mark‐recapture analysis, we corrected survey counts for visibility bias resulting from missing dolphin groups at the surface and submerged groups. Dolphin groups were considered “recaptured” when we determined that both observer teams had detected the same group. This tandem method is highly useful for estimating abundance (and visibility bias) for species where population closure may be assumed between flights. We assumed population closure between flights and matched groups using geographic location, group size, and expected travel rates. We derive a new variance estimator of population size which incorporates group‐size variability commonly encounteted in cetacean surveys. From six tandem surveys conducted from 1991 to 1994, we estimated the abundance of southern California coastal bottlenose dolphins to be between 78 (95% CI 60‐102) and 271 (240‐306) animals, with an average of 140 (128‐154). Variability in abundance estimates is likely due to seasonal and interannual movement of animals along the California and Baja California coast. Abundance estimates from tandem surveys averaged 53% higher than dolphin counts obtained from individual survey flights, demonstrating the importance of correcting for visibility bias.
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

Abstract

Habitat 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

Abstract

Samples 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

Abstract

Observations 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

Abstract

During 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

Abstract

Pups 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

Abstract

We 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

Abstract

Life 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

Abstract

The 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

Abstract

We 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

Abstract

Steller 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

Abstract

Population 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

Abstract

Theodolite 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

Abstract

Adrenal 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

Abstract

Despite 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

Abstract

Three 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.
GRAY WHALES (ESCHRICHTIUS ROBUSTUS) OFF SAKHALIN ISLAND, RUSSIA: SEASONAL AND ANNUAL PATTERNS OF OCCURRENCE1
Authors: Weller David W. , Würsig Bernd , Bradford Amanda L. , Burdin Alexander M. , Blokhin Sergey A. , Minakuchi Hiroya , Brownell Robert L.
Published: August 2006

Abstract

The annual return, seasonal occurrence, and site fidelity of Korean‐Okhotsk or western gray whales on their feeding grounds off northeastern Sakhalin Island, Russia, were assessed by boat‐based photo‐identification studies in 1994‐1998. A total of 262 pods were observed, ranging in size from 1 to 9 whales with an overall mean of 2.0. Sixty‐nine whales were individually identified, and a majority of all whales (71.0%) were observed in multiple years. Annual sighting frequencies ranged from 1 to 18 d, with a mean of 5. 4 d. The percentage of whales reidentified from previous years showed a continuous annual increase, reaching 87.0% by the end of the study. Time between first and last sighting of identified individuals within a given year was 1‐85 d, with an overall mean of 40.6 d. Annual calf proportions ranged from 4.3% (1997) to 13.2% (1998), and mother‐calf separations generally occurred between July and September. The seasonal site fidelity and annual return of whales to this part of the Okhotsk Sea emphasize its importance as a primary feeding ground for this endangered population.
THE EFFECTS OF ACOUSTIC ALARMS ON THE BEHAVIOR OF HARBOR PORPOISES (PHOCOENA PHOCOENA) IN A FLOATING PEN
Authors: Kastelein R. A. , Rippe H. T. , Vaughan N. , Schooneman N. M. , Verboom W. C. , Haan D. De
Published: August 2006

Abstract

In an attempt to test the effectiveness of sounds in deterring harbor porpoises from nets and reducing porpoise bycatch in gill net fisheries, two harbor porpoises, kept in a large floating pen at Neeltje Jans, The Netherlands, were subjected to 3 different underwater sounds. The effect of each sound was judged by comparing the animals' behavior during a 15‐min test period with that during a 15‐min baseline period immediately before the test and a 15‐min recovery period immediately after the test. The effects of the alarms were quantified as the distance between the porpoises' surfacings and the alarm and the animals' respiration rates. Each alarm was tested in two positions in the pen. The behavior observed was related to the sound‐pressure‐level distribution in the pen. All three alarms: the standard Dukane alarm (a commercially available alarm with a regular pulse interval of 4.3 sec used to deter dolphins from fishing nets), the random Dukane alarm (the same alarm with random pulse interval of between 2 and 30 sec), and the “bird alarm” (a sound from a generator) resulted in increases in both the distance of the animals' surfacings from the alarms and their respiration rates. The standard Dukane alarm and the bird alarm were more effective than the random Dukane alarm in inducing the animals to swim away from the sound source.
HABITAT USE AND PREFERENCES OF INDO‐PACIFIC HUMPBACK DOLPHINS SOUSA CHINENSIS IN ALGOA BAY, SOUTH AFRICA
Authors: Karczmarski Leszek , Cockcroft Victor G. , Mclachlan Anton
Published: August 2006

Abstract

This paper examines environmental and behavioral determinants of the habitat use and preferences of Indo‐Pacific humpback dolphins inhabiting the Algoa Bay region on the south Eastern Cape coast of South Africa. In order to quantify the habitat use and preference, two indices were used, the Coefficient of Area Use (AU) and the Activity Index (AI). The dolphins inhabit a narrow strip of shallow, inshore waters of Algoa Bay and remain mostly within 400 m of the shore, in water less than 15 m deep, with no apparent preference for clear or turbid water. Water depth is probably the main factor limiting their inshore distribution, and the 25‐m isobath seems to represent the critical depth. Within this confined, inshore distribution, dolphin activities concentrate in the vicinity of rocky reefs‐their primary feeding grounds. Dolphin dependence on these shallow‐water habitats is evident throughout the year and, consequently, the inshore shallow reefs are identified as the “key habitat” which is of primary importance for humpback dolphins in Eastern Cape waters. The dolphins' dependence on this restricted type of habitat within an already restricted inshore distribution makes them particularly vulnerable to alteration or loss of this habitat.
LASER SAFETY THRESHOLDS FOR CETACEANS AND PINNIPEDS
Authors: Zorn Heather M. , Churnside James H. , Oliver Charles W.
Published: August 2006

Abstract

An increase in the use of oceanographic lidar has raised concern over laser safety for marine mammals. We were able to address some of these concerns by combining information about current laser safety standards, retinal damage mechanisms for humans, and research on eye anatomy for humans, cetaceans, and pinnipeds. To estimate the irradiance at the retina, the image size at the retina and pupil diameter must be known. We estimate the smallest spot size using retinal resolution or visual acuity for six species of cetaceans and five species of pinnipeds. A sensitivity ratio was calculated for each species using the ratio of the irradiance at the retina of the marine mammal to the irradiance at the retina of humans. The sensitivity ratio was used to suggest exposure limits for the various species. Because the human eye is more sensitive than either the cetacean or pinniped eye, we conclude that laser energies that are eye‐safe for humans will also be safe for marine mammals, and higher laser irradiances may be permissible if illumination of humans is avoided.
SURFACE BEHAVIOR OF BOTTLENOSE DOLPHINS IS RELATED TO SPATIAL ARRANGEMENT OF PREY
Authors: Acevedo‐Gutiérrez Alejandro , Parker Nadine
Published: August 2006

Abstract

We tested the hypothesis that spatial arrangement and movements of bottlenose dolphins (Tursiops truncatus) are related to the spatial arrangement of their prey. From 65 groups we: (1) classified feeding behavior of dolphins according to spatial arrangement and movements of individuals; (2) assessed spatial arrangement and location of prey from direct observations, numbers of associated seabirds, and echosounder recordings; and (3) related feeding behavior of dolphins to spatial arrangement and location of prey. Four feeding categories were defined from cluster and principal component analyses: (1) moving rapidly with no diving, (2) milling with no diving, (3) diving in several locations, and (4) diving in one location. These feeding categories were related to spatial arrangement and location of prey.
THE DIET OF GALÁPAGOS SPERM WHALES PHYSETER MACROCEPHALUS AS INDICATED BY FECAL SAMPLE ANALYSIS
Authors: Smith Sean C. , Whitehead Hal
Published: August 2006

Abstract

Fecal samples were collected while following sperm whales (Physeter macrocephalus) off the Galápagos Islands, Ecuador. They contained 133 upper beaks and 164 lower beaks of cephalopods. Analysis of the lower beaks suggests that the sperm whales fed primarily on three genera of cephalopods; Histioteutbis (62%), Ancistrocbeirus (16%), and Octopoteutbis (7%). The beak dimensions indicate that the cephalopods ranged in mantle length from 5 to 54 cm and in mass from 12 to 650 g. Fecal samples varied significantly between five study years and over different parts of the study area, but the number of beaks collected per sample did not correlate significantly with defecation rate (a measure of feeding success). Using beak material from fecal samples gives a biased estimate of sperm whale diet, reducing the frequencies of very small and very large cephalopods. However, all other available methods of assessing sperm whale diet also possess biases.
IDENTIFYING DIURNAL FORAGING HABITAT OF ENDANGERED HAWAIIAN MONK SEALS USING A SEAL‐MOUNTED VIDEO CAMERA
Authors: Parrish Frank A. , Craig Mitchell P. , Ragen Timothy J. , Marshall Gregory J. , Buhleier Birget M.
Published: August 2006

Abstract

The Hawaiian monk seal (Monachus schauinslandi) is thought to be a foraging generalist, preying on numerous species in diverse habitats of the subtropical Northwestern Hawaiian Islands. At the atoll of French Frigate Shoals, recent evidence of emaciation and low survival in monk seals prompted a search for their specific prey communities and foraging habitat.

A video camera (National Geographic Television's CRITTERCAM) fitted to 24 adult male seals documented benthic and demersal foraging on the deep slopes (50‐80 m) of the atoll and neighboring banks. The number of bottom searches for prey was compared by year, time of day, type of bottom, individual seal, and length of bottom time. Analysis of variance identified a significant interaction of seal and bottom type, explaining 65% of the total variance. Seals fed on communities of cryptic fauna (fish and large invertebrates) in transitional “ecotone” regions of low relief where consolidated substrate, rubble, and talus bordered areas of sand. Independent areal surveys of bottom types throughout the atoll and neighboring banks suggest that the type of bottom selected as foraging habitat represents a relatively small percentage of the total benthic area available.
THE NORTHEASTERN ALBORAN SEA, AN IMPORTANT BREEDING AND FEEDING GROUND FOR THE LONG‐FINNED PILOT WHALE (GLOBICEPHALA MELAS) IN THE MEDITERRANEAN SEA
Authors: Cañadas Ana , Sagarminaga Ricardo
Published: August 2006

Abstract

Little is known about the long‐finned pilot whale's population size, structure, distribution, and dynamics in the Western Mediterranean basin. The research region covered since 1992 in southeast Spain, at the edge of the Alboran Sea, is considered an important oceanographic transition zone between the Mediterranean and the Atlantic Ocean. The research ship Toftevaag carried out surveys covering a total of 10,173 nmi (18,840 km) from April to September each year, 1992‐1997, all years pooled. Effort for ten‐by‐ten‐mile quadrants was stratified by depth and sea state to ascertain encounter rates. Tracking was used together with photo‐identification of animals to analyze home range of groups. Behavior was recorded ad libitum, and underwater video taping was used to analyze specific behavior patterns. One hundred and nine sightings of pilot whales were made. The average group size was 41.4 ± 58.4, ranging from 1 to 350. The average depth at encounters was 848.7 ± 281.2 m ranging from 300 to 1,800 m. Compatison of results for encounter rate and group size with those for other Mediterranean regions, together with site fidelity shown by photo‐identification and observations of reproductive behavior, reflect the importance of the Alboran Sea to the species in the Mediterranean.
AERIAL VIDEOGRAMMETRY FROM A TETHERED AIRSHIP TO ASSESS MANATEE LIFE‐STAGE STRUCTURE
Authors: Flamm Richard O. , Owen Edward C. G. , Owen Caryn F. W. , Wells Randall S. , Nowacek Doug
Published: August 2006

Abstract

Aerial videogrammetry from an airship tethered to a boat was used to assess the life‐stage structure of manatees in the Blue Waters area of the Homosassa River on the west coast of central Florida. Individual frames of videos were loaded onto a computer and lengths of manatees measured using graphics software. All images of manatees were measured independently by three observers. Measurements were transformed to total manatee lengths by calculating the ratio between the measurements of a reference object of known length and the measurement of the manatee. Length estimates were highly variable but were unbiased with respect to observer. Results of an analysis of variance suggested that the hypothesis that lengths differed among days and among observers should not be rejected. Life‐stage structures were represented in three schemes. One scheme‐which included four life stages: dependent calves, juveniles, animals in tramsition between juvenile and adult, and adults‐was included to provide the most information without sacrificing confidence in the life‐stage distribution. Overall, the video system was effective at capturing images of manatees for life‐stage characterization and, with improvements in image resolution, could become a valuable tool for photo‐identification in sight‐resight experiments.
USE OF PHOTOGRAPHIC IDENTIFICATION IN CAPTURE‐RECAPTURE STUDIES OF MEDITERRANEAN MONK SEALS
Authors: Forcada Jaume , Aguilar Alex
Published: August 2006

Abstract

The use of photo‐identification and its reliability in capture‐recapture studies of Mediterranean monk seals were assessed using slides collected in the colony at Cap Blanc, western Sahara, from 1993 to 1996. Five tests indicated that researchers involved in photo‐identification were proficient in matching slides of identified seals, consistent in classifying the side of the seal shown in slides and in assigning the morphological stage of the seal, and that changes of markings over a period of three years were insufficient to affect matching success. The certainty of identifying a seal was not dependent on the number of slides used but on distinctiveness of the markings and the quality of the slides taken. Capture‐recapture abundance estimates were biased upwards when including poor quality slides. The exclusive use of excellent‐ and good quality slides provided the best estimates. The proportion of distinctive seals varied between morphological stages and was significantly lower in juveniles. When including the identification histories of juveniles, the heterogeneity of capture probabilities was higher. Therefore, abundance estimates were less biased when all juveniles were considered as non‐distinctive seals. Reliable abundance estimates required a balance between duration of capture occasions and time interval between these.
SURVIVAL RATES OF SEA OTTER PUPS IN ALASKA AND CALIFORNIA
Authors: Monnett Charles , Rotterman Lisa Mignon
Published: August 2006

Abstract

Adult female sea otters (Enhydra lutris) were instrumented with implanted radio‐transmitters in Prince William Sound (PWS), Alaska, and survival rates were estimated for their dependent pups. Overall, 94 of 141 (67%) of the pups studied survived to a minimum age of 120 d and were assumed to have successfully weaned. Survival of pups in six cohorts ranged from 53% to 88%. The mean interval between successive visual observations was 12.5 d. For these calculations, the assumption was made that pups were successfully weaned if they accompanied mothers for at least 120 d. Estimated survival rates were different when this assumption was changed to either 90 d or 150 d (73% and 52%, respectively).

Females were palpated for pregnancy when instrumented. Of 19 believed to be pregnant, 17 were subsequently seen with young pups giving a detection rate for births of 89.5%. When the above observed survival rate of pups was adjusted for undetected births, the estimated overall survival rate for the study population was 60% (120 d minimum dependency).

Survival rates of pups in PWS and a population at Kodiak Archipelago (KOD) (Monson and DeGange 1995) were compared with that of pups in the population in California (CA, four studies). These data did not support the hypothesis that survival rates were lower in California (CA: 103/160, Psurv. 0.64; PWS: 94/141, Psurv.= 0.67; KOD: 19/23, Psurv.= 0.83; pairwise comparisons, X2, P > 0.05). Comparison of pup survival rates among studies was hindered by small sample sizes, methodological differences, and lack of detail about assumptions underlying estimates.
NEW GENUS OF DORUDONTINE ARCHAEOCETE (CETACEA) FROM THE MIDDLE‐TO‐LATE EOCENE OF SOUTH CAROLINA
Authors: Uhen Mark D. , Gingerich Philip D.
Published: August 2006

Abstract

A new archaeocete whale from the late middle or early late Eocene of South Carolina, Chrysocetus healyorum gen. et sp. nov., is described on the basis of a single subadult specimen. This individual includes: a partial skull; hyoid apparatus; lower jaws; teeth; all cervical, some thoracic and some lumbar vertebrae; ribs and sternum; left forelimb elements; and pelves. The specimen includes portions of much of the body, but while some of the bones are fairly complete, others are damaged, particularly the skull. The pelves resemble those of Basilosaurus, documenting a similar stage of hind limb reduction in dorudontines and suggesting that Chrysocetus was not able to support its body on land. The acetabulum for articulation of the femur is well formed and indicates that the hip joint was functional. Chrysocetus is distinguishable from other described dorudontines based on body size, characteristics of the teeth, and forelimb elements. Absence of deciduous teeth in a subadult individual of Chrysocetus may be indicative of an early stage of the evolution of monophyodonty.
COLLISIONS BETWEEN SHIPS AND WHALES
Authors: Laist David W. , Knowlton Amy R. , Mead James G. , Collet Anne S. , Podesta Michela
Published: August 2006

Abstract

Although collisions with motorized ships are a recognized source of whale mortality, little has been done to compile information on the frequency of their occurrence or contributing factors. We searched historical records and computerized stranding databases for evidence of ship strikes involving great whales (i. e., baleen whales and the sperm whale). Historical records suggest that ship strikes fatal to whales first occurred late in the 1800s as ships began to reach speeds of 13‐15 kn, remained infrequent until about 1950, and then increased during the 1950s‐1970s as the number and speed of ships increased. Of 11 species known to be hit by ships, fin whales (Balaenoptera physalus) are struck most frequently; right whales (Eubalaena glacialis and E. australis), humpback whales (Megaptera novaeangliae), sperm whales (Physeter catodon), and gray whales (Escbricbtius robustus) are hit commonly. In some areas, one‐third of all fin whale and right whale strandings appear to involve ship strikes. To assess contributing factors, we compiled descriptions of 58 collisions. They indicate that all sizes and types of vessels can hit whales; most lethal or severe injuries are caused by ships 80 m or longer; whales usually are not seen beforehand or are seen too late to be avoided; and most lethal or severe injuries involve ships travelling 14 kn or faster. Ship strikes can significantly affect small populations of whales, such as northern right whales in the western North Atlantic. In areas where special caution is needed to avoid such events, measures to reduce the vessel speed below 14 kn may be beneficial.
PHOTOGRAPHIC IDENTIFICATION OF NORTHERN BOTTLENOSE WHALES (HYPEROODON AMPULLATUS): SOURCES OF HETEROGENEITY FROM NATURAL MARKS
Authors: Gowans Shannon , Whitehead Hal
Published: August 2006

Abstract

The use of natural marks in capture‐recapture studies can lead to unequal capture probabilities. This paper examined a catalog of northern bottlenose whale (Hyperoodon ampullatus) photographs from the Gully, Nova Scotia, to identify potential sources of heterogeneity. This information can be used to select appropriate individuals and photographs to include in analyses. Individual northern bottlenose whales were sufficiently marked to uniquely identify individuals (x̄= 14.5 marks/individual; range 1‐67), but not all mark types persisted over time. Reliable marks were defined as mark types that were not lost over the nine‐yeat study period (notches, back indentation, and mottled patches). Individuals were considered reliably marked if they possessed at least one back indentation or mottled patch (located within one dorsal fin width, at the base of the dorsal fin) or a notch on the dorsal fin. Sixty‐six percent (SE = 5%) of the population were reliably marked. Longterm analyses (months to years) should use only reliably marked individuals, and the results scaled to account for the rest of the population. Our results also showed that photographic quality affected an observer's ability to identify individuals. For this catalog, quantitative analysis indicated only photographs of Q ≥ 4 (on a 6‐point scale with 6 representing the highest quality) should be included in mark‐recapture analyses sensitive to heterogeneity.