bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NEW ABUNDANCE ESTIMATE FOR VAQUITAS: FIRST STEP FOR RECOVERY1
Authors: Jaramillo‐Legorreta Armando M. , Rojas‐Bracho Lorenzo , Gerrodette Tim 
Published: August 2006

AbstractA line‐transect survey specifically designed to estimate vaquita (Phocoena sinus) abundance over its entire range was carried out by three boats in the summer of 1997. There was a total of 125 sightings of vaquita groups, mainly due to the use of large 25 ± 150 binoculars, which were seven times more effective in detecting vaquitas than hand‐held 7 ± binoculars. Results confirmed that the range of the vaquita is restricted to the northwestern corner of the Gulf of California, Mexico, but that the boundaries of the Upper Gulf of California and Colorado River Delta Biosphere Reserve do not correspond well with the distribution of vaquitas. The shallow water north of the town of San Felipe was found to have a higher density of animals than had been indicated by previous surveys. The total population size was estimated to be 567 animals, with a 95% confidence interval from 177 to 1,073. This estimate is an improvement over previous estimates, which had low numbers of sightings, relied on parameters taken from other species, and/or did not cover all areas where vaquitas could potentially be found. The 1997 estimate was more than twice the 1993 estimate, but there are several reasons why the numbers cannot be directly compared, and it should not be concluded the population is increasing. This first complete estimate of vaquita abundance can be a beginning for the recovery of this highly endangered species.
BEHAVIORAL ASPECTS OF SLEEP IN PACIFIC WHITE‐SIDED DOLPHINS (LAGENORHYNCHUS OBLIQUIDENS, GILL 1865)1
Authors: Goley Patricia Dawn 
Published: August 2006

AbstractDolphin sleep is unlike typical mammalian sleep in that slow wave sleep occurs in one hemisphere at a time and rapid eye movement (REM) sleep is apparently reduced or absent (Mukhametov 1987). Lilly (1964) observed that bottlenose dolphins (Tursiops truncatus) sleep with one eye open and one eye closed and suggested that the open eye monitored the immediate area for predators. Mukhametov (1987) and Supin et al. (1978) found no physiological correlation between the active brain hemisphere and the open eye, and suggested that no sentinel function exists. I describe the behavioral and social aspects of sleep in a captive school of four Pacific white‐sided dolphins (Lagenorhynchus obliquidens) at Long Marine Lab at the University of California at Santa Cruz for 32 nights. As the animals swam in formation, I recorded their positions and eye condition. Dolphins did not close their eyes or switch positions in the school randomly. While in formation, dolphins switched positions in bouts while concurrently changing eye condition. This resulted in a sleeping formation in which the dolphins likely had the eye open towards schoolmates, not toward the external environment. I suggest that this allows sleep to proceed while allowing dolphins to maintain visual contact with group members.
HEART RATE AND ELECTROCARDIOGRAM CHARACTERISTICS OF A YOUNG CALIFORNIA GRAY WHALE (ESCHRICHTIUS ROBUSTUS)1
Authors: Ponganis P. J. , Kooyman G. L. 
Published: August 2006

AbstractElectrocardiogram (ECG) analyses of Holter monitor recordings from a young California gray whale were performed to determine ECG waveform characteristics, evaluate the heart rate pattern for sinus arrhythmia, obtain resting heart rates at known body masses as the whale increased in size, and compare those heart rates with predicted heart rates from allometric equations. The PR and QRS intervals (475 ± 35 msec, 208 ± 24 msec, respectively, n= 20) support the concept (Meijler et al. 1992) that atrioventricular transmission and ventricular excitation times do not increase linearly in very large mammals. A sinus arrhythmia pattern at rest (apneic heart rates of 15–25 beats per min [bpm] and eupneic heart rates of 34–40 bpm) is consistent with a relative eupneic tachycardia and apneic bradycardia during diving activity of whales. The heart rate‐body mass measurements (35–24 bpm at body masses of 3,591‐8,200 kg) in this study (1) extend the range of allometric heart rate and body mass data in mammals a full order of magnitude, to almost 10,000 kg, (2) support the use of allometric equations (based primarily on mammals <1,000 kg in body mass) in estimating resting heart rates in whales, and (3) demonstrate that previously reported heart rates in large whales are not representative of resting heart rate, probably secondary to circumstances during measurement.
AN ACOUSTIC LINK BETWEEN BLUE WHALES IN THE EASTERN TROPICAL PACIFIC AND THE NORTHEAST PACIFIC1
Authors: Stafford Kathleen M. , Nieukirk Sharon L. , Fox Christopher G. 
Published: August 2006

AbstractBlue whale calls in the eastern North Pacific Ocean consist of a two‐part call often termed the A‐B call. This call has been described for regions offshore of Oregon, Washington, and California, USA and the Sea of Cortez, Mexico (reviewed in Rivers 1997). Data collected from moored hydrophones in the eastern tropical Pacific (ETP) indicate that the A‐B pattern is common in this region as well. There is consistency in this call type throughout the eastern North Pacific and throughout the year. This acoustic evidence indicates continuity between blue whales in the ETP and those found west of North America. The acoustic data suggest that the population of blue whales generally referred to as the “Californi/Mexico” stock might better be termed the “northeast Pacific” stock of blue whales.
GROWTH LAYER PATTERNS IN TEETH FROM THE FRANCISCANA, PONTOPORIA BLAINVILLEI: DEVELOPING A MODEL FOR PRECISION IN AGE ESTIMATION
Authors: Pinedo Maria Cristina , Hohn Aleta A. 
Published: August 2006

AbstractA model for estimating age from teeth of the franciscana, Pontoporia blainvillei, was developed using teeth from 72 specimens taken incidentally in fishing nets in Brazil and Uruguay. The goal of the model was to allow for accurate and precise age estimates for a larger sample of specimens. Growthlayer characteristics were selected on the basis of similarities in growth layers among various species of cetaceans, including those whose growth layers have been calibrated for time, and on length groups in the franciscana, which calves seasonally. Growth‐layer patterns, including relative size and appearance, in both dentine and cementum did not vary by sex but did vary by the orientation of the tooth when it was sectioned. The model developed proved useful in providing guidelines for consistency in age estimation for biological studies of the larger sample of animals. We recommend the development of this type of model for other species to facilitate standardizing age estimation.
FORAGING STRATEGIES OF SYMPATRIC KILLER WHALE (ORCINUS ORCA) POPULATIONS IN PRINCE WILLIAM SOUND, ALASKA
Authors: Saulitis Eva , Matkin Craig , Barrett‐Lennard Lance , Heise Kathy , Ellis Graeme 
Published: August 2006

AbstractKiller whales (Orcinus orca) feed on a wide variety of fish, cephalopods, and marine mammals throughout their cosmopolitan range; however, the dietary breadth that characterizes the species is not reflected in all populations. Here, we present the findings of a 14‐yr study of the diet and feeding habits of killer whales in Prince William Sound, Alaska. Two non‐associating forms of killer whale, termed resident and transient (Bigg et al. 1987), were identified. All prey seen taken by transients were marine mammals, including harbor seals (Phoca vitulina), Dall's porpoises (Phocoenoides dalli), Steller sea lions (Eumetopias jubatus), and harbor porpoises (Phocoena phocoena). Resident killer whales appeared to prey principally on salmon (Oncorhynchus spp.), preferring coho salmon (O. kisutch) over other, more abundant salmon species. Pacific herring (Clupea pallasi) and Pacific halibut (Hippocampus stenolepis) were also taken. Resident killer whales frequently were seen to interact in non‐predatory ways with Steller sea lions and Dall's porpoises, while transients were not. Differences in the social organization and behavior of the resident and transient killer whales in Prince William Sound are discussed in the light of the dietary differences documented here.
DIVE CHARACTERISTICS OF SATELLITE‐MONITORED BLUE WHALES (BALAENOPTERA MUSCULUS) OFF THE CENTRAL CALIFORNIA COAST
Authors: Lagerquist B. A. , Stafford K. M. , Mate B. R. 
Published: August 2006

AbstractDive habits of four Northeast Pacific blue whales (Balaenoptera musculus) were studied using satellite‐monitored radio tags. Tags summarized dive‐duration data into eight 3‐h periods daily. One tag additionally summarized dive depth and time‐at‐depth information for these same periods. Tracking periods ranged from 0.6 to 12.7 d and provided data for 17 three‐hour summary periods, representing 2,007 dives (788 of which provided depth information). Total number of dives during a 3‐h summary period ranged from 83 to 128. Seventy‐two percent of dives were ≤ 1 min long. All whales spent >94% of their time submerged. Average duration of true dives (dives >1 min) ranged from 4.2 to 7.2 min. Seventy‐five percent of depth‐monitored dives were to ≤16 m, accounting for 78% of that animal's time. Average depth of dives to >16 m was 105 ± 13 m.
CHARACTERISTICS OF MINKE WHALE (BALAENOPTERA ACUTOROSTRATA) PULSE TRAINS RECORDED NEAR PUERTO RICO
Authors: Mellinger David K. , Carson Carol D. , Clark Christopher W. 
Published: August 2006

AbstractA nine‐day acoustic and visual survey was conducted off the West Indies in March 1994 to study the pulse trains that were detected on SOSUS arrays throughout winter in deep water between the West Indies and Bermuda. During the survey, pulse train sounds were consistently recorded in an area 190–350 km northeast of Puerto Rico. Vocalizing animals were never visually observed, but visual sighting conditions were often poor and observation height was low. Pulse trains occurred in two basic forms. The “speed‐up” pulse train was characterized by an accelerating series of pulses with energy in the 200–400 Hz band, with individual pulses lasting 40‐60 msec. Speedup pulse trains started with average pulse rates of 1.5 pulses/sec, lasted 43.7 ± 6.0 sec, and ended with average pulse rates of 2.8 pulses/sec. The less common “slow‐down” pulse train was characterized by a decelerating series of pulses with energy in the 250‐350 Hz band. Slow‐down pulse trains started at pulse rates averaging 4.5 pulses/sec, lasted 60.9 ± 5.8 sec, and ended with average pulse rates of 2.9 pulses/sec. We believe the recorded pulse trains are from minke whales based on careful reanalysis of, and comparison to, minke whale pulse‐train sounds recorded in the Caribbean by Winn and Perkins (1976).
A REASSESSMENT OF THE IMPACT OF THEEXXON VALDEZOIL SPILL ON HARBOR SEALS (PHOCA VITULINA RICHARDSI) IN PRINCE WILLIAM SOUND, ALASKA
Authors: Hoover‐Miller Anne , Parker Keith R. , Burns John J. 
Published: August 2006

AbstractAnalyses of population trends and movements of harbor seals in Prince William Sound (PWS) casts doubt on published findings that 302 seals were killed by theExxon Valdezoil spill in 1989. Assumptions that seals have 100% fidelity to a haul‐out, that they were not displaced by the spill and associated disturbances, and that population trends throughout PWS varied similarly, except for oil spill effects, are not supported. Survey efforts to account for missing seals in 1989 were incomplete, too late in the year, and geographically limited. Basic assumptions required for statistical comparisons of oiled and unoiled haul‐outs were violated. Fourteen dead seals, mostly pups, were recovered in PWS. Cause of death in most instances could not be determined, nor could the proportion that would have died naturally. Evidence does not support high unsubstantiated mortality, but is more consistent with seals avoiding or moving away from some oiled haul‐outs. Interpretation of survey results requires consideration of temporal and regional variation. “Route A” surveys of central and eastern PWS do not represent population trends in western PWS or at glacial haul‐outs. To adequately monitor population trends of PWS as a whole, broader sampling must be conducted on a routine basis.
STATUS AND ECOLOGY OF SOTALIA FLUVIATILIS IN THE CAYOS MISKITO RESERVE, NICARAGUA
Authors: Edwards Holly H. , Schnell Gary D. 
Published: August 2006

AbstractIn March through May of 1996–1998, we conducted research in the Cayos Miskito Reserve, Nicaragua, to assess the status, ecology, and distribution of Sotalia fluviatilis, a dolphin known from southern Brazil to Honduras. Aerial and boat surveys of lagoons, inlets, and coastal areas were conducted and observational information collected on Sotalia activity, behavior, and other factors relating to its ecology. During boat surveys 183 groups (536 individuals) were sighted (for areas with Sotalia, mean overall density = 0.604 individuals/km2, coastal areas = 0.647/km2, inlets = 0.578/km2, and lagoons = 0.486/km2). Overall, based on all sightings, mean group size was 3.01 (SD = 1.79, range 1–15) and varied among years (x̄= 4.20 in 1996, 2.58 in 1997, and 3.39 in 1998), but not for different months. We estimate that 49 Sotalia inhabited the portions of the Reserve we studied. Sightings of Sotalia groups were non‐random (nearest‐neighbor analysis); clumping of sightings indicates that some areas were preferred. In both Pahara inlet and Wauhta lagoon, sightings were more frequent after 1200 than in the morning. In coastal areas Sotalia were sighted most often within 100 m of shore (54.0%), less often from 101 to 200 m (39.1%), and infrequently from 201 to 300 m (6.8%). Seldom were animals observed in more than 5 m of water, and usually it was considerably shallower (i. e., <2 m). Feeding was the predominant of five recorded activities (i. e., traveling, feeding, socializing, resting, and other), based on time of group sighting (70.3%) and during instantaneous sampling (56.3%). Resource distribution appears to be an important factor influencing Sotalia distribution in the Reserve.
KILLER WHALE PREDATION ON SPERM WHALES: OBSERVATIONS AND IMPLICATIONS
Authors: Pitman Robert L. , Ballance Lisa T. , Mesnick Sarah I. , Chivers Susan J. 
Published: August 2006

AbstractIn October 1997 we observed a herd of approximately 35 killer whales (Orcinus orca) attack a pod of nine sperm whales (Physeter macrocephalus) 130 km off the coast of central California. During the four hours we watched, adult female killer whales, including some with calves, attacked in waves of four to five animals in what was apparently a “wound and withdraw” strategy. Adult male killer whales stood by until the very end when one charged in and quickly killed a seriously wounded sperm whale that had been separated from the group. The sperm whales appeared largely helpless: their main defensive behavior was the formation of a rosette (“marguerite”‐heads together, tails out). When the killer whales were successful in pulling an individual out of the rosette, one or two sperm whales exposed themselves to increased attack by leaving the rosette, flanking the isolated individual, and leading it back into the formation. Despite these efforts, one sperm whale was killed and eaten and the rest were seriously, perhaps mortally, wounded. We also present details of two other encounters between sperm whales and killer whales that we observed. Although sperm whales, because of various behavioral and morphological adaptations, were previously thought to be immune to predation, our observations clearly establish their vulnerability to killer whales. We suggest that killer whale predation has potentially been an important, and underrated, selective factor in the evolution of sperm whale ecology, influencing perhaps the development of their complex social behavior and at‐sea distribution patterns.
PUPPING PHENOLOGY AND DEMOGRAPHY OF HARBOR SEALS (PHOCA VITULINA RICHARDSI)ON TUGIDAK ISLAND, ALASKA
Authors: Jemison Lauri A. , Kelly Brendan P. 
Published: August 2006

AbstractThe number of seals on shore at Tugidak Island (Gulf of Alaska) declined 72%–85% between 1976 and 1988 and increased during the 1990s. We compared pupping phenology and the ratio of pupping‐period counts to molting‐period counts between declining (1976–1979) and increasing (1994–1998) years, and examined the sex/age structure of seals ashore during the 1990s. In the 1970s the onset and peak of pupping occurred 6–18 d later than in the 1990s. Rate of pup abandonment was higher in 1978 than in the 1990s. Between 1994 and 1995, the maximum and mean number of seals ashore increased >50%, largely due to an increase in non‐pups. From 1995 to 1998, the sex/age structure of seals ashore was similar among years. We observed three to four times as many seals during the molting period than during the pupping period in the 1970s, whereas similar numbers were ashore during these periods in the 1990s, perhaps reflecting changes in demography and/or haul‐out behavior. Changes in pupping phenology and demography may reflect environmental changes, such as food availability, and when monitored in conjunction with population counts, may help us better interpret changes in the number of seals ashore.
COMPARISON OF METHODS USED TO ESTIMATE NUMBERS OF WALRUSES ON SEA ICE
Authors: Udevitz Mark S. , Gilbert James R. , Fedoseev Gennadii A. 
Published: August 2006

AbstractThe US and former USSR conducted joint surveys of Pacific walruses on sea ice and at land haul‐outs in 1975, 1980, 1985, and 1990. One of the difficulties in interpreting results of these surveys has been that, except for the 1990 survey, the Americans and Soviets used different methods for estimating population size from their respective portions of the sea ice data. We used data exchanged between Sovier and American scientists to compare and evaluate the two estimation procedures and to derive a set of alternative estimates from the 1975, 1980, and 1985 surveys based on a single consistent procedure. Estimation method had only a small effect on total population estimates because most walruses were found at land haul‐outs. However, the Sovievr method is subject to bias that depends on the distribution of the population on the sea ice and this has important implications for interpreting the ice portions of previously reported surveys for walruses and other pinniped species. We recommend that the American method be used in future surveys. Future research on survey methods for walruses should focus on other potential sources of bias and variation.
SHORT‐TERM EFFECTS OF BOAT TRAFFIC ON BOTTLENOSE DOLPHINS,TURSIOPS TRUNCATUS, IN SARASOTA BAY, FLORIDA
Authors: Nowacek Stephanie M. , Wells Randall S. , Solow Andrew R. 
Published: August 2006

AbstractCoastal cetaceans are subject to potential injury or disturbance from vessels. In Sarasota, Florida, where about 120 resident bottlenose dolphins,Tursiops truncatus, share the inshore waters with over 34,000 registered boats, disturbance potential is high. We assessed specific behavioral responses of individual dolphins to boat traffic. We conducted focal animal behavioral observations during opportunistic and experimental boat approaches involving 33 well‐known identifiable individual bottlenose dolphins. Dolphins had longer interbreath intervals (IBI) during boat approaches compared to control periods (no boats within 100 m). Treatment IBI length was inversely correlated with distance to the nearest boat in opportunistic observations. During 58 experimental approaches to 18 individuals, a video system suspended from a tethered airship was used to observe subsurface responses of focal dolphins as boats under our control, operating at specified speeds, were directed near dolphins. Dolphins decreased interanimal distance, changed heading, and increased swimming speed significantly more often in response to an approaching vessel than during control periods. Probability of change for both interanimal distance and heading increased when dolphins were approached while in shallow water. Our findings provide additional support for the need to consider disturbance in management plans for cetacean conservation.
DISTRIBUTION OF THE PYGMY RIGHT WHALE, CAPEREA MARGINATA, IN THE AUSTRALASIAN REGION
Authors: Kemper Catherine M. 
Published: August 2006

AbstractThe latitudinal range of all records of sightings (n= 9), and live strandings and carcasses (n= 180) of Caperea marginata in the Australasian region was 32°00′–47°00′S. Records were concentrated on the edge of the South Australian gulfs, around Tasmania, at Stewart Island, in Cook Strait, and in the Auckland area. Limited data suggest that these may be related to planktonrich waters nearby. Body lengths ranged from 198 to 650 cm. Overall sex ratio was 0.70 (males: females). In regions north of about 41°S, juveniles (preweaning) made up 41% of the records and subadults (postweaning) were rare (13%). In regions south of about 41°S subadults (36%) were proportionately more abundant than juveniles (17%). Neonates were recorded from 35°37′ to 47°00′S. Adults were found throughout the latitudinal range of the species in Australasia. The diet of the pygmy right whale included copepods and small euphausiids. Behavior consistent with feeding has been observed in coastal waters of Australia.
DETERMINATION OF PREGNANCY STATUS FROM BLUBBER SAMPLES IN MINKE WHALES (BALAENOPTERA ACUTOROSTRATA)
Authors: Mansour Atef A. H. , Mkay Donald W. , Lien Jon , Orr James C. , Banoub Joseph H. , ØIen Nils , Stenson Garry 
Published: August 2006

AbstractMeasurement of progesterone concentration in blubber was developed as a method to detect pregnancy in minke whales. Progesterone was extracted and quantified from blubber samples of minke whale carcasses by radioimmunoassay. Results showed a highly significant difference (almost 60‐fold) between blubber progesterone concentrations of anatomically determined pregnant females versus non‐pregnant female or male carcasses. The results of the study suggest that the blubber progesterone concentrations might be used to determine pregnancy status in free‐ranging whales.
HAUL‐OUT ACTIVITY OF RINGED SEALS (PHOCA HISPIDA) DETERMINED FROM SATELLITE TELEMETRY
Authors: Born E. W. , Teilmann J. , Riget F. 
Published: August 2006

AbstractThe haul‐out activity of 15 ringed seals (Phoca hispida) equipped with satellite‐linked radio transmitters was studied in NW Greenland (ca.73°‐78°N). Between 19 June 1997 and 30 June 1999, telemetry data on haulout activity were obtained by the “Land‐Sea‐Reporter” (LSR), “Time‐at‐Depth” (TAD), and “Timelines” (TIM) systems housed within the satellite transmitters. The haul‐out activity (% of total time hauled out) reported by the TIM system, which is specifically designed for collecting haul‐out data, was about 1.4 times higher than that inferred from the LSR, but only about 0.7 of that inferred from TAD data. The TIM were used to describe haul‐out activity. A total of 1,011 d with TIM were obtained (64.5% of a total of 1,568 “seal‐days” monitored) representing data from nearly an entire annual cycle. No differences were found in percentage of time hauled out per month among various age categories. At all seasons the haul‐out time showed considerable individual variation. There were no trends in percentage of time hauled out per month during late summer, fall, and winter (August‐February). During the High Arctic winter darkness (November‐January) the percentage of haul‐out per month ranged between 3.9% in an adult (SD = 2.44, range: 1.1%‐5.7%,n= 3 mo) and 15.7% in a subadult (SD = 1.95, range: 13.7%‐17.6%,n= 3 mo). From late March there was a significant increase in haul‐out time. Between 1 and 30 June, when aerial surveys of basking ringed seals usually are conducted, the haul‐out time (% per day) increased from about 25% to about 57%. No tendencies in diel haul‐out activity were revealed.