bluuebunny/crossref_metadata_2025_split huggingface dataset:
FIRST ESTIMATES OF VAQUITA ABUNDANCE
Authors: Barlow Jay , Gerrodette Tim , Silber Greg 
Published: August 2006

AbstractThe abundance of the only population of vaquitas, Gulf of California harbor porpoise (Phocoena sinus), is estimated from four surveys conducted in Mexico between 1986 and 1993, using a variety of methods. A line‐transect approach was applied, using some parameters estimated from a related species, the harbor porpoise (Phocoena phocoena). Vaquita abundance is estimated as 503 (CV = 0.63) from 1986–1988 boat surveys, 885 (CV = 0.50) from 1988–1989 aerial surveys, 572 (CV = 1.43) from a 1991 aerial survey, and 224 (CV = 0.39) from a 1993 ship survey. A weighted log‐linear regression indicates a rate of population change (decline) of −17.7% per year (95% CI =−43.2% to +19.3%) between 1986 and 1993. All of these estimates of vaquita abundance indicate that the species is at a critically low level.
AGGREGATIONS OF MATURE MALE SPERM WHALES ON THE GALÁPAGOS ISLANDS BREEDING GROUND
Authors: Christal Jenny , Whitehead Hal 
Published: August 2006

AbstractThe distribution and behavior of mature (12.3–16.3 m) male sperm whales (Physeter macrocephalus) were studied on the Galápagos Islands breeding ground from April to June 1995. In contrast to previous research seasons when males were observed only in close spatial and temporal proximity to mixed schools of females and immature animals, in 1995 males were sighted in loose aggregations, separated by hours to days from our vessel's encounters with mixed schools. Only one of ten identified males was observed in spatial proximity to a mixed school.Aggregations consisted of two to four (minimum estimates) mature males travelling within a range of a few kilometers and were characterized by consistency of heading among individuals. Aggregations moved over time. During encounters, one to three males were observed at the surface at the same time, with interindividual distances of less than 1,000 m. Synchrony of heading was apparent between spatial associates, and its extent appeared to be related to interindividual distance. Clustering (two or more individuals within 100 m) was observed on only two occasions. No agonistic behaviors were seen.Functions of mature male aggregation on a breeding ground remain unclear. Possible explanations for our observations are local prey abundance, or some form of sociality mediated over spatial scales of hundreds to thousands of meters.
A QUANTITATIVE ASSESSMENT OF DOMINANCE RELATIONS AMONG BOTTLENOSE DOLPHINS
Authors: Samuels Amy , Gifford Tara 
Published: August 2006

AbstractAgonistic behavior of bottlenose dolphins was studied at Brookfield Zoo for nearly 4.5 yr, and dominance relationships were determined using a quantitative technique adapted from primate behavioral research. Dominance relations among dolphins were influenced by the gender of participants. Male dolphins were clearly and consistently dominant to females, and intersexual agonism occurred at moderate rates with seasonal peaks in spring and fall. Dominance relationships among female dolphins were age‐ordered and stable, even though agonism among females did occur at uniformly low rates. In contrast, the two males had a changeable dominance relationship in which periods of stability and low‐level agonism were interspersed with episodes of intense competition. Zoo‐based research revealed patterns of behavior that conformed to current knowledge about bottlenose dolphin social structure. Moreover, research in a zoo setting facilitated development of a quantitative technique that can be used to assess cetacean dominance relationships in field research.
POPULATION ANALYSIS OF NORTHERN BOTTLENOSE WHALES IN THE GULLY, NOVA SCOTIA
Authors: Whitehead HAL , Gowans Shannon , Faucher Annick , Mccarrey Stephen W. 
Published: August 2006

ABSTRACTNorthern bottlenose whales (Hyperoodon ampullatus) are consistently found through the year in the Gully, a prominent submarine canyon on the edge of the Scotian Shelf. Individuals were photographically identified during field studies between 1988 and 1995. About 70% of the population is identifiable, and 29% have markings which persist reliably over periods of years. A mark‐recapture analysis of photographic individual identifications collected between 1988 and 1995 indicates that the population using the Gully numbers about 230 animals (approximate 95% confidence interval 160‐360). The rate of mortality plus emigration plus mark change (in animals with reliable long‐term marks) is about 12% per year, although this estimate has wide and uncertain confidence limits. Members of the Gully population, which includes calves and mature males, are shorter than animals caught off Labrador. The small size of the Gully population and its persistent use of a very small, bathy‐metrically unique ocean area make it vulnerable to human disturbance.
A VIDEO SONAR AS A NEW TOOL TO STUDY MARINE MAMMALS IN THE WILD: MEASUREMENTS OF DOLPHIN SWIMMING SPEED
Authors: Ridoux Vincent , Guinet Christophe , Liret Céline , Creton POL , Steenstrup Resen , Beauplet Gwenaël 
Published: August 2006

ABSTRACTThe use of a multibeam sonar for fine‐scale studies of the foraging activity of bottlenose dolphins (Tursiops truncatus) was tested in a coastal environment where a group of 14 individuals is known to be resident. The sonar was set on a rubber boat and the signals were received continuously as the dolphins were foraging in a pass swept by strong tidal currents. These signals were recorded in HI 8 video standard. The system produced real‐time undistorted images of the dolphins and of their movements within the limits of the sonar beam (15° vertical width, 90° horizontal width, range set at 50 m). The average swimming speed relative to the bottom was 1.8 m ·sec−1 but swimming speed relative to the water was 2.2 m‐sec−1 when allowance was made for the average 1.2 m·sec−1 tidal current. Maximum swimming speed relative to the water was as high as 4.8 m·sec−1. It is estimated from studies of swimming energetics that continuously foraging in a current vein flowing at 1.2 m·sec1 would represent only small additional costs compared to foraging out of these currents. However, previous observations of the same pod have shown that these dolphins keep foraging in this site when current speed reaches 2.7 m·sec−1; under such circumstances, the cost of foraging in this site was calculated to increase by 96%. This suggests that foraging efficiency should be dramatically enhanced during rising tide since the dolphins consistently forage in these currents year round.
THE SCIENTIFIC DISCOVERY OF THE AMAZON RIVER DOLPHIN INIA GEOFFRENSIS
Authors: Romero A. , Agudo A. I. , Agudo S. J. Blondell de 
Published: August 2006

AbstractAnalysis of little‐known manuscripts revealed that there have been at least two pre‐Linnean descriptions of the South American freshwater dolphin Inia geoffrensis (Blainville, 1817). The earliest one that we found was made by Frei Cristóvâo de Lisboa in a manuscript written around 1627. The second one was by Pehr Löfling, a disciple of Linnaeus, who wrote a very detailed and accurate description of this mammal in 1755. He used the binomial system to designate this species, and his description was much more complete and sophisticated than the ones used by Linnaeus in the 10th edition of System Naturae for other cetaceans. This and other zoological work by Löfling remains almost completely unexamined to date. Like the outcome of other field work carried out by many Spanish scientists in America, failure to publish the findings of the expeditions resulted in scientific information being largely lost.
DISTRIBUTION AND ABUNDANCE OF THE AMAZON RIVER DOLPHIN (INIA GEOFFRENSIS) AND THE TUCUXI (SOTALIA FLUVIATILIS) IN THE UPPER AMAZON RIVER
Authors: Vidal Omar , Barlow Jay , Hurtado Luis A. , Torre Jorge , Cendón Patricia , Ojeda Zully 
Published: August 2006

AbstractA boat survey was conducted from 5 to 26 June 1993 to estimate the abundance of the Amazon river dolphin (Inia geoffrensis) and the tucuxi (Sotalia fluviatilis) along ca. 120 km of the Amazon River bordering Colombia, Peru, and Brazil. Two survey methods were used: line transects during 5 d and strip transects during 15 d. The line transects were used to estimate the abundance of both species in the main channels of the Amazon at distances greater than 200 m from river banks and islands, and strip transects were used to estimate abundance in the remainder of the habitat. A total of 29 sightings was obtained using line transects, including 8 of Inia, 15 of Sotalia, and 6 with both species present. The total number of sightings made while using strip transects was 143, including 78 of Inia, 51 of Sotalia, and 14 with both species present. The distributions of sightings with respect to distance from the nearest bank were not significantly different between the two species. Based on the results from the two methods, we estimate that there are 346 (CV = 0.12) Inia and 409 (CV = 0.13) Sotalia in the study area. Overall, the mean group size for Inia was 2.9 individuals and for Sotalia was 3.9 individuals. Inia density (dolphin/km2) was highest in tributaries (4.8), followed by areas around islands (2.7) and along main banks (2.0); while Sotalia density was highest in lakes (8.6), followed by areas along main banks (2.8) and around islands (2.0). These are among the highest densities measured to date for any cetacean.
A HARP SEAL × HOODED SEAL HYBRID
Authors: Kovacs Kit M. , Lydersen Christian , Hammill Mike O. , White Bradley N. , Wilson Paul J. , Malik Sobia 
Published: August 2006

AbstractIn this study we report the first documentation of mating between harp (Phoca groenlandica) and hooded seals (Cystophora cristata). The production of this hybrid was quite unusual, being the result of a cross between parents of different genera which are morphologically dissimilar and have quite different mating behavior and dramatically different body sizes. The molecular techniques (mtDNA and macrosatellite nuclear DNA banding patterns) used in this study will undoubtedly be applied widely to many different taxa in the near future, allowing us to re‐examine many suspected cases of hybridization among marine mammals and, in a larger context, the meaning of the species concept.
A NEW GEOGRAPHIC FORM OF THE SPINNER DOLPHIN, STENELLA LONGIROSTRIS, DETECTED WITH AERIAL PHOTOGRAMMETRY
Authors: Perryman Wayne L. , Westlake Robin L. 
Published: August 2006

AbstractAnalyses of skeletal and external morphology of spinner dolphins killed in to the yellowfin tuna purse‐seine fishery in the eastern tropical Pacific led to the description of two subspecies of spinners from this region, the eastern spinnen dolphin and the Central American spinner dolphin (Perrin 1990). However, when we examined lengths of spinner dolphins taken from vertical aerial photographs from the same area, we found three unique morphotypes. Two of these forms correspond, at least in average length and distribution, to the existing subspecies. The third form is intermediate in length between the two recognized subspecies and is found along the edge of the continental shelf north of Cabo Corrientes, Mexico. We provisionally call this form the “Tres Marias spinner dolphin.” Our results demonstrate the value of a mix of fishery and fishery‐independent data in studies of stock structure of impacted species.
HOMING BEHAVIOR OF JUVENILE NORTHERN ELEPHANT SEALS
Authors: Oliver Guy W. , Morris Patricia A. , Thorson Philip H. , le Boeuf Burney J. 
Published: August 2006

AbstractThe aim of this study was to determine if juvenile northern elephant seals,Mirounga angustirostris, translocated from their rookery would return to it quickly and reliably. During the spring and fall of 1990 and 1991 we captured 75 seals at Año Nuevo State Reserve, CA, U. S. A. and translocated them to release sites up to 100 km away. Eighty‐eight percent of the seals returned to the capture site within 4.7 ± 4.3 d. Homing rate increased with age, but even the youngest seals (8–10 mo) homed at a 73% rate. Homing rate did not vary significantly with sex, season, or year. Data from diving instruments suggested that the seals often followed direct routes home, arrived on the rookery significantly more often at night than during the day, and when released together, returned separately. Mean homing speed of 18 seals with complete diving records was 39 km/d (range 3–70 km/d). Instruments on seals had no detectable effect on homing rate or homing speed. The translocation paradigm provides a powerful tool for conducting intensive shortterm studies on free‐ranging seals.
PREHENSILE USE OF PERIORAL BRISTLES DURING FEEDING AND ASSOCIATED BEHAVIORS OF THE FLORIDA MANATEE (TRICHECHUS MANATUS LATIROSTRIS)
Authors: Marshall C. D. , Huth G. D. , Edmonds V. M. , Halin D. L. , Reep R. L. 
Published: August 2006

AbstractThe use of perioral bristles (modified vibrissae) by 17 captive Florida manatees and approximately 20 wild manatees was analyzed. Captive manatees were fed six species of aquatic vegetation normally eaten in the wild (four freshwater species and two seagrasses). Inanimate objects were placed in the holding tanks with manatees at Lowry Park Zoological Gardens (Tampa, FL) to determine the degree to which perioral bristles were used in exploration and to define the range of manipulative behavior. In addition, behavioral observations were made on the use of perioral bristles during social interactions with conspecifics. Observations were recorded using a Hi8‐format video camera. Florida manatees possess an unusually large degree of fine motor control of the snout and perioral bristles. The large and robust perioral bristle fields of the upper lip were used in a prehensile manner during feeding. Bristle use by manatees feeding on submerged vegetation differed from that seen during feeding on floating vegetation. Other behavioral use of the perioral bristles shows variation depending upon the situation encountered. The degree of plasticity of perioral bristle use supports our hypothesis that the vibrissal‐muscular complex of the Florida manatee has evolved to increase the efficiency of grazing and browsing on aquatic vegetation and to fully maximize the potential of the manatee as a generalist feeder. The manipulative and sensitive nature of the manatee snout is likely a manifestation of a complex sensory and motor system which has evolved for marine mammal aquatic herbivores living in shallow turbid habitats.
DIEL PATTERNS IN AGGREGATIONS OF PELAGIC DOLPHINS AND TUNAS IN THE EASTERN PACIFIC
Authors: Scott Michael D. , Cattanach Karen L. 
Published: August 2006

AbstractData collected by scientific technicians aboard tuna purse seiners in the eastern Pacific Ocean since the early 1970s have allowed us to study the biology and herd dynamics of pelagic dolphins. A pattern of increasing group size in the morning and subsequent decline in the late afternoon or night was evident for spotted, spinner, and common dolphins, as well as for large yellowfin tuna that associate with dolphins. Diel patterns were also apparent in the formation of mixed‐species herds of spotted and spinner dolphins and tuna‐dolphin aggregations. Different patterns, however, were displayed by bottlenose dolphins and by yellowfin and skipjack tunas that did not associate with dolphins. It appears that these diel patterns are produced by an interaction of predation pressure and prey distribution.
CETACEANS OF THE WESTERN TROPICAL INDIAN OCEAN: DISTRIBUTION, RELATIVE ABUNDANCE, AND COMPARISONS WITH CETACEAN COMMUNITIES OF TWO OTHER TROPICAL ECOSYSTEMS
Authors: Ballance Lisa T. , Pitman Robert L. 
Published: August 2006

AbstractWe conducted a cetacean survey in the pelagic western tropical Indian Ocean (WTIO) aboard an 85‐m research vessel from March to July 1995, covering 9,784 linear km. Using 25 × binoculars and line‐transect methods, we recorded 589 sightings of 21 species. Stenella longirostris was the most abundant cetacean, in terms of number of individuals sighted, by an order of magnitude above any other species, while Physeter macrocephalus was the most frequently sighted, in terms of number of schools. Twelve species were widespread, seven were rare, and two were localized; our sightings include new distributional records for 12 species. Significant observations included the following: (1) Delphinus cf. tropicalis was abundant off the coast of Oman (16 sightings) and readily distinguishable in the field from D. delphis and D. capensis, (2) Balaenoptera musculus was fairly common and localized in the area of the Maldives (17 sightings), and (3) three sightings were made of an unidentified bottlenose whale tentatively referred to as Indopacetus (i. e., Mesoplodon) pacificus. We recorded 26 mixed‐species cetacean schools, 43 schools with which seabirds associated, and 17 schools associated with tuna. Notable among these were mixed aggregations of Stenella attenuata, S. longirostris, yellowfin tuna, and seabirds.The cetacean community of the WTIO was similar to that of the eastern tropical Pacific (ETP) and the Gulf of Mexico (GM) in several respects. First, differences in abundance rank of individual species were small, with the result that common species were common and rare species were rare, regardless of ocean. Second, these differences in abundance were due primarily to differences in encounter rate, which varied with ocean by as much as 3,000%, and less so to school size, which generally varied less than 100%. Third, regardless of ocean, three species comprised the majority of cetaceans in the community, Stenella attenuata, S. longirostris, and S. coeruleoalba, representing 62%‐82% of all individuals for all species. However, the rank order of abundance for these three species differed with ocean. Most notably, S. attenuata was abundant in the ETP and GM (abundance rank = 2 and 1, respectively) but much less common in the WTIO (abundance rank = 6). Although habitat preferences for S. attenuata appear to overlap considerably with those of S. longirostris in the ETP, our results suggest there may actually be significant differences between these two species. Detailed analysis of oceanographic correlates of distribution will be necessary in order to understand fully the habitat requirements of these pelagic dolphins, often the most conspicuous elements of tropical cetacean communities around the world.
SEASONAL PATTERNS IN THE ABUNDANCE AND DISTRIBUTION OF CALIFORNIA CETACEANS, 1991–1992
Authors: Forney Karin A. , Barlow Jay 
Published: August 2006

AbstractThis study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100‐150 nmi (185‐278 km) of the California coast during 1991 and 1992. The results of a shipboard line‐transect survey conducted in July‐November 1991 (“summer”) were compared to those from aerial line‐transect surveys conducted in March‐April 1991 and February‐April 1992 (“winter”). Using a confidence‐interval‐based bootstrap procedure, abundance estimates for six of the eleven species included in the comparison exhibited significant (α= 0.05) differences between the winter and summer surveys. Pacific white‐sided dolphins (Lagenorhynchus obliquidens), Risso's dolphins (Grampus griseus), common dolphins (Delphinus spp.), and northern right whale dolphins (Lissodelphis borealis) were significantly more abundant in winter. The abundance of blue whales (Balaenoptera musculuss) and gray whales (Eschrichtius robustus) reflected well‐documented migratory patterns. Fin whales (B. physalus) were significantly more abundant during summer. No significant differences in seasonal abundance were identified for Dall's porpoises (Phocoenoides dalli), bottlenose dolphins (Tursiops truncatus), killer whales (Orcinus orca), sperm whales (Physeter macrocephalus), or humpback whales (Megaptera novaeangliae). Significant north/south shifts in distribution were found for Dall's porpoises, common dolphins, and Pacific white‐sided dolphins, and significant inshore/offshore differences were identified for northern right whale dolphins and humpback whales.
ISOLATION AND EXPRESSION OF THE INTERLEUKIN‐2 GENE FROM THE KILLER WHALE, ORCINUS ORCA
Authors: Ness Traci L. , Bradley W. Guy , Reynolds John E. , Roess William B. 
Published: August 2006

AbstractComplementary DNA encoding interleukin‐2 (IL‐2) was isolated, cloned, and sequenced from the killer whale, Orcinus orca. The sequence of the killer whale IL‐2 coding region consists of 455 nucleotides which translate into a polypeptide containing 151 amino acids. Killer whale IL‐2 displays 88%, 88%, 87%, 87%, 85%, 84%, 80%, and 71% nucleotide sequence homology and 76%, 76%, 76%, 73%, 68%, 73%, 64%, and 56% amino acid homology with the cow, sheep, pig, red deer, horse, human, manatee, and mouse, respectively. High levels of killer whale recombinant IL‐2 were generated by transiently transfecting killer whale IL‐2/pCMV Blue plasmid DNA into cultured monkey kidney cells (Cos‐1). Generation of this recombinant IL‐2 will allow the development of assays useful for assessing IL‐2 levels in the serum and from isolated lymphocytes of killer whales and possibly other species of cetaceans. A major contribution and significance of the in vitro expression of killer whale IL‐2 exists in its potential to be used as a therapeutic agent.
ESTIMATING NATURAL MORTALITY RATE IN REPRODUCTIVELY ACTIVE FEMALE SOUTHERN RIGHT WHALES, EUBALAENA AUSTRALIS
Authors: Best P. B. , Kishino H. 
Published: August 2006

AbstractCow‐calf pairs of southern right whales on the South African coast have been photographed in aerial surveys in October each year since 1979. In this paper 469 resightings of 177 individually identified cows photographed in the first six years of surveys have been analyzed in two ways to produce estimates of natural mortality rate. Both methods assume that all females calve either two, three, or four years after their previous calf. In Method A there is assumed to be no systematic trend with time in the probability of a female being photographed on each calving occasion. Natural logarithms of the numbers photographed 2‐4, 5‐7, 8‐10, etc. yr after being first seen are regressed against time, the slope of which provides an estimate of natural mortality rate of 0.0255 ± 0.0071. The intercept value for this regression provides an estimate of the detection probability, or 0.769 ± 0.011. In Method B it is assumed that if a female has not been photographed for at least nine years then it is dead. Annual mortality estimates are obtained from the proportional reduction in the numbers of females known to be alive at each three‐year interval after being first photographed, up to at least 6‐8 yr from the present. Method B produces an estimate of natural mortality of 0.0260 ± 0.0190 (corrected to 0.0227 ± 0.0192 using the average detection probability). Both methods may be subject to various biases that tend to inflate estimates of natural mortality.