bluuebunny/crossref_metadata_2025_split huggingface dataset:
ESTIMATION OF TOTAL BODY WATER IN HARBOR SEALS: HOW USEFUL IS BIOELECTRICAL IMPEDANCE ANALYSIS?
Authors: Bowen W. Don , Boness D. J. , Iverson S. J. 
Published: August 2006

AbstractWe evaluated bioelectrical impedance analysis (BIA) as a means of rapidly and inexpensively estimating total body water (TBW) of harbor seals (Phoca vitulina). Deuterium oxide dilution was used to estimate TBW in 17 adult females and 16 of their pups between birth and late lactation. Isotope dilution was also used to determine TBW in 12 adult males early and 10 of these males late in the breeding season. At the same time, resistance (Rs) and reactance (Xc) measurements were taken using a tetrapolar, impedance plethysmograph (Model 101 A, RJL Systems). Seals were sedated with diazepam prior to taking BIA measurements. Within‐day duplicate Rs measurements on pups and adults, taken 2‐240 min apart, differed by an average of 3.0%± 1.4% (n= 42, CV = 102%). Movement of the seal during BIA measurements caused variability in both Rs and Xc values. BIA measurements were generally poor predictors of TBW. Rs was significantly correlated with TBW in pups only (Rs= 0.93, P= 0.001, n= 11). Bioelectrical conductor volume (length2/Rs) was significantly correlated with TBW only in adult females (Rs= 0.63, P= 0.02, n= 14). We conclude that BIA is not a reliable method of estimating TBW in wild harbor seals.
GROWTH AND SEXUAL DIMORPHISM OF ATLANTIC WALRUSES (ODOBENUS ROSMARUS ROSMARUS) IN FOXE BASIN, NORTHWEST TERRITORIES, CANADA
Authors: Garlich‐Miller J. L. , Stewart R. E. A. 
Published: August 2006

AbstractGrowth of Atlantic walruses (Odobenus rosmarus rosmarus) was investigated using morphological data collected in association with Inuit subsistence walrus hunts. Four growth models were examined. The growth parameters of a constrained Richards model were used to quantify growth and to test for sexual dimorphism. The asymptotic length of male walruses (315.2 cm ± 3.8 (SE),n= 103) was significantly larger (t= 7.21, df = 191,P< 0.05) than the asymptotic length of females (276.6 cm ± 3.4,n= 90). Sexual size dimorphism in adults was due to a longer growth period and a faster growth rate in males. The predictive equation relating mass (M, kg) to standard length (SL, cm) was: Log10M= ‐3.74 + 2.68(Log10SL),n= 25,r2= 0.98. There were no significant differences in the size of male walruses from Foxe Basin collected in the 1950s and this study. There were too few data to compare females. There were no significant differences in size between walruses sampled in Greenland and Foxe Basin in the 1980s and 1990s. Foxe Basin walruses were significantly larger than walruses sampled in northern Hudson Bay in the 1950s. Female Atlantic walruses sampled in Foxe Basin were larger than female Pacific walruses (Odobenus rosmarus divergens) sampled in Alaska.
BEHAVIORAL RESPONSE OF FOUR SPECIES OF BALAENOPTERID WHALES TO BIOPSY SAMPLING
Authors: Gauthier J. , Sears R. 
Published: August 2006

AbstractBehavioral responses to biopsy sampling of four species of northwestern Atlantic balaenopterid whales summering in the estuary and Gulf of St. Lawrence, Quebec, from 1990 to 1995 were studied to determine if this technique was an important disturbance to the whales. A total of 447 biopsy samples were taken using a small punch‐type biopsy tip fired from a crossbow. Biopsies were successfully taken from 91.2% of the whales approached. Whales displayed no reaction to 45.2% of the successful biopsy attempts. Whales that responded to biopsy sampling typically resumed their normal behavior immediately or within a few minutes. Most humpback whales displayed a hard tail flick, and the majority of fin and blue whales submerged following biopsy sampling. Significantly different frequencies and intensities of responses were found between whale species. Minke and humpback whales were found to be more sensitive to biopsy sampling than fin and blue whales. Response frequencies were similar between females and males for all species, with the exception of fin whales where females had a higher response frequency than males. Biopsy sample length, i. e., penetration depth, did not explain variations in response intensity but may influence response frequency to biopsy sampling. Group size, geographical region, and number of biopsies taken per whale were not factors that explained variation in behavioral responses. The biopsy technique was found to be an efficient method for obtaining high‐quality whale skin and blubber samples with limited behavioral disturbance to balaenopterid whales.
DIETARY STUDIES OF MARINE MAMMALS USING STABLE CARBON AND NITROGEN ISOTOPIC RATIOS OF TEETH
Authors: Walker Jane L. , Macko Stephen A. 
Published: August 2006

AbstractThis study used naturally occurring carbon and nitrogen stable isotopes of teeth to study the diets of marine mammals. The isotopic ratios of nonchemically preserved teeth from eight species of marine mammals, representing 87 individuals that spanned the trophic continuum, were found to reflect nutritional sources. The δ13C signals distinguished animals that lived in waters dominated by different primary producers (e. g., seagrass, kelp, and phytoplankton), and δ15N values indicated the diet and trophic level of the species. This research suggests that isotopic signatures of teeth can be used in dietary studies to show differences and similarities among age classes, genders, geographic locations, and time periods.
RANGE CHARACTERISTICS OF PACIFIC COAST BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN THE SOUTHERN CALIFORNIA BIGHT
Authors: Defran R. H. , Weller David W. , Kelly Dennis L. , Espinosa Miriam A. 
Published: August 2006

AbstractBoat‐based photoidentification surveys of bottlenose dolphins (Tursiops truncatus) were conducted from 1982 to 1989 in three discrete coastal study areas within the Southern California Bight: (1) Santa Barbara, California; (2) Orange County, California; (3) Ensenada, Baja California, Mexico. A total of 207 recognizable dolphins were identified in these three “secondary” study areas. These individuals were compared to 404 dolphins identified from 1981 to 1989 in our “primary” study area, San Diego, California, to examine the coastal movement patterns of bottlenose dolphins within the Southern California Bight. A high proportion of dolphins photographed in Santa Barbara (88%), Orange County (92%), and Ensenada (88%) were also photographed in San Diego. Fifty‐eight percent (n= 120) of these 207 dolphins exhibited back‐and‐forth movements between study areas, with no evidence of site fidelity to any particular region. Minimum range estimates were 50 and 470 km. Minimum travel‐speed estimates were 11‐47 km/d, and all dolphin schools sighted during the study were within 1 km of the shore. These data suggest that bottlenose dolphins within the Southern California Bight are highly mobile within a relatively narrow coastal zone. Home‐range dimensions and movement patterns for many vettebrate species are influenced, in part, by variation in food resources. The unique range characteristics documented during this study may reflect the highly dynamic nature of this coastal ecosystem and the associated patchy distribution of food resources available to these bottlenose dolphins.
LOCAL ABUNDANCE AND DISTRIBUTION OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN THE NEARSHORE WATERS OF VIRGINIA BEACH, VIRGINIA
Authors: Barco Susan G. , Swingle W. Mark , Mlellan William A. , Harris Reid N. , Pabst D. Ann 
Published: August 2006

AbstractWe investigated patterns of abundance and distribution for coastal migratory Atlantic bottlenose dolphins (Tursiops truncatus) that appear seasonally in the nearshore waters of Virginia Beach, Virginia. The study was conducted along 24 km of shoreline at the southern point of the Chesapeake Bay mouth from April 1994 to March 1995. This is the first study to investigate the relationship between the abundance of coastal migratory dolphins and factors that might affect their movement. A profile analysis of variance revealed significant differences in local abundance and distribution throughout the year. Dolphin number was positively correlated with water temperature and not correlated with photoperiod. Although prey distribution and abundance are two factors thought to affect dolphin presence, in this study the relationship between these two factors and dolphin abundance was unclear. Greater numbers of dolphins were found in the ocean section of the study area. However, significantly higher ratios of neonatal dolphins were observed in the bay section, suggesting the bay serves as a nursery area. The observed relationship between local dolphin abundance and environmental factors in Virginia may provide insight into dolphin distribution and migration along the Atlantic coast of the United States.
SKIN SWABBING FOR GENETIC ANALYSIS: APPLICATION TO DUSKY DOLPHINS (LAGENORHYNCHUS OBSCURUS)
Authors: Harlin April Dawn , Würsig Bernd , Baker C. Scott , Markowitz Tim M. 
Published: August 2006

AbstractExfoliated skin was collected from bowriding dolphins with the use of a sterilized nylon scrub pad affixed to a wooden dowel. Initial tests of the effectiveness of the technique and dolphin behavioral responses were conducted on dusky dolphins off Kaikoura, New Zealand. During 14 sampling days, 128 contacts using this procedure were made with bowriding dolphins, of which 114 showed behavioral response. Responses during sampling were mild, with 11% of contacted individuals showing no visible response, and 66% of individuals which could be monitored for 30 sec after contact returning to bowride within 30 sec. Mean return time was 10 sec postcontact and did not vary significantly for groups of different sizes. Behavioral controls suggest that a proportion of responses could be explained by typical dolphin behavior in the presence of boats. Seventy‐eight percent of contacts resulted in successful collection of tissue samples. Sample time was three minutes on average. Size of group and behavioral state did not appear to influence sample time. Preliminary genetic analyses revealed that tissue collected by this technique was suitable for amplification and sequencing of mitochondrial DNA (mtDNA) via PCR. Comparisons of mtDNA control region sequences with those from known L. obscurus and other delphinid samples verified that this technique was robust against contamination from elements in sea water.
PHYLOGENETIC RELATIONSHIPS AMONG THE DELPHINID CETACEANS BASED ON FULL CYTOCHROME B SEQUENCES
Authors: Leduc R. G. , Perrin W. F. , Dizon A. E. 
Published: August 2006

AbstractComplete cytochrome b gene sequences from all but one species of delphinid plus four outgroups were analyzed using parsimony, maximum likelihood, and neighbor‐joining methods. The results indicate the need for systematic revision of the family; a provisional classification is presented and compared to previous studies. Among the suggested revisions are removal of Orcinus from the Globicephalinae, placement of Grampus within the Globicephalinae, removal of all Lagenorhynchus spp. from the Delphininae, and placement of Sousa in the Delphininae. The genus Lagenorhynchus is found to be polyphyletic. L. albirostris (type species for the genus) and L. acutus are not closely related to each other or to nominal congeners. L. acutus is therefore assigned to the genus Leucopleurus. The remaining four Lagenorhynchus species are closely related to Lissodelphis and Cephalorbynchus and are placed in the genus Sagmatias. These three genera constitute the revised Lissodelphininae. Within the Delphininae, a well‐supported clade includes the two species of Delphinus, Stenella clymene, S. frontalis, S. coeruleoalba, and the aduncus form of Tursiops truncatus. Accepting the monophyly of this group renders the genera Stenella and Tursiops polyphyletic. Apart from this finding, phylogenetic resolution within the Delphininae was poor, so comprehensive taxonomic revision of this group awaits further study.
GASTROINTESTINAL HELMINTHS OF THE DUSKY DOLPHIN, LAGENORHYNCHUS OBSCURUS (GRAY, 1828), OFF PATAGONIA, IN THE SOUTHWESTERN ATLANTIC
Authors: Dans Silvana L. , Reyes Laura M. , Pedraza Susana N. , Raga Juan A. , Crespo Enrique A. 
Published: August 2006

AbstractThe stomachs and intestines of 23 dusky dolphins incidentally caught in a trawl fishery off Patagonia were surveyed for helminths. All the dolphins were parasitized, with a total of 3,936 helminth individuals. Only five species occurred, of which three were common (prevalence ± 10%): Anisakis simplex, Braunina cordiformis and Hadwenius sp. A. simplex was present in all the dolphins and showed the highest abundance and mean intensity (104.9 individuals/infected host). B. cordiformis was next most common (87%), and Hadwenius sp. third (52.2%). A. simplex was found mostly in the stomach (94.8%), B. cordiformis in the duodenal ampulla (51.4%), and Hadwenius sp. in the stomach (64.5%). The rare species Corynosoma australe (immature specimens) and Pholeter gastrophilus occurred in the stomach. A. simplex and B. cordiformis showed a clumped distribution along the intestine. Brillouin's diversity and evenness indices for the intestinal helminth community were 0.329 and 0.393, respectively. The diversity values and the number of parasite species were within the range for other small cetaceans.
HAS THE AGE AT TRANSITION OF SOUTHERN HEMISPHERE MINKE WHALES DECLINED OVER RECENT DECADES?
Authors: Thomson R. B. , Butterworth D. S. , Kato H. 
Published: August 2006

AbstractThe earplugs of several baleen whale stocks exhibit seasonal growth layers which have been shown for some species to indicate the total age of the animals. A transition from early, irregular layers, to later, more regular layers can be seen in these earplugs, and this is thought to indicate the age at maturity of the whale. The earplugs of Southern Hemisphere minke whales are relatively difficult to read, particularly for the age at transition, and it has been suggested that these readings reflect no more than random allocations by the reader, rather than any real effect. Plots of average transition phase against year of birth (cohort) show a decline in the average age at transition. However, certain factors can result in a downward bias in this trend, particularly when only a short time‐series is available for analysis, as was the case when this trend was first estimated some 15 yr ago. Data collected over 25 yr are now available and are reanalyzed here. A plot of mean age at transition against year of sampling for animals of similar age shows a decline, as does the conventional plot against cohort, suggesting that the decline is real. A model that simulates random allocation of the transition phase by earplug readers yields predictions that show systematic deviations from the data. In contrast, a second model that allows for a real trend in the average age at transition and that takes account of two potentially biasing effects (termed truncation and the fringe effect) fits the data well. A tendency is evident for readers to recognize a transition phase in a greater proportion of the earplugs that they read as they gain experience over time. This is taken into account in the model. This model shows a decline in the average age at transition from roughly 11 for the cohorts of the 1950s to roughly 7 for those of the 1970s. These results suggest that minke whale transition‐phase readings are related to a real signal in the data and are not simply an artefact, and further that there has been a real decline in the age to which this signal corresponds.
ESTIMATING BODY LENGTH OF PYGMY RIGHT WHALES (CAPEREA MARGINATA) FROM MEASUREMENTS OF THE SKELETON AND BALEEN
Authors: Kemper Catherine M. , Leppard Phillip 
Published: August 2006

AbstractVarious parts of the skeleton and/or the longest baleen plate of 46 specimens of Caperea marginata from Australia and New Zealand were measured and related to body length. Of the 32 skull, postcranial and baleen‐plate measurements available, eight were analysed and seven found to be good predictors of body length, by using a curvilinear model describing their relationship with body length. Greatest skull width, supraoccipital length and mandible length had the smallest prediction limits (± 0.28‐0.33 m in small animals, ±0.44‐0.58 m in large animals) when compared with postcranial measurements (scapula length, vertebra 7 centrum width). Baleen‐plate length was also a useful predictor of body length (±0.32‐0.77 m). There was a substantial increase in the arch of the skull as body length increased. Bulla length was not a good predictor of body length, because measurements were highly variable and because the bulla grew little during postnatal life. Physical maturity occurred at body lengths of at least 5.9 m, also the shortest length at which both epiphyses of the humerus and proximal epiphyses of the radius and ulna were fused. Weaning appears to occur at about 3‐3.5 m. The following approximate relative age/length classes were erected: dependent calves, <3.6 m; subadults, 3.6‐5.5 m; adults, >5.5 m. Females were significantly longer than males in the sample of 22 animals greater than 5.9 m, length of the smallest recorded physically mature animal.
GENETIC BASIS AND EVOLUTIONARY SIGNIFICANCE OF VENTRAL SKIN COLOR MARKINGS IN NORTH ATLANTIC RIGHT WHALES (EUBALAENA GLACIALIS)
Authors: Schaeff C. M. , Hamilton P. K. 
Published: August 2006

AbstractApproximately one third of the North Atlantic right whale population has white ventral skin patches. Most white‐marked animals have both a belly and a chin patch, and the distribution of white pigment suggests that the patches represent a single ventral marking that varies in size and location. Population frequencies and cow‐calf inheritance patterns indicate that the white mark is an autosomal recessive trait. There is no evidence to suggest that ventral coloration patterns are currently under selection. White‐marked and black cows appear to experience similar levels of reproductive success based on calving intervals and length of sighting histories. Also, white‐marked animals were equally common among cows and nulliparous adult females and among live vs. dead animals. Male reproductive success could not be tested because calf paternity is not known; white‐marked and black males exhibit similar survival rates. White‐marked cows were more common among females that took some or all of their calves to the Bay of Fundy summer nursery area compared to females that did not visit Fundy. This suggests that female habitat‐use patterns may influence nuclear gene flow. Increased sample sizes and additional markers are needed to further investigate gene flow.
AGE‐LENGTH RELATIONSHIPS IN HUMPBACK WHALES: A COMPARISON OF STRANDINGS IN THE WESTERN NORTH ATLANTIC WITH COMMERCIAL CATCHES
Authors: Stevick Peter T. 
Published: August 2006

AbstractStrandings of previously identified individuals, while rare, provide an opportunity to examine age‐length relationships in humpback whales (Megaptera novacangliae) from the North Atlantic. Ages and lengths of 23 individuals are presented: 11 females and 12 males, 9 of known age and 14 with estimated minimum ages. Lengths ranged from 853 to 1, 430 cm, ages 0.5–17 yr. These individuals were generally smaller and more variable in size at age than reported from commercial catches. Fifteen of the stranded individuals were four years of age or younger, while few of the animals taken by whalers were this young, and these probably represented the larger individuals in these age categories. Thus the data presented herein help to give more definition to the early growth curve for the humpback whale than has previously been available. Growth equations illustrate a difference of about one meter in asymptotic length through age five between stranding and catch data. The close fit of growth models to data from younger and older animals separately and the difficulty of fitting a single growth model to animals of all ages, could indicate that a dynamic or staged growth pattern exists in this species.
USING TREND INDICES FOR ENDANGERED SPECIES
Authors: Eberhardt L. L. , Garrott R. A. , Becker B. L. 
Published: August 2006

AbstractInitial appraisals of the status of endangered large‐mammal populations may have to depend on indices of population trend. Such indices may possibly be improved by using auxiliary variables. Various models were studied for populations of the Florida manatee (Trichechus manatus latirostris), Yellowstone grizzly bear (Ursus arctos horribilis), and Hawaiian monk seal (Monachus schauinslandi). Several criteria for checking validity of the fitted models were considered, and the simpleR2criterion appears to provide useful comparisons. Multiple regression models overestimated the rate of change of the East Coast manatee population as determined from three other sources (a covariance model, a non‐linear model, and the rate estimated from reproductive and survival data). A multiple regression model for grizzly bears using three auxiliary variables exhibited a fairly highR2(0.84) and appeared to provide a better fit than did a non‐linear model. A beach count index for Hawaiian monk seals seemed to be unreliable for year‐to‐year comparisons in contrast to total population counts and estimates from a capture‐recapture method. The use of auxiliary variables for checking and improving trend index data appears feasible and well worthwhile.
EXAMINING THE RISK OF INBREEDING DEPRESSION IN A NATURALLY RARE CETACEAN, THE VAQUITA (PHOCOENA SINUS)1
Authors: Taylor Barbara L. , Rojas‐Bracho Lorenzo 
Published: August 2006

AbstractUncertainty about the magnitude of various risks facing endangered species can paralyze conservation action. The vaquita is a naturally rare porpoise that has declined to the low hundreds of individuals because of gillnet mortality over the past 57 years. No variability in mitochondrial DNA (mtDNA) was found in vaquitas (n= 43). Because reducing gillnet mortality will require strong conservation action, the question was raised whether vaquitas are doomed because of inbreeding depression and whether, therefore, mitigation efforts would be futile. We use simulations to investigate the “doom hypothesis” by first asking whether the current level of genetic variability results from the recent decline or from historical factors. If fixation was historical then deleterious alleles could have been selected out of vaquitas over thousands of years, reducing concerns about inbreeding depression. Simulations showed that fixation most likely resulted from historical rather than recent loss. Of 1,000 simulations done at plausible abundances and mutation rates, 247 (84.3%) fixed before and 46 (15.7%) fixed during the recent decline. Fixation correlates with historical abundance, making it more likely that because vaquitas are fixed, they are also a naturally rate species. However, because studies on purging deleterious alleles have not shown purging to be universally beneficial we also examine the doom hypothesis using data on the response to inbreeding of a wide variety of captive animals. Responses are so variable that the doom hypothesis cannot be affirmed. We further explore whether more data from vaquitas would lead to conclusive results and found that the data required, such as the adult survival rate, will be impossible to obtain. We conclude that because the doom hypothesis cannot be affirmed this risk factor should not delay conservation actions.