bluuebunny/crossref_metadata_2025_split huggingface dataset:
AGE DETERMINATION IN MANATEES USING GROWTH‐LAYER‐GROUP COUNTS IN BONE
Authors: Marmontel Miriam , Nhea Thomas J. , Kochman Howard I. , Humphrey Stephen R. 
Published: August 2006

AbstractGrowth layers were observed in histological preparations of bones of known‐age, known minimum‐age, and tetracycline‐marked free‐ranging and captive Florida manatees (Trichechus manatus latirostris), substantiating earlier preliminary findings of other studies. Detailed analysis of 17 new case histories showed that growth‐layer group (GLG) counts in the periotic bone were consistent with known age, or time since tetracycline administration, but were less reliable in other bones. GLG counts were also made in periotic bones of 1,196 Florida manatees of unknown age found dead from 1974 through 1991. These counts were conducted in order to assess variability and to determine relationships among estimated age, size, sex, and degree of bone resorption. Resorption can interfere with accuracy of GLG counts. This effect does not occur until ages greater than about 15 yr and body lengths greater than 300 cm are attained. GLGs were also observed in periotic bones of Antillean manatees (Trichechus manatus manatus) but were not validated against known‐age specimens. Use of GLG counts in the periotic bone is suitable for application to studies of population dynamics and other age‐related aspects of manatee biology.
ANALYSIS OF CORPORA LUTEA TO ESTIMATE REPRODUCTIVE CYCLES OF WILD HAWAIIAN MONK SEALS (MONACHUS SCHAUINSLANDI)
Authors: Iwasa M. , Atkinson S. 
Published: August 2006

ABSTRACTOvaries from 14 female Hawaiian monk seals, O‐24 yr of age, collected from the northwestern Hawaiian Islands were analyzed by gross and histological examination for the presence of corpora hemorrhagica (CH), lutea (CL), albicantia (CA), and dominant follicles. Seven seals, 5‐24 yr of age, were mature females, and another seven seals, O‐5 yr of age, were immature based on the presence or absence of CL and CA in the ovaries. Two 5‐yr‐old seals did not have CL and CA, but one J‐yr‐old and both 6‐yr‐old seals had CL or CA. In addition, the weight of the more active ovary increased at 5 yr of age, indicating that puberty in these female Hawaiian monk seals occurred about 5 yr of age. The total number of CL and CA was significantly correlated to the ovarian weight, but not age of the seals, indicating that visible CA of Hawaiian monk seals probably degenerate within a year. If an ovulation resulted in pregnancy, we assumed that the resulting CL from that pregnancy persisted throughout gestation and regressed approximately 2 yr after ovulation. However, the CL of pregnancy were not easily differentiated from cyclic CL that did not result in pregnancy. Four of seven mature seals were clearly polyestrous from the analyses of their ovaries and reproductive histories. The remaining three seals were pregnant in previous consecutive years, and we could not positively determine whether they were also polyestrous. The ovaries from Hawaiian monk seals had unusually large, rounded granular cells containing the aging pigment, lipofuscin. These cells were located between loose fibrous tissues in all regressing CL and CA but were not present in any CH.
CLASSIFICATION OF WEDDELL SEAL DIVING BEHAVIOR
Authors: Schreer Jason F. , Testa J. Ward 
Published: August 2006

ABSTRACTMost studies of pinniped diving behavior have manually grouped dives according to similarities in the depth, duration, and appearance of the dive profile. Dives of 15 adult female Weddell seals (Leptonychotes weddellii) were recorded with time‐depth recorders and 39, 119 dives were classified manually and statistically (principal components analysis, discriminant function analysis, cluster analysis, and shape‐fitting algorithms). Four dive types, common to all classification methods, and a fifth dive type, common to two of the methods, represented most of the observed diving behavior. However, a few variations of these dive types, specifically a flat‐bottomed dive determined manually, may have also represented important behavior. Using a combination of these methods, all dives were classified into six dive types, Inspection of dive variables (mean maximum depth, mean duration, and frequency) over time for each dive type, as well as comparisons to previous studies of pinniped diving behavior, indicated different behaviors that the dive types may represent. Hypothesized functions for the dive types were pelagic foraging, benthic foraging, exploration, and traveling. The results indicate that there are strong similarities in diving behavior across various phocid species, that statistical analyses of diving behavior are useful in the analysis of a large data set, and that these analyses reduced human subjective bias in interpreting diving behavior.
PLASMA PROGESTERONE CONCENTRATIONS MEASURED USING AN ENZYME‐LINKED IMMUNOSORBENT ASSAY USEFUL FOR DIAGNOSING PREGNANCY IN HARBOR SEALS (PHOCA VITULINA)
Authors: Gardiner K. J. , Boyd I. L. , Racey P. A. , Reijnders P. J. H. , Thompson P. M. 
Published: August 2006

ABSTRACTWild‐caught female harbor seals (Phoca vitulina) were classified as sexually mature or immature on the basis of standard body length (< 125 cm immature, > 125 cm mature) and plasma progesterone concentrations measured using an enzyme‐linked immunosorbent assay (ELISA), a technique usable in the field. Sexually mature females were classified as pregnant or non‐pregnant on the basis of their plasma progesterone concentrations. Of 28 wild mature female harbor seals caught in the Moray Firth, N.E. Scotland, between the end of February and the end of May, 79% had plasma progesterone concentrations greater than 60 nmol liter−1, the lowest plasma progesterone concentration measured in one of eight females later observed with a pup, and were diagnosed as pregnant. A linear discriminant function, calculated to provide a method of distinguishing pregnant and non‐pregnant females, predicted 100% of non‐pregnant females and 95.8% of pregnant females using plasma progesterone concentration, standard length, and month of capture as parameters. Plasma progesterone concentrations were less than 30 nmol liter−1 in all mature and immature males and immature females. In mature females plasma progesterone concentrations ranged from 0‐318 nmol liter−1.
GENETIC SUBSTRUCTURE OF THE PACIFIC HARBOR SEAL (PHOCA VITULINA RICHARDSI) OFF WASHINGTON, OREGON, AND CALIFORNIA
Authors: Lamont Margaret M. , Vida J. T. , Harvey James T. , Jeffries Steven , Brown Robin , Huber Harriet H. , Delong Robert , Thomas W. Kelley 
Published: August 2006

AbstractGenetic substructure among groups of Pacific harbor seals,Phoca vitulina richardsi, along the western coast of the United States was investigated using mitochondrial DNA sequences. Blood and tissue samples were removed from 86 seals inhabiting Puget Sound and the Pacific coasts of Washington, Oregon, and California. A 320 base‐pair segment of the control region was amplified using the polymerase chain reaction and directly sequenced. These data indicated a high level of diversity. Thirty variable sites were found that define 47 mitochondrial haplotypes. Among groups ofP. v. richardsisampled, 5 haplotypes were shared, but most (42) were unique to a locality. Haplotypic frequency and an Analysis of Molecular Variance (Amova) revealed significant differences (P= 0.001) among regions. Phylogenetic analysis indicated Puget Sound seals possess unique divergent lineages not found in seals from the coasts of Washington, Oregon, and California. These lineages may represent haplotypes from north of Washington, which is consistent with late reproductive timing of harbor seals from Puget Sound.
THE LIFE HISTORY OF FREE‐RANGING ATLANTIC SPOTTED DOLPHINS (STENELLA FRONTALIS): AGE CLASSES, COLOR PHASES, AND FEMALE REPRODUCTION
Authors: Herzing Denise L. 
Published: August 2006

AbstractAtlantic spotted dolphins (Stenella frontalis) were observed underwater and from the surface from 1985 to 1996 and photographed through successive years. Individuals were categorized into age classes by their degree of spotting and color phases. Dolphins spent an average of 3 yr in the two‐tone color phase, 5 yr in the speckled phase, 7 yr in the mottled phase and up to 10 yr or more in the fused phase.Sex ratios were close to parity, with old adults skewed towards females and juveniles and young adults skewed towards males. The average calving interval for 24 females was 2.96 years with a range of 1–5 yr. Females whose calves survived the first year had a significantly longer calving interval (3.56 years). The ages of first parturition for five females were estimated to be 10–12 yr. The age at sexual maturation was estimated to range from 8 to 15 yr.Pregnancy rate fluctuated annually, with an average rate of 0.25 (range 0.07–0.57). Annual average birth rate was 0.08 (range 0.07–0.14), average calf production was 0.33 (range 0.06–0.52), average fecundity was 0.23 (range 0.13–0.30), and average recruitment was 0.06 (range 0.03–0.08). Most females who lost a calf conceived the same or following year.Lactation lasted up to 5 yr, and 45% of visibly pregnant females were also lactating. Age of first parturition was associated with the mottled color phase. Average first‐year mortality rate of calves was 0.24.
ESTIMATION OF BODY MASS IN THE SOUTHERN ELEPHANT SEAL, MIROUNGA LEONINA, BY PHOTOGRAMMETRY AND MORPHOMETRICS
Authors: Bell Cameron M. , Hindell Mark A. , Burton Harry R. 
Published: August 2006

AbstractA simple photographic technique was developed to indirectly estimate body mass data for southern elephant seal (Mirounga leonina) cows (postlactation), yearlings, and immature males and females. Regressions of mass on both photographic and morphometric variables (together and separately) yielded useful, predictable models. Using such variables, the best estimation of the actual mass was for postlactation cows, with a 95% confidence interval of ± 2.66% of the predicted body mass. Although combining photographic and morphometric variables produced the most reliable models specifically for cows and yearlings, the most practical model contained only the morphometric variables length and girth squared. Side area was the best correlated single photographic variable and this corresponded with other studies. Photogrammetry could be useful when animals cannot be sedated and are located on a flat surface, but it does require animals to be motionless when approached. Thus, the procedure may be more suited to bulls rather than other age classes and could have a role in studies where large numbers of mass estimations are rapidly required. If sedation is utilized in smaller animals, then the use of body length and girth is the most suitable indirect mass estimation technique to avoid the use of heavy weighing equipment.
DEVELOPMENT AND HOMOLOGIES OF HEAD STRIPES IN THE DELPHINOID CETACEANS
Authors: Perrin William F. 
Published: August 2006

AbstractOntogeny and variation of head stripes were investigated inStenella attenuata, S. longirostris, andDelphinus delphis. Theeye stripeand theblowhole stripetogether comprise thebridle. TheAnlageof the bridle is a line extending across the back of the head in small fetuses. As the blowhole moves posteriorly and the rostrum lengthens, an inflection point develops in the line above the eye. This point moves forward, creating a progressively greater triangular area between the incipient eye and blowhole stripes. Well before birth, the inflection point is close to the apex of the melon, and the eye and blowhole stripes are narrow and well defined. This process proceeds to varying degrees in the other delphinoids. For example, inPeponocephala electraand inCephalorhynchusspp., the inflection point migrates only part of the way to the apex of the melon, and the resulting “blowhole stripe” remains a broad caplike feature, resembling the state of development in small fetuses ofStenellaandDelphinus. A simple eye spot without a stripe may be primitive, as it occurs in non‐delphinoid cetaceans. Presence of the bridle only in the delphinids and phocoenids may unite them in a clade exclusive of the monodontids.
DENSITY AND HAUL‐OUT BEHAVIOR OF LEOPARD SEALS (HYDRURGA LEPTONYX) IN PRYDZ BAY, ANTARCTICA
Authors: ROGERS T. L. , BRYDEN M. M. 
Published: August 2006

ABSTRACTThe spatial distribution of leopard seals along the fast‐ice edge in the austral spring and summer of 1992 and 1993 in Prydz Bay, Antarctica, was determined by aerial surveys. Fewer individuals were observed within the area, and the seals observed were larger, in 1992 than in 1993. Comparison of the distributions and relative sizes of the seals suggests that there may be an age‐related difference in spatial behavior. The greater degree of separation among older seals may be due to intraspecific aggression increasing with age, a hypothesis supported by the high incidence of intraspecific scarring noted on leopard seals in this region. The seals’haul‐out behavior was negatively related to wind‐chill index.
STOMACH CONTENTS OF LONG‐FINNED PILOT WHALES (GLOBICEPHALA MELAS) STRANDED ON THE U.S. MID‐ATLANTIC COAST
Authors: Gannon Damon P. , Ready Andrew J. , Craddock James E. , Mead James G. 
Published: August 2006

AbstractTen prey taxa were recorded from the stomach contents of eight long‐finned pilot whales (Globicepbala melas) independently stranded along the U.S. mid‐Atlantic coast. Relative importance of prey species was determined by methods that incorporate prey frequencies of occurrence, proportions of numerical abundance, and proportions of reconstructed mass. Separate analyses of trace (free, durable body parts representing well‐digested prey items) and non‐trace (relatively intact prey specimens) food material were conducted in order to address biases caused by differential rates of digestion and passage through the gastrointestinal tract. Different measures of prey importance yielded varying results, but the long‐finned squid (Loligo pealei) was the most important prey species regardless of how prey importance was defined. Fishes were relatively unimportant in the diet. Our results indicate that the diets of western North Atlantic long‐finned pilot whales differ substantially from what has been previously reported in the literature and that results from food‐habits studies that utilize different techniques may not be comparable.
DIVING BEHAVIOR AND PERFORMANCE OF HARBOR PORPOISES, PHOCOENA PHOCOENA, IN FUNKA BAY, HOKKAIDO, JAPAN
Authors: Otani Seiji , Naito Yasuhiko , Kawamura Akito , Kawasaki Masahiro , Nishiwaki Shigetoshi , Kato Akiko 
Published: August 2006

AbstractIn order to monitor the diving behavior of free‐ranging cetaceans, microdataloggers, with pre‐programmed release mechanisms, were attached to the dorsal fins of two female harbor porpoises (Phocoena phocoena) in Funka Bay, Hokkaido, Japan, in 1994. The two loggers were successfully recovered and a total of 141 h of diving data (depth and water temperature in 4,671 dives) was obtained. Both porpoises dived almost continuously, rarely exhibiting long‐term rest at the surface. Maximum dive depths were 98.6 m and 70.8 m, respectively, with more than 70% of diving time at 20 m or less. Most shallow dives were V‐shaped with no bottom time. The V‐shaped dives were significantly shallower in dive depth and shorter in dive duration than U‐shaped dives. Descent rate was not constant during a dive. The deeper the dive depths, the faster the mean descent and initial descent rates. This suggests that porpoises have anticipated the depth to which they will dive before initiating the dive itself.
POPULATION INDEX ESTIMATES FOR THE ST. LAWRENCE BELUGAS, 1973–1995
Authors: Kingsley Michael C. S. 
Published: August 2006

AbstractThe belugas (Delpbinapterus leucas) inhabiting the St. Lawrence estuary were freely hunted until 1979 and thereby much reduced in numbers. In the late 1970s concerns for their future, and for the effect of contaminants, habitat modification, and marine traffic, became acute, and they were declared “Endangered” in 1983.The numerical progress of the population has been monitored since 1973 by continued sample surveys. Nine of 10 surveys were aerial, and of those 9, 7 used high‐altitude aerial photography. Published indices of population size showed an average increase of about 17 belugas per year (SE = 4) and a 1995 smoothed value of about 650 (SE = 40) belugas. This apparent temporal trend might be open to question owing to slight variation in survey methods and in the area covered by different surveys, so factors were developed to correct for differences in survey coverage and in treatment of data and for the effect of hunting on population trajectory. Revised assessments of the population trajectory and of the present smoothed index value changed little as a result. A series of total‐count surveys in 1987‐1992 estimated a decline of about 6 belugas per year, and when they were combined with sample surveys flown in 1984‐1995, an increase of 10 belugas per year was estimated and a 1995 standardized index of about 640 (SE = 43). It appeared that hunting in the 1970s could have consumed all of, perhaps even slightly more than, the potential for natural increase of this population.
KILLER WHALE (ORCINUS ORCA) AUDITORY EVOKED POTENTIALS TO RHYTHMIC CLICKS
Authors: Szymanski M. D. , Supin A. YA. , Bain D. E. , Henry K. R. 
Published: August 2006

AbstractTemporal auditory mechanisms were measured in killer whales (Orcinus orca) by recording auditory evoked potentials (AEPs) to clicks. Clicks were presented at rates from 10/sec to 1,600/sec. At low rates, clicks evoked an AEP similar to the auditory brainstem response (ABR) of other odontocetes; however, peak latencies of the main waves were 3–3.7 msec longer than in bottlenose dolphins. Fourier analysis of the ABR showed a prominent peak at 300–400 Hz and a smaller one at 800–1,200 Hz. High‐rate click presentation (more than 100/sec) evoked a rate‐following response (RFR). The RFR amplitude depended little on rate up to 400/sec, decreased at higher rates and became undetectable at 1,120/sec. Fourier analysis showed that RFR fundamental amplitude dependence on frequency closely resembled the ABR spectrum. The fundamental could follow clicks to around 1,000/sec, although higher harmonics of lower rates could arise at frequencies as high as 1,200 Hz. Both RFR fundamental phase dependence on frequency and the response lag after a click train indicated an RFR group delay of around 7.5 msec. This corresponds to the latency of ABR waves PIII‐NIV, which indicates the RFR originates as a rhythmic, overlapping ABR sequence. The data suggest the killer whale auditory system can follow high click rates, an ability that may have been selected for as a function of high‐frequency hearing and the use of rapid clicks in echolocation.
HEMATOLOGY VALUES OF WILD HARBOR PORPOISES (PHOCOENA PHOCOENA) FROM THE BAY OF FUNDY, CANADA
Authors: Koopman Heather N. , Westgate Andrew J. , Read Andrew J. 
Published: August 2006

AbstractClinical hematology values were determined for 29 harbor porpoises (Phocoena phocoena) released from herring weirs in the Bay of Fundy, Canada. Erythrocyte values exhibited narrow ranges, but there was a high degree of individual variability in counts of white blood cells. Total white cell counts ranged from 2.6 to 15.5 ± 109/liter, with an overall mean of 6.5 ± 2.7 ± 10±/liter. There were significant differences among reproductive classes in mean values of total red blood cells, hematocrit (HCT), mean cell volume (MCV), mean cell hemoglobin (MCHC) and total monocyte count. Wild harbor porpoises had fewer white blood cells, lower relative total number of neutrophils and lymphocytes, and higher percentages of monocytes and eosinophils than reported in the literature for captive porpoises. Compared to published values for other odontocetes, the hemograms of harbor porpoises were most similar to those of Pacific white‐sided dolphins (Lagenorhynchus acutus). These hematology data represent a baseline from free‐ranging harbor porpoises that can be used as a reference for long‐term monitoring of the health of this population and as a tool for rehabilitation facilities.
AGONISTIC BEHAVIOR IN HARBOR SEALS (PHOCA VITULINA) IN RELATION TO THE AVAILABILITY OF HAUL‐OUT SPACE
Authors: Neumann Dirk R. 
Published: August 2006

AbstractThe hypothesis that haul‐out space is a contested resource among harbor seals (Phoca vitulina) was tested by comparing the number of agonistic interactions and the time devoted to them, at a haul‐out with unlimited space and a haul‐out with limited space, in Humboldt County, California. 798 agonistic interactions were recorded in 160 h of observation. The average number of agonistic interactions per seal per hour and the time spent on these interactions were significantly higher at the site with limited haul‐our space (P< 0.05,n= 20). At this restricted site, the frequency of agonistic interactions was positively correlated with seal density (r= 0.61,P< 0.05,n= 20), as was time spent on agonistic interactions (r= 0.84,P< 0.05,n= 20). Size, sex, and age‐class of individuals all influenced agonistic interactions. In 72.5% of displacements, smaller seals were displaced by larger ones. This may support claims that some harbor seal populations maintain a size‐based dominance hierarchy. The results of this study support the hypothesis that there is competition among harbor seals for suitable haul‐out space where this resource is limited. The outcome of these interactions may be predicted, at least in part, by theoretical models on pay‐off asymmetries, resource holding power, and the prior residency effect.
BODY SIZE, SURVIVAL, AND DECLINE OF JUVENILE HAWAIIAN MONK SEALS,MONACHUS SCHAUINSLANDI
Authors: Craig Mitchell P. , Ragen Timothy J. 
Published: August 2006

AbstractIn the mid 1980s half of the entire Hawaiian monk seal species was located at French Frigate Shoals, and this colony may have reached environmental carrying capacity. Since 1989 this colony has declined by 55%, primarily from poor juvenile survival. Only 8%–25% of weaned pups have survived to age 2 during this period, compared to at least 80% between 1984 and 1987. We characterize (1) this drop in survival, (2) a strong, but variable, correlation between survival and size at weaning, (3) interisland differences in size from weaning to age 2 in 1991 through 1993, and (4) decadal‐scale changes in mean measures of size at weaning. We compare observations at French Frigate Shoals with the colony at Laysan Island where abundance is well below historical levels and was therefore expected to be below carrying capacity. At Laysan Island juvenile survival has also been poor (30%‐70%), and the size of weaned pups has decreased during the past decade. Our hypothesis is that poor survival may be due to reduced prey availability at both sites, but particularly at French Frigate Shoals. Evidence to support this hypothesis includes a large increase in total abundance at French Frigate Shoals; reduced size of weaned pups; decreased survival, emaciation, and slower growth rates of juvenile seals; and declining primary productivity. Regardless of cause, the immediate consequences at French Frigate Shoals and Laysan Island, and for the species overall, will likely be poor recruitment and productivity. Because the decline is still in progress, the ultimate consequences for the species' viability are of great concern in light of its already low abundance.