bluuebunny/crossref_metadata_2025 huggingface dataset:
CYCLIC OCULAR HYPERTENSION IN CETACEANS
Authors: Dawson William W. , Schroeder J. Pete , Dawson Judyth C. , Nachtigall Paul E.
Published: August 2006

In the laboratory, intraocular pressure (IOP) was measured in each eye of two adult Tursiops truncatus and one Grampus griseus. Measures were made in alternation between eyes over a time span. Means and standard deviations were calculated. Mean IOP's ranged from 33.4 mm Hg (SD = 2.4) in the male Tursiops to 24.6 (SD = 2.3) in the female Tursiops. IOP in the Grampus was intermediate. Tonograph functions for the Tursiops over periods greater than 25 min had a cyclic character with maxima and minima. These cycles were fitted with a polynomial function with periods of 15 min (female) and 20 to 26 min (male). There was no significant correlation of the IOP variations with time between eyes in either Tursiops. Compared to humans, these cetaceans exhibit clinical ocular hypertension bilaterally. The range of pressures they exhibit, over time, is much greater than reported previously for several terrestrial mammals.
SOUNDS OF A PYGMY RIGHT WHALE (CAPEREA MARGINATA)
Authors: Dawbin William H. , Cato Douglas H.
Published: August 2006

Abstract: This is the first report of recordings of sounds from the pygmy right whale, Caperea marginata. The recordings were obtained in the presence of a juvenile in the harbor at Portland, on the southeastern corner of the Australian continent. Only one type of sound was heard‐a short thump‐like pulse or tone burst with a downsweep in frequency and decaying amplitude, with most energy between 60 and 120 Hz. The pulses occurred predominantly in pairs and once in a trio. The sounds are simpler than those of most baleen whales, but they show some similarity in characteristics. Source levels are in the lower end of the range determined for other species. There was no evidence to indicate the purpose of these sounds.
BILIARY BILE ACID COMPOSITION OF THE PHYSETERIDAE (SPERM WHALES)
Authors: Hagey Lee R. , Odell Daniel , Rossi Steven S. , Crombie Diane L. , Hofmann Alan F.
Published: August 2006

Abstract: The bile acid composition of bile obtained from the hepatopancreatic ducts of three species of sperm whales (Cetacea: Physeteridae) was investigated. Bile acids were isolated by adsorption chromatography and analyzed by sequential HPLC, SIMS, and GLC‐MS. In each species the dominant bile acids were deoxycholic acid (a secondary bile acid formed by bacterial 7α‐dehydroxylation of cholic acid), and chenodeoxycholic acid (a primary bile acid) which together composed more than 86% of biliary bile acids in all three species. In Physeter catodon (sperm whale) deoxycholic acid constituted 79%, and in Kogia breviceps (pygmy sperm whale) it was 61% of biliary bile acids. The sperm whale, which differs from other whales in having a remnant of a large intestine, is the second mammal identified to date in which deoxycholic acid is the predominant bile acid. The high proportion of deoxycholic acid indicates that in the Physeteridae, anaerobic fermentation occurs in its cecum, and that bile acids undergo enterohepatic cycling. Also found were minor proportions of cholic acid, as well as bacterial derivatives of chenodeoxycholic acid (ursodeoxycholic acid, lithocholic acid, and the 12β‐epimer of allo‐deoxycholic acid). Bile acids were conjugated with taurine in all species; however, in the sperm whale (Physeter) glycine conjugates were present in trace proportions. The bile acid hydroxylation pattern (12α‐ but not 6α‐hydroxylation), lack of primary 5α‐ (allo) bile acids, and presence of glycine conjugated bile acids suggests the possibility that sperm whales originated from ancient artiodactyls.
SPERM WHALES TAGGED WITH TRANSPONDERS AND TRACKED UNDERWATER BY SONAR
Authors: Watkins William A. , Daher Mary Ann , Fristrup Kurt M. , Howald Terrance J. , Di Sciara Giuseppe Notarbartolo
Published: August 2006

Abstract: Two sperm whales tagged with acoustic transponder tags were tracked by sonar during a cruise from 16 to 30 October 1991 in the southeast Caribbean west of Dominica Island. The whales dove to depths of 400–600 m and more, including a dive to 1,185 m and one possibly to 2,000 m. They were tracked for periods of 3–14 h, over distances of 8.5–40 km. The tagged whales were found together four and eight days after tagging, and were tracked simultaneously for 13 h, over 31 km. Whale movements on different days at the surface averaged from 0.68 to 0.82 m/set, with dive descent rates from 0.82 to 1.13 m/set, ascent rates from 0.74 to 1.16 m/set, and horizontal movement during dives from 0.76 to 1.29 m/set. Dives lasted from 18 min to 1 h and 13 min, averaging 33 and 41 min on different days. Every track ended when tag signals became obscured at night by dense biological scatterers concentrated in offshore areas where the whales were diving. Both tagged whales appear to have been males of 15 and 11m, each dominant in different groups; but when together the larger whale was dominant, as evidenced by chases and agonistic vocalizations. The whales did not appear to react to the tags or to the sounds associated with tracking (30, 32, and 36 kHz).
REPRODUCTIVE CHARACTERISTICS OF FEMALE SEA OTTERS
Authors: Jameson Ronald J. , Johnson Ancel M.
Published: August 2006

Abstract: Several important aspects of reproduction in the female sea otter, such as gestation, pupping frequency, period of pup dependency, and annual pupping rate, were unclear when this study was begun. We present data from 75 tagged adult females that indicate gestation is variable, but on average is about 6 months, the length of pup dependency is 6 mo, thus the pupping interval is usually 12–13 mo. Most females breed for the first time in their fifth year of life. About 85–90% of adult females pup in a given year.
IMMOBILIZATION OF WALRUS WITH ETORPHINE HYDROCHLORIDE AND ZOLETIL®
Authors: Griffiths David , Wiig ØYstein , Gjertz Ian
Published: August 2006

Abstract: The paper describes the use of the drugs Zoletil® and etorphine for the immobilization of walrus (Odobenus rosmarus rosmarus) for attachment of satellite telemetry equipment. Three animals weighing approximately 1,500 kg each were injected intramuscularly with Zoletil® at a dose between 1.4 and 2.2 mg/kg. One walrus died while the two others were adequately restrained. The induction time was between 14 and 29 minutes and the effect lasted for 75‐220 min.

Thirty‐eight animals of weight 900‐1,500 kg were darted intramuscularly with etorphine at a dose between 3.3 and 8 mg/kg. Thirty‐six were immobilized although one died later. The induction time for etorphine was two to ten minutes. The action of this drug was terminated with an injection of the antidote di‐prenorphine.

The use of etorphine was accompanied by convulsive movements and apnoea while Zoletil® produced a gradual and smooth entry into and withdrawal from immobilization.
VOCALIZATIONS OF A CAPTIVE JUVENILE AND FREE‐RANGING ADULT‐CALF PAIRS OF BRYDE'S WHALES, BALAENOPTERA EDENI
Authors: Edds Peggy L. , Odell Daniel K. , Tershy Bernie R.
Published: August 2006

Abstract: Vocalizations were recorded from a captive juvenile Bryde's whale, Balaenoptera edeni, that stranded off the gulf coast of Florida (Pinellas Co.) and was held at Sea World of Florida. The most common vocalization was a pulsed moan with durations of 0.5–51 set and acoustic energy from 200–900 Ht. Although these sounds are unlike any reported previously from this species, there are similarities to moans recorded opportunistically during a feeding study of free‐ranging B. edeni in the Gulf of California (GOC). The pulsed moans recorded from Bryde's whale adults in the GOC were shorter in duration (0.7–1.4 set) than those recorded from the captive juvenile, but the frequencies were similar (165–875 Hz). In addition, a series of discrete, regularly spaced pulses (interpulse interval = 0.5–1.0 set, 700–950 Hz) were recorded only in the presence of Bryde's whale calves in the GOC.

Pulse rates produced by the captive juvenile (20–70 pulses/set) were intermediate between those recorded in the presence of GOC adults (60–130/sec) and calves (10–20/set). With these limited data it is not possible to determine to what extent the intermediate qualities of the juvenile call reflect maturational differences in the sound production apparatus, a phase of learning to vocalize like an adult, or the characteristics of a context‐dependent call not recorded in the GOC.
SURVIVAL RATES FOR THE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)
Authors: Gilmartin William G. , Johanos Thea C. , Eberhardt L. Lee
Published: August 2006

Abstract: Endangered Hawaiian monk seal (Monachs schauinslandi) pups at all the major breeding islands in the Northwestern Hawaiian Islands have been tagged since the early 1980s. Pups were double flipper tagged as soon as possible post‐weaning. With few exceptions, an extensive tag resighting effort was conducted annually at the same islands. These resighting data were used to estimate seal survival rates from the time of tagging to age one at all locations using the ratio of seals alive in the second year to number of pups tagged. These survival rates among the islands, from weaning to age one, averaged over the years of the study, ranged from 0.80 to 0.90. For young seals over age one, capture‐recapture methods were used to calculate survival pooled through several years, and these rates ranged from 0.85 to 0.98. At French Frigate Shoals and Laysan Island, the higher numbers of tagged pups allowed separate estimates of male and female survival to be calculated. These rates suggested that survival of immature females was better than males. Beginning in 1989, survival of immature seals at French Frigate Shoals declined sharply.
NEW ZEALAND HERD STRANDING SITES DO NOT RELATE TO GEOMAGNETIC TOPOGRAPHY
Authors: Brabyn Mark , Frew Richard V. C.
Published: August 2006

Abstract

Recent theories relating cetacean stranding sites to geomagnetic topography were tested for the New Zealand coastline. New Zealand herd strandings showed no relationship to either perpendicular geomagnetic contours or magnetic minima, nor did whales appear to be avoiding magnetic gradients. Single‐live stranding sites also showed no geomagnetic relationship.
ANNUAL REPRODUCTIVE CYCLE OF THE FEMALE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)
Authors: Johanos Thea C. , Becker Brenda L. , Ragen Timothy J.
Published: August 2006

Abstract: The annual reproductive cycle is described for the adult female Hawaiian monk seal (Monachus schauinslandi) from data collected at Laysan Island (1982–1991) and Lisianski Island (1982–1983) in the Northwestern Hawaiian Islands. Pupping, lactation, weaning, and molting were directly observed, while mating was rarely observed and was, therefore, inferred from the occurrence of mounting injuries and from adult male and female association patterns. Pooled birth rates during the study period were 0.544 for all adult‐sized females and 0.675 for females parous in earlier years. For parturient females, pupping peaked in late March and early April, weaning in May, mounting injuries in May and June, and molting in July. For non‐parturient females, the median mounting injury and molting dates occurred 17 and 28 days earlier, respectively. Pupping date set the timing of subsequent events in the annual cycle, but the timing of those events was adjusted by loss of the pup or poor physical condition of the female. Individual pupping patterns varied widely. The mean interval for births in consecutive years was 381 days; females that pupped in consecutive years gave birth later each season. Conversely, females who skipped a year or more gave birth earlier their next pupping season.
CETACEANS OF THE NORTHERN GULF OF CALIFORNIA: DISTRIBUTION, OCCURRENCE, and RELATIVE ABUNDANCE
Authors: Silber Gregory K. , Newcomer Michael W. , Silber Patricia C. , Pérez‐Cortés M. Héctor , Ellis Graeme M.
Published: August 2006

Abstract

A total of 1,715 km of boat‐based surveys and 1,521 km of aircraft‐based surveys was conducted from 1986–1989 to assess the distribution, relative abundance, and ecological relationships of cetaceans in the northern Gulf of California. Seven cetacean species were seen; in decreasing frequency of groups encountered they were: bottlenose dolphins, Tursiops truncatus; vaquitas, Phocoena sinus; common dolphins, Delphinus delphis; fin whales, Balaenoptera physalus; Bryde's whales, B. edeni; gray whales, Eschrichtius robustus, and killer whales, Orcinus orca. Common dolphins were numerically dominant and bottlenose dolphins were seen most often. Bryde's whales and vaquitas had the smallest group sizes. In general, the odontocete cetaceans were separated spatially, whereas the distribution of Bryde's and fin whales overlapped considerably.
DIGESTIBILITY OF CRUSTACEANS and CAPELIN IN HARP SEALS (PHOCA GROENLANDICA)
Authors: Mårtensson P.‐E. , Nordøy E. S. , Blix A. S.
Published: August 2006

Abstract

Gross energy intake (GEI), apparent digestible efficiency (%DE), and body‐mass change were studied both in recently weaned and in subadult harp seals fed capelin (Mallotus villosus) and crustaceans (Parathemisto libellula and Thysanoessa sp.) ad lib. The median %DE of Parathemisto libellula (with a wet‐weight energy density (ED) of 3.9 kJ/g) and Thysanoessa sp. (ED: 2.3 kJ/g) was 81% and 83%, respectively, while the median %DE of capelin (ED: 8.6 kJ/g) was 94% and 93% for subadult harp seals and one harp seal pup, respectively. No correlation between age and %DE was obtained (P > 0.05). Despite ad lib. access to the food, the harp seal pups were unable to maintain body mass while on a crustacean diet, and it is therefore suggested that harp seal pups most likely must supplement their crustacean diets with fish to maintain growth.
ECHOLOCATION RATES OF TWO HARBOR PORPOISES (PHOCOENA PHOCOENA)
Authors: Akamatsu Tomonari , Hatakeyama Yoshimi , Kojima Takahito , Soeda Hideo
Published: August 2006

Abstract

The rate of occurrence of click trains of two harbor porpoises (Phocoena phocoena) were counted during 14 nights. We developed an echolocation signal detection system that was harnessed to a porpoise and activated a light when the animal emitted an echolocation signal. This device, referred to as a click‐light, detects echolocation signals above 150 dB re 1 μPa in the 28–180 kHz range. Echolocation rates, i.e., occurrences of click trains, changed frequently, ranging from 0 to 25 per minute. Echolocation rates were affected by feeding, individual difference, and enclosure type such as the net enclosure and the pool. The porpoise echolocation rates seemed to show acclimation.
A COMPARISON OF SOME CYCLOHEXAMINE BASED DRUG COMBINATIONS FOR CHEMICAL RESTRAINT OF SOUTHERN ELEPHANT SEALS (MIROUNGA LEONINA)
Authors: Woods Rupert , McLean Stuart , Nicol Stewart , Burton Harry
Published: August 2006

Abstract

This study compared the effects of drug combinations commonly used for chemical restraint of southern elephant seals. The combinations were: ketamine and diazepam, ketamine and midazolam, ketamine and xylazine, and tiletamine and zolazepam. The main aims were to gather basic information regarding the response of the animals to the different combinations, and to determine which were most useful for routine chemical restraint. All drug combinations could be used safely although apnea and whole‐body shaking occurred with each. There were significant differences in several of the responses measured. Poor muscle relaxation and prolonged apnea were associated with ketamine and diazepam use. Animals given ketamine and xylatine were more depressed, took longer to recover, had a higher incidence of thermoregulatory problems, and lower heart rate than after other combinations. Ketamine and midazolam and tiletamine and zolazepam produced fewer complications than the other drug combinations, and tiletamine and zolazepam showed greater predictability of response and ease of use, making it preferable for use by people with little experience in anesthesia of elephant seals.
FEEDING, SOCIAL AND MIGRATION BEHAVIOR OF BOWHEAD WHALES, BALAENA MYSTICETUS, IN BAFFIN BAY VS. THE BEAUFORT SEA—REGIONS WITH DIFFERENT AMOUNTS OF HUMAN ACTIVITY
Authors: Richardson W. John , Finley Kerwin J. , Miller Gary W. , Davis Rolph A. , Koski William R.
Published: August 2006

Abstract

This paper compares the behavior of bowhead whales of the Davis Strait/Baffin Bay stock, as observed along the east coast of Baffin Island in 1979–1986, with behavior of the Bering/Chukchi/Beaufort Sea stock observed in the Beaufort Sea in 1980–1986. All data used here were collected during late summer and early autumn in the absence of acute human disturbance. The behavioral repertoires of the two populations were similar. However, quantitative differences were found for whales engaged in all three activities studied: (1) Bowheads feeding in deep water off Isabella Bay, Baffin Island, had longer dives and surfacings, on average, than noted for bowheads feeding in the Beaufort Sea. (2) Among whales socializing in shallow water, we saw sexual interactions more often at Isabella Bay than in the Beaufort Sea. Calls emitted by socializing whales off Baffin Island were similar to those heard in the Chukchi and Beaufort Seas. However, pulsed tonal calls were longer off Baffin Island, and previously undescribed mechanical “crunch” sounds were recorded there near socializing bowheads. (3) During autumn migration, “fluke‐out” dives were less common, and dive durations were longer, in the Beaufort Sea than off Baffin Island (P<0.001). Multivariate and other analyses indicated that some but not all differences can be ascribed to regional differences in the natural environment or in whale activities, However, during 1974–1986, Bering/Chukchi/Beaufort bowheads were exposed to more industrial, hunting and other human activity than Davis Strait/Baffin Bay bowheads. The “inconspicuous” behavior during autumn migration in the Beaufort may have been attributable to human activities, but causative links cannot be isolated.
DETECTION OF SEA OTTERS IN BOAT‐BASED SURVEYS OF PRINCE WILLIAM SOUND, ALASKA
Authors: Udevitz Mark S. , Bodkin James L. , Costa Daniel P.
Published: August 2006

Abstract

Boat‐based surveys have been commonly used to monitor sea otter populations, but there has been little quantitative work to evaluate detection biases that may affect these surveys. We used ground‐based observers to investigate sea otter detection probabilities in a boat‐based survey of Prince William Sound, Alaska. We estimated that 30% of the otters present on surveyed transects were not detected by boat crews. Approximately half (53%) of the undetected otters were missed because the otters left the transects, apparently in response to the approaching boat. Unbiased estimates of detection probabilities will be required for obtaining unbiased population estimates from boat‐based surveys of sea otters. Therefore, boat‐based surveys should include methods to estimate sea otter detection probabilities under the conditions specific to each survey. Unbiased estimation of detection probabilities with ground‐based observers requires either that the ground crews detect all of the otters in observed subunits, or that there are no errors in determining which crews saw each detected otter. Ground‐based observer methods may be appropriate in areas where nearly all of the sea otter habitat is potentially visible from ground‐based vantage points.
MAXIMUM NET PRODUCTIVITY LEVEL ESTIMATION FOR THE NORTHERN FUR SEAL (CALLORHINUS URSINUS) POPULATION OF ST. PAUL ISLAND, ALASKA
Authors: Ragen Timothy J.
Published: August 2006

Abstract

The goal of this study was to assess the maximum net productivity level for the northern fur seal (Callorhinus ursinus) population of St. Paul Island, Alaska. Definitive determination of this level is not possible due to uncertainty in life table parameters and density‐dependent changes in those parameters. To account for such uncertainty, repetitive numerical simulations were used to generate frequency distributions of estimates for the maximum net productivity level and related population parameters. This approach systematically varied simulation input parameters, ran a separate simulation with each input parameter combination, and validated the simulations on the basis of comparison with historical observations. Results from validated simulations were compiled in frequency distributions to provide a measure of confidence for MNPL estimates. The distributions confirm that this population is probably well below its maximum net productivity level. Because they reflect the uncertainty in our understanding of northern fur seal population dynamics, these distributions are a more realistic basis for management than single point estimates.
AN ASSESSMENT OF CHANGES WITH TIME IN THE MARKING PATTERNS USED FOR PHOTOIDENTIFICATION OF INDIVIDUAL SPERM WHALES, PHYSETER MACROCEPHALUS
Authors: Dufault Susan , Whitehead HAL
Published: August 2006

Abstract

We observed changes with time in the patterns of characteristic fluke markings used to identify sperm whales. Changes were categorized as minor, moderate, or major based on their severity. These change types were found to occur at rates of 0.9%, 11.8%, and 1.3% per individual per year, respectively. Gain and loss rates for each of seven different mark types were also calculated. The highest estimated rate was the gain of small nicks at 0.08 per individual per year. Most individuals identified by us possess at least a few characteristic marks and, therefore, changes of the type observed in this study are unlikely to severely affect their recognizability. For all but one mark type, gain rates were higher than loss rates, indicating that individuals may be accumulating marks with age. Over long periods this could eventually make individuals unrecognizable, with the result that population sizes calculated from these data may be overestimated. As long as photoidentification studies are conducted sufficiently often, and these changes are as gradual as they appear to be, this problem should be minimal.
REPRODUCTION IN THE FEMALE SUBANTARCTIC FUR SEAL, ARCTOCEPHALUS TROPICALIS
Authors: Bester Martháan N.
Published: August 2006

Abstract

The reproductive tracts of 89 female subantarctic fur seals, taken at Gough Island between November 1977 and October 1978, were examined. Females started ovulating at age 4 yr and all 6‐yr‐old females were sexually mature. They are mono‐ovulatory, alternating between ovaries, and only single embryos were found. Females older than 13 yr (n= 11) showed poor follicular development and some failed to ovulate. The gestation period (first recorded ovulation to first recorded birth) was 360 d, while delayed implantation (first recorded ovulation to first recorded implantation) lasted for 139 days. Follicle numbers in the functional ovary declined sharply after ovulation while the corpus luteum increased in size until at least 1 mo prior to parturition. The number of follicles in the contralateral ovary increased after midwinter (June/July), and the mean size of the largest follicles peaked prior to ovulation in December. The mean size of the largest follicles increased in both ovaries near implantation time, after reaching a low subsequent to, ovulation. The regressing corpus albicans, conspicuous for approximately 3 mo after parturition, could not be detected macroscopically within one year postpartum. Subantarctic fur seals at Gough Island have a distinct postreproductive class of older females. The pregnancy rate for all females ≥4 yr of age was 79%, and it was 84.5% for the sexually mature group of ≥6 yr of age, while the mean age at puberty was 4.80 yr.
BLOOD CHEMISTRY OF WILD HARBOR PORPOISES PHOCOENA PHOCOENA (L.)
Authors: Koopman H. N. , Westgate A. J. , Read A. J. , Gaskin D. E.
Published: August 2006

Abstract

Blood chemistry values were measured from 31 harbor porpoises (Phocoena phocoena) released from herring weirs in the Bay of Fundy, Canada. Sodium, phosphorus, calcium, chloride, magnesium, total protein, albumin, globulin, urea, cholesterol, serum osmolality, and alanine aminotransferase levels fell within ranges reported for captive harbor porpoises and other odontocetes. Glucose, potassium, creatine kinase, aspartate aminotransferase, hemoglobin, thyroxine, bilirubin, and alkaline phosphatase levels were generally higher than those reported for captive odontocetes. Cortisol and creatinine levels were significantly higher (P= 0.0356 and 0.0174, respectively) in porpoises that were handled for longer periods and fitted with electronic tags (mean cortisol value = 314 ± 107 nmol/L, mean creatinine value = 94 ± 14 μmol/L) than those receiving roto‐tags (mean cortisol value = 222 ± 82 nmol/L, mean creatinine value = 75 ± 15 μmol/L). A more controlled study of duration of handling, time spent out of water, degree of manipulation, and method of tag attachment is required to identify which factors are responsible for the stress response.
DOLPHIN THYROID AND ADRENAL HORMONES: CIRCULATING LEVELS IN WILD AND SEMIDOMESTICATED TURSIOPS TRUNCATUS, AND INFLUENCE OF SEX, AGE, AND SEASON
Authors: St. Aubin D. J. , Ridgway S. H. , Wells R. S. , Rhinehart H.
Published: August 2006

Abstract

Biological and environmental influences on circulating adrenal and thyroid hormones were investigated in 36 wild and 36 semidomesticated Atlantic bottlenose dolphins, Tursiops truncatus, matched by age, sex, and time of year when the samples were collected. Serum concentrations of thyroxine (free [fT41 and total [tT4]), triiodothyronine (free [fT3], total [tT3], and total reverse [rT37), cortisol, and aldosterone were determined by radio‐immunoassay, Wild female dolphins had significantly higher levels of tT4, fT4 and fT3, an effect that was possibly related to reproduction and lactation. Semidomesticated females had higher tT3 than their wild counterparts. fT4 declined with age in wild dolphins, whereas rT3 was greatest in the older animals. Cortisol and aldosterone were both higher in wild animals sampled after a variable interval of up to four hours after encirclement by capture net. The pattern of adrenal hormone release suggested a mild stress response. Levels of both adrenal hormones were low in semidomesticated dolphins conditioned to present voluntarily their tails for blood sampling, an approach that appears to yield specimens representative of resting values for these constituents.
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

Abstract

Growth 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

Ovaries 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

Most 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

Wild‐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

Abstract

Genetic 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

Abstract

Atlantic 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

Abstract

A 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

Abstract

Ontogeny 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

The 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

Abstract

Ten 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

Abstract

In 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

Abstract

The 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

Abstract

Temporal 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

Abstract

Clinical 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

Abstract

The 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.