bluuebunny/crossref_metadata_2025_split huggingface dataset:
AN INTRAPERITONEAL RADIO TRANSMITTER FOR SEA OTTERS
Authors: Ralls Katherine , Siniff Donald B. , Williams Thomas D. , Kuechle V. B. 
Published: August 2006

AbstractA small intraperitoneal radio transmitter was developed and used successfully in California sea otters. The transmitter weighs about 120 g and has an internal antenna. Thirty‐five implanted transmitters were located for an average of 526 d. The carcasses of five animals that died were recovered; there were no complications associated with the transmitters in these individuals. Reproductive performance of the adult females with implanted transmitters appeared normal. The main advantages of this transmitter are its reliability and long life. It has enabled the collection of significant new information on California sea otters.
INTER‐OBSERVER COUNT DISCREPANCIES IN A SHORE‐BASED CENSUS OF GRAY WHALES (ESCHRICHTIUS ROBUSTUS)
Authors: Rugh David J. , Ferrero Richard C. , Dahlheim Marilyn E. 
Published: August 2006

AbstractEstimations of gray whale abundance have generally assumed that shore‐based observers record all whales migrating through the viewing area during periods uncompromised by visibility. We tested the repeatability of data collected at the standard gray whale census site at Granite Canyon Marine Laboratory in central California by using pairs of observers maintaining independent sighting records. Proximal shore sites were occupied 6 d (60 h) in January 1986 where one team counted 845 whales in 427 groups while the other team counted 990 whales in 477 groups. A comparison of the records showed that the first team missed 290 whales seen by the second team, and the second team missed 204 whales seen by the first team. The total number of whales in the viewing area was calculated for each team by the Petersen estimate, using mutually sighted whale groups as “recaptures”. On average, observers recorded only 79% of the whales. More whales (68%) were missed when entire groups of whales were not seen rather than when groups were undercounted (32%). Visibility did not appear to affect observed rates of missed whales. Whales migrating at intermediate distances from the shore were less often missed than were those > 6 km or < 1 km offshore. This count discrepancy test confirms that an uncorrected calculation of population size for gray whales based on sighting records from solitary observers will be underestimated.
MAJOR DECLINE IN NUMBER OF HARBOR SEALS,PHOCA VITULINA RICHARDSI, ON TUGIDAK ISLAND, GULF OF ALASKA
Authors: Pitcher Kenneth W. 
Published: August 2006

AbstractTugidak Island, located in the Gulf of Alaska, was once the site of one of largest local concentrations of harbor seals (Phoca vitulina richardsi) in the world. This population, which probably consisted of about 20,500 animals in the mid‐1960s declined by about 85% between 1976 and 1988. The population appeared to decline more rapidly during the late 1970s than during the 1980s. Causes for the decline are not apparent. There appear to be both similarities and dissimilarities between this decline and recent declines in abundance of northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumetopias jubatus) in the Bering Sea and Gulf of Alaska.
EFFECTS OF FASTING AND FEEDING ON SERUM UREA AND SERUM CREATININE LEVELS IN POLAR BEARS
Authors: Derocher Andrew E. , Nelson Ralph A. , Stirling Ian , Ramsay Malcolm A. 
Published: August 2006

AbstractPolar bears were held in captivity and fasted for an average of 38 d prior to being fed for three days. Blood samples were collected prior to feeding and then at one and three days post‐feeding in 1984 and at one, four, and seven days post‐feeding in 1985. The ratio of serum urea to serum creatinine varied significantly in 1984, rising from a pre‐feeding mean of 11.0 (SE = 2.6) to 32.0 (SE = 3.2) on the first day post‐feeding and then dropped to 22.8 (SE =3.2) in the last sample. In 1985, the ratio of serum urea to serum creatinine increased from a pre‐feeding mean of 15.8 (SE = 2.3) to 61.2 (SE = 10.6) after three days of feeding and dropped to a mean of 29.2 (SE = 5.1) seven days after feeding ended. Serum urea levels varied over the study period in both years. No significant variation in serum creatinine levels was found in 1984, but in 1985, serum creatinine levels demonstrated significant variation, declining from the pre‐feeding mean of 1.83 mg/dl (SE = 0.29) to 0.96 mg/dl (SE = 0.12) in the last sample.The findings suggest that polar bears can have a low serum urea to serum creatinine ratio, similar to that found in hibernating black bears, or higher ratios after feeding. Polar bears can rapidly return to a fasting serum urea to creatinine ratio after food is withheld. Polar bears may demonstrate urea conservation, similar to that found in black bears, and may be able to move between a fasting and a feeding metabolism based on food availability throughout the year, an adaptation to life on the labile sea ice.
SEX AND AGE SEGREGATION BYPHOCA VITULINA CONCOLORAT HAUL‐OUT SITES DURING THE BREEDING SEASON IN THE PASSAMAQUODDY BAY REGION, NEW BRUNSWICK
Authors: Kovacs Kit M. , Jonas Krista M. , Welke Sylvia E. 
Published: August 2006

AbstractThe size and composition of groups of harbor seals at two haul‐out sites were studied during the breeding season of 1989, in the Passamaquoddy Bay region of Atlantic Canada. Evidence of segregation both by age and sex was found in the distinct composition of the two groups. One group contained mainly males and no pups, and the other had a sex ratio not significantly different from one and contained pups. The proportion of females increased at the nursery site with the onset of birthing in the region while the proportion of males increased through the breeding season at the other site. No increase in the number of adults, in total, was detected over the study period, suggesting that sexual segregation and not a change in haul‐out frequency was responsible for the disparity in the sex structure of the two groups. The proportion of juveniles was significantly greater at the male dominated site than at the nursery site.
POPULATION SIZE AND BREEDING SEASON OF THE ANTARCTIC FUR SEAL ARCTOCEPHALUS GAZELLA AT HEARD ISLAND—1987/88
Authors: Shaughnessy P. D. , Goldsworthy S. D. 
Published: August 2006

AbstractBreeding colonies of the antarctic fur seal Arctocephalus gazella on Heard Island (53°10′S, 73°30′E) are situated on the sheltered northern and eastern coasts on flat vegetated terrain near streams and pools. Pupping in the 1987/88 summer began on 21 November, with 90% of births in 26 d. The median birth date was 11 December. Pup counts at Heard Island made in seven breeding seasons from 1962/63 to 1987/88 show an exponential rate of increase of 21%, which may be inflated due to undercounting in early years. The total of 248 births in 1987/88 represents an exponential increase of 37% since the previous year, but pups may have been undercounted then. Based on the number of pups born, the breeding population is estimated at 870–1,120. During the breeding season, the largest number of animals ashore was 835. Many non‐breeding fur seals began hauling out from early January and 15,000 animals were estimated to be ashore by late February, a fat larger number than expected from the size of the breeding population. Both the breeding and non‐breeding components of the population may be augmented by immigration. The source of immigrants may be undiscovered breeding colonies of this species in the northwestern sector of the Kerguelen Archipelago or the concentration at South Georgia. Further censuses are required at Heard Island to monitor the population growth.
SEXUAL DIMORPHISM IN BOTTLENOSE DOLPHINS FROM THE EAST COAST OF FLORIDA
Authors: Hersh Sandra L. , Odell Daniel K. , Asper Edward D. 
Published: August 2006

AbstractSkulls of 69 bottlenose dolphins (genus Tursiops) from the Indian/Banana River on the east coast of Florida were examined for evidence of sexual dimorphism. The only sexual dimorphism shown by t‐tests on 28 morphological and four meristic skull characters was that males have, on average, more teeth than females in all four arcades. Results of covariance analysis, employed to account for variation in size, indicate minor dimorphism in parietal width of the skull. Twenty body measurements of 29 Tursiops originating in the same area were also analysed for differences between males and females. Statistical results indicate the possibility of sexual dimorphism in the length from the snout to the umbilicus and in flipper width. No evidence was found for differences in overall skull or body length between the sexes.
MORPHOMETRIC COMPARISON OF MINKE WHALES BALAENOPTERA ACUTOROSTRATA FROM DIFFERENT AREAS OF THE NORTH ATLANTIC
Authors: Christensen Ivar , Haug Tore , Wiig ØYstein 
Published: August 2006

AbstractMultivariate statistical analyses of 18 morphometric characters were performed in order to evaluate potential heterogeneity between predefined minke whale stock unit areas in the North Atlantic (West Greenland, Central, and Northeastern stocks). Results from principal component analyses suggested that the data cannot be regarded as random samples drawn from one uniform distribution. The overlap between groups was too substantial, however, to allow a firm conclusion concerning the question of isolated breeding stocks versus a large common breeding pool.
INCIDENTAL CATCH OF HECTOR'S DOLPHIN IN INSHORE GILLNETS
Authors: Dawson Stephen M. 
Published: August 2006

AbstractThe incidental catch of Hector's dolphins (Cephalorhynchus hectori) in gillnets in Pegasus Bay and Canterbury Bight, New Zealand is assessed. From 1984 to 1988, at least 230 Hector's dolphins were killed in groundfish gillnets by commercial and amateur fishermen. Approximately 91% of entanglements occurred from November to February. Seasonality of catch corresponded to increased commercial gillnetting inshore in spring and summer. Most entanglements (89%) occurred within 4 nautical miles (7.4 km) of the shore, and most dolphins (86%) were caught in water less than 20 m deep. The dolphin's summer inshore movement also coincided with high levels of inshore gillnetting by amateur fishermen. The age‐frequency of net‐caught dolphins suggested that young animals were particularly vulnerable to entanglement.
MODELING AGE‐SPECIFIC MORTALITY FOR MARINE MAMMAL POPULATIONS
Authors: Barlow Jay , Boveng Peter 
Published: August 2006

AbstractA method is presented for estimating age‐specific mortality based on minimal information: a model life table and an estimate of longevity. This approach uses expected patterns of mammalian survivorship to define a general model of age‐specific mortality rates. One such model life table is based on data for northern fur seals (Callorhinus ursinus) using Siler's (1979) 5‐parameter competing risk model. Alternative model life tables are based on historical data for human females and on a published model for Old World monkeys. Survival rates for a marine mammal species are then calculated by scaling these models by the longevity of that species. By using a realistic model (instead of assuming constant mortality), one can see more easily the real biological limits to population growth. The mortality estimation procedure is illustrated with examples of spotted dolphins (Stenella attenuata) and harbor porpoise (Phocoena phocoena).
INTERACTIONS BETWEEN KURIL SEALS AND SALMON TRAP NET FISHERY IN THE COASTAL WATERS OF SOUTHEASTERN HOKKAIDO
Authors: Wada Kazuo , Hayama Shin‐Ichi , Nakaoka Toshiyasu , Uno Hiroyuki 
Published: August 2006

AbstractAn annual average of 163 Kuril seals was found dead in two years in salmon trap nets along the coastal waters of the Nemuro Peninsula and adjacent areas. The seal‐caused damage to the total salmon catch at the salmon trap nets was concentrated in some of them, particularly No. 27, where seals killed or injured 5.1% of the catch in 1982, and 1.8% in 1983. Based on the proportion of Kuril seals among the dead seals in the trap nets, it was estimated that Kuril seals damaged 4.7% of the total salmon catch at No. 27 in 1982, and 1.7% in 1983. Not all seals that entered the trap net drowned; some killed or damaged salmon, and then escaped.
SURVIVAL RATES OF PHOTOGRAPHICALLY IDENTIFIED HECTOR'S DOLPHINS FROM 1984 TO 1988
Authors: Slooten Elisabeth , Dawson Stephen M. , Lad Frank 
Published: August 2006

AbstractRe‐sightings of photographically identified individuals were used to estimate survival rates for a free‐living population of Hector's dolphins Cephalorhynchus hectori, a species endemic to New Zealand waters. Most individuals were identified from injuries to the dorsal fin. Consequently, the photographic catalog contained very few young individuals. Our analysis included no newborn calves or yearlings, and provided estimates of survival rates only after the first year of life. We used two complementary methods for calculating survival rates: a modified Jolly‐Seber model, and a simpler method which corrects in a more explicit way for individual dolphins being alive but not sighted. Selection of the most reliable subset of the data had a greater effect on computed survival rates than did the difference between the two methods. We conclude that careful inspection of resighting data before analysis, and, if necessary, selection of a subset, is very important in studies of this kind. Survival rate estimates came from a population which was subject to relatively heavy mortality from gillnet entanglement. Standard errors of the survival rate estimates have been used to assess the conditional probability of population decline given three fertility scenarios. The high probability that the Banks Peninsula Hector's dolphin population was decreasing during the study period (0.78 to 0.99) suggests that gillnet entanglement constituted a serious risk to this population.
SURFACE MORPHOLOGY OF THE FOREBRAIN OF THE BOWHEAD WHALE, BALAENA MYSTICETUS
Authors: Duffield Dennis W. , Haldiman Jerrold T. , Henk William G. 
Published: August 2006

AbstractObservations were made on 11 brains from bowhead whales subsistence‐harvested by Alaskan Eskimos under International Whaling Commission guidelines. This study is part of a larger project to determine the basic morphology of this endangered species. The bowhead brain is similar to other cetacean brains, particularly that of the southern right whale. Long olfactory peduncles are reflected upon the rostrodorsal surface of the cerebral hemispheres. Olfactory bulbs have not been recovered but are presumed to exist since nerve fibers have been identified histologically in the olfactory peduncles. The induseum griseum is evident on the corpus callosum. The hippocampus proper is small but protrudes into the lateral ventricle. The cruciate sulcus runs diagonally across the rostral surface, limiting a small frontal lobe. The structure of the floor of the sylvian fissure varies from a few short gyri radiating toward the circular sulcus to a more extensive and complex two‐tiered arrangement including numerous gyri perpendicular to the gyrus bordering the paleocortex. Pineal‐body‐like tissue was present in one specimen. There is no interthalamic adhesion. The lateral geniculate body is elevated but smaller than the large medial geniculate body. The neurohypophysis was adherent on most brain specimens received.
GROWTH AND DISTRIBUTION OF A SOUTHERN ELEPHANT SEAL COLONY
Authors: Campagna Claudio , Lewis Mirtha 
Published: August 2006

AbstractIn contrast with most southern elephant seal, Mirounga leonina, colonies, births at Península Valdes, Argentina, increased from 7,455 in 1982 to 9,636 in 1990. Colony size during the 1990 breeding season, including pups, was estimated at 19,000. Colony growth may respond to abundant food resources and lack of competitors. The range of distribution of elephant seals in Patagonia has not changed since at least 1972 but the spatial distribution of births along the coastline of Peninsula Valdes has varied. In 1982, 58% of the births occurred in the northeast portion of the Peninsula versus 36% in 1990. Females may prefer to give birth on broad, sandy beaches. In 1982, 56% of the females gave birth on pebble beaches and 44% on sandy beaches. In 1990, 24% bred on pebbles versus 76% on sand. Sand substrate may be preferred by females because it may confer thermoregulatory advantages in relieving heat stress.
SEGREGATIVE MIGRATION OF DALL'S PORPOISE (PHOCOENOIDES DALLI) IN THE SEA OF JAPAN AND SEA OF OKHOTSK
Authors: Amano Masao , Kuramochi Toshiaki 
Published: August 2006

ABSTRACTDall's porpoises from the Sea of Japan population taken by a dolphin fishery vessel were examined. Estimated body lengths at sexual maturity were similar to those for the truei‐type population off the Pacific coast of Japan but larger than those for the offshore dalli‐type in the North Pacific. The Sea of Japan population is known to migrate to the Pacific coast of Japan through Tsugaru Strait and to the Sea of Okhotsk through Soya Strait in summer. From the difference of catch composition, individuals of different reproductive status in this population are considered to have different patterns of summer migration. Most of the individuals which migrate into the Pacific Ocean through Tsugaru Strait are sexually immature, while those migrating into the Sea of Okhotsk are mature. The Sea of Okhotsk is thought to be a breeding area for this population. The calving season is estimated to be May through June, which is earlier than that of the truei‐type off the Pacific coast of northern Japan. This may be an adaptation to lower water temperatures in the Sea of Japan during winter.
DISTRIBUTION and NUMBERS OF STRIPED DOLPHINS IN THE WESTERN MEDITERRANEAN SEA AFTER THE 1990 EPIZOOTIC OUTBREAK
Authors: Forcada Jaume , Aguilar Alex , Hammond Philip S. , Pastor Xavier , Aguilar Ricardo 
Published: August 2006

AbstractA survey was conducted in the summer of 1991 in the western Mediterranean to map the distribution and to estimate the number of striped dolphins surviving the 1990 outbreak of the morbillivirus epizootic. The highest densities of striped dolphins were found in the Alboran Sea and the Ligurian Sea. Total numbers were estimated at 117,880 (SE: 38,962; 95% CI: 68,379–214,800). The mortality resulting from the epizootic is unknown but may have been severe because the mean size of dolphin schools observed during the epizootic outbreak was significantly smaller than that before the event. A return to larger school sizes after the 1990 outbreak is not evidence of a recovery but can be viewed as a regrouping of individuals into schools of a preferred size. Calves were observed in 24.6% of the schools. They were not seen in schools of ten or less but were present in about half the schools of 30 or more dolphins, a result which suggests segregation similar to that seen in populations of this species elsewhere in the world.
DEVELOPMENT, SEXUAL DIMORPHISM, and INDIVIDUAL VARIATION IN THE SKELETON OF THE FINLESS PORPOISE, NEOPHOCAENA PHOCAENOIDES, IN THE COASTAL WATERS OF WESTERN KYUSHU, JAPAN
Authors: Yoshida Hideyoshi , Shirakihara Miki , Takemura Akira , Shirakihara Kunio 
Published: August 2006

AbstractDevelopment, sexual dimorphism, and individual variation were examined in the skeleton of the finless porpoise in the coastal waters of western Kyushu, Japan. Skulls ceased growing by 4 yr. Postcranial skeletons ceased increasing in size at an age older than 11 yr. The finless porpoise was estimated to attain cranial maturity by 4 yr and physical maturity at 14–23 yr. Sexual dimorphism was not detectable in most of the cranial characters but was detected in more than half of the postcranial characters. Females tended to show larger values of postcranial characters. The shape of the pelvic bone was obviously different between males and females. Thus, a discriminant function was proposed to determine sex using measurements of this bone. Individual variation was greatest in the feeding apparatus such as length of the rostrum, and least in the braincase.
BEHAVIORAL RESPONSES OF EAST AUSTRALIAN HUMPBACK WHALES MEGAPTERA NOVAEANGLIAE TO BIOPSY SAMPLING
Authors: Brown M. R. , Corkeron P. J. , Hale P. T. , Schultz K. W. , Bryden M. M. 
Published: August 2006

AbstractThe response of migrating humpback whales to biopsy sampling was investigated off North Stradbroke Island, South East Queensland. Whales were allocated a behavioral category prior to biopsy sampling according to the general behavior of their pod. Behavioral reactions were recorded after each attempt. Sex was determined using a molecular genetic technique.Detectable reactions occurred in 41.6% of successful biopsy attempts, a significantly lower response rate than that reported by two studies carried out on the feeding and breeding grounds of the North Atlantic. There was no difference in the response rate of whales on their northward or southward migration. Pod size was not an important factor in predicting the response of an individual. Females responded to biopsy sampling at a significantly higher rate than males.Our results indicate that a substantial difference in response rate can occur between studies. Factors such as the type of boat used and the prior exposure of whales to human impact may be of importance. Our study suggests that female humpback whales may be particularly responsive to human disturbances. Overall, however, biopsy sampling has minimal impact on humpback whales.
INTRASPECIFIC GENETIC DIFFERENTIATION IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS) FROM SOUTHERN CALIFORNIA AND THE GULF OF CALIFORNIA
Authors: Maldonado Jesús E. , Davila Flavio Orta , Stewart Brent S. , Geffen Eli , Wayne Robert K. 
Published: August 2006

AbstractIntraspecific patterns of mitochondrial DNA sequence variation were determined among California sea lions (Zalophus califomianus californianus) from three colonies along the Pacific coast of southern and Baja California and one colony in the Gulf of California. We found no variation in 368 base pairs (bp) of cytochrome b sequence among 40 sea lions from these localities, but analysis of 360 base pairs of control region revealed eleven genotypes. The four genotypes found in the Gulf of California population were unique and phylogenetically distinct from those found in sea lions along the Pacific coast. The average sequence divergence between Gulf and Southern California genotypes was 4.3%, suggesting a relatively long period of isolation. However, colonies along the Pacific coast, which are less than 200 km apart, shared mtDNA genotypes, indicating that recent genetic exchange has occurred between them. Therefore, we suggest that regional female philopatry exists in California sea lions. Regional boundaries may be related to oceanic currents or patchiness in the distribution of resources. Further research is needed to better understand the underlying causes of genetic differentiation in the California sea lion.
INDICES OF BODY CONDITION AND BODY COMPOSITION IN FEMALE ANTARCTIC FUR SEALS (ARCTOCEPHALUS GAZELLA)
Authors: Arnould John P. Y. 
Published: August 2006

AbstractAn attempt was made to develop simple, inexpensive, rapid means of determining body composition in Antarctic fur seals (Arctocephalus gazella). Measurements of total body water (TBW) and total body lipid (TBL), obtained by hydrogen isotope dilution, were compared to the results of bioelectrical impedance analysis (BIA) and morphometric indices of body condition in 52 adult females. TBW was weakly correlated with BIA measurements of resistance (v= ‐0.30, P < 0.03). Conductor volume (length2/resistance) was more highly correlated with TBW(r= 0.75, P < 0.0001) and the inclusion of mass into the predictive equation improved the correlation further (r= 0.95, P < 0.0001). A body condition index (mass/length) previously used in pinniped studies was positively correlated to TBL (r= 0.77, P < 0.0001) validating its use as a relative index of condition. However, body mass alone was highly correlated to TBW (r= 0.94, P < 0.0001) and appears to provide a simple, rapid means of estimating body composition in adult females. This technique may also be applicable to juvenile male Antarctic fur seals.