bluuebunny/crossref_metadata_2025_split huggingface dataset:
SPERM WHALE DIVES TRACKED BY RADIO TAG TELEMETRY
Authors: Watkins William A. , Daher Mary Ann , Dimarzio Nancy A. , Samuels Amy , Wartzok Douglas , Fristrup Kurt M. , Howey Paul W. , Maiefski Romaine R. 
Published: August 2006

AbstractDives of a 12‐m sperm whale (Physeter catodon Linnaeus, 1758) were tracked in the southeast Caribbean by long range, 30 MHz radio tag with dive‐profile telemetry over 4.6 d, 26 April‐1 May 1995. Over the 295‐km track, average speed was 0.7 m/sec (2.6 km/h). Of 158 dives (defined as submergences longer than 3 min), 65 were shallow (<200 m). The 93 deep dives averaged 990 m (range 420–1,330 m) in depth, and 44.4 min in duration (range 18.2–65.3 min). Water depth was at least 200 m deeper than the whale dive depth. The whale was engaged in activities at or near the surface, shallow dives, and deep dives during 22.6%, 23.4%, and 54% of the time, respectively. Depth and duration of dives were correlated, but there was little relationship between the length or depth of dives with the duration of surfacings either before or after dives. Deep dives occurred day and night. In 44.4% of the deep dives, the vertical movement of descents and ascents was interrupted at intermediate depths, lengthening these dives by an average of 10.8 min. During dives without stops at intermediate depths, descents averaged 11 min at 1.52 m/sec, and ascents averaged 11.8 min at 1.4 m/sec.
GEOGRAPHIC VARIATION IN SKULL MORPHOLOGY OF ADULT STELLER SEA LIONS (EUMETOPIAS JUBATUS)
Authors: Brunner Sylvia 
Published: August 2006

AbstractData from cranial specimens of adult E. jubatus were analyzed to compare intraspecific morphology of skulls. Males and females were grouped separately to avoid bias from sexual dimorphism. Geographic variation was observed in adult male E. jubutus, indicating the potential presence of three morphologically disparate groups: those from Alaska, those from California, and those from Japan and Russia. Although sample sizes were small, results from cluster and discriminant function analyses indicated that specimens from eastern and western Alaska were morphologically similar, and that the most divergent specimens for the species appeared to be those from Japan. Skulls from Alaska possessed a typically longer, less robust skull, whereas those from Japan appeared smaller, yet most robust. Skulls from California were intermediate.
INVESTIGATING THE BIASES IN THE USE OF HARD PREY REMAINS TO IDENTIFY DIET COMPOSITION USING ANTARCTIC FUR SEALS (ARCTOCEPHALUS GAZELLA) IN CAPTIVE FEEDING TRIALS
Authors: Staniland I. J. 
Published: August 2006

AbstractThe analysis of pinniped scats has been used to quantify their diet, using prey remains to identify species and to estimate the numbers and sizes of prey consumed. There are, however, potential biases involved with scat analysis and, for this method to be used successfully, these biases need to be quantified. Thirty‐six Antarctic fur seals (Arctocephalus gazella) were fed meals of exclusively either fish, squid, or krill and their scats were collected and analyzed. The major sources of error in the analysis of prey remains from scats were the differential erosion and passage rate of items in relation to their size. However, using simple correction functions, such as those which model otolith erosion, it is possible to reduce these errors. Using plastic beads as dietary markers showed recovery rates were negatively related to their size. Larger squid beaks had lower recovery rates than smaller beaks, but there was no size‐related bias in the recovery rates of krill carapaces. Only 33% of the squid beaks and 27% of the otoliths originally fed were recovered from the scats. Recovery rates were greater for squid (77%) and fish (50%) eye lenses and these structures gave a better estimate of numbers eaten. Differences found between experimentally derived and published regression equations (used to calculate prey sizes eaten from prey remains) highlights the need for regression equations based on local prey characteristics, if these are to be used with any success to describe the prey eaten.
HAWAIIAN MONK SEALS (MONACHUS SCHAUINSLANDI) FORAGING IN DEEP‐WATER CORAL BEDS
Authors: Parrish Frank A. , Abernathy Kyler , Marshall Gregory J. , Buhleier Birgit M. 
Published: August 2006

AbstractPlans to harvest deep‐water corals in the remote Northwestern Hawaiian Islands, close to populations of endangered Hawaiian monk seals (Monachus schauinslandi), have raised concerns about the seals' use of deep‐water habitats. Movements and diving patterns of seals studied at French Frigate Shoals (FFS) Atoll indicated two areas where five males out of 33 instrumented seals dove deep enough (300–500 m) to encounter commercially sought deep‐water corals. Submarine surveys conducted at each location found beds of gold (Gerurdia sp.) and pink (Corallium sp.) precious coral suggesting an overlap between the foraging habitat of some seals and the target of the coral fishery. Areas adjacent to the coral beds that were visually censused using submersibles showed significantly fewer precious corals. Precious coral beds were not found on previous submarine surveys at other regions around FFS, supporting the notion that seals were selecting the areas with corals as forage habitat. Five male seals were fitted with back‐mounted video cameras to document feeding among precious corals. None of the five seals dove deep enough to encounter precious corals (>300 m). However, three of the seals visited beds of black coral (Cirrhipdhes sp.) at shallower depths (∼ 80 m). One seal was observed revisiting the black coral beds on three successive nights to feed on fish hiding among the coral stems.
TRENDS IN MANATEE (TRICHECHUS MANATUS LATIROSTRIS) COUNTS AND HABITAT USE IN TAMPA BAY, 1987–1994: IMPLICATIONS FOR CONSERVATION
Authors: Wright Irene E. , Reynolds John E. , Ackerman Bruce B. , Ward Leslie I. , Weigle Bradley L. , Szelistowski William A. 
Published: August 2006

AbstractAerial surveys (n= 88) were used to document locations and count sightings of manatees (Trichechus manatus latirostris) in the inshore waters of Tampa Bay, Florida, between November 1987 and May 1994. We made 5,358 sightings of manatees in 1,958 groups. Calves represented 8% of the manatees sighted. Counts were significantly higher in winter (x̄= 79,n= 29 flights) than in non‐winter (x̄= 46,n= 47) months. Counts of manatees in winter increased significantly during the study, but warm‐season counts did not. Regression models demonstrated a relationship between counts and environmental factors. Year‐round counts were related to air temperatures and seasons, with highest counts in winter. However, in the winter season, counts were significantly correlated only with wind speed, not air temperature. Yearround counts were predicted to be curvilinear with highest counts at 15°C average air temperature. Areas used differed with season: in cold weather, 76% of all sightings occurred in zones with warm‐water sources. High‐use areas were identified for summer months. Spatial filter analysis was used to compare manatee density in high‐use areas between two two‐year time periods. The data indicate that (1) manatee use of Tampa Bay was high and increasing in winter, (2) there are particular zones of the bay where conservation of manatees and habitat should be a priority, and (3) sufficient information has been collected for management agencies to develop and implement manatee protection plans.
POPULATION GENETIC STRUCTURE OF FINLESS PORPOISES, NEOPHOCAENA PHOCAENOIDES, IN CHINESE WATERS, INFERRED FROM MITOCHONDRIAL CONTROL REGION SEQUENCES
Authors: Yang Guang , Ren Wenhua , Zhou Kaiya , Liu Shan , Ji Guoqing , Yan Jib , Wang Limin 
Published: August 2006

AbstractSeven hundred and twenty base pairs (bp) of the mitochondrial control region from 73 finless porpoises, Neophocaena phocaenoides, in Chinese waters were sequenced. Thirteen variable sites were determined and 17 haplotypes were defined. Of these, 5 and 7 were found only in the Yellow Sea population and the South China Sea population, respectively, whereas no specific haplo‐type was found in the Yangtze River population. Phylogenetic analyses using NJ and ML algorithm did not divide the haplotypes into monophyletic clades representing recognized geographic populations of finless porpoises in Chinese waters, suggesting the existence of migration and gene flow among populations. Analysis of molecular variance showed the obvious population genetic structure (φst= 0.41, P < 0.05); however, the structure was mainly between either the Yangtze River population or the Yellow Sea population and the South China Sea population. The genetic diversity (nucleotide diversity and haplotypic diversity) of the Yellow Sea population was significantly higher than those of the Yangtze River population and the South China Sea population, suggesting the relatively later divergence of the latter two populations and supporting the Yellow Sea population as the original center of Neophocaena.
DIET OF GRAY WHALES (ESCHRICHTIUS ROBUSTUS) IN CLAYOQUOT SOUND, BRITISH COLUMBIA, CANADA
Authors: Dunham Jason S. , Duffus David A. 
Published: August 2006

AbstractIn Clayoquot Sound, British Columbia, gray whales (Eschrichtius robustus) forage for pelagic, hyperbenthic, and benthic invertebrates. Prey types were collected near feeding whales and at sites where no whales were observed to ascertain whales' diets and to describe prey populations and distributions. Characteristics of prey that are examined include species composition, density, biomass, and size. Whales foraged for mysids, Holmesimysis sculpta being the most abundant species collected. Whales foraged near concentrated patches of porcelain crab zoeal larvae, composed primarily of Pachycheles rudis, 21 –294 times the average density and biomass normally collected. Amphipod biomass, composed primarily of Ampelisca agassizi and A. careyi, was 160 ± 150 g/m2 where whales foraged. Larger amphipods, rather than higher density, resulted in higher amphipod biomass between years. Whales foraged where there was a high proportion (61%) of amphipods > 6 mm in length. Whales initially foraged for amphipods along the 20‐m depth contour line; amphipod biomass was best developed and least variable at depths between 16 and 20 m.
GROWTH RATES OF ANTARCTIC FUR SEALS AS INDICES OF ENVIRONMENTAL CONDITIONS
Authors: Reid Keith 
Published: August 2006

AbstractThe growth rates of Antarctic fur seal (Arctocephalus gazella) pups estimated from weighing cross‐sections of the population were compared with measured/ inferred changes in the availability of their main prey species, Antarctic krill (Euphausia superba) from 1989 to 2000. There was no relationship between growth rate and mass at weaning and there were counter‐intuitive indications of higher growth rates in years of low krill availability. Biases reflecting changes in the component of the population available for sampling appear to invalidate the widely held assumption that interannual differences in growth rate can reliably be derived from differences in the slope of a linear relationship based on cross‐sectional population samples. A new index was developed, based on the deviation of pup mass at age in each year compared to the multiyear mean, that was not dependent on assumptions of linearity. The indices of growth deviates produced a more logical relationship with other indices of pup development and related more appropriately to variations in prey availability. The potential impact of methodological biases on the interpretation of growth rate suggests that comparisons of growth rates should not rely on assumptions regarding the underlying growth pattern.
GROWTH AND DEVELOPMENT IN FREE‐RANGING HARBOR SEAL (PHOCA VITULINA) PUPS FROM SOUTHERN BRITISH COLUMBIA, CANADA
Authors: Cottrell Paul E. , Jeffries Steven , Beck Brian , Ross Peter S. 
Published: August 2006

AbstractHarbor seals (Phoca vitulina) are small pinnipeds that are widely distributed throughout the temperate coastal regions of the Atlantic and Pacific oceans. We determined birth mass, neonatal growth rates, weaning age, and weaning mass of NE Pacific harbor seals (P. v. richardsi) during a capture‐recapture study that spanned the nursing period (Sidney Island, British Columbia, Canada). Of 46 harbor seal pups initially captured, 28 were classified as newborns (i. e., < 24 h old). Mean body mass of newborns was 11.2 ± SE 0.31 kg. Pups were individually tagged and recaptured throughout the nursing period. Average daily mass gain during the nursing period was 394 ± 26 g. Mean birth mass of males did not differ significantly from females, although pups found with fetal pelage (lanugo) (21.4% of all newborns) were smaller at birth (9.8 ± 0.44 kg) than non‐lanugo pups (11.6 ± 0.33 kg). Mean weaning mass was estimated at 23.6 ± 1.2 kg at a mean weaning age of 32 d ± 1.5 d. While birth and weaning masses differed little from the published data for offshore Sable Island harbor seals (P. v. concolor), British Columbia harbor seals are characterized by half the daily mass gain and a longer nursing period.
AN ALGORITHM TO IMPROVE GEOLOCATION POSITIONS USING SEA SURFACE TEMPERATURE AND DIVING DEPTH
Authors: Beck C. A. , McMillan J. I. , Bowen W. D. 
Published: August 2006

AbstractThe at‐sea movement of marine mammals is an important component of their foraging ecology, but has been difficult to study. Geolocation timed‐data recorders (GLTDRs) estimate positions using measured light level to calculate day length and local noon. It is well known that these location estimates are imprecise (mean error of > 1°). Satellite telemetry generally provides a more accurate, but also more expensive means of monitoring movement. We evaluated the accuracy and precision of geolocation positions by comparing these locations with satellite data from Service Argos for eight free‐ranging gray seals (Halichoerns grypus) equipped with both a satellite‐linked data recorder (SDR) and a GLTDR. Geolocation positions differed by 1,026.0 ± 292.28 km from the corresponding Argos locations. We developed an algorithm to correct geolocation positions by comparing surface water temperature (ST) and dive depth collected by GLTDRs with existing sea‐surface temperature and bathymetry databases. The corrected positions were significantly closer (P < 0.025) to the Argos locations of these seals (94.2 ± 8.22 km). The original geolocation positions would have led to incorrect conclusions about the use of space by gray seals; however, the corrected positions can be reliably used to study the large‐scale spatial distribution of individuals.
ABUNDANCE OF INDO‐PACIFIC BOTTLENOSE DOLPHINS, TURSIOPS ADUNCUS, OFF POINT LOOKOUT, QUEENSLAND, AUSTRALIA
Authors: Chilvers B. Louise , Corkeron Peter J. 
Published: August 2006

AbstractManaging escalating human impacts on nearshore cetaceans requires information on a species' demography and distribution patterns at appropriate spatial scales. Identification photographs of individuals of a population of inshore Indo‐Pacific bottlenose dolphins, Tursiops aduncus, were obtained in the open coastal waters off North Stradbroke Island, Australia and used to estimate population density and residency. Five hundred and eighty‐one individuals were identified from 342 school sightings during 1998 and 1999. Mark‐recapture analysis using closed population models estimated a population size of between 700 and 1,000 individuals within the study area during winter, with evidence that the population contained resident individuals. This represents an extremely high number of dolphins within a small area, which requires a pre‐emptive management strategy to ensure their continued occupancy.
MOLTING PHENOLOGY OF HARBOR SEALS ON TUGIDAK ISLAND, ALASKA
Authors: Daniel Raychelle G. , Jemison Lauri A. , Pendleton Grey W. , Crowley Shannon M. 
Published: August 2006

AbstractWe documented the progression and timing of the annual molt of harbor seals on Tugidak Island, Alaska, from 1997 to 1999. In all years the timing of molting differed among age‐sex classes. Yearlings molted first, subadults second, adult females third, and lastly adult males. Timing of molting was nearly identical in 1997–1998, whereas in 1999 molting occurred three to six days later for all age‐sex classes except yearlings. Estimated dates when peak proportions of each age‐sex class were molting ranged from 2 August (yearlings) to 2 September (adult males). The number of seals hauled out was positively related to the proportion of seals in the molt and negatively related to the proportion of seals in the postmolt. Population trend estimates, based on aerial counts conducted during a narrow window within the molting period, are likely biased toward certain age‐sex classes. Statistical models used to estimate trend include covariates to help account for within‐year variation in seal numbers, but do not account for compositional changes that occur during molting. Population modeling may elucidate the effects of within‐year population structure on trend estimates. Monitoring molting phenology at additional sites is necessary to determine the extent of geographic variation in molting.
ESTIMATING PUP PRODUCTION OF HARP SEALS, PAGOPHILUS GROENLANDICUS, IN THE NORTHWEST ATLANTIC
Authors: Stenson G. B. , Rivest L.‐P. , Hammill M. O. , Gosselin J. F. 
Published: August 2006

AbstractPhotographic and visual aerial surveys to determine current pup production of Northwest Atlantic harp seals were conducted off Newfoundland and in the Gulf of St. Lawrence during March 1999‐Photographic surveys were conducted on all whelping concentrations between 14 and 24 March, whereas a visual survey was made of the southern Gulf concentrations on 14 March. Pup production was estimated to be 739,100 (SE = 96,300, CV = 13.0%) at the Front, 82,600 (SE = 22,500, CV = 27.2%) in the northern Gulf, and 176,200 (SE = 25,400, CV = 14.4%) in the southern Gulf (Magdalen Island) for a total of 997,900 (SE = 102,100, 10.2%). Changes in aerial survey estimates indicate that pup production has increased since 1994. A new method to correct for the temporal change in the proportion of pups present on the ice was examined by fitting the percentage of pups observed in three age‐dependent stages to a Normal distribution. The results were compared to those obtained from a more complex model used previously. The Simple model produced slightly higher, and hence more conservative, estimates of the proportion of births that had occurred before the time of the survey than the Complex model. When using the Simple model fewer assumptions regarding the start date of pupping and the proportion of older pups remaining on the ice were required, the herd had to be followed for a shorter period, and a more convenient means of calculating confidence limits was available.
ENTRANCE INTO STAGE III FASTING BY STARVELING NORTHERN ELEPHANT SEAL PUPS
Authors: Houser Dorian S. , Costa Daniel P. 
Published: August 2006

AbstractBlood metabolites and urea kinetics were determined in starveling elephant seal pups to assess the transition to stage III fasting in this fasting‐adapted species. Five postmolt and two premolt starvelings, denned as having a mass <50 kg, were studied until death or departure to sea. Premolt starvelings died on the rookery while postmolt starvelings departed to sea. Increased mass loss and a significant inverse relationship between mass and the ratio of blood urea nitrogen to creatinine suggested that premolt starvelings had enrered stage III starvation prior to death while urea kinetics suggested that postmolt pups engaged stage III starvation prior to departure. The mean rate of protein catabolism was estimated at 19.4 g/d for departing starvelings, twice the absolute rate and about four times the mass‐specific rate estimated in healthy weanlings after eight weeks of fasting. Three starvelings stranded after departure, possibly as a result of thermoregulatory challenges and inefficient dive behavior. Entrance into stage III fasting interrupts the development of diving in emaciated pups (<50 kg) suggesting that an increased rate of protein catabolism might be linked to the cue to forage. This biochemical trigger is possibly different than the cue to feed in healthy weanlings, which depart the rookery with substantial fat stores.
TRENDS IN ABUNDANCE OF ALASKA HARBOR SEALS, 1983–2001
Authors: Small Robert J. , Pendleton Grey W. , Pitcher Kenneth W. 
Published: August 2006

AbstractWe estimated trends in abundance of harbor seals (Phoca vitulina richardsii) using over dispersed, multinomial models and counts obtained during aerial surveys conducted during 1983–2001 in the Ketchikan, Sitka, Kodiak, and Bristol Bay areas of Alaska. Harbor seal numbers increased significantly at 7.4%/yr during 1983–1998 and 5.6%/yr during 1994–1998 in the Ketchikan area, and 6.6%/yr during 1993–2001 in the Kodiak area. Counts were stable (trends not significant) during 1984–2001 (0.7%/yr) and 1995–2001 (‐0.4%/yr) in Sitka, and during 1998–2001 (‐1.3%/yr) in Bristol Bay. The influence of covariates (e.g., survey date, tide height) on trend estimates was significant and varied among areas and across years, demonstrating the need to include covariates in statistical analyses to accurately estimate trend. Our increasing trend estimate for Kodiak represents the first documented increase in harbor seal numbers over a relatively expansive area in the Gulf of Alaska. However, the trend for the Gulf of Alaska stock is equivocal due to the continued decline in Prince William Sound. Similarly, the trend for the Southeast Alaska stock is equivocal based on our increasing (Ketchikan) and stable (Sitka) trend estimates, and a recent decline reported for Glacier Bay. The Bering Sea stock appears stable after a period of possible decline.
AN ENEMA METHOD FOR OBTAINING FECAL MATERIAL FROM KNOWN INDIVIDUAL SEALS ON LAND
Authors: Staniland I. J. , Taylor R. I. , Boyd I. L. 
Published: August 2006

AbstractFemale Antarctic fur seals returning ashore after foraging trips were restrained, and fecal material was obtained by introducing approximately one litre of warm water into the animal's colon via the anus. The material then naturally expelled by the animal was collected and analyzed. Of 159 enemas attempted, 148 (93%) produced enough fecal material for subsequent analysis, i.e., where ten or more carapaces or one or more otoliths were recovered. The method produced no obvious external signs of damage to any of the animals, and all were observed suckling their pups within the same season. There was no significant difference in the mean krill sizes collected by enema compared to scat sampling. Also, using their incidence, there was no significant difference in the two sampling methods for any of the fish species considered, though using the proportion of otoliths of a given species of the total otoliths found, there was a difference with one species, Gymnoscopelus nicbolsi. With this technique, it is possible to target individual seals or specific demographic categories for diet analysis. This means that, by using feces collected from enemas, a wider range of questions can be addressed than are currently possible using scat collection alone.