bluuebunny/crossref_metadata_2025_split huggingface dataset:
INCIDENTAL MORTALITY OF NORTHERN SEA LIONS IN SHELIKOF STRAIT, ALASKA
Authors: Loughlin Thomas R. , Nelson Russell 
Published: August 2006

AbstractThe incidental catch of northern sea lions (Eumetopias jubatus) in the walleye pollock (Theragra chalcogramma) joint‐venture fishery in Shelikof Strait, Alaska, was studied during 1982–1984 to assess the nature and magnitude of the catch. Data were obtained by placing U.S. observers on foreign processing vessels. Dead sea lions recovered from trawl nets were counted, sexed and measured, teeth were removed for age determination by dental laminae; and stomach contents were analyzed. Although the fishery has continued to expand both in number of boats and estimated total catch (74,136 metric tons [t] in 1982 to 171,539 t in 1984), the estimated incidental catch of northern sea lions has declined (ranging from 958 to 1,436 in 1982, 216 to 324 in 1983 and 237 to 355 in 1984). Of the sea lions processed, 73 percent were caught between 2000 and 0500 h, probably during net retrieval. Most caught sea lions were females ranging in age from 1–25 yr with a mean age of 6.43 yr; 79 percent of the females were sexually mature and probably part of the reproducing population. Males had a mean age of 4.8 yr and only 12 percent were old enough to obtain and defend territories. Analysis of stomach contents showed that the sea lions consumed pollock the same size as that taken by the commercial fishery. The impact of the incidental catch on the Gulf of Alaska sea lion population is unknown.
INTERSPECIFIC AND INTRASPECIFIC MORPHOLOGICAL VARIATION IN MANATEES (SIRENIA: TRICHECHUS)
Authors: Domning Daryl P. , Hayek Lee‐Ann C. 
Published: August 2006

AbstractThe three living species of Trichechus are clearly defined and well exemplify the degree of variability and taxonomic value of morphological characters in a well‐understood mammalian genus. Statistical analysis of the largest sample of manatee skulls yet studied has allowed us to identify small suites of characters that effectively distinguish these species. The two subspecies of T. manatus proposed by Hatt (1934) can likewise be distinguished, and their use as taxonomic categories seems justified. This suggests that the cool winters of the northern Gulf Coast, on the one hand, and the deep water and strong currents of the Straits of Florida, on the other, are effective barriers to gene flow between Florida and Antillean manatees. Alleged taxonomic distinctions within T. senegalensis, however, have no demonstrated basis. No significant sexual dimorphism was detected in skulls of any of the species. Many interspecific differences can be correlated with feeding ecology, but others remain unexplained. Features of tooth crown morphology are among the most constant characters examined, but some osteological characters are equally good. T. manatas and T. senegalensis (which are phenetically the most similar) also seem to share a more recent common ancestor than either does with T. inunguis. However, the three species probably separated from each other at nearly the same time. T. inunguis has since become the most derived species, while T. senegalensis has changed the least.
WEIGHTS AND ANATOMICAL MEASUREMENTS OF NORTHEASTERN ATLANTIC FIN (BALAENOPTERA PHYSALUS, LINNAEUS) AND SEI (B. BOREALIS, LESSON) WHALES
Authors: Lockyer Christina , Waters Timothy 
Published: August 2006

AbstractPiecemeal body weights of eleven fin and four sei whales and intact weights of three foetuses, obtained from Iceland, are compared with published weight data. The Icelandic fin are similar to other northern hemisphere animals but are significantly leaner than their Antarctic counterparts. The Icelandic sei appear heavier than the North Pacific sei whales. Their weights cannot be predicted from a North Pacific sei whale weight/length formula. Length, girth and blubber thickness measurements indicate changes in relative body dimensions in the early fin whale foetus compared with juveniles and adults; however, the midterm sei whale foetus is similar to the adult and juvenile sei whales. The blubber appears to form a major component even in the foetal body. The integration of a standard series of lengths, girths and blubber thicknesses in juveniles and adults can provide an estimate of the blubber component. Both girth and length are significant parameters in estimating body weight, a simple weight/length formula being found to be inadequate to allow for variability in body fatness. Evaluation of such a multiple parameter formula for calculating weight appears satisfactory for both fin and sei whales. Apparent weight/length differences between species and stocks may thus be partly due to variations in body fatness.
ADRENOCORTICAL FUNCTION IN PINNIPED HYPONATREMIA
Authors: St. Aubin D. J. , Geraci J. R. 
Published: August 2006

AbstractPotentially fatal sodium imbalance occurs in captive and free‐ranging pinnipeds and is associated with a variety of stressors. We sought to determine the role of adrenal hormones, principally aldosterone, in the development of this condition. To induce hyponatremia, two ringed seals, Phoca hispida, were maintained in fresh water and fed a low‐sodium diet; as controls, two other ringed seals were held in salt water and received a salt‐supplemented diet. After 3–6 mo, adrenocorticotropic hormone (ACTH) was used to assess adrenocortical function. In normonatremic control seals, ACTH produced a 2‐j‐fold increase in circulating cortisol and a 7‐fold increase in aldosterone. One of the experimental seals maintained normal plasma sodium levels, and ACTH elicited an exaggerated aldosterone response. The other salt‐deprived seal became hypo‐natremic, and ACTH had little effect on plasma aldosterone levels. An ACTH stimulation test performed on a spontaneously hyponatremic harp seal, P. groenlandica, which had been maintained in a salt‐rich environment, failed to elicit cortisol or aldosterone secretion from the adrenal cortex. This study demonstrated the unusual sensitivity of the seal's zona glomerulosa to central stimulation, providing a mechanism through which the stress response might exhaust adrenal hormone reserves or desensitize the cortex to other physiological stimuli.
ATYPICAL PUP REARING STRATEGIES BY SEA OTTERS
Authors: Garshelis David L. , Garshelis Judith A. 
Published: August 2006

ABSTRACTEight tagged sea otter (Enhydra lutris) pups in central Prince William Sound, Alaska, weighed 6–15 kg at the time of separation from their mother. Four pups weighing 15 kg were able to forage successfully on their own. Three pups weighing ≤9 kg had negligible chances of survival and apparently were abandoned by sick females. Abandonment of a pup may reduce the burden on a sick female, enabling recovery and subsequent reproduction. One of the three sick females that abandoned a pup in this study recovered and pupped again. Abandonment of pups should occur most often in populations where females are stressed by poor food resources. Reassociation with a previous offspring, as observed once in this study, also may occur most frequently in food‐limited populations where reproductive failures are most common and pup survivorship is significantly increased by additional maternal assistance.
ASSESSING NORTHERN ELEPHANT SEAL FEEDING HABITS BY STOMACH LAVAGE
Authors: Antonelis George A. , Lowry Mark S. , DeMaster Douglas P. , Fiscus Clifford H. 
Published: August 2006

AbstractStomach lavaging was used to study the feeding habits of northern elephant seals (Mirounga angustirostris) found on San Miguel Island, California, during the spring of 1984. Fifty‐nine elephant seals were chemically immobilized with an intramuscular injection of ketamine hydrochloride. Once immobilized, an animal's stomach was intubated, filled with 3–4 liters of water to create a slurry of the undigested food items, and evacuated into a collection device. The stomachs of 57 (96.6%) of the animals lavaged contained identifiable parts of prey. Twenty‐nine different food items were identified, 12 of which have not been previously reported as prey of the northern elephant seal: two teleost fish, Coryphaenoides acrolepis (Pacific rattail) and another unidentified macrourid; two crustaceans, Pasiphaea pacifica (glass shrimp) and Euphausia sp.; six squid, Abraliopsis felis, Gonatus berryi, Histioteuthis dofleini, Cranchia scabra, Taonius pavo, and Galiteuthis sp. and two octopi, Octopus dofleini and Octopus rubescens.
ECOTOXICOLOGICAL PERSPECTIVES IN MARINE MAMMALOGY: RESEARCH PRINCIPLES AND GOALS FOR A CONSERVATION POLICY1
Authors: Reijnders Peter J. H. 
Published: August 2006

AbstractIn integrating ecotoxicology and marine mammalogy two principal themes are conceivable: (1) the impact of contaminants on marine mammals and (2) the feasibility of monitoring marine pollution with marine mammals. Monitoring should be an alert procedure, carried out with a sensitive sensor. Uncertainties in interpreting analyses and the low susceptibility of marine mammals to short‐term changes in pollution, make them inappropriate for pollution monitoring at present.To answer the question whether pollutants affect marine mammals, the occurrence of contaminants and the response of the animals to those chemicals have to be assessed. In studying the occurrence of contaminants it is essential that atmospheric and riverine input, geochemical processes, and processes involved with the occurrence of natural compounds are considered. To investigate the mechanisms by which pollutants affect physiological processes the kinetics of contaminants in the animals and their clinical toxicity effects have to be studied. Comparative reference data on physical and chemical blood parameters facilitates checking for hematological disorders, electrolyte imbalance, serum biochemistry and hormonal changes. Following such a concept the retrospective study of pollution effects on marine mammals might be turned into a predictive approach.
BEHAVIORAL EVIDENCE FOR HEARING THROUGH THE LOWER JAW BY AN ECHOLOCATING DOLPHIN (TURSIOPS TRUNCATUS)
Authors: Brill Randall L. , Sevenich Martha L. , Sullivan Timothy J. , Sustman Janet D. , Witt Ronald E. 
Published: August 2006

AbstractOn the basis of disputed physiological evidence the fat‐filled lower jaw of odontocete cetaceans has previously been hypothesized as the primary pathway to the inner ear for acoustic signals. To gain behavioral evidence, a dolphin was trained to perform an echolocation task while wearing suction cups over its eyes and either of two neoprene robber hoods over its lower jaw. One hood allowed returning acoustic signals to pass. The other substantially attenuated such signals. The dolphin's performance was significantly hindered while wearing the attenuating hood (P <. 001, ψ2) as would be expected if the lower jaw was critically important in the reception of high frequency signals.
REBUILDING SEAL STOCKS IN THE KATTEGAT‐SKAGERRAK
Authors: Heide‐Jørgensen Mads‐Peter , Härkönen Tero J. 
Published: August 2006

AbstractThe harbor seal (Phoca vitulina) population in the Kattegat‐Skagerrak area has been dwindling for several centuries due to excessive hunting pressure. Corrected hunting statistics during 1890–1976 are used to estimate changes in population size over the past century. After protection was introduced in the 1960s and 1970s the harbor seal population in the area increased at an exponential rate of 0.12 and exceeded 5,000 animals in 1986. The present rate of population growth is used for modelling the influence of fertility and age‐specific mortality. It is found that the observed high rate of increase is only realistic if female fertility rate is very high, the range of juvenile mortality rate is 0.33–0.52 and adult mortality is less than 0.15. Commonly cited higher mortality rates are not realistic in the Kattegat‐Skagerrak area.
ZOOGEOGRAPHY OF OREGON COAST MARINE MAMMALS: THE LAST 3,000 YEARS
Authors: Lee Lyman R. 
Published: August 2006

AbstractMammalian faunal remains recovered from three archaeological sites on the Oregon, U.S.A. coast provide strong evidence that 18th and 19th century commercial exploitation of marine mammals had major effects on the zoogeography and demography of those taxa.Zalophus californianusandCallorhinus ursinusbred and pupped along the Oregon coast between 3,000 and 100 yr ago. About 100 yr agoEumetopias jubatusabandoned a major rookery that had been utilized since at least 400 yr ago.Phoca vitulinadoes not appear to have suffered major modifications to coastal use or demographic patterns in Oregon during the last 3,000 yr, although a minor incident of intensified utilization of one location about 1,000 yr ago is suggested. All age‐sex classes ofEnhydra lutrislived on the Oregon coast until about A.D. 1900. Oregon's prehistoric remains ofE. lutrisdisplay some dental characters similar to modern Alaskan specimens, and other dental characters similar to modern Californian specimens, conforming to a latitudinal dine reflected by historic specimens. Additional evidence for many of these observations is found in faunal remains recovered from archaeological sites on the coast of Vancouver Island, the Washington coast, and the northern California coast.
THE TAPETUM FIBROSUM IN THE EYES OF TWO SMALL WHALES
Authors: Young NinaM. , Hope G. Marion , Dawson WilliamW. , Jenkins RobertL. 
Published: August 2006

AbtractThe pygmy sperm whale (Kogia breviceps) and the bottlenose dolphin (Tursiops truncatus) are equipped with a tapetum fibrosum and, with other Cetacea, are the only carnivores known to possess this typically ungulate tapetal type. Tapeta from two regions of a retina, each with a different spectral reflectance (blue and green), were found to have significantly different fibrillar diameters and inter‐fibrillar spacing. When the measured values are applied to a dielectric reflector model, the predicted wavelengths agree with the observed reflectance of the flat‐mounted tapeta. The spatial properties of the fibrils change progressively from the tapetal origin in the fibroblast layer to the pigment epithelium, suggesting that different wavelengths may be reflected systematically with tapetal depth. The very large number of reflecting layers characterizing these tapeta, relative to those of other carnivores, may provide for increased spectral purity and efficiency.
DEVELOPMENTAL PATTERN OF THE BONY FALX AND BONY TENTORIUM OF SPOTTED DOLPHINS (STENELLA ATTENUATA) AND THE RELATIONSHIP BETWEEN DEGREE OF DEVELOPMENT AND AGE
Authors: Nojima Takao 
Published: August 2006

AbstractThe bony falx (BF) and bony tentorium (BT) of spotted dolphins (Stenella attenuata) at different growth stages were observed. The BF and BT were observed to have the shape of the entire falx cerebri (FC) and tentorium cerebelli (TC), respectively, in adults, but were not seen in fetuses at all. Partially formed BF and BT were observed in the young. The BF and BT of spotted dolphins are formed by ossification in the FC and TC in the course of aging. Based on age determination by means of dentinal growth layers of the maxillary teeth, the ossification in the FC and TC of spotted dolphins begins by about 1 yr of age, and is completed, except for the passage of nerves and blood vessels, by about 9 yr of age. The BF and BT of spotted dolphins are formed possibly by continual dietary intake of large amounts of calcium, phosphorus and vitamin D.
BOOTSTRAP CORRECTION FOR DIURNAL ACTIVITY CYCLE IN CENSUS DATA FOR ANTARCTIC SEALS1
Authors: Erickson Albert W. , Bledsoe Lewis J. , Hanson M. Bradley 
Published: August 2006

AbstractAntarctic phocid seals and particularly the crabeater (Lobodon carcinophagus) have been observed to display a diurnal cycle in their propensity to haul out on pack ice where they are visible for census. The fact that they are not visible for much of the 24‐h period means that density estimates made over broad geographic areas at various times of the day statistically confound this cycle with geographic variability. Limitation of census observations to times of peak haulout results in extreme logistical difficulties and/or considerable reduction in sample size upon which to base population estimates. Reduced sample size results in high variability in population estimates and broad confidence bands. To develop a model with which to correct density estimates for variability due to diurnal cycle, a series of stationary censuses at fixed locations in the Antarctic continental ice pack was made over significant fractions of several days. A unimodal polynomial model for the observed density variation in any one location was statistically significant; a similar model combining multiple locations with densities standardized to peak daily values was also significant. The latter model was used to make corrections for time of day to density estimates in three test data sets taken over broad geographic areas of the Antarctic. Statistical simulation (bootstrap) methods were used to determine if variances of corrected density estimates were lower than those based on uncorrected observations taken only during the peak haulout times of the day. Results were that 95% interval estimates for corrected densities were narrowed to between 40% and 61% of the uncorrected estimates. While there are additional possible sources of variation in haulout tendency, pending further data collection and analyses, the model developed represents a considerably more precise methodology than either averaging over haulout variability or limiting observations to peak daily periods.
CRABEATER SEALS LOBODON CARCINOPHAGUS DURING THE BREEDING SEASON: OBSERVATIONS ON FIVE GROUPS NEAR ENDERBY LAND, ANTARCTICA
Authors: Shaughnessy P. D. , Kerry K. R. 
Published: August 2006

AbstractObservations on five groups of crabeater seals were conducted between 29 October and 17 November 1985 in the Antarctic pack ice near 66°S 50°E, off Enderby Land. The pups studied were born in the last half of October. Two of them increased in weight at a rate of approximately 4.2kg per day. Pups were weaned in the first half of November at 80–110 kg. The lactation period was 2–3 wk and thus is one of the briefest among pinnipeds. Pups decreased in weight after weaning. The only pup visited after it left the natal floe must have been feeding, as it had lost only 2 kg in a 10–day period during which it moved 13 km. Molt of lanugo appeared to be influenced more by a pup's weight than by whether or not it was weaned.
ICE‐BASED CENSUS OF BOWHEAD WHALES MIGRATING PAST POINT BARROW, ALASKA, 1978‐1983
Authors: Krogman Bruce , Rugh David , Sonntag Ronald , Zeh Judith , Ko Daijin 
Published: August 2006

AbstractBowhead whale (Balaena mysticetus) census data obtained during the northward spring migration are summarized for 1978–1983. Population size estimates are derived from counts made by observers standing on the seaward edge of shorefast ice in the vicinity of Point Barrow, Alaska, from mid‐April to early June. The research design utilized two counting stations: South Perch, the primary counting station, and North Perch, used to determine the number of whales missed by South Perch observers. The percentage missed is estimated for each visibility category and used here to correct the census counts. Each season's population estimate is calculated as the sum of the number of trials of several independent multinomial distributions representing different visibility conditions. Corrections are applied for unwatched hours and hours with inferior visibility. A mean estimate of the number of whales passing within view of the census station was computed as 3,674 ± 299. This estimate was based on data collected in 1978, 1981, 1982, and 1983, years with the least apparent biases. Aerial survey data provide estimates of the proportion of whales passing at various distances seaward of the census sites as follows: 0.58 from the ice edge to 2 km, 0.76 to 3 km, and 0.80 to 4 km. Correcting for whales too far offshore to be seen by the ice‐based observers results in a population estimate of over 4,200 bowheads.
A DWARF FORM OF THE SPINNER DOLPHIN (STENELLA LONGIROSTRIS) FROM THAILAND
Authors: Perrin William F. , Miyazaki Nobuyuki , Kasuya Toshio 
Published: August 2006

AbstractA very small form of the spinner dolphin has been found to inhabit the Gulf of Thailand. Ten specimens taken incidentally in a local shrimp fishery differ from specimens of this species collected elsewhere in body size and shape, skull size and shape, number of teeth and numbers of thoracic and lumbar vertebrae. Four cranially adult males were 129–137 cm long, well below the ranges for the Indian Ocean, western Pacific, central Pacific, eastern Pacific and Atlantic. The skull is also very small. Tooth counts and vertebral counts average lower than in other series. The color pattern is not significantly different from that of spinner dolphins in the central and western Pacific, Atlantic and Indian Oceans but differs from that of the small eastern spinner of the eastern Pacific. The Gulf of Thailand specimens are morphologically separable from all other specimens, but it is to be expected that when larger samples are available there will be some overlap. The dwarf form may overlap in body and skull size with small spinner dolphins taken incidentally in a gillnet fishery for sharks off northern Australia. The geographic range of the dwarf spinner may be restricted. The size and status of the population and the impact of the shrimp fishery are unknown and should be investigated. The dwarf spinner may have an ecology different from that of other spinners, feeding mainly on reef‐associated and benthic organisms rather than mesopelagic animals.
MOVEMENTS OF SOUTHERN ELEPHANT SEALS AND SUBANTARCTIC FUR SEALS IN RELATION TO MARION ISLAND
Authors: Bester Marthán N. 
Published: August 2006

AbstractBased primarily on an intensive marking/resighting program conducted at Marion Island (46°54′S, 37°45′E) in the Southern Ocean, the inter‐island movements of southern elephant seals, Mirounga leonina, and fur seals Arctocephalus spp., were investigated to elucidate their little known pelagic phase. Southern elephant seals, in particular immature animals, readily move between the proximate Marion and Prince Edward islands. Some range as far afield as Iles Crozet, approximately 1,000 km distant where they haul out for the summer molt or during an autumn resting phase. The exchange of individuals between Marion Island and Iles Crozet during the return of immatures for the molt after a winter at sea, suggests overlapping of the foraging ranges of the two populations. Despite their wanderings, the majority of M. leonina from Marion Island probably feed in the proximity of the island, and relocate onto the island for breeding, molting and resting. Of the fur seals, only a few A. tropicalis were seen away from their natal island, in some cases covering distances in excess of 2,000 km. displaying a remarkable dispersal capacity.
GROWTH LAYERS IN TEETH FROM KNOWN‐AGE, FREE‐RANGING BOTTLENOSE DOLPHINS
Authors: Hohn Aleta A. , Scott Michael D. , Wells Randall S. , Sweeney Jay C. , Irvine A. Blair 
Published: August 2006

AbstractGrowth layers were examined in teeth collected from free‐ranging bottlenose dolphins, Tursiops truncatus, from Florida that have been part of a long‐term study begun in 1970; 26 of the dolphins were of known or approximately known age, and 19 were of minimum known age. A second tooth was extracted from 6 animals for examination of growth that had taken place in the interval following the initial extraction. The teeth were read for age estimates without knowledge of any data pertaining to the animals. Most of the estimated ages were the same as or close to the known and approximately known ages of the animals, ranging from 2 to 16 yr. We conclude that the structures we define as dentinal growth layer groups (GLGs) are annual, we describe sources of error in age estimates, and we provide a description of the GLG pattern that can be used by others to estimate age for dolphins.