bluuebunny/crossref_metadata_2025_split huggingface dataset:
SPINNER DOLPHINS (STENELLA LONGIROSTRIS) OF THE WESTERN PACIFIC AND SOUTHEAST ASIA: PELAGIC AND SHALLOW‐WATER FORMS1
Authors: Perrin William F. , Dolar Ma. Louella L. , Robineau Daniel 
Published: August 2006

AbstractA dwarf form of the spinner dolphin has been reported from the Gulf of Thailand, while more typical large spinner dolphins have been described from Japanese waters and other localities in the western Pacific. These reports have been based on very few specimens. Our purpose in this study was to determine the affinities of spinner dolphins throughout the region based on larger samples and to review their taxonomic status, with an hypothesis of two widespread ecotypic forms, or subspecies. We examined 213 osteological specimens, from a tuna gillnet fishery in the Philippines, from the former Taiwanese shark gillnet fishery in the Timor and Arafura Seas off northern Australia, from the Gulf of Thailand, from other areas in the western Pacific and Southeast Asia, from the eastern Indian Ocean, and from the Central and South Pacific. Results show that spinner dolphins from the deep inner waters of the Philippines conform to the large pelagic type of spinner dolphin that inhabits the Central and South Pacific, the western Pacific and the eastern Indian Ocean. The skull is similar in size and shape to the holotype specimen of S. longirostris (from unknown locality). This form feeds primarily on small mesopelagic fishes and squids. Spinner dolphins from the shallow waters of inner Southeast Asia represented in the sample, including the Gulf of Thailand, Timor Sea and Arafura Sea, are smaller in body and skull size, have fewer teeth and vertebrae, and feed mainly on benthic and coral reef fishes and invertebrates. We hypothesize that this form also inhabits the Java Sea and other shallow waters throughout inner Indonesia and Malaysia. We redescribe a subspecies corresponding to the small form and based on Delphinus roseiventris Wagner 1846 from the Arafura Sea, designating a neotype and paraneotype specimens.
DIURNAL BEHAVIOR OF FREE‐RANGING BOTTLENOSE DOLPHINS IN THE KVARNERIĆ (NORTHERN ADRIATIC SEA)1
Authors: Bearzi Giovanni , Politi Elena , di Sciara Giuseppe Notarbartolo 
Published: August 2006

AbstractThe diurnal behavior of a bottlenose dolphin (Tursiops truncatus) community was observed from small inflatable craft between 1987 and 1994. Following a preliminary ad libitum study 11,839 3‐min behavioral samples were recorded in 1991‐1994. The behavioral budget showed a predominance (about 80%) of activities characterized by long (>30 sec) dives, considered to be largely related to prey search or feeding. Obvious foraging near the surface was observed rarely. The frequent following of trawlers (accounting for 4.6% of the behavioral budget) was indicative of the presence of alternative strategies for finding food. Yearly and seasonal behavioral variation‐particularly in feeding‐related and travel behaviors‐was consistent with the hypothesis of behavioral flexibility as a response to environmental changes and fluctuating prey kind and availability. Yearly shifts in social behavior appeared to be partly influenced by breeding cycles. Groups engaged in feeding‐related activities were significantly smaller than traveling or socializing groups, and dramatic interannual group‐size shifts seemed to be largely affected by environmental variables, rather than being entirely determined by behavioral activity changes. The remarkable behavioral flexibility of this bottlenose dolphin community may contribute to its survival in the shifting environmental conditions of the northern Adriatic Sea. However, the high proportion of time consistently devoted to feeding‐related activities, as compared to other areas, suggests that food resources in the Kvarnerić were not only highly variable but also depleted.
POPULATION ANALYSES OF INDO‐PACIFIC HUMPBACK DOLPHINS SOUSA CHINENSIS IN ALGOA BAY, EASTERN CAPE, SOUTH AFRICA1
Authors: Karczmarski Leszek , Winter Paul E. D. , Cockcroft Victor G. , Mclachlan Anton 
Published: August 2006

AbstractMark‐recapture analyses were performed on photo‐identification data for Indo‐Pacific humpback dolphins (Sousa chinensis) inhabiting Algoa Bay, on the Eastern Cape coast of South Africa. Boat‐based photo‐ID surveys were undertaken between May 1991 and May 1994. The rate of discovery of newly identified dolphins, distribution of sightings and frequency of resightings of known individuals indicate a high level of seasonal immigration of humpback dolphins into, and emigration from, the Algoa Bay region in summer. Consequently, humpback dolphins from Algoa Bay appear to be part of a substantially larger population that uses a considerable length of the coastal zone. The minimum population size is estimated to be about 466 dolphins.
VARIATION IN THE VISUALLY OBSERVABLE BEHAVIOR OF GROUPS OF GALÁPAGOS SPERM WHALES1
Authors: Whitehead Hal 
Published: August 2006

AbstractThe behavior of groups of female and immature sperm whales (Physeter macrocephalus) was measured on 117 d within an 11‐yr period off the Galápagos Islands, Ecuador. On each day, up to 18 measures of visually observable behavior were calculated. These concerned speeds, headings, movement patterns, diving synchrony, foraging formations, time spent socializing, and aerial behavior. The measured behavior of the sperm whales was considerably more variable when they were socializing than when foraging. None of the measures showed much correlation with sea‐surface temperature, and only measures of consistency of movement were significantly correlated with defecation rate, an indicator of feeding success. However, month‐long time periods accounted for over 50% of the variance in eight of eighteen measures, and, in the cases of surface speed and dive synchrony, the effects were statistically significant. In contrast, there was no autocorrelation with lag of one day in the residuals of any of the measures. Thus, behavior may be tracking substantial temporal variation in the whales' environment over scales of about several months. Groups of whales had significantly different travel patterns, but there was little other evidence for group‐specific behavior, perhaps because tests of group‐specific effects were not of adequate statistical power. Variation in sperm whale behavior, especially over time scales of a few months or longer and spatial scales of a few hundred kilometers or larger, should be considered when estimating densities from sighting surveys.
WHY DO BALEEN WHALES MIGRATE?1
Authors: Corkeron Peter J. , Connor Richard C. 
Published: August 2006

AbstractThe annual migrations of baleen whales are a conspicuous but unexplained feature of their behavioral repertoire. Some hypotheses offered to explain whale migration focus on direct benefits to the calf (thermoregulation, calm water) and some do not (resource tracking, and the “evolutionary holdover” hypothesis). Here, we suggest that a major selective advantage to migrating pregnant female baleen whales is a reduced risk of killer whale (Orcinus orca) predation on their newborn calves in low‐latitude waters. Killer whale abundance in high latitudes is substantially greater than that in lower latitudes, and most killer whales do not appear to migrate with baleen whales. We suggest that the distribution of killer whales is determined more by their primary marine mammal prey, pinnipeds, and that following the baleen whale migrations would remove them from their pinniped prey. There are problems with all current hypotheses, most of which stem from a lack of directed research. We explore variation in migratory habits between species, populations, and individuals that may provide a “natural laboratory” for discriminating among the competing hypotheses.
PHYLOGENETIC RELATIONSHIPS OF BRYDE'S WHALES IN THE WESTERN NORTH PACIFIC AND ADJACENT WATERS INFERRED FROM MITOCHONDRIAL DNA SEQUENCES1
Authors: Yoshida Hideyoshi , Kato Hidehiro 
Published: August 2006

AbstractTo clarify phylogenetic relationships of Bryde's whales, we examined the nucleotide sequence of the mitochondrial control region and cytochromebgene in 33 animals: 12 from offshore waters of the western North Pacific, five from off the Solomon Islands, and 16 from the East China Sea and coastal waters of Kochi in southwestern Japan. For reference purposes, homologous sequences from fourBalaenopteraspecies including four Bryde's whales collected in the eastern Indian Ocean were added. We found whales from the three sampling areas to be genetically distinct. The control region sequences suggested that the whales from the three areas separate at higher than the populational level from one another. The cytochromebdata indicated that genetic differences between whales off the Solomon Islands and animals in the other two areas are equivalent to values found among recognizedBalaenopteraspecies, although such a relationship was not observed between the other two areas. We conclude that whales in the East China Sea and coastal waters of Kochi separate from Bryde's whales in offshore waters of the western North Pacific at higher than the populational level but lower than the specific level (i. e., at the subspecific level) and that whales off the Solomon Islands do not belong genetically to the Bryde's whale as previously recognized.
DARK ADAPTATION AND VISUAL SENSITIVITY IN SHALLOW AND DEEP‐DIVING PINNIPEDS1
Authors: Levenson David H. , Schusterman Ronald J. 
Published: August 2006

AbstractPinnipeds forage almost exclusively underwater. Consequently, observing them is difficult and relatively little is known of how they use their senses to locate prey, avoid predators, and navigate while diving. Vision has been presumed to be of primary importance, although previous measurements of visual functioning in pinnipeds have been restricted to just a few shallow‐diving species. As diving pinnipeds experience rapid changes in light levels during descent/ascent and low light levels at depth, it has not been clear whether they possess visual capabilities adequate for use while diving, particularly in the case of deep‐diving species. To examine this issue, behavioral psychophysics have been used to assess and compare the dark adaptation rates and relative light sensitivities of a deep‐diving pinniped (northern elephant seal, Mirounga angustirostris), two shallow‐diving species (California sea lion, Zalophus californianus, and harbor seal, Phoca vitulina), and a human subject.In comparison to the human subject, both the California sea lion and the harbor seal dark‐adapted relatively quickly and were more light sensitive. These findings suggest that both of these species are well suited for vision in the moderately dim shallow‐water environments in which they dive to forage. In contrast, the elephant seal reached complete dark adaptation in less than half the time taken by the other pinnipeds, and it was significantly more light sensitive. Unlike the shallower‐diving species, the visual abilities of the elephant seal are commensurate with the extreme conditions experienced while deep diving. Thus, we conclude that elephant seals are sufficiently adapted to rely on vision underwater, even while diving to depths in excess of 1000 meters where bioluminescence may be the sole source of ambient light.
OCCURRENCE, PHOTO‐IDENTIFICATION AND PREY OF PACIFIC WHITE‐SIDED DOLPHINS (LAGENORHYNCUS OBLIQUIDENS) IN THE BROUGHTON ARCHIPELAGO, CANADA 1984–1998
Authors: Morton Alexandra 
Published: August 2006

AbstractThis study summarizes occurrence of Pacific white‐sided dolphins (Lagenorhyncus obliquidens) in the Broughton Archipelago on the west coast of Canada, from October 1984 through December 1998. Dolphins were detected on 472 d. The annual percent of total occurrence rose from 0.4% in 1984 to 19% in 1994 and then declined to 2% in 1998. Seasonal occurrence peaked from 1 October through January. Dolphin group size ranged from 2 to 1,000; the most common range was 11‐50. While unreported for the Broughton Archipelago prior to 1984, the species is represented by teeth distributed throughout the past 2,000 yr of First Nations midden sediment, suggesting sporadic long‐term occurrence. Increased water temperature from the 1937–1984 mean of 8.6°C, to the 1985–1998 mean of 9.3°C and increased abundance of two fish populations in the study area are considered potential factors in the recent increase in occurrence. Of the 675 naturally marked dolphins that were photo‐identified, 214 were resighted. A pair of dolphins was photographed swimming in tandem, fourteen months apart. Tight groups, of five or fewer extensively scarred dolphins with extremely falcate dorsal fins were seen within every aggregation of over 50 animals, suggesting the existence of all‐male associations. Prey species were collected from 25 encounters with feeding dolphins; they included herring (Clupea harengus), capelin (Mallotus villosus), and Pacific sardine (Sardinops sagax). Predation on eulachon (Thaleichthys pacificus) is suspected. Unreported for the Broughton Archipelago, the capelin sampled in this study may belong to the Bering Sea population. Pacific sardines returned to commercial viability on the British Columbia coast in 1997 after a 60‐yr population collapse. Dolphin frequency of occurrence declined following introduction of underwater acoustic deterrent devices into the study area.
BACULAR AND TESTICULAR GROWTH AND ALLOMETRY IN THE CAPE FUR SEALARCTOCEPHALUS P. PUSILLUS(OTARIIDAE)
Authors: Oosthuizen W. H. , Miller E. H. 
Published: August 2006

AbstractThe baculum inArctocephalus p. pusillusreaches up to 14.1 cm in length, 13.5 g in mass, and 1.3 g/cm in density (= mass/length). A pubertal growth spurt occurs between 2 and 3 yr of age, when bacular length increases by 28%, mass by 124%, and density by 77%; concurrently, body length increases by 14%. A second, weaker spurt occurs at social maturity (9‐10 yr of age). Testes grow most rapidly between 1 and 2 yr of age, when testicular length increases by 29%. After 3 yr of age, growth in bacular and testicular length slows, and bacular mass continues to increase approximately linearly. Bacular and testicular lengths average 6.8% and 3.4% (respectively) of body length in adults, compared with 9.9% and 5.7% in the promiscuous harp seal (Pagophilus groenlandicus). Bacular length, mass, and density, and testicular length, are positively allometric to body length over growth; bacular length is isometric to testicular length. Among animals of the same age, bacular length and mass are positively allometric to body length in young animals, with negative allometry or isometry thereafter; testicular length is isometric to body length in young animals and negatively allometric thereafter. Patterns of early growth and allometry of the baculum and testes are interpreted as adaptations for mating opportunities, years before territoriality is possible. The baculum and testes of adult Cape fur seals and other otariids are small compared with those of most phocids, because sperm competition among male otariids is weak.
ATTENDANCE PATTERNS OF CALIFORNIA SEA LION (ZALOPHUS CALIFORNIANUS) FEMALES AND PUPS DURING THE NON‐BREEDING SEASON AT SAN MIGUEL ISLAND
Authors: Melin Sharon R. , Delong Robert L. , Thomason James R. , Vanblaricom Glenn R. 
Published: August 2006

AbstractThe attendance patterns of California sea lions were studied during the non‐breeding seasons from 1991 to 1994. Lactating females frequented the rookery to nurse their pups until weaning; most non‐lactating females left the rookery for the season. Females spent over 70% of their time at sea except in 1993 when they spent 59% of their time at sea. The mean foraging trip length in the winter and spring ranged from 3.3 to 4.6 d; the mean nursing visit ranged from 1.2 to 1.4 d. The duration of foraging trips and nursing visits was variable over the season for individuals but no pattern of change was detected. Interannual and seasonal differences were not significant for time at sea, visits ashore, or foraging‐trip duration before, during, or after the 1992‐1993 El Niño event. Pups spent an average of 66.6% of their time ashore and up to three days away from the rookery during their mother's absence. Most females and pups stayed associated until April or May. The results suggest that seasonal movement of prey is more important in determining attendance patterns late in the lactation period than increasing energy demands of the pup.
AGE‐ AND SEX‐SPECIFIC MORTALITY AND POPULATION STRUCTURE IN SEA OTTERS
Authors: Bodkin James L. , Burdin Alexander M. , Ryazanov Dmitry A. 
Published: August 2006

AbstractWe used 742 beach‐cast carcasses to characterize age‐ and sex‐specific sea otter mortality during the winter of 1990‐1991 at Bering Island, Russia. We also examined 363 carcasses recovered after the 1989 grounding of the T/V Exxon Valdez, to characterize age and sex composition in the living western Prince William Sound (WPWS) sea otter population. At Bering Island, mortality was male‐biased (81%), and 75% were adults. The WPWS population was female‐biased (59%) and most animals were subadult (79% of the males and 45% of the females). In the decade prior to 1990‐1991 we found increasing sea otter densities (particularly among males), declining prey resources, and declining weights in adult male sea otters at Bering Island. Our findings suggest the increased mortality at Bering Island in 1990‐1991 was a density‐dependent population response. We propose male‐maintained breeding territories and exclusion of juvenile females by adult females, providing a mechanism for maintaining densities in female areas below densities in male areas and for potentially moderating the effects of prey reductions on the female population. Increased adult male mortality at Bering Island in 1990‐1991 likely modified the sex and age class structure there toward that observed in Prince William Sound.
REPRODUCTIVE RATES OF HUMPBACK WHALES OFF CALIFORNIA
Authors: Steiger Gretchen H. , Calambokidis John 
Published: August 2006

AbstractFrom 1986 to 1996 we examined the reproductive rates, calving rates, and reproductive histories of mature females as part of photo‐identification studies of humpback whales that feed off California, Oregon, and Washington during summer and fall. Annual reproductive rates were measured by two methods: proportion of all whales that were calves based on sightings (0.6%‐5.9% per year, mean = 3.6%, SD = 1.6) and based on individually identified animals (1.1%‐8.0% per year, mean = 4.1%, SD = 1.8). The reproductive rate based on sightings varied significantly by year (G test, P < 0.001), region (G test, P < 0.001), and by month (G test, P < 0.05). Seventy‐nine sexually mature females were identified with 97 calves out of a total of 844 known individuals over the 11‐yr study. Mother‐calf separation on the feeding grounds was recorded in several instances. The apparent reproductive rates of this population are considerably lower than rates of 4%–15% reported from other feeding areas for this species. Our estimates are likely biased downward because this population has been increasing at about 5% per year. Calves may have been missed due to early weaning and because of our sampling from small boats late in the season. We also found evidence of geographic segregation of mother‐calf pairs within our large study area. Despite these factors, we conclude the reproductive rate of this population appears to be lower than has been reported in other areas.
POLYDACTYLY AND OTHER FEATURES OF THE MANUS OF THE VAQUITA, PHOCOENA SINUS
Authors: Ortega‐Ortiz Joel G. , Villa‐Ramírez Bernardo , Gersenowies Jorge R. 
Published: August 2006

AbstractThe vaquita (Phocoena sinus) manus was examined in 16 individuals. The carpus has a proximal row of three bones and a cartilaginous accessory carpal element distocaudal to the ulna. Five metacarpal bones are present. A process in distocaudal aspect of Metacarpal III and an additional digital ray were present in all individuals examined. The number of phalanges in the additional digital ray varied among individuals and, sometimes, between the left and the right flipper of the same individual. The suggested phalangeal formula is I‐1, II‐7‐8, III‐6‐7, IV‐0‐3, V‐3‐4, VI‐1. The presence of this particular form of polydactyly may be the result of genetic drift in the small vaquita population.
RIGHT WHALES (EUBALAENA GLACIALIS) ON JEFFREYS LEDGE: A HABITAT OF UNRECOGNIZED IMPORTANCE?
Authors: Weinrich Mason T. , Kenney Robert D. , Hamilton Phillip K. 
Published: August 2006

AbstractNorth Atlantic right whales (Eubalaena glacialis) are known to spend the majority of the year between the Great South Channel southeast of Cape Cod, and the Nova Scotian shelf. We examined sightings of right whales on and around Jeffreys Ledge, a 54‐km‐long glacial deposit off the coast of northern Massachusetts, New Hampshire, and Maine. Sightings on Jeffreys Ledge were extracted from three data sets: (1) a systematic survey of the entire northeastern continental shelf between 1979 and 1982, (2) whale‐watch and research‐cruise sighting data from 1984 to 1997, and (3) a collaborative database of sightings collected by organizations conducting right whale research and all other available sources. Each database supported two seasonal sighting peaks. During summer (especially July and August) sightings were primarily of mother‐calf pairs. Several cow‐calf pairs were seen over several days to weeks. Several females were resighted in more than one year, but only when calves were present. During October, November, and December, sightings included all age classes, surface‐feeding behavior was frequently observed, and some animals were resighted over several weeks. Given the relatively reduced sighting effort during fall, this number of sightings is surprising. During the 20 yr of observations, 52 of 374 photo‐identified North Atlantic right whales (13.9%) were seen at least once on Jeffreys Ledge. We suggest that Jeffreys Ledge may be a more important right whale habitat than previously believed, and that it may play an important role in annual movements and distribution of this population.
STELLER SEA LION BODY CONDITION INDICES
Authors: Pitcher K. W. , Calkins D. G. , Pendleton G. W. 
Published: August 2006

AbstractWe evaluated various measurements of mass, morphology, and blubber thickness as indices of fatness for Steller sea lions by correlation with the percentage of total body mass comprised by the sculp (%SCULP). We concluded LMD‐index was the best index evaluated because it had a relatively high r2 (0.58), had a linear relationship with %SCULP, and the intercept term was not different from O. We suggest the development of a LMD‐index for otariids would likely reduce the unexplained variation in the index. We developed a multiple regression model (r2= 0.745, P < 0.001) for predicting %SCULP with LMD‐index and functions of sex, age, and season as predictor variables. Steller sea lions < 5 yr of age had higher %SCULP values than those ≥ 5 yr. %SCULP declined with age for sea lions < 5 yr. Both younger and older males were fatter during the winter/spring period than during summer/ fall. Females of both age classes had similar %SCULP values throughout the year. Steller sea lions are relatively lean pinnipeds; estimates of blubber and total body lipids ranged from 5% to 17% of total body mass.