bluuebunny/crossref_metadata_2025 huggingface dataset:
THE SCIENTIFIC DISCOVERY OF THE AMAZON RIVER DOLPHIN INIA GEOFFRENSIS
Authors: Romero A. , Agudo A. I. , Agudo S. J. Blondell de
Published: August 2006

Abstract

Analysis of little‐known manuscripts revealed that there have been at least two pre‐Linnean descriptions of the South American freshwater dolphin Inia geoffrensis (Blainville, 1817). The earliest one that we found was made by Frei Cristóvâo de Lisboa in a manuscript written around 1627. The second one was by Pehr Löfling, a disciple of Linnaeus, who wrote a very detailed and accurate description of this mammal in 1755. He used the binomial system to designate this species, and his description was much more complete and sophisticated than the ones used by Linnaeus in the 10th edition of System Naturae for other cetaceans. This and other zoological work by Löfling remains almost completely unexamined to date. Like the outcome of other field work carried out by many Spanish scientists in America, failure to publish the findings of the expeditions resulted in scientific information being largely lost.
DISTRIBUTION AND ABUNDANCE OF THE AMAZON RIVER DOLPHIN (INIA GEOFFRENSIS) AND THE TUCUXI (SOTALIA FLUVIATILIS) IN THE UPPER AMAZON RIVER
Authors: Vidal Omar , Barlow Jay , Hurtado Luis A. , Torre Jorge , Cendón Patricia , Ojeda Zully
Published: August 2006

A boat survey was conducted from 5 to 26 June 1993 to estimate the abundance of the Amazon river dolphin (Inia geoffrensis) and the tucuxi (Sotalia fluviatilis) along ca. 120 km of the Amazon River bordering Colombia, Peru, and Brazil. Two survey methods were used: line transects during 5 d and strip transects during 15 d. The line transects were used to estimate the abundance of both species in the main channels of the Amazon at distances greater than 200 m from river banks and islands, and strip transects were used to estimate abundance in the remainder of the habitat. A total of 29 sightings was obtained using line transects, including 8 of Inia, 15 of Sotalia, and 6 with both species present. The total number of sightings made while using strip transects was 143, including 78 of Inia, 51 of Sotalia, and 14 with both species present. The distributions of sightings with respect to distance from the nearest bank were not significantly different between the two species. Based on the results from the two methods, we estimate that there are 346 (CV = 0.12) Inia and 409 (CV = 0.13) Sotalia in the study area. Overall, the mean group size for Inia was 2.9 individuals and for Sotalia was 3.9 individuals. Inia density (dolphin/km2) was highest in tributaries (4.8), followed by areas around islands (2.7) and along main banks (2.0); while Sotalia density was highest in lakes (8.6), followed by areas along main banks (2.8) and around islands (2.0). These are among the highest densities measured to date for any cetacean.
A HARP SEAL × HOODED SEAL HYBRID
Authors: Kovacs Kit M. , Lydersen Christian , Hammill Mike O. , White Bradley N. , Wilson Paul J. , Malik Sobia
Published: August 2006

Abstract

In this study we report the first documentation of mating between harp (Phoca groenlandica) and hooded seals (Cystophora cristata). The production of this hybrid was quite unusual, being the result of a cross between parents of different genera which are morphologically dissimilar and have quite different mating behavior and dramatically different body sizes. The molecular techniques (mtDNA and macrosatellite nuclear DNA banding patterns) used in this study will undoubtedly be applied widely to many different taxa in the near future, allowing us to re‐examine many suspected cases of hybridization among marine mammals and, in a larger context, the meaning of the species concept.
A NEW GEOGRAPHIC FORM OF THE SPINNER DOLPHIN, STENELLA LONGIROSTRIS, DETECTED WITH AERIAL PHOTOGRAMMETRY
Authors: Perryman Wayne L. , Westlake Robin L.
Published: August 2006

Abstract

Analyses of skeletal and external morphology of spinner dolphins killed in to the yellowfin tuna purse‐seine fishery in the eastern tropical Pacific led to the description of two subspecies of spinners from this region, the eastern spinnen dolphin and the Central American spinner dolphin (Perrin 1990). However, when we examined lengths of spinner dolphins taken from vertical aerial photographs from the same area, we found three unique morphotypes. Two of these forms correspond, at least in average length and distribution, to the existing subspecies. The third form is intermediate in length between the two recognized subspecies and is found along the edge of the continental shelf north of Cabo Corrientes, Mexico. We provisionally call this form the “Tres Marias spinner dolphin.” Our results demonstrate the value of a mix of fishery and fishery‐independent data in studies of stock structure of impacted species.
HOMING BEHAVIOR OF JUVENILE NORTHERN ELEPHANT SEALS
Authors: Oliver Guy W. , Morris Patricia A. , Thorson Philip H. , le Boeuf Burney J.
Published: August 2006

Abstract

The aim of this study was to determine if juvenile northern elephant seals,Mirounga angustirostris, translocated from their rookery would return to it quickly and reliably. During the spring and fall of 1990 and 1991 we captured 75 seals at Año Nuevo State Reserve, CA, U. S. A. and translocated them to release sites up to 100 km away. Eighty‐eight percent of the seals returned to the capture site within 4.7 ± 4.3 d. Homing rate increased with age, but even the youngest seals (8–10 mo) homed at a 73% rate. Homing rate did not vary significantly with sex, season, or year. Data from diving instruments suggested that the seals often followed direct routes home, arrived on the rookery significantly more often at night than during the day, and when released together, returned separately. Mean homing speed of 18 seals with complete diving records was 39 km/d (range 3–70 km/d). Instruments on seals had no detectable effect on homing rate or homing speed. The translocation paradigm provides a powerful tool for conducting intensive shortterm studies on free‐ranging seals.
PREHENSILE USE OF PERIORAL BRISTLES DURING FEEDING AND ASSOCIATED BEHAVIORS OF THE FLORIDA MANATEE (TRICHECHUS MANATUS LATIROSTRIS)
Authors: Marshall C. D. , Huth G. D. , Edmonds V. M. , Halin D. L. , Reep R. L.
Published: August 2006

Abstract

The use of perioral bristles (modified vibrissae) by 17 captive Florida manatees and approximately 20 wild manatees was analyzed. Captive manatees were fed six species of aquatic vegetation normally eaten in the wild (four freshwater species and two seagrasses). Inanimate objects were placed in the holding tanks with manatees at Lowry Park Zoological Gardens (Tampa, FL) to determine the degree to which perioral bristles were used in exploration and to define the range of manipulative behavior. In addition, behavioral observations were made on the use of perioral bristles during social interactions with conspecifics. Observations were recorded using a Hi8‐format video camera. Florida manatees possess an unusually large degree of fine motor control of the snout and perioral bristles. The large and robust perioral bristle fields of the upper lip were used in a prehensile manner during feeding. Bristle use by manatees feeding on submerged vegetation differed from that seen during feeding on floating vegetation. Other behavioral use of the perioral bristles shows variation depending upon the situation encountered. The degree of plasticity of perioral bristle use supports our hypothesis that the vibrissal‐muscular complex of the Florida manatee has evolved to increase the efficiency of grazing and browsing on aquatic vegetation and to fully maximize the potential of the manatee as a generalist feeder. The manipulative and sensitive nature of the manatee snout is likely a manifestation of a complex sensory and motor system which has evolved for marine mammal aquatic herbivores living in shallow turbid habitats.
DIEL PATTERNS IN AGGREGATIONS OF PELAGIC DOLPHINS AND TUNAS IN THE EASTERN PACIFIC
Authors: Scott Michael D. , Cattanach Karen L.
Published: August 2006

Abstract

Data collected by scientific technicians aboard tuna purse seiners in the eastern Pacific Ocean since the early 1970s have allowed us to study the biology and herd dynamics of pelagic dolphins. A pattern of increasing group size in the morning and subsequent decline in the late afternoon or night was evident for spotted, spinner, and common dolphins, as well as for large yellowfin tuna that associate with dolphins. Diel patterns were also apparent in the formation of mixed‐species herds of spotted and spinner dolphins and tuna‐dolphin aggregations. Different patterns, however, were displayed by bottlenose dolphins and by yellowfin and skipjack tunas that did not associate with dolphins. It appears that these diel patterns are produced by an interaction of predation pressure and prey distribution.
CETACEANS OF THE WESTERN TROPICAL INDIAN OCEAN: DISTRIBUTION, RELATIVE ABUNDANCE, AND COMPARISONS WITH CETACEAN COMMUNITIES OF TWO OTHER TROPICAL ECOSYSTEMS
Authors: Ballance Lisa T. , Pitman Robert L.
Published: August 2006

Abstract

We conducted a cetacean survey in the pelagic western tropical Indian Ocean (WTIO) aboard an 85‐m research vessel from March to July 1995, covering 9,784 linear km. Using 25 × binoculars and line‐transect methods, we recorded 589 sightings of 21 species. Stenella longirostris was the most abundant cetacean, in terms of number of individuals sighted, by an order of magnitude above any other species, while Physeter macrocephalus was the most frequently sighted, in terms of number of schools. Twelve species were widespread, seven were rare, and two were localized; our sightings include new distributional records for 12 species. Significant observations included the following: (1) Delphinus cf. tropicalis was abundant off the coast of Oman (16 sightings) and readily distinguishable in the field from D. delphis and D. capensis, (2) Balaenoptera musculus was fairly common and localized in the area of the Maldives (17 sightings), and (3) three sightings were made of an unidentified bottlenose whale tentatively referred to as Indopacetus (i. e., Mesoplodon) pacificus. We recorded 26 mixed‐species cetacean schools, 43 schools with which seabirds associated, and 17 schools associated with tuna. Notable among these were mixed aggregations of Stenella attenuata, S. longirostris, yellowfin tuna, and seabirds.

The cetacean community of the WTIO was similar to that of the eastern tropical Pacific (ETP) and the Gulf of Mexico (GM) in several respects. First, differences in abundance rank of individual species were small, with the result that common species were common and rare species were rare, regardless of ocean. Second, these differences in abundance were due primarily to differences in encounter rate, which varied with ocean by as much as 3,000%, and less so to school size, which generally varied less than 100%. Third, regardless of ocean, three species comprised the majority of cetaceans in the community, Stenella attenuata, S. longirostris, and S. coeruleoalba, representing 62%‐82% of all individuals for all species. However, the rank order of abundance for these three species differed with ocean. Most notably, S. attenuata was abundant in the ETP and GM (abundance rank = 2 and 1, respectively) but much less common in the WTIO (abundance rank = 6). Although habitat preferences for S. attenuata appear to overlap considerably with those of S. longirostris in the ETP, our results suggest there may actually be significant differences between these two species. Detailed analysis of oceanographic correlates of distribution will be necessary in order to understand fully the habitat requirements of these pelagic dolphins, often the most conspicuous elements of tropical cetacean communities around the world.
SEASONAL PATTERNS IN THE ABUNDANCE AND DISTRIBUTION OF CALIFORNIA CETACEANS, 1991–1992
Authors: Forney Karin A. , Barlow Jay
Published: August 2006

Abstract

This study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100‐150 nmi (185‐278 km) of the California coast during 1991 and 1992. The results of a shipboard line‐transect survey conducted in July‐November 1991 (“summer”) were compared to those from aerial line‐transect surveys conducted in March‐April 1991 and February‐April 1992 (“winter”). Using a confidence‐interval‐based bootstrap procedure, abundance estimates for six of the eleven species included in the comparison exhibited significant (α= 0.05) differences between the winter and summer surveys. Pacific white‐sided dolphins (Lagenorhynchus obliquidens), Risso's dolphins (Grampus griseus), common dolphins (Delphinus spp.), and northern right whale dolphins (Lissodelphis borealis) were significantly more abundant in winter. The abundance of blue whales (Balaenoptera musculuss) and gray whales (Eschrichtius robustus) reflected well‐documented migratory patterns. Fin whales (B. physalus) were significantly more abundant during summer. No significant differences in seasonal abundance were identified for Dall's porpoises (Phocoenoides dalli), bottlenose dolphins (Tursiops truncatus), killer whales (Orcinus orca), sperm whales (Physeter macrocephalus), or humpback whales (Megaptera novaeangliae). Significant north/south shifts in distribution were found for Dall's porpoises, common dolphins, and Pacific white‐sided dolphins, and significant inshore/offshore differences were identified for northern right whale dolphins and humpback whales.
ISOLATION AND EXPRESSION OF THE INTERLEUKIN‐2 GENE FROM THE KILLER WHALE, ORCINUS ORCA
Authors: Ness Traci L. , Bradley W. Guy , Reynolds John E. , Roess William B.
Published: August 2006

Abstract

Complementary DNA encoding interleukin‐2 (IL‐2) was isolated, cloned, and sequenced from the killer whale, Orcinus orca. The sequence of the killer whale IL‐2 coding region consists of 455 nucleotides which translate into a polypeptide containing 151 amino acids. Killer whale IL‐2 displays 88%, 88%, 87%, 87%, 85%, 84%, 80%, and 71% nucleotide sequence homology and 76%, 76%, 76%, 73%, 68%, 73%, 64%, and 56% amino acid homology with the cow, sheep, pig, red deer, horse, human, manatee, and mouse, respectively. High levels of killer whale recombinant IL‐2 were generated by transiently transfecting killer whale IL‐2/pCMV Blue plasmid DNA into cultured monkey kidney cells (Cos‐1). Generation of this recombinant IL‐2 will allow the development of assays useful for assessing IL‐2 levels in the serum and from isolated lymphocytes of killer whales and possibly other species of cetaceans. A major contribution and significance of the in vitro expression of killer whale IL‐2 exists in its potential to be used as a therapeutic agent.
ESTIMATING NATURAL MORTALITY RATE IN REPRODUCTIVELY ACTIVE FEMALE SOUTHERN RIGHT WHALES, EUBALAENA AUSTRALIS
Authors: Best P. B. , Kishino H.
Published: August 2006

Abstract

Cow‐calf pairs of southern right whales on the South African coast have been photographed in aerial surveys in October each year since 1979. In this paper 469 resightings of 177 individually identified cows photographed in the first six years of surveys have been analyzed in two ways to produce estimates of natural mortality rate. Both methods assume that all females calve either two, three, or four years after their previous calf. In Method A there is assumed to be no systematic trend with time in the probability of a female being photographed on each calving occasion. Natural logarithms of the numbers photographed 2‐4, 5‐7, 8‐10, etc. yr after being first seen are regressed against time, the slope of which provides an estimate of natural mortality rate of 0.0255 ± 0.0071. The intercept value for this regression provides an estimate of the detection probability, or 0.769 ± 0.011. In Method B it is assumed that if a female has not been photographed for at least nine years then it is dead. Annual mortality estimates are obtained from the proportional reduction in the numbers of females known to be alive at each three‐year interval after being first photographed, up to at least 6‐8 yr from the present. Method B produces an estimate of natural mortality of 0.0260 ± 0.0190 (corrected to 0.0227 ± 0.0192 using the average detection probability). Both methods may be subject to various biases that tend to inflate estimates of natural mortality.
ESTIMATION OF TOTAL BODY WATER IN HARBOR SEALS: HOW USEFUL IS BIOELECTRICAL IMPEDANCE ANALYSIS?
Authors: Bowen W. Don , Boness D. J. , Iverson S. J.
Published: August 2006

Abstract

We evaluated bioelectrical impedance analysis (BIA) as a means of rapidly and inexpensively estimating total body water (TBW) of harbor seals (Phoca vitulina). Deuterium oxide dilution was used to estimate TBW in 17 adult females and 16 of their pups between birth and late lactation. Isotope dilution was also used to determine TBW in 12 adult males early and 10 of these males late in the breeding season. At the same time, resistance (Rs) and reactance (Xc) measurements were taken using a tetrapolar, impedance plethysmograph (Model 101 A, RJL Systems). Seals were sedated with diazepam prior to taking BIA measurements. Within‐day duplicate Rs measurements on pups and adults, taken 2‐240 min apart, differed by an average of 3.0%± 1.4% (n= 42, CV = 102%). Movement of the seal during BIA measurements caused variability in both Rs and Xc values. BIA measurements were generally poor predictors of TBW. Rs was significantly correlated with TBW in pups only (Rs= 0.93, P= 0.001, n= 11). Bioelectrical conductor volume (length2/Rs) was significantly correlated with TBW only in adult females (Rs= 0.63, P= 0.02, n= 14). We conclude that BIA is not a reliable method of estimating TBW in wild harbor seals.
GROWTH AND SEXUAL DIMORPHISM OF ATLANTIC WALRUSES (ODOBENUS ROSMARUS ROSMARUS) IN FOXE BASIN, NORTHWEST TERRITORIES, CANADA
Authors: Garlich‐Miller J. L. , Stewart R. E. A.
Published: August 2006

Abstract

Growth of Atlantic walruses (Odobenus rosmarus rosmarus) was investigated using morphological data collected in association with Inuit subsistence walrus hunts. Four growth models were examined. The growth parameters of a constrained Richards model were used to quantify growth and to test for sexual dimorphism. The asymptotic length of male walruses (315.2 cm ± 3.8 (SE),n= 103) was significantly larger (t= 7.21, df = 191,P< 0.05) than the asymptotic length of females (276.6 cm ± 3.4,n= 90). Sexual size dimorphism in adults was due to a longer growth period and a faster growth rate in males. The predictive equation relating mass (M, kg) to standard length (SL, cm) was: Log10M= ‐3.74 + 2.68(Log10SL),n= 25,r2= 0.98. There were no significant differences in the size of male walruses from Foxe Basin collected in the 1950s and this study. There were too few data to compare females. There were no significant differences in size between walruses sampled in Greenland and Foxe Basin in the 1980s and 1990s. Foxe Basin walruses were significantly larger than walruses sampled in northern Hudson Bay in the 1950s. Female Atlantic walruses sampled in Foxe Basin were larger than female Pacific walruses (Odobenus rosmarus divergens) sampled in Alaska.
BEHAVIORAL RESPONSE OF FOUR SPECIES OF BALAENOPTERID WHALES TO BIOPSY SAMPLING
Authors: Gauthier J. , Sears R.
Published: August 2006

Abstract

Behavioral responses to biopsy sampling of four species of northwestern Atlantic balaenopterid whales summering in the estuary and Gulf of St. Lawrence, Quebec, from 1990 to 1995 were studied to determine if this technique was an important disturbance to the whales. A total of 447 biopsy samples were taken using a small punch‐type biopsy tip fired from a crossbow. Biopsies were successfully taken from 91.2% of the whales approached. Whales displayed no reaction to 45.2% of the successful biopsy attempts. Whales that responded to biopsy sampling typically resumed their normal behavior immediately or within a few minutes. Most humpback whales displayed a hard tail flick, and the majority of fin and blue whales submerged following biopsy sampling. Significantly different frequencies and intensities of responses were found between whale species. Minke and humpback whales were found to be more sensitive to biopsy sampling than fin and blue whales. Response frequencies were similar between females and males for all species, with the exception of fin whales where females had a higher response frequency than males. Biopsy sample length, i. e., penetration depth, did not explain variations in response intensity but may influence response frequency to biopsy sampling. Group size, geographical region, and number of biopsies taken per whale were not factors that explained variation in behavioral responses. The biopsy technique was found to be an efficient method for obtaining high‐quality whale skin and blubber samples with limited behavioral disturbance to balaenopterid whales.
DIETARY STUDIES OF MARINE MAMMALS USING STABLE CARBON AND NITROGEN ISOTOPIC RATIOS OF TEETH
Authors: Walker Jane L. , Macko Stephen A.
Published: August 2006

Abstract

This study used naturally occurring carbon and nitrogen stable isotopes of teeth to study the diets of marine mammals. The isotopic ratios of nonchemically preserved teeth from eight species of marine mammals, representing 87 individuals that spanned the trophic continuum, were found to reflect nutritional sources. The δ13C signals distinguished animals that lived in waters dominated by different primary producers (e. g., seagrass, kelp, and phytoplankton), and δ15N values indicated the diet and trophic level of the species. This research suggests that isotopic signatures of teeth can be used in dietary studies to show differences and similarities among age classes, genders, geographic locations, and time periods.
RANGE CHARACTERISTICS OF PACIFIC COAST BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN THE SOUTHERN CALIFORNIA BIGHT
Authors: Defran R. H. , Weller David W. , Kelly Dennis L. , Espinosa Miriam A.
Published: August 2006

Abstract

Boat‐based photoidentification surveys of bottlenose dolphins (Tursiops truncatus) were conducted from 1982 to 1989 in three discrete coastal study areas within the Southern California Bight: (1) Santa Barbara, California; (2) Orange County, California; (3) Ensenada, Baja California, Mexico. A total of 207 recognizable dolphins were identified in these three “secondary” study areas. These individuals were compared to 404 dolphins identified from 1981 to 1989 in our “primary” study area, San Diego, California, to examine the coastal movement patterns of bottlenose dolphins within the Southern California Bight. A high proportion of dolphins photographed in Santa Barbara (88%), Orange County (92%), and Ensenada (88%) were also photographed in San Diego. Fifty‐eight percent (n= 120) of these 207 dolphins exhibited back‐and‐forth movements between study areas, with no evidence of site fidelity to any particular region. Minimum range estimates were 50 and 470 km. Minimum travel‐speed estimates were 11‐47 km/d, and all dolphin schools sighted during the study were within 1 km of the shore. These data suggest that bottlenose dolphins within the Southern California Bight are highly mobile within a relatively narrow coastal zone. Home‐range dimensions and movement patterns for many vettebrate species are influenced, in part, by variation in food resources. The unique range characteristics documented during this study may reflect the highly dynamic nature of this coastal ecosystem and the associated patchy distribution of food resources available to these bottlenose dolphins.
LOCAL ABUNDANCE AND DISTRIBUTION OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN THE NEARSHORE WATERS OF VIRGINIA BEACH, VIRGINIA
Authors: Barco Susan G. , Swingle W. Mark , Mlellan William A. , Harris Reid N. , Pabst D. Ann
Published: August 2006

Abstract

We investigated patterns of abundance and distribution for coastal migratory Atlantic bottlenose dolphins (Tursiops truncatus) that appear seasonally in the nearshore waters of Virginia Beach, Virginia. The study was conducted along 24 km of shoreline at the southern point of the Chesapeake Bay mouth from April 1994 to March 1995. This is the first study to investigate the relationship between the abundance of coastal migratory dolphins and factors that might affect their movement. A profile analysis of variance revealed significant differences in local abundance and distribution throughout the year. Dolphin number was positively correlated with water temperature and not correlated with photoperiod. Although prey distribution and abundance are two factors thought to affect dolphin presence, in this study the relationship between these two factors and dolphin abundance was unclear. Greater numbers of dolphins were found in the ocean section of the study area. However, significantly higher ratios of neonatal dolphins were observed in the bay section, suggesting the bay serves as a nursery area. The observed relationship between local dolphin abundance and environmental factors in Virginia may provide insight into dolphin distribution and migration along the Atlantic coast of the United States.
SKIN SWABBING FOR GENETIC ANALYSIS: APPLICATION TO DUSKY DOLPHINS (LAGENORHYNCHUS OBSCURUS)
Authors: Harlin April Dawn , Würsig Bernd , Baker C. Scott , Markowitz Tim M.
Published: August 2006

Abstract

Exfoliated skin was collected from bowriding dolphins with the use of a sterilized nylon scrub pad affixed to a wooden dowel. Initial tests of the effectiveness of the technique and dolphin behavioral responses were conducted on dusky dolphins off Kaikoura, New Zealand. During 14 sampling days, 128 contacts using this procedure were made with bowriding dolphins, of which 114 showed behavioral response. Responses during sampling were mild, with 11% of contacted individuals showing no visible response, and 66% of individuals which could be monitored for 30 sec after contact returning to bowride within 30 sec. Mean return time was 10 sec postcontact and did not vary significantly for groups of different sizes. Behavioral controls suggest that a proportion of responses could be explained by typical dolphin behavior in the presence of boats. Seventy‐eight percent of contacts resulted in successful collection of tissue samples. Sample time was three minutes on average. Size of group and behavioral state did not appear to influence sample time. Preliminary genetic analyses revealed that tissue collected by this technique was suitable for amplification and sequencing of mitochondrial DNA (mtDNA) via PCR. Comparisons of mtDNA control region sequences with those from known L. obscurus and other delphinid samples verified that this technique was robust against contamination from elements in sea water.
PHYLOGENETIC RELATIONSHIPS AMONG THE DELPHINID CETACEANS BASED ON FULL CYTOCHROME B SEQUENCES
Authors: Leduc R. G. , Perrin W. F. , Dizon A. E.
Published: August 2006

Abstract

Complete cytochrome b gene sequences from all but one species of delphinid plus four outgroups were analyzed using parsimony, maximum likelihood, and neighbor‐joining methods. The results indicate the need for systematic revision of the family; a provisional classification is presented and compared to previous studies. Among the suggested revisions are removal of Orcinus from the Globicephalinae, placement of Grampus within the Globicephalinae, removal of all Lagenorhynchus spp. from the Delphininae, and placement of Sousa in the Delphininae. The genus Lagenorhynchus is found to be polyphyletic. L. albirostris (type species for the genus) and L. acutus are not closely related to each other or to nominal congeners. L. acutus is therefore assigned to the genus Leucopleurus. The remaining four Lagenorhynchus species are closely related to Lissodelphis and Cephalorbynchus and are placed in the genus Sagmatias. These three genera constitute the revised Lissodelphininae. Within the Delphininae, a well‐supported clade includes the two species of Delphinus, Stenella clymene, S. frontalis, S. coeruleoalba, and the aduncus form of Tursiops truncatus. Accepting the monophyly of this group renders the genera Stenella and Tursiops polyphyletic. Apart from this finding, phylogenetic resolution within the Delphininae was poor, so comprehensive taxonomic revision of this group awaits further study.
GASTROINTESTINAL HELMINTHS OF THE DUSKY DOLPHIN, LAGENORHYNCHUS OBSCURUS (GRAY, 1828), OFF PATAGONIA, IN THE SOUTHWESTERN ATLANTIC
Authors: Dans Silvana L. , Reyes Laura M. , Pedraza Susana N. , Raga Juan A. , Crespo Enrique A.
Published: August 2006

Abstract

The stomachs and intestines of 23 dusky dolphins incidentally caught in a trawl fishery off Patagonia were surveyed for helminths. All the dolphins were parasitized, with a total of 3,936 helminth individuals. Only five species occurred, of which three were common (prevalence ± 10%): Anisakis simplex, Braunina cordiformis and Hadwenius sp. A. simplex was present in all the dolphins and showed the highest abundance and mean intensity (104.9 individuals/infected host). B. cordiformis was next most common (87%), and Hadwenius sp. third (52.2%). A. simplex was found mostly in the stomach (94.8%), B. cordiformis in the duodenal ampulla (51.4%), and Hadwenius sp. in the stomach (64.5%). The rare species Corynosoma australe (immature specimens) and Pholeter gastrophilus occurred in the stomach. A. simplex and B. cordiformis showed a clumped distribution along the intestine. Brillouin's diversity and evenness indices for the intestinal helminth community were 0.329 and 0.393, respectively. The diversity values and the number of parasite species were within the range for other small cetaceans.
HAS THE AGE AT TRANSITION OF SOUTHERN HEMISPHERE MINKE WHALES DECLINED OVER RECENT DECADES?
Authors: Thomson R. B. , Butterworth D. S. , Kato H.
Published: August 2006

Abstract

The earplugs of several baleen whale stocks exhibit seasonal growth layers which have been shown for some species to indicate the total age of the animals. A transition from early, irregular layers, to later, more regular layers can be seen in these earplugs, and this is thought to indicate the age at maturity of the whale. The earplugs of Southern Hemisphere minke whales are relatively difficult to read, particularly for the age at transition, and it has been suggested that these readings reflect no more than random allocations by the reader, rather than any real effect. Plots of average transition phase against year of birth (cohort) show a decline in the average age at transition. However, certain factors can result in a downward bias in this trend, particularly when only a short time‐series is available for analysis, as was the case when this trend was first estimated some 15 yr ago. Data collected over 25 yr are now available and are reanalyzed here. A plot of mean age at transition against year of sampling for animals of similar age shows a decline, as does the conventional plot against cohort, suggesting that the decline is real. A model that simulates random allocation of the transition phase by earplug readers yields predictions that show systematic deviations from the data. In contrast, a second model that allows for a real trend in the average age at transition and that takes account of two potentially biasing effects (termed truncation and the fringe effect) fits the data well. A tendency is evident for readers to recognize a transition phase in a greater proportion of the earplugs that they read as they gain experience over time. This is taken into account in the model. This model shows a decline in the average age at transition from roughly 11 for the cohorts of the 1950s to roughly 7 for those of the 1970s. These results suggest that minke whale transition‐phase readings are related to a real signal in the data and are not simply an artefact, and further that there has been a real decline in the age to which this signal corresponds.
ESTIMATING BODY LENGTH OF PYGMY RIGHT WHALES (CAPEREA MARGINATA) FROM MEASUREMENTS OF THE SKELETON AND BALEEN
Authors: Kemper Catherine M. , Leppard Phillip
Published: August 2006

Abstract

Various parts of the skeleton and/or the longest baleen plate of 46 specimens of Caperea marginata from Australia and New Zealand were measured and related to body length. Of the 32 skull, postcranial and baleen‐plate measurements available, eight were analysed and seven found to be good predictors of body length, by using a curvilinear model describing their relationship with body length. Greatest skull width, supraoccipital length and mandible length had the smallest prediction limits (± 0.28‐0.33 m in small animals, ±0.44‐0.58 m in large animals) when compared with postcranial measurements (scapula length, vertebra 7 centrum width). Baleen‐plate length was also a useful predictor of body length (±0.32‐0.77 m). There was a substantial increase in the arch of the skull as body length increased. Bulla length was not a good predictor of body length, because measurements were highly variable and because the bulla grew little during postnatal life. Physical maturity occurred at body lengths of at least 5.9 m, also the shortest length at which both epiphyses of the humerus and proximal epiphyses of the radius and ulna were fused. Weaning appears to occur at about 3‐3.5 m. The following approximate relative age/length classes were erected: dependent calves, <3.6 m; subadults, 3.6‐5.5 m; adults, >5.5 m. Females were significantly longer than males in the sample of 22 animals greater than 5.9 m, length of the smallest recorded physically mature animal.
GENETIC BASIS AND EVOLUTIONARY SIGNIFICANCE OF VENTRAL SKIN COLOR MARKINGS IN NORTH ATLANTIC RIGHT WHALES (EUBALAENA GLACIALIS)
Authors: Schaeff C. M. , Hamilton P. K.
Published: August 2006

Abstract

Approximately one third of the North Atlantic right whale population has white ventral skin patches. Most white‐marked animals have both a belly and a chin patch, and the distribution of white pigment suggests that the patches represent a single ventral marking that varies in size and location. Population frequencies and cow‐calf inheritance patterns indicate that the white mark is an autosomal recessive trait. There is no evidence to suggest that ventral coloration patterns are currently under selection. White‐marked and black cows appear to experience similar levels of reproductive success based on calving intervals and length of sighting histories. Also, white‐marked animals were equally common among cows and nulliparous adult females and among live vs. dead animals. Male reproductive success could not be tested because calf paternity is not known; white‐marked and black males exhibit similar survival rates. White‐marked cows were more common among females that took some or all of their calves to the Bay of Fundy summer nursery area compared to females that did not visit Fundy. This suggests that female habitat‐use patterns may influence nuclear gene flow. Increased sample sizes and additional markers are needed to further investigate gene flow.
AGE‐LENGTH RELATIONSHIPS IN HUMPBACK WHALES: A COMPARISON OF STRANDINGS IN THE WESTERN NORTH ATLANTIC WITH COMMERCIAL CATCHES
Authors: Stevick Peter T.
Published: August 2006

Abstract

Strandings of previously identified individuals, while rare, provide an opportunity to examine age‐length relationships in humpback whales (Megaptera novacangliae) from the North Atlantic. Ages and lengths of 23 individuals are presented: 11 females and 12 males, 9 of known age and 14 with estimated minimum ages. Lengths ranged from 853 to 1, 430 cm, ages 0.5–17 yr. These individuals were generally smaller and more variable in size at age than reported from commercial catches. Fifteen of the stranded individuals were four years of age or younger, while few of the animals taken by whalers were this young, and these probably represented the larger individuals in these age categories. Thus the data presented herein help to give more definition to the early growth curve for the humpback whale than has previously been available. Growth equations illustrate a difference of about one meter in asymptotic length through age five between stranding and catch data. The close fit of growth models to data from younger and older animals separately and the difficulty of fitting a single growth model to animals of all ages, could indicate that a dynamic or staged growth pattern exists in this species.
USING TREND INDICES FOR ENDANGERED SPECIES
Authors: Eberhardt L. L. , Garrott R. A. , Becker B. L.
Published: August 2006

Abstract

Initial appraisals of the status of endangered large‐mammal populations may have to depend on indices of population trend. Such indices may possibly be improved by using auxiliary variables. Various models were studied for populations of the Florida manatee (Trichechus manatus latirostris), Yellowstone grizzly bear (Ursus arctos horribilis), and Hawaiian monk seal (Monachus schauinslandi). Several criteria for checking validity of the fitted models were considered, and the simpleR2criterion appears to provide useful comparisons. Multiple regression models overestimated the rate of change of the East Coast manatee population as determined from three other sources (a covariance model, a non‐linear model, and the rate estimated from reproductive and survival data). A multiple regression model for grizzly bears using three auxiliary variables exhibited a fairly highR2(0.84) and appeared to provide a better fit than did a non‐linear model. A beach count index for Hawaiian monk seals seemed to be unreliable for year‐to‐year comparisons in contrast to total population counts and estimates from a capture‐recapture method. The use of auxiliary variables for checking and improving trend index data appears feasible and well worthwhile.
EXAMINING THE RISK OF INBREEDING DEPRESSION IN A NATURALLY RARE CETACEAN, THE VAQUITA (PHOCOENA SINUS)1
Authors: Taylor Barbara L. , Rojas‐Bracho Lorenzo
Published: August 2006

Abstract

Uncertainty about the magnitude of various risks facing endangered species can paralyze conservation action. The vaquita is a naturally rare porpoise that has declined to the low hundreds of individuals because of gillnet mortality over the past 57 years. No variability in mitochondrial DNA (mtDNA) was found in vaquitas (n= 43). Because reducing gillnet mortality will require strong conservation action, the question was raised whether vaquitas are doomed because of inbreeding depression and whether, therefore, mitigation efforts would be futile. We use simulations to investigate the “doom hypothesis” by first asking whether the current level of genetic variability results from the recent decline or from historical factors. If fixation was historical then deleterious alleles could have been selected out of vaquitas over thousands of years, reducing concerns about inbreeding depression. Simulations showed that fixation most likely resulted from historical rather than recent loss. Of 1,000 simulations done at plausible abundances and mutation rates, 247 (84.3%) fixed before and 46 (15.7%) fixed during the recent decline. Fixation correlates with historical abundance, making it more likely that because vaquitas are fixed, they are also a naturally rate species. However, because studies on purging deleterious alleles have not shown purging to be universally beneficial we also examine the doom hypothesis using data on the response to inbreeding of a wide variety of captive animals. Responses are so variable that the doom hypothesis cannot be affirmed. We further explore whether more data from vaquitas would lead to conclusive results and found that the data required, such as the adult survival rate, will be impossible to obtain. We conclude that because the doom hypothesis cannot be affirmed this risk factor should not delay conservation actions.
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

Abstract

A 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

Abstract

The 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

Abstract

Mark‐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

Abstract

The 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

Abstract

The 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.