bluuebunny/crossref_metadata_2025 huggingface dataset:
THE POPULATION DYNAMICS OF NORTHERN SEA LIONS, 1975‐1985
Authors: York Anne E.
Published: August 2006

Abstract: Populations of northern sea lions (Eumetopias jubatus) in the vicinity of Marmot Island, Alaska declined during 1975–1985 at about 5% per year (Merrick et al. 1987). The cause of this decline is not known. A life table for the northern sea lion was calculated assuming that life spans follow a Weibull distribution. Samples of northern sea lions taken in the vicinity of Marmot Island, Alaska during 1975–1978 and 1985–1986 indicate that the average age of females older than 3 yr increased about 1.55 yr (SD = 0.35 yr) while the population was declining at about 5% per year. Fecundity rates decreased by 10% over the same period, but the decrease was not statistically significant (Calkins and Goodwin 1988). Possible causes of the population decline and the change in age structure were examined by writing the Leslie matrix population equation in terms of changes in juvenile and adult survival rates and fecundity, and examining the short–term behavior of the trajectories of the average age of adult females, total number of females, and total number of pups with respect to those changes in the vital parameters. From the observed rate of declines of adults and the changes in average age of adult females and fecundity, estimates of the changes in adult and juvenile survival were calculated; estimates of the standard deviations of these changes were estimated via a bootstrap procedure. One purpose of this exercise is to aid in setting priorities for research for determining the cause of the decline. An explanation for the observed declines in numbers of adult sea lions consistent with the observed fecundity rates, a rate of decrease of 5% in the number of adults, and the corresponding increase in average age (of females age 3 yr and older) was a 10%–20% decrease in the survival of juveniles (age 0‐3 yr) coupled with an insignificant change in adult survival (0.03%, SD = 1%).
AGE and SEX COMPOSITION OF THE STRIPED DOLPHIN DIE‐OFF IN THE WESTERN MEDITERRANEAN
Authors: Calzada Nuria , Lockyer Christina H. , Aguilar Alex
Published: August 2006

Abstract

During the morbillivirus epizootic that affected the Mediterranean striped dolphins (Stenella coeruleoalba)in 1990–1992, several thous and individuals are believed to have died. In order to determine the segments of the population that were affected by the event, the sex‐ and age‐frequency distributions of the animals that were washed ashore on the Spanish coasts were studied. The age of the animals was determined by counting dentine growth layer groups in the teeth. The results obtained indicate that both sexes were affected similarly by the disease and that the population component that suffered the largest mortality was that of sexually mature individuals, although substantial mortality of calves, probably still dependent on their mothers, was also observed. Juveniles, in contrast, appeared to be only slightly affected by the epizootic. This pattern of mortality is not consistent with the epidemiology of morbillivirus infections previously observed in other mammals. Possible explanations of this particular age distribution include behavioral factors, increased susceptibility to the disease in adults due to the effects of pollution, high temperatures and decreased food availability, or allopatric geographical distribution of population components and, therefore, of their associated mortality.
SEASONAL CHANGES IN FOOD INTAKE OF HARP SEALS (PHOCA GROENLANDICA) AT 69°N
Authors: Lager A. R. , Nordøy E. S. , Blix A. S.
Published: August 2006

Abstract

Food intake (PI), body mass (BM), and compartmental growth were recorded for 12 mo in four captive 2–4‐yr‐old male harp seals (Phoca groenlandica), exposed to an artificial light regime that closely resembled natural day length at 69°. In early May before molting, both FZ and BM decreased in all four animals. Total body fat (TBF) declined from 51% of BM in March (n = 4) to 30% in August (n = 2), while total body water (TBW) concomitantly increased from 37% to 51% and total body protein (TBP) from 11% to 17%. In July FI started to increase, while BM started to increase in August. TBF increased while TBW and TBP decreased from August, all three parameters reaching a stable level in October at 47%, 39%, and 12%, respectively. Thereafter, body composition was maintained rather constant until May. Between October and March/April FI fluctuated for all animals, while BM showed a fairly steady increase. Average daily amount of capelin consumed was 2.67 kg·d−1, equivalent to 25,600 kJ·d−1, or 343 kJ·kg−1·d−1.
CONCENTRATIONS OF ESTRONE SULFATE and PROGESTERONE IN PLASMA and SALIVA, VAGINAL CYTOLOGY, and BIOELECTRIC IMPEDANCE DURING THE ESTROUS CYCLE OF THE HAWAIIAN MONK SEAL (MONACHUS SCHAUNSLAnDI)
Authors: Pietraszek J. , Atkinson S.
Published: August 2006

Abstract

Blood and saliva samples, vaginal swabs, and bioelectric impedance measurements were collected 1–3 times per week from a captive adult female Hawaiian monk seal (Monacbus schauinslandi) during the spring and summer of 1991. During 1992 saliva only was collected on average 4 times weekly. Concentrations of progesterone and estrone sulfate, and the periodic appearance of cornified epithelial cells from the vagina indicated consecutive estrous cycles ranging 35 ± 3 days in duration. Progesterone concentrations in plasma and saliva had a correlation of 0.868, while estrone sulfate had a correlation of 0.982. Bioimpedance of the whole seal body resulted in a pattern similar to the estrone sulfate concentrations, but shifted forward by 2 d. Bioimpedance of the upper vaginal tissues paralleled the estrone sulfate pattern while the bioimpedance of the lower reproductive tract fluctuated without a distinct pattern. The luteal phase ranged 17–20 d and the follicular phase was 15–18 d in length. These results indicate that: (1) the Hawaiian monk seal, in captivity, is a polyestrous seal, in contrast to other phocid seals that have been studied; (2) salivary concentrations of estrogen and progesterone may provide an accurate, less‐invasive method of monitoring reproductive hormones in captive Hawaiian monk seals; and (3) vaginal cytology and bioelectric impedance reflect physiological changes associated with the estrous cycle.
HARBOR SEAL (PHOCA VITULINA) PREDATION ON SEINED SALMONIDS IN THE LOWER KLAMATH RIVER, CALIFORNIA
Authors: Stanley William T. , Shaffer Kevin E.
Published: August 2006

Abstract

Feeding activity of harbor seals (Phoca vitulina) was monitored while the California Department of Fish and Game seined and tagged migrating adult salmonids between 1984 and 1988. The number of predations observed each week of observation was significantly correlated with the number of fish seined during that week. There was a significantly higher number of predations observed on days when seining took place than on days when no seining occurred. Our observations suggest that most, if not all, predations we observed on days when seining occurred involved fish that had been recently seined and released. The estimated percentage of seined fish taken by seals was relatively constant over the five years of the study, ranging from 3.1% to 5.5%. Various strategies for reducing the level of predation on seined salmonids in the lower Klamath River are discussed.
SURVIVAL OF FIVE SPECIES OF CAPTIVE MARINE MAMMALS
Authors: Small Robert J. , Demaster Douglas P.
Published: August 2006

Abstract

Survival in captivity was calculated for 1,707 bottlenose dolphins (BD), 72 killer whales (KW), 73 white whales (WW), 3,090 California sea lions (CSL), and 47 Steller sea lions (SSL) based on data in the Marine Mammal Inventory Report (MMIR) of the NMFS. Mean annual survival rates (ASRs) between 1988 and 1992 were 0.951, 0.937, and 0.954 for BD, KW, and WW, respectively, and 0.952 and 0.969 for CSL and SSL, respectively. These estimates represent significant increases in survival for both BD and CSL over the last 5 yr. Using all of the MMIR data (1940–1992), the ASR of BD calves (< 1 yr of age) was significantly less than the ASR of non‐calves (0.666 vs.948, 0.001). Similarly, the ASR of CSL pups (< 1 yr of age) was significantly less than survival of non‐pups (0.858 vs.962, 0.001). Survival of captive‐born CSL was significantly higher than those born in the wild (0.962 vs.945, 0.003), but the difference was not significantly different for BD (0.948 vs.944, 0.60). For non‐calf BD and KW, captive animals survived at a slightly lower rate (BD 0.944 vs.961, = 0.07; KW 0.938 vs.976, 0,001) than animals in the wild (BD: Wells and Scott 1990, KW: Olesiuk 1990). Survival of captive non‐pup SSL was slightly higher (0.968 vs.930) than animals in the wild (York 1994, life‐table analyses). Survival rates were significantly different among institutions for BD calves and non‐calves, CSL pups and non‐pups, and SSL non‐pups.
SATELLITE‐MONITORED MOVEMENTS AND DIVE BEHAVIOR OF A BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) IN TAMPA BAY, FLORIDA
Authors: Mate Bruce R. , Rossbach Kelly A. , Nieukirk Sharon L. , Wells Randall S. , Blair Irvine A. , Scott Michael D. , Read Andrew J.
Published: August 2006

Abstract

An adult, female bottlenose dolphin (Tursiops trucncatus) was radio tagged and monitored via satellite‐based Argos receivers for 25 d from 28 June to 23 July 1990, in Tampa Bay, Florida. A total of 794 transmissions were obtained during 106 satellite passes. A mean of 3.9 (SE = 0.24) locations/day were determined by Service Argos and showed the animal remained in the bay, usually close to the southeastern shore. The dolphin moved at least 581 km at a minimum mean speed of 1.2 (SE = 0.1) km/h. Data from 63, 922 dives were recorded. The animal spent an average of 87.1 (SE = 0.6)% of the time submerged, with a mean dive duration of 25.8 (SE = 0.5) sec. Mean dive duration differed significantly between four periods of the day, as did the mean percent of time spent submerged. During the early morning the animal spent more time at the surface, averaged shorter dives, and was submerged less than other times of day. This is the first study to demonstrate die1 dive cycles in a bottlenose dolphin. Four months after tag loss, the dolphin was photographed with no evidence of necrosis or disfigurement of the dorsal fin. Satellite telemetry was demonstrated as an effective means of documenting the movements and dive behavior of a small inshore cetacean.
APPARENT BOTTOM FEEDING BY HUMPBACK WHALES ON STELLWAGEN BANK
Authors: Hain James H. W. , Ellis Sara L. , Kenney Robert D. , Clapham Phillip J. , Gray Belinda K. , Weinrich Mason T. , Babb Ivar G.
Published: August 2006

Abstract

Humpback whales, Megaptera novaeangliae, on Stellwagen Bank off eastern Massachusetts, U.S.A., apparently bottom feed on northern sand lance, Ammodytes dubius. The feeding behavior is characterized by the whales brushing the bottom in depths of less than 40 m, causing sand lance burrowed in the bottom to be flushed up into the water column. The greatest densities of sand lance were in beds of shells and shell debris, termed “shell hash.” The brushing against or along the bottom, particularly in these shell hash areas, caused the humpbacks to acquire abrasions and wounding, sometimes rather extensive, of the lateral lower jaw, and lateral and dorso‐lateral upper jaw, here termed “jaw scuffing.” Scuffing of the dorsal fin and fluke edges was also common and may be at least partially related to this feeding behavior. Both mature and immature, and male and female, humpbacks exhibited jaw scuffing. The bottom‐feeding behavior was not exclusive, as jaw‐scuffed individuals were also observed to use other feeding behaviors. In recent years (1991‐1993), however, bottom feeding appears to have become relatively more common, particularly among young animals. Overall, in the Stellwagen Bank area between 1979 and 1993, a majority of the population engaged in, or had engaged in, bottom feeding and the associated prey flushing.
QUANTITATIVE BEHAVIORAL STUDY OF BOTTLENOSE DOLPHINS IN SWIM‐WITH‐DOLPHIN PROGRAMS IN THE UNITED STATES
Authors: Samuels AMY , Spradlin Trevor R.
Published: August 2006

Abstract

The behavior of dolphins in four Swim‐With‐Dolphin programs was compared by type of Swim encounter, defined by the presence (“Controlled“) or absence (“Not‐Controlled“) of explicit trainer regulation of interactions between dolphins and human swimmers. Dolphin‐swimmer interactions involving aggressive, submissive, or sexual behavior were designated as “high‐risk” in the Swim context; sexual behavior was included as high‐risk based on analyses that demonstrated co‐occurrence of sexual and agonistic behaviors. High‐risk activity comprised a substantial proportion of dolphin‐swimmer social activity during Not‐Controlled Swims. In contrast, high‐risk activity rarely occurred during Controlled Swims, even though agonistic and sexual behaviors were normal components of the same dolphins’ free‐time social repertoire. These results indicated that direct trainer control of dolphin‐swimmer interactions virtually eliminated high‐risk activity from the Swim context, and thereby diminished the potential for dolphin distress, swimmer injury, and rejection of dolphins from Swim programs due to swimmer injury. This study illustrates effective use of quantitative behavioral sampling techniques for evaluation of captive management concerns and promotes broader use of these techniques for a better understanding of cetacean behavior.
A CETACEAN BIOPSY SYSTEM USING LIGHTWEIGHT PNEUMATIC DARTS, AND ITS EFFECT ON THE BEHAVIOR OF KILLER WHALES
Authors: Barrett‐Lennard LanceG. , Smith Tom G. , Ellis Graeme M.
Published: August 2006

Abstract

Lightweight untethered pneumatic darts were used to biopsy killer whales, Orcinus orca, for genetic and toxicological analysis. Samples of epidermal, dermal, and hypodermal tissue weighing approximately 0.5 g were obtained by 65% of the 91 darts fired during the study. Sufficient DNA for multiple analyses was extracted from the biopsies, which were also used for fatty acid and toxic contaminant analyses. Reactions such as momentary shakes or accelerations were observed after 81% of the dart hits and 53% of the misses. Aversion to the research vessel was assessed by reapproaching target whales after the sampling attempts. In 6% of the hits and 8% of the misses aversion to the research boat increased immediately following the attempt. No similar increases in aversion were seen when killer whales were reapproached one day to one year after being hit. The darts were also tested successfully on humpback whales, Megaptera novaeangliae. In view of the simplicity of the system, its effectiveness in acquiring multipurpose samples, and the apparently short‐term disturbance it caused, it is recommended for future cetacean biopsy studies.
RELATIONSHIPS AMONG MORPHOLOGICAL STATUS, STEROID HORMONES, AND POST‐THAWING VIABILITY OF FROZEN SPERMATOZOA OF MALE MINKE WHALES (BALAENOPTERA ACUTOROSTRATA)
Authors: Fukui Y. , Mogoe T. , Jung Y. G. , Terawaki Y. , Miyamoto A. , Ishikawa H. , Fujise Y. , Ohsumi S.
Published: August 2006

Abstract

Spermatozoa from 21 mature minke whales (Balaenoptera acutorostrata) taken in the Antarctic Ocean for Japanese research were recovered from vasa deferentia, diluted 1:9 in a Tris‐based diluent, and frozen at ‐ 80°C on board the vessel. After a period ranging from 45 to 125 d, the samples were transferred to liquid nitrogen and transported to the laboratory. After thawing at 37°C the motility (percentage of motile spermatozoa), vitality (proportion of live spermatozoa), and sperm concentration were determined for each sample. These values were tested for correlations with morphological measurements (body size, body weight, testis weight) and serum concentrations of progesterone (Pd), estradiol‐17β (E2), and testosterone (T). Ten of 21 samples had motile spermatozoa (2%‐40%). Although no motile spermatozoa were observed in 1.1 samples, all sperm samples were examined by eosinnigrosin staining and showed vitality levels of 3%44%. It was found that the motility (Y = 0.54) and vitality (r = 0.53) of the spermatozoa were significantly (P < 0.01) correlated with the E2 levels (8.50 ± 1.80 pg/ml). Serum T levels (0.07 ± 0.02 ngml) were significantly correlated with the E2 levels (r = 0.58, P < 0.01>, but sperm concentrations were not correlated with either Ea or T levels. The present study demonstrates that spermatozoa of minke whales can be successfully cryopreserved.
ISOLATION AND CHARACTERIZATION OF A cDNA ENCODING INTERLEUKIN 2 FROM THE FLORIDA MANATEE,TRICHECHUS MANATUS LATIROSTRIS
Authors: Cashman Mary E. , Ness Traci L. , Roess William B. , Bradley W. Guy , Reynolds John E.
Published: August 2006

Abstract

Interleukin‐2 (IL‐2) production is essential for optimal mammalian immune response; therefore, a cDNA encoding IL‐2 was isolated and characterized for the endangered Florida manatee,Trichechus manatus latirostris. The manatee IL‐2 cDNA was cloned by reverse transcription/polymerase chain reaction (PCR), using primers derived from IL‐2 regions conserved among various mammalian species. Manatee IL‐2 cDNA consisted of 450 base pairs encoding a predicted product of 150 amino acid residues and displayed 87%, 82%, 79%, 78%, 75%, and 73% DNA sequence homology and 74%, 69%, 63%, 62%, 61%, and 57% amino acid sequence homology with human, pig, sheep, cow, rat, and mouse IL‐2, respectively.
“PUSHY” BEHAVIOR IN A WILD DOLPHIN FEEDING PROGRAM AT TANGALOOMA, AUSTRALIA
Authors: Orams Mark B. , Hill Greg J. E. , Baglioni Anthony J.
Published: August 2006

Abstract

A program where wild bottlenose dolphins (Tursiops truncatus) are fed by tourists in shallow water adjacent to a wharf has been established at Tangalooma, Queensland, Australia. Up to nine dolphins attend the nightly feedings, and between 60 and 80 resort guests are permitted to hand feed these dolphins each night. Since this program began in 1992, the dolphins have increased in confidence and have started, at times, to make forceful contact with guests who enter the water to feed them. This paper categorizes such behavior as “pushy” and reports on a study which quantifies the “pushiness” of the dolphins which feed at Tangalooma. The study examines ecological variables which may determine how pushy the dolphins are at different feeding sessions. The number of dolphins attending a particular feeding significantly increases the pushiness. In addition, the presence of adult males at a feeding is likely to increase pushing. Tidal state also influences how pushy the dolphins are. At low tide, when the dolphins’mobility is restricted by the water depth, they are less likely to be pushy. Given the problems experienced in a number of other situations where wild animals are fed by humans, it is important to monitor carefully the escalation of pushy behavior in this dolphin feeding program, as it may be a precursor to more aggressive actions on the part of the dolphins.
DURATION OF STEREOTYPED UNDERWATER VOCAL DISPLAYS BY MALE ATLANTIC WALRUSES IN RELATION TO AEROBIC DIVE LIMIT
Authors: Nowicki S. N. , Stirling Ian , Sjare Becky
Published: August 2006

Abstract

During the breeding season from January to mid‐April, adult male Atlantic walruses (Odobenus rosmarus rosmarus) dive repeatedly for an average duration of 4–6 min and give stereotyped underwater vocal displays. Between dives, they surface for 1–2 min, take 4–6 breaths, and give stereotyped vocalizations between breaths. Male walruses vocalize in the presence of groups of females and calves, young adult males, or by themselves as lone singers. This pattern is repeated throughout the breeding season and can be maintained for extended periods, sometimes exceeding 48 h. The prolonged underwater vocal displays of male walruses seem possible because the animals do not exceed the aerobic dive limit (ADL), estimated to be 9.8 min for a 1,100‐kg animal, nor do they exceed the behavioral ADL of 7.9 min, determined from the histogram of dives for males singing alone. The number of breaths taken after dives and the postdive surface times remained fairly constant despite dive duration, suggesting that the walruses remained within their aerobic dive limits. The duration of most dives made by displaying males vocalizing alone during the breeding season, and dive duration of walruses feeding for protracted periods outside the breeding season, are both roughly half the estimated ADL.
THE DISTRIBUTION OF RISSO'S DOLPHIN (GRAMPUS GRISEUS) WITH RESPECT TO THE PHYSIOGRAPHY OF THE NORTHERN GULF OF MEXICO
Authors: Baumgartner Mark F.
Published: August 2006

Abstract

The distribution of Risso's dolphin (Grampus griseus) was examined with respect to two physiographic variables, water depth and depth gradient (sea floor slope), in the northern Gulf of Mexico, using shipboard and aerial survey data collected from 1992 to 1994. Univariate x2 analyses demonstrated that Risso's dolphins are distributed non‐uniformly with respect to both depth and depth gradient. A bivariate analysis of the shipboard data indicated that Risso's dolphins utilize the steep sections of the upper continental slope in the northern Gulf of Mexico. This narrow core habitat is in waters bounded by the 350‐m and 975‐m1 isobaths with depth gradients greater than 24 m per 1.1 km and consists of only 2% of the surface area of the entire Gulf of Mexico. Sighting rates inside this region were nearly 5 and 6 times the average for the shipboard and aerial surveys, respectively. Of the groups sighted outside this region, 40% (shipboard) and 73% (aerial) were encountered within 5 km of it. Since it is unlikely that the physiography alone can attract dolphins, oceanographic mechanisms that may concentrate prey along the steep upper continental slope are discussed. The implications of this distribution, including potential prey species, foraging strategies, and impacts of proposed mineral exploration and development, are also considered.
SEASONAL CHANGES IN BLUBBER DISTRIBUTION IN ATLANTIC HARBOR SEALS: INDICATIONS OF THERMODYNAMIC CONSIDERATIONS
Authors: ROSEN DAVID A. S. , RENOUF DEANE
Published: August 2006

Among its functions, the hypodermal blubber layer of pinnipeds serves as both an energy reserve and insulation. This study examined seasonal changes in blubber distribution and body morphology in a group of captive changesharbor seals to test whether these changes were designed to maximize insulative effectiveness. Seasonal changes were found in girth, blubber volume, mean blubber depth, and the ratio of blubber depth to body radius (d/r ratio). These changes were more evident in older seals. The d/r ratio demonstrated a smaller relative annual change than mean blubber depth. The d/r ratio also exhibited less variation along the length of the seal than blubber depth at any given time. Similar to reports for ringed seals, and contrary to those for southern elephant seals, the harbor seals preferentially lost blubber from overinsulated areas of the body. These results suggest that core tissue and blubber mass are lost in a manner that maximizes insulative effectiveness.
IN VITRO FERTILIZATION OF IN VITRO MATURED MINKE WHALE (BALAENOPTERA ACUTOROSTRATA) FOLLICULAR OOCYTES
Authors: Fukui Yutaka , Mogoe Toshihiro , Ishikawa Hajime , Ohsumi Seiji
Published: August 2006

Abstract

In vitro fertilization of follicular oocytes harvested from ovaries and matured in vitro was attempted for 55 minke whales (Balaenoptera acutorostrata) captured for Japanese research purposes in the Antarctic Ocean during the period from November 1995 to March 1996. In Experiment 1, effects of culture duration (96 h or 120 h) on maturation of follicular oocytes and addition of caffeine (5 mM) and/or heparin (100 pg/ml) on sperm penetration and pro‐nuclear formation were investigated. Spermatozoa recovered from the vasa deferentia of four mature males were diluted (5‐fold) and frozen at ‐ 80°C. The post‐thawed and pooled spermatozoa were used for in vitro insemination. A higher (P < 0.05) proportion of the oocytes cultured for 120 h (34.2% of 260) progressed beyond the second metaphase stage than of the oocytes cultured for 96 h (26.0% of 262). For the matured oocytes, higher rates of penetration (P < 0.05) and pronuclear formation (P < 0.01) were obtained in the oocytes cultured for 120 h (55.1% and 40.4%) than in those cultured for 96 h (32.4 % and 20.6%). Addition of caffeine and heparin did not show a significant effect. In Experiment 2, follicular oocytes matured for 120 h and then inseminated were cultured to examine the subsequent development in two culture systems (with and without co‐cultured cumulus cells). Of 448 inseminated oocytes, cleaved embryos (2–16 cells) were observed with (5.8%) and without (4.9%) co‐cultured systems. No cleavage was observed in 54 ova without insemination. These results indicate that in vitro fertilization of minke whale in vitro matured follicular oocytes with cryopreserved spermatozoa is possible, yielding cleaved embryos.
NEMATODE (OTOSTRONGYLUS CIRCUMLITUS) INFESTATION OF NORTHERN ELEPHANT SEALS (MIROUNGA ANGUSTIROSTRIS) STRANDED ALONG THE CENTRAL CALIFORNIA COAST
Authors: Gulland F. M. D. , Beckmen K. , Burek K. , Lowenstine L. , Werner L. , Spraker T. , Dailey M. , Harris E.
Published: August 2006

Abstract

Between 1 January 1992 and 31 December 1995, 73 of 487 (15%) juvenile northern elephant seals (Mirounga angustirostris) that stranded along the central California coastline and were transported to a rehabilitation center had similar clinical signs. These signs included anorexia, depression, dehydration, and epistaxis, and were accompanied by a neutrophilia. Coagulation assays on five of these animals indicated all five were in a state of disseminated intra‐vascular coagulation. Sixty‐five of the 73 animals died, and post‐mortem examination revealed heavy burdens of Otostrongylus circumlitas in the right ventricle and atrium of the hearts and pulmonary arteries, with occasional nem‐atodes in the bronchi and bronchioles. Histologic examination of 33 of these seals showed multiple pulmonary thromboses associated with a suppurative arteritis and occasionally intravascular nematodes, suggesting disseminated intravascular coagulation triggered by an arteritis may be important in causing mortality of elephant seals infested with O. circumlitus. This pathology, combined with the observation that death of juvenile northern elephant seals infected with O. circumlitus usually occurs prior to the parasite reaching reproductive maturity, suggests this is a relatively recent host‐parasite association.
EXPERIMENTAL RETURN TO THE WILD OF TWO BOTTLENOSE DOLPHINS
Authors: Wells Randall S. , Bassos‐Hull Kim , Norris Kenneth S.
Published: August 2006

Abstract

In the first scientific experiment of its kind, two young male bottlenose dolphins (Tursiops truncatus) were captured in Tampa Bay, Florida, and then returned to the wild at the same locale in October 1990, after two years in captivity. The dolphins' age/sex class and the capture and release site were selected prior to their collection. The ranging and social association patterns of the host community were examined prior to, and, including the two animals, after release. The dolphins remained together for the first month, then began interacting more with other dolphins and less with each other. Within the first year, one dolphin returned to the waters near his capture site and has remained there at least through September 1993. The other dolphin has remained in his original home range at least through June 1996. Observations of each dolphin have shown them to be fully integrated into the local dolphin societies. They displayed typical behavioral, ranging, and social association patterns. Their body condition has been excellent at each observation. They have not been observed interacting with humans. The apparent success of this experiment cannot necessarily be generalized to all potential candidates for return to the wild, but the results can be used to guide future experiments.
HEMATOLOGY AND BLOOD CHEMISTRY OF A BRYDE'S WHALE, BALAENOPTERA EDENI, ENTRAPPED IN THE MANNING RIVER, NEW SOUTH WALES, AUSTRALIA
Authors: Priddel David , Wheeler Robert
Published: August 2006

Abstract

A Bryde's whale, Balaenoptera edeni, was rescued after having been entrapped in the Manning River, Australia, for 100 d. Blood, skin, and epidermal tissue were analyzed to determine the whale's taxonomic status, gender, and health. This paper reports the results of these analyses and discusses the findings in relation to the potential physiological damage to the whale from its protracted stay in the river. Molecular genetic analysis of epidermal tissue identified the whale as a male of the rare pygmy form of Bryde's whale. The 10.3‐m whale was diagnosed as emaciated, parasitized, under stress, and in a state of profound catabolism at the time of its rescue. Although it had greatly depleted its energy reserves, the whale was rescued from the river before the onset of ill health or irreparable physiological damage. No organ dysfunction was evident with the possible exception of some deterioration in kidney function most likely caused by parasitism. The whale swam away srongly on release, and its chances of survival appeared to be good.
STABLE ISOTOPE ANALYSES OF TOOTH ANNULI REVEAL TEMPORAL DIETARY RECORDS: AN EXAMPLE USING STELLER SEA LIONS
Authors: Hobson Keith A. , Sease John L.
Published: August 2006

Abstract

Stable isotope analysis of teeth of marine mammals can provide valuable information on trophic level and source of feeding. However, the isotopic analysis of whole teeth presents only an average dietary estimate for individuals across the period of growth of that tooth. While such analyses can be valuable, particularly in the case of fossil material, in contrast, isotopic analysis of individual annuli of teeth can provide dietary information for each year of tooth growth, in some cases representing the whole of the animal's life. We measured stable‐carbon isotope ratios (13C/12C) in the inorganic (hydroxyapatite) and stable‐nitrogen isotope ratios (15N/14N) in the organic (primarily collagenous) components of individual tooth annuli of 18 male Steller sea lions (Eumetopias jubatus) obtained from archived collections from the Bering Sea and Gulf of Alaska and from single northern fur seals (Callorbinus ursinus) and northern elephant seals (Mirounga angustirostris) from the central Aleutian Islands and eastern Gulf of Alaska, respectively. In several individuals, we detected considerable variation in stable isotope values among annuli, up to 6.1%O for δ15N and 5.1%O for δ13C values. Enrichment in δ15N and depletion of δ13C values in the first annulus may correspond to dietary inputs from mother's milk during the period of suckling. Other variations among years may be caused by dietary changes or movements of individuals between regions differing in isotopic signatures of foodweb primary production. Our study indicates that the isotopic signatures of foodweb primary production. Our study indicates that the isotopic analysis of individual tooth annuli represents a fine‐seale tool for dietary reconstructions involving marine mammals, and cautions against the use of whole‐tooth material averaged over several annuli.
MANDIBULAR DENTAL ONTOGENY OF RINGED SEALS (PHOCA HISPIDA)
Authors: Stewart Barbara E. , Innes Stuart , Stewart Robert E. A.
Published: August 2006

Abstract

X‐rays of mandibles from ringed seal fetuses (n= 15), newborns (n= 12), and young‐of‐the‐year (n= 11), collected up to early June, were examined for the presence, location, and eruption patterns of deciduous and permanent teeth. The presence of a neonatal line and cementum in permanent canines was determined microscopically. Fetuses sampled in October‐November had only unerupted, deciduous tooth germs, but by late January there were robust, deciduous teeth at il‐2 pc2‐4 and small permanent teeth at 11‐2 Cl PCl‐5. In newborns collected in early April, 109 of 143 (76%) deciduous teeth were resorbed completely. The remaining 34 deciduous teeth were partially resorbed; six (18%) had erupted and likely would be shed. By late April young‐of‐the‐year had no deciduous teeth remaining. In newborns 54% of the permanent teeth (102/188) were erupted < 2 mm, and by late May the permanent dentition was erupted fully. The neonatal line first appeared in the canine teeth of young‐of‐the‐year collected in mid‐April and was 100% present after early May. There was no cementum apparent on any canine collected up to early June. Two seals were missing one and two permanent incisors, respectively. No supernumerary teeth or morphological variants were observed.
THE MUSCULAR HYDROSTAT OF THE FLORIDA MANATEE (TRICHECHUS MANATUS LATIROSTRIS): A FUNCTIONAL MORPHOLOGICAL MODEL OF PERIORAL BRISTLE USE
Authors: Marshall C. D. , Clark L. A. , Reep R. L.
Published: August 2006

Abstract

Facial musculature was examined in the Florida manatee, Tricbecbus manatus latirostris, in order to develop a functional model of perioral bristle use. Muscles identified include the M. levator nasolabialis, M. buccinatorius, M. maxillonasolabialis, M. centralis nasi, M. lateralis nasi, M. spbincter colli profundus pars oris, M. orbicularis oris, M. mandibularis, and M. mentalis. A new muscle, M. centralis nasi, has been named and is an integral part of perioral bristle movement. The snout of the Florida manatee is capable of performing complex movements. The prehensile ability of Florida manatees can be explained in the context of a muscular hydrostat as defined by Kier and Smith (1985). Eversion of certain bristles in the upper lip occurs by shortening longitudinal, transverse, and semicircular muscles in combination with volume displacement due to compensatory changes in the shape of the snout. Midline sweeping of these bristles is accomplished by the contraction of M. centralis nasi. Eversion of bristles on the lower jaw is a result of shortening of M. mentalis. Contraction of M. orbicularis oris pushes vegetation into the oral cavity. All observed movement patterns and uses of perioral bristles can be explained by variation of these sequences within the context of muscular hydrostat function.
PHYSICAL HABITAT OF CETACEANS ALONG THE CONTINENTAL SLOPE IN THE NORTHCENTRAL AND WESTERN GULF OF MEXICO
Authors: Davis R. W. , Fargion G. S. , May N. , Leming T. D. , Baumgartner M. , Evans W. E. , Hansen L. J. , Mullin K.
Published: August 2006

Abstract

The physical habitat of cetaceans found along the continental slope in the north‐central and western Gulf of Mexico was characterized from shipboard sighting data, simultaneous hydrographic measurements, and satellite remote sensing. The study area was encompassed by the longitude of the Florida‐Alabama border (87.5°W), the southernmost latitude of the Texas‐Mexico border (26.0°N), and the 100‐m and 2,000‐m isobaths. Shipboard surveys were conducted seasonally for two years from April 1992 to May 1994. A total of 21,350 km of transect was visually sampled in an area of 154,621 km2.

Sighting localities of species in the study area were differentiated most clearly with bottom depth. Atlantic spotted dolphins (Stenella frontalis) were consistently found in the shallowest water on the continental shelf and along the shelf break. In addition, the bottom depth gradient (sea floor slope) was less for Atlantic spotted dolphins than for any other species. Bottlenose dolphins (Tursiops truncatus) were found most commonly along the upper slope in water significantly deeper than that for Atlantic spotted dolphins. All the other species and species categories were found over deeper bottom depths; these were Risso's dolphins (Grampus griseus), short‐finned pilot whales (Glob‐icephala macrorhynchus), pygmy/dwarf sperm whales (Kogia spp.), roughtoothed dolphins (Steno bredanensis), spinner dolphins (Stenella longirostris), sperm whales (Physeter macrocephalus), striped dolphins (Stenella coeruleoalba),Mesoplodonspp., pantropical spotted dolphins (Stenella attenuata), Clymene dolphins (Stenella clymene) and unidentified beaked whales (Ziphiidae). Risso's dolphins and short‐finned pilot whales occurred along the upper slope and, as a subgroup, were significantly different from striped dolphins,Mesoplodonspp., pantropical spotted dolphins, Clymene dolphins, and unidentified beaked whales, which occurred in the deepest water. Pygmy/dwarf sperm whales, rough‐toothed dolphins, spinner dolphins, and sperm whales occurred at intermediate depths between these two subgroups and overlapped them.
GENERIC NAMES OF NORTHERN AND SOUTHERN FUR SEALS (MAMMALIA: OTARIIDAE)
Authors: Gardner Alfred L. , Robbins C. Brian
Published: August 2006

Abstract

We have resolved a nomenclatural problem discovered during research on the northern fur seal that concerns the correct generic name for this taxon and for fur seals of the Southern Hemisphere. The unfortunate practice by some 19th‐century authors to use names in their Latinized form but to date them from their first appearance as French common names led to the use ofArctocepbalusfor southern fur seals when the name correctly applies to the northern fur seal, known today asCallorbinus ursinus. However,ArctocepbalusandCallorbinusare antedated byOtoesG. Fischer, 1817, which is the earliest available generic name for the fur seal of the northern Pacific. The earliest available generic name for southern fur seals isHalarctusGill, 1866. To avoid the confusion that would result from replacing the currently used generic names with those required by strict adherence to the Principle of Priority, we have petitioned the International Commission on Zoological Nomenclature to preserveArctocepbalusandCallorbinusfor the southern and northern fur seals, respectively.
DIVE DATA FROM SATELLITE TAGS AND TIME‐DEPTH RECORDERS: A COMPARISON IN WEDDELL SEAL PUPS
Authors: Burns Jennifer M. , Castellini Michael A.
Published: August 2006

Abstract

The diving behavior of juvenile Weddell seals, Leptonychotes weddellii, was monitored simultaneously with time‐depth recorders (TDRs) and satellitelinked time‐depth recorders (SLTDRs). Recovered TDRs provided a complete record of the depth and duration of all dives, while data received from SLTDR tags via the ARGOS satellite system were compressed into the number of dives in each of six depth or duration bins. The dive information from the two types of tags was compared to determine if data compression, processing, and transmission influenced the data received.

While only half of the dive data collected by TDRs was also received from the SLTDR tags, the chance of receiving SLTDR data was independent of when diving occurred, when data was transmitted, and the subsequent dive activity. In addition, the number of dives in each depth and duration bin was an accurate representation of the actual dive behavior. Therefore, SLTDR tags were judged to provide data qualitatively similar to that provided by TDRs. The accuracy of seal locations provided by Service ARGOS was estimated by comparison to Global Positioning System (GPS) locations, and the average position error found to be significantly greater than predicted by Service ARGOS or reported in other studies (LCO locations ± 11.4 km, LC1 ± 5.0 km).
SPERM WHALE DISTRIBUTIONS AND COMMUNITY ECOLOGY ASSOCIATED WITH A WARM‐CORE RING OFF GEORGES BANK
Authors: Griffin Robert B.
Published: August 2006

Abstract

Sperm whale (Physeter macrocephalus) sighting rate in the vicinity of a thermal front on the eastern boundary of a Gulf Stream warm‐core ring was five times greater than the pooled rate in the remainder of the study area. No sperm whales were sighted within the ring away from frontal boundaries. Sperm whale distribution patterns associated with the ring were examined using hydrographic and zooplankton data.

Hydrographic structure and zooplankton densities and community composition differed between the high‐use region and the remainder of the study area, suggesting that mesoscale patterns in the biological and physical environments regulate sperm whale habitat usage. Satellite thermal images indicated cool water associated with the eastern front was shelf or slope water entrained from the Scotian Shelf to the north.

Interaction of the warm‐core ring with the shelf or slope water is probably indirectly responsible for greater sperm whale presence on the eastern boundary of the ring, providing suitable habitat for their squid prey. Entrainment of shelf water by warm‐core rings occurs frequently, providing potential sperm whale habitat in the vicinity of rings. Surveys of warm‐core rings and other Gulf Stream features are needed to improve accuracy of sperm whale population estimates.
BEHAVIORAL SAMPLING METHODS FOR CETACEANS: A REVIEW AND CRITIQUE
Authors: Mann Janet
Published: August 2006

Abstract

Behavioral scientists have developed methods for sampling behavior in order to reduce observational biases and to facilitate comparisons between studies. A review of 74 cetacean behavioral field studies published from 1989 to 1995 in Marine Mammal Science and The Canadian Journal of Zoology suggests that cetacean researchers have not made optimal use of available methodology. The survey revealed that a large proportion of studies did not use reliable sampling methods. Ad libitum sampling was used most often (59%). When anecdotal studies were excluded, 45% of 53 behavioral studies used ad libitum as the predominant method. Other sampling methods were continuous, onezero, incident, point, sequence, or scan sampling. Recommendations for sampling methods are made, depending on identifiability of animals, group sizes, dive durations, and change in group membership.
ELEMENTS IN LIVER TISSUES OF BOWHEAD WHALES (BALAENA MYSTICETUS)
Authors: Krone Cheryl A. , Robisch Paul A. , Tilbury Karen L. , Stein John E. , Mackey Elizabeth A. , Becker Paul R. , O'hara Todd M. , Philo L. Michael
Published: August 2006

Abstract

Livers from 20 bowhead whales taken in subsistence hunts at Barrow, Alaska, were analyzed for essential and non‐essential elements. Concentrations of essential elements were similar to those found in other cetaceans. Non‐essential element concentrations were generally comparable to other baleen whales and very low compared to most odontocetes. One deviation from this pattern was a relatively high level of hepatic cadmium that may be related to specific dietary factors of this krill‐dependent species. No sex‐related differences were found in element concentrations. Hepatic cadmium and mercury increased with animal length, and significant positive interelement correlations were found between copper/zinc and mercury/selenium. We found a mercury‐toselenium ratio much lower (1:40) than the frequently reported ratio of one to one. The data suggest that further studies of the postulated mercurydetoxifying role of selenium are warranted.
DEMOGRAPHY AND BREEDING BIOLOGY OF A SMALL, LOCALIZED POPULATION OF SOUTHERN ELEPHANT SEALS (MIROUNGA LEONINA)
Authors: Galimberti Filippo , Boitani Luigi
Published: August 2006

Abstract

Southern elephant seals have been studied in depth in most of their breeding range. One notable exception is the Falkland Islands population. We present data on demography and breeding biology of elephant seals of Sea Lion Island, the main breeding site of this species in the Falklands. Sea Lion Island shelters a small, localized population of southern elephant seals (516 breeding females in 1995 and 518 in 1996). Comparison with the few available census data collected prior to our study suggests that the population has been stable in the short term (1989‐1996). Females produced pups at maximum rate and pup mortality was low (2.13%). Breeding sex ratio was strongly unbalanced, with about 14 females per breeding male and 47 females per harem‐holding male at peak haul‐out. Survival rate between breeding seasons was 67.4% for females and 50% for males. Timing of the breeding season was very similar to that recorded in other populations and was in accordance with clinal variation with latitude. Sex ratio at birth was balanced, and no significant weight dimorphism at weaning between sexes was detected (males: 135.4 kg; females: 132.0 kg). Weaning weight was correlated with size class of the mother.
RETINAL TOPOGRAPHY AND VISUAL ACUITY IN THE RIVERINE TUCUXI (SOTALIA FLUVIATILIS)
Authors: Mass Alla M. , Supin Alexander Ya.
Published: August 2006

Abstract

The distribution and size of ganglion cells in the retina of two tucuxi were investigated. Retinal cell size varied from 10 to 50 μm with a polymodal size distribution; major groups were seen with sizes of 8‐20, 21‐35, and more than 35 μm. Ganglion cells concentrated at two spots of the highest density in the nasal and temporal quadrants, about 10 mm (60′) from the optic disk. The mean peak cell density in both spots was 188‐198 cells/mm2. With a posterior nodal distance of 9.5‐10 mm (underwater), the density at those two spots corresponded to 5.4‐5.7 cells/deg2, which provides a retinal resolution of 25′‐26′ (1.16‐1.19 cycle/deg) in water and 33′‐34′ (0.9 cycle/deg) in air.
OCCURRENCE, DISTRIBUTION, SITE FIDELITY, AND SCHOOL SIZE OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) OFF SAN DIEGO, CALIFORNIA
Authors: Defran R. H. , Weller David W.
Published: August 2006

Abstract

The occurrence, distribution, site fidelity, and school size of bottlenose dolphins (Tursiops truncatus) in the coastal waters of north San Diego County, California were assessed during a six‐year boat‐based photoidentification study. A total of 146 photographic surveys were conducted between January 1984 and December 1989. Dolphin schools were encountered on 79% of all surveys, and 2, 869 individuals were observed in 145 separate schools. Three‐hundred seventy‐three dolphins were individually identified. All schools were sighted within 1 km of shore, and more than two thirds of the schools were encountered in the southern half of the 32‐km long study area. School size (mean = 19.8, SD = 18.40) and the number of dolphins encountered per survey (mean = 26.8, SD = 22.30) were highly variable. Low resighting rates of known individuals provided little evidence for longterm site fidelity. When our six‐year photoidentification database was combined with previous data, 404 dolphins were identified in the study area from September 1981 to December 1989. Jolly‐Seber population estimates during the 1984‐1989 study period varied between 234 and 285. The combination of regular dolphin occurrence, low site fidelity by known individuals, and the continuous increase in the rate at which new dolphins were identified indicates that numerous different individuals were visiting the study area across and within years. The open California coastline differs in habitat structure and prey distribution from more protected study areas where bottlenose dolphins display site fidelity. These habitat differences may help to explain the observed intraspecific behavioral variability of this species.