scholarly journals Parasitological examination of northern elephant seal (Mirounga angustirostris) pups for presence of hookworms (Uncinaria spp.) on San Miguel Island, California

2016 ◽  
Vol 53 (2) ◽  
pp. 191-194
Author(s):  
E. T. Lyons ◽  
T. A. Kuzmina ◽  
T. R. Spraker ◽  
R. L. Delong
Keyword(s):  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
California Sea Lions ◽  
Northern Elephant Seal ◽  
Parasitological Examination ◽  
Sea Lions ◽  
Fur Seals ◽  
Third Stage ◽  
Northern Fur Seals ◽  
San Miguel Island

SummaryNecropsy and extensive parasitological examination of dead northern elephant seal (NES) pups was done on San Miguel Island, California, in February, 2015. The main interest in the current study was to determine if hookworms were present in NESs on San Miguel Island where two hookworm species of the genus Uncinaria are known to be present - Uncinaria lyonsi in California sea lions and Uncinaria lucasi in northern fur seals. Hookworms were not detected in any of the NESs examined: stomachs or intestines of 16 pups, blubber of 13 pups and blubber of one bull. The results obtained in the present study of NESs on San Miguel Island plus similar finding on Año Nuevo State Reserve and The Marine Mammal Center provide strong indication that NES are not appropriate hosts for Uncinaria spp. Hookworm free-living third stage larvae, developed from eggs of California sea lions and northern fur seals, were recovered from sand. It seems that at this time, further search for hookworms in NESs would be nonproductive.

scholarly journals Creation Nerves of the Lumbar and Sacral Plexus in California Sea Lions (Zalophus Californianus) and Northern Elephant Seals (Mirounga Angustirostris)/Formiranje Nerava Iz Lumbalnog I Sakralnog Pleksusa Kod Kalifornijskog Morskog Lava (Zalophus Californianus) I Severnomorskog Slona (Mirounga Angustirostris)

2014 ◽  
Vol 64 (3) ◽  
pp. 293-306 ◽  
Author(s):  
Mihelić Damir ◽  
Smodlaka Hrvoje ◽  
Tkalčić Suzana ◽  
Palmer Lauren ◽  
Mršić Gordan ◽  
...  
Keyword(s):  
Femoral Nerve ◽  
Elephant Seal ◽  
Zalophus Californianus ◽  
Mirounga Angustirostris ◽  
California Sea Lions ◽  
Northern Elephant Seal ◽  
Elephant Seals ◽  
Sea Lions ◽  
Northern Elephant Seals ◽  
Sacral Nerves

Abstract The lumbosacral plexus was investigated in the California sea lion and Northern elephant seal. In 9 California sea lions and 2 Northern elephant seals the femoral nerve rises from the ventral branches of the 3rd and 4th lumbar nerves, whilst in one male and two specimens of the Northern elephant seal the 5th lumbar nerve was also involved. Ventral branches of the 3rd and 4th lumbar nerves comprised the obturatorius nerve in 7 specimens; in 3 specimens the 5th lumbar nerve additionally supplements the obturatorius nerve. In Northern elephant seals the obturatorius nerve originates from the ventral branches of the 3rd, 4th and 5th lumbar nerves. The ischiadic nerve originates from the ventral branches of the 4th, 5th lumbar and 1st sacral nerves in 8 specimens California sea lions and in 2 North elephant seals. In 2 specimens of both species the 2nd sacral nerve also participates. The gluteal nerve created ventral branches of the 5th lumbar and 1st sacral nerves in three specimens; however in one specimen the 4th and 5th lumbar nerves gave rise to the same nerve in the Northern elephant seal. In California sea lions the gluteal nerve originates from the ventral branches of the 5th lumbar nerve in seven specimens, nonetheless in 3 specimens the 4th lumbar nerve also participates in its formation.

Foraging characteristics of female northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus)

1990 ◽  
Vol 68 (1) ◽  
pp. 150-158 ◽  
Author(s):  
George A. Antonelis ◽  
Brent S. Stewart ◽  
Wayne F. Perryman
Keyword(s):  
Water Depth ◽  
Zalophus Californianus ◽  
Callorhinus Ursinus ◽  
California Sea Lions ◽  
Merluccius Productus ◽  
Sea Lions ◽  
Fur Seals ◽  
Northern Fur Seals ◽  
San Miguel Island ◽  
Northern Anchovy

The foraging characteristics of northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus) from San Miguel Island, California, were studied during the 1985 summer breeding season. A radio transmitter was attached to 25 postpartum females of each species and used to determine their locations at sea and the frequency and duration of their feeding trips. Northern fur seals usually foraged in the oceanic zone where the mean water depth was 933 m (n = 12). California sea lions principally were found in the neritic zone, where water depth averaged 323 m (n = 9). Most fur seals (92%) were found northwest of San Miguel Island, whereas the sea lions were commonly found to the northwest (55%) or in areas south (22%) of the island. Although both species evidently foraged at similar distances from the island, foraging trips of fur seals [Formula: see text] were over twice as long as those of sea lions [Formula: see text]. Fur seals were ashore less time [Formula: see text] than were sea lions [Formula: see text] between foraging trips. Analysis of scats revealed that fur seals and sea lions ate similar prey (northern anchovy, Engraulis mordax; Pacific whiting, Merluccius productus; juvenile rockfish, Sebastes spp.; market squid, Loligo opalescens; and nail squid, Onychoteuthis borealijaponicas), although the relative proportions of these prey differed. Factors influencing the observed foraging characteristics probably were availability of prey and phylogenetic constraints associated with life-history traits of northern fur seals and California sea lions.

scholarly journals Causes of mortality in northern elephant seal pups on San Miguel Island, California

2020 ◽  
Vol 32 (2) ◽  
pp. 312-316
Author(s):  
Terry R. Spraker ◽  
Tetiana A. Kuzmina ◽  
Robert L. DeLong
Keyword(s):  
Congenital Anomalies ◽  
Bacterial Infections ◽  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
Northern Elephant Seal ◽  
Hemolytic Streptococcus ◽  
E Coli ◽  
Necrotizing Myopathy ◽  
San Miguel Island ◽  
Causes Of Mortality

In February 2015, we conducted a field study of causes of mortality of northern elephant seal ( Mirounga angustirostris) pups on San Miguel Island, California. Autopsies were performed on 18 freshly dead pups. Ages of pups ranged from stillborn to 6–8 wk. Gross and histologic lesions included trauma (9 of 18 pups), multifocal necrotizing myopathy (8 of 18), starvation with emaciation (7 of 18), congenital anomalies (3 of 18), bacterial infections (3 of 18), and perinatal mortality (stillbirths and neonates; 2 of 18). Trauma and emaciation or starvation were the most significant contributors to death. Bacterial infections included hemolytic Escherichia coli isolated from the lungs of 2 pups with pneumonia. Additionally, non-hemolytic Streptococcus sp. and hemolytic E. coli were isolated from the liver of an emaciated pup that had mild multifocal suppurative hepatitis. Other lesions, including a previously described necrotizing myopathy, congenital anomalies, and bacterial infections, were detected concurrently in cases with starvation and/or emaciation or trauma.

Multifocal Necrotizing Myopathy in Northern Elephant Seal (Mirounga angustirostris) Pups, San Miguel Island, California

2018 ◽  
Vol 56 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Terry R. Spraker ◽  
Tetiana A. Kuzmina ◽  
Eugene T. Lyons ◽  
Robert L. DeLong ◽  
Claire Simeone ◽  
...  
Keyword(s):  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
Northern Elephant Seal ◽  
Vacuolar Degeneration ◽  
Necrotizing Myopathy ◽  
Eosinophilic Cytoplasm ◽  
Northern Elephant Seals ◽  
San Miguel Island ◽  
System Degeneration ◽  
Causes Of Mortality

A field study addressing causes of mortality in freshly dead northern elephant seals ( Mirounga angustirostris, Gill, 1866) was conducted on San Miguel Island, California, in February 2015. Necropsies were performed on 18 pups ranging in age from stillbirths to approximately 7 to 8 weeks. The primary gross diagnoses in these pups included trauma, myopathy, starvation/emaciation, infections, congenital anomalies, and perinatal mortality. However, 6 (33%) had a previously unrecognized myopathy characterized by multiple white streaks that were most obvious within the inner layer of the abdominal wall and the small innermost ventral intercostal muscles. Following histological examination, 2 more pups from San Miguel Island and 6 pups from The Marine Mammal Center (Sausalito, California) were found to have similar lesions. Histologically, the lesions within the skeletal muscles were characterized by a multifocal polyphasic, mild to severe, acute to subacute necrotizing myopathy with mineralization. Acute necrosis and degeneration characterized by pyknotic nuclei, eosinophilic cytoplasm and cytoplasmic vacuolization were found in smooth muscle myocytes within the urinary bladder and digestive system. Degeneration of myocytes was present in the tunica media of a few small- to medium-sized vessels and was characterized by a vacuolar degeneration and occasionally necrosis. This condition has been termed multifocal necrotizing myopathy. A cause of this myopathy was not identified.

Mother-Offspring Separation and Acoustic Stereotypy: a Comparison of Call Morphology in Two Species of Pinnipeds

Behaviour ◽  
1992 ◽  
Vol 120 (1-2) ◽  
pp. 103-122 ◽  
Author(s):  
Stephen J. Insley
Keyword(s):  
Individual Variation ◽  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
Northern Fur Seal ◽  
Northern Elephant Seal ◽  
Fur Seals ◽  
Fur Seal ◽  
Species Analysis ◽  
Northern Elephant Seals ◽  
Discriminant Analyses

AbstractI have compared structural variation of the primary vocalizations used between mother-offspring pairs in two species of pinnipeds that differ fundamentally in their breeding behaviour: northern elephant seal (Mirounga angustirostris) mothers and offspring normally are together throughout the nursing period; northern fur seal (Callorhinus ursinus) females regularly separate from their offspring while nursing. Two predictions were tested: (1) these vocalizations should be individually-distinct (stereotyped) in females and pups of both species if they serve to function for recognition, and (2) because individuality should be more pronounced in a species where separations and reunions are common, the vocalizations used between northern fur seal mother-offspring pairs should be more individually-stereotyped than those of the northern elephant seal. Principal components analyses revealed structural differences between the calls of females and pups in both species. Analysis of variance showed the calls of individual seals to be acoustically distinct in all cases. The calls used between mother-offspring pairs of northern fur seals were more stereotyped than those of northern elephant seals. These calls had less within-individual variation, greater among-individual variation and were more often correctly predicted in discriminant analyses. The results indicate that selective pressure to develop vocal recognition exists in both species but is greater in the northern fur seal.

scholarly journals Stress-related and reproductive hormones in hair from three north Pacific otariid species: Steller sea lions, California sea lions and northern fur seals

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Mandy J Keogh ◽  
Angela Gastaldi ◽  
Patrick Charapata ◽  
Sharon Melin ◽  
Brian S Fadely
Keyword(s):  
Physiological Stress ◽  
In Utero ◽  
Reproductive Hormones ◽  
Steller Sea Lions ◽  
Sea Lion ◽  
California Sea Lions ◽  
Sea Lions ◽  
Fur Seals ◽  
Hair Samples ◽  
Northern Fur Seals

Abstract Assessing the physiological impact of stressors in pinnipeds is logistically challenging, and many hormones are altered by capture and handling, limiting the utility of metabolically active tissues. Hair is increasingly being used to investigate stress-related and reproductive hormones in wildlife populations due to less-invasive collection methods, being metabolically inert once grown and containing multiple biomarkers of ecological interest. We validated enzyme immunoassays for measuring aldosterone, cortisol, corticosterone, and testosterone in lanugo (natal hair grown in utero) samples collected from Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), and northern fur seals (Callorhinus ursinus). We applied laboratory validation methods including recovery of added mass, parallelism and dilution linearity. We found no effects due to differences in alcohol- versus detergent-based cleaning methods. Further, there were no significant differences in hormone concentrations in hair samples collected immediately after the molt and the subsequent samples collected over 1 year, indicating steroid hormones are stable once deposited into pinniped hair. We found no sex differences in any hormone concentrations, likely due to the lanugo being grown in utero and influenced by maternal hormone concentrations. For Steller sea lion and California sea lion pups, we found hormone concentrations significantly differed between rookeries, which warrants future research. Hair provides a novel tissue to explore the intrinsic or extrinsic drivers behind hormone measurements in otariids, which can be paired with multiple health-related metrics to further investigate possible drivers of physiological stress.

Pupillometry in seals and sea lions: ecological implications

1997 ◽  
Vol 75 (12) ◽  
pp. 2050-2057 ◽  
Author(s):  
David Hendrik Levenson ◽  
Ronald J. Schusterman
Keyword(s):  
Sensory Modality ◽  
Maximum Size ◽  
Harbor Seal ◽  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
Sea Lion ◽  
Northern Elephant Seal ◽  
California Sea Lion ◽  
Sea Lions ◽  
Light Levels

Phocid and otariid pinnipeds forage almost exclusively under water, where observing them is difficult. As a result, little is known of how their senses are used while diving to locate and capture prey. In this study we used pupillometric methods to describe the relative visual abilities of three pinniped species: the northern elephant seal (Mirounga angustirostris), the harbor seal (Phoca vitulina), and the California sea lion (Zalophus californianus). The range of pupillary area and lower limit of pupillary adjustment were determined for each species. The northern elephant seal exhibited the largest range of pupillary area of the species examined. Furthermore, the elephant seal's pupil was found to reach maximum size only under extremely dim conditions. Both the harbor seal and California sea lion exhibited maximum pupillary dilation in conditions several log units brighter. These results indicate that the elephant seal's visual system is designed to function in dimmer conditions and to respond to greater changes in light levels than those of the harbor seal and sea lion. Such findings support the hypothesis that the visual systems of these pinnipeds are adapted for use in their respective foraging environments, and thus suggest that the visual sense is probably an important sensory modality used to locate and capture prey while diving.

Sexual Behavior in the Northern Elephant Seal Mirounga Angustirostris

Behaviour ◽  
1972 ◽  
Vol 41 (1-2) ◽  
pp. 1-26 ◽  
Author(s):  
Burney J. Leboeuf
Keyword(s):  
Social Systems ◽  
Elephant Seal ◽  
Social Hierarchy ◽  
Mirounga Angustirostris ◽  
Northern Elephant Seal ◽  
Female Behavior ◽  
Elephant Seals ◽  
Sea Lions ◽  
The Social ◽  
Breeding Seasons

AbstractThe mating behavior of Northern elephant seals, Mirounga angustirostris, was studied during the I968, I969 and I970 breeding seasons at Año Nuevo Island, I9 miles north of Santa Cruz, California. Copulation takes place primarily on land, from January to March; it is initiated and terminated by the male and lasts approximately 5 minutes. A few males do most of the breeding and the higher a male's rank in the social hierarchy, the more frequently he copulates. Some bulls may maintain high rank and participate in mating for 3 breeding seasons. Low ranking males are kept out of the harem so they attempt to copulate with females on the periphery or in the water with departing females. Males prevent subordinates from mounting females and disrupt copulations in progress. The higher a male's rank, the more freedom he has to copulate without interference, and the more frequently he interferes with the copulation of others. The highest ranking males interrupt their own copulations prematurely to attack other males and prevent them from copulating. Males mount weaned pups, yearlings, and non-estrous females in addition to estrous females; the latter are mounted most frequently. Females come into estrus 24 days after parturition. They are receptive for about 3 days (range I-I3 days), during which they may copulate several different times with one or more males. Females are usually in estrus when they leave the rookery and return to sea. The greatest difference in the copulatory pattern of the elephant seal, a true seal, and members of the sea lion family, is that the former interfere with the copulations of other males while the latter do not. This may he due to differing social systems, a social hierarchy in elephant seals and a territorial system in sea lions. In elephant seals, where copulations are interrupted, mating may be incomplete. This is not as likely with sea lions where copulations are never interrupted because males honor the boundaries of their neighbors. The differences in female behavior and sexual physiology - a long promiscuous estrous period in elephant seals as opposed to a brief estrus with only one copulation in sea lions - may have evolved as a compensation for the consequences of the social behavior of males.

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