Robert L. DeLong

NOAA National Marine Fisheries Service Alaska Fisheries Science Center

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Sharon R. Melin

NOAA National Marine Fisheries Service

ΕT

Ε. T. Lyons

University of Kentucky

Terry R. Spraker

Colorado State University

Frances M. D. Gulland

Marine Mammal Center

Brent S. Stewart

Hubbs-Sea World Research Institute

Jeffrey L. Laake

NOAA National Marine Fisheries Service

Todd J. Braje

San Diego State University

Anthony J. Orr

NOAA National Marine Fisheries Service Alaska Fisheries Science Center

Jon M. Erlandson

University of Oregon

Torben C. Rick

National Museum of Natural History

Cooperative Institutions

NOAA National Marine Fisheries Service

National Oceanic and Atmospheric Administration

University of California, Davis

Oregon State University

Oregon Department of Fish and Wildlife

NOAA National Marine Fisheries Service Alaska Fisheries Science Center

NOAA National Marine Fisheries Service Southwest Fisheries Science Center

University of Washington

United States Geological Survey

University of California, Santa Cruz

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ATTENDANCE PATTERNS OF CALIFORNIA SEA LION (ZALOPHUS CALIFORNIANUS) FEMALES AND PUPS DURING THE NON‐BREEDING SEASON AT SAN MIGUEL ISLAND

Marine Mammal Science (2000)

Sharon R. Melin Robert L. DeLong James R. Thomason Glenn R. VanBlaricom

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

Rookery

Zalophus californianus

10.1111/j.1748-7692.2000.tb00911.x

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Citations (57)

Effects of the 1982–83 El Niño on Several Population Parameters and Diet of California Sea Lions on the California Channel Islands

Ecological studies (1991)

Robert L. DeLong George A. Antonelis Christine Oliver Brent S. Stewart M. C. Lowry

Zalophus californianus

10.1007/978-3-642-76398-4_18

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Citations (46)

Impact of the 1982–1983 El Niño on the Northern Fur Seal Population at San Miguel Island, California

Ecological studies (1991)

Robert L. DeLong George A. Antonelis

Fur seal

10.1007/978-3-642-76398-4_8

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Citations (45)

DIEL HAUL‐OUT PATTERNS AND SITE FIDELITY OF HARBOR SEALS (PHOCA VITULINA RICHARDSI) ON SAN MIGUEL ISLAND, CALIFORNIA, IN AUTUMN

Marine Mammal Science (1987)

Pamela K. Yochem Brent S. Stewart Robert L. DeLong Douglas P. DeMaster

A bstract We studied the haul‐out patterns and movements of harbor seals ( Phoca vitulina richardsi ) on San Miguel Island, California, from 23 October through 6 December 1982 by attaching a radio transmitter to each of 18 seals and monitoring their presence ashore with continuously scanning receivers. Seals hauled out at all hours although, on average, the largest proportion of tagged seals was ashore between 1300 and 1500 h. Median durations of haul‐out bouts of individual seals ranged from 4.7 to 21.8 h; 81% of all haul‐out bouts were less than 12 h and 3% were longer than 24 h. Eighty‐one percent of the seals that were resighted at least twice used only the sites where they were tagged; two seals used two sites and one seal used three. Most seals were hauled out on fewer than 51% of the days sampled. On average, about 41% of tagged seals hauled out each day whereas an average of about 19% was hauled out during peak afternoon hours. Using telemetry data to correct a count of 412 seals made during an aerial survey, we estimated absolute abundance at about 2,168 seals; a modified Peterson mark‐recapture model produced an estimate of about 1,445 seals.

Harbor seal

Diel vertical migration

10.1111/j.1748-7692.1987.tb00319.x

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Citations (105)

Aerobic bacterial flora of the vagina and prepuce of California sea lions (Zalophus californianus) and investigation of associations with urogenital carcinoma

Veterinary Microbiology (2005)

Steven Johnson Linda Lowenstine Frances M. D. Gulland S.S. Jang Denise M. Imai

Zalophus californianus

Preputial gland

Corynebacterium

Bacteriology

10.1016/j.vetmic.2005.11.045

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Citations (46)

VARIATION IN STABLE CARBON AND NITROGEN ISOTOPE VALUES FROM MULTIPLE TISSUES OF CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS)

Anthony J. Orr Seth D. Newsome Robert L. DeLong

Stable nitrogen and carbon isotope analyses have increasingly been used to investigate the foraging ecology of marine mammals, particularly in response to the limitations of using conventional dietary analysis techniques. In this study, we compared nitrogen (δ15N) and carbon (δ13C) values of four different tissues (i.e., fur, red blood cells, serum, and plasma) from California sea lions (Zalophus californianus; n = 58) of various age classes (i.e., pup, yearling, juvenile, and adult). Metabolically active tissues with relatively high turnover rates (plasma and serum) had similar δ15N and δ13C values, but these two tissues had significantly higher δ15N values and lower δ13C values in comparison to red blood cells or fur. In general, δ15N values decreased with increasing age; δ15N values for pups were between 1.2‰ (fur) to 2.0‰ (serum) greater in comparison to adult females. In general, δ13C values increased with age (except red blood cells). Pups had mean δ13C values that were 0.4‰ (plasma) to 0.5‰ (fur and serum) lower than mean values of adult females. Stable isotope analysis of various tissues can provide dietary information at the individual level on different temporal and spatial scales, as well as reveal patterns of the foraging ecology among groups of animals.

Zalophus californianus

δ15N

Isotope Analysis

Isotopes of nitrogen

Source

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Citations (4)

Multivariate State Hidden Markov Models for Mark-Recapture Data

Statistical Science (2016)

Devin S. Johnson Jeff Laake Sharon R. Melin Robert L. DeLong

State-based Cormack–Jolly–Seber (CJS) models have become an often used method for assessing states or conditions of free-ranging animals through time. Although originally envisioned to account for differences in survival and observation processes when animals are moving though various geographical strata, the model has evolved to model vital rates in different life-history or diseased states. We further extend this useful class of models to the case of multivariate state data. Researchers can record values of several different states of interest, for example, geographic location and reproductive state. Traditionally, these would be aggregated into one state with a single probability of state uncertainty. However, by modeling states as a multivariate vector, one can account for partial knowledge of the vector as well as dependence between the state variables in a parsimonious way. A hidden Markov model (HMM) formulation allows straightforward maximum likelihood inference. The proposed HMM models are demonstrated with a case study using data from a California sea lion vital rates study.

State vector

Mark and recapture

10.1214/15-sts542

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Citations (17)

Seals, Sea Lions, and the Erosion of Archaeological Sites on California's Channel Islands

The Journal of Island and Coastal Archaeology (2009)

Torben C. Rick Jon M. Erlandson Todd J. Braje Robert L. DeLong

Click to increase image sizeClick to decrease image size ACKNOWLEDGEMENTS We thank Ann Huston, Kelly Minas, and Ian Williams of Channel Islands National Park, Steve Schwartz of the Naval Air Weapons Station at Point Mugu, and our home institutions for supporting our work. Qun-Tan Shup provided invaluable assistance and guidance in the field.

10.1080/15564890902791391

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Citations (9)

Age-prevalence of Otarine Herpesvirus-1, a tumor-associated virus, and possibility of its sexual transmission in California sea lions

Veterinary Microbiology (2006)

Elizabeth L. Buckles Linda J. Lowenstine Robert L. DeLong Sharon R. Melin Regina K. Vittore

Sexual transmission

Viremia

Sex organ

10.1016/j.vetmic.2006.10.002

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Citations (29)

Comparative Biology ofUncinariaSpp. in the California Sea Lion (Zalophus californianus) and the Northern Fur Seal (Callorhinus ursinus) in California

Journal of Parasitology (2000)

Ε. T. Lyons Robert L. DeLong Frances M. D. Gulland Sharon R. Melin S. C. Tolliver

Studies on several aspects of the life cycle of hookworms (Uncinaria spp.) in the California sea lion (Zalophus californianus) and northern fur seal (Callorhinus ursinus) were conducted on material collected on San Miguel Island (SMI), California and at The Marine Mammal Center, Sausalito, California in 1997, 1998, and 1999. Examination of Z. californianus intestines for adult hookworms and feces for eggs revealed that longevity of these parasites in pups is about 6-8 mo, and infections are probably not present in older sea lions. Parasitic third-stage larvae (L3) were recovered from the ventral abdominal tissue of Z. californianus, suggesting transmammary transmission. Callorhinus ursinus pups had no hookworm eggs in their feces or adult worms (except for 1 probable contaminant) in their intestines in the fall and early winter, revealing that adult Uncinaria spp. are spontaneously lost at <3 mo of age of the pups. Sand samples from rookeries, used by both Z. californianus and C. ursinus, on SMI were negative for free-living, L3 in summer months but positive in fall and winter months, indicating seasonality occurred.

Zalophus californianus

Fur seal

Elephant seal

Rookery

Marine mammal

Harbor seal

10.1645/0022-3395(2000)086[1348:cbousi]2.0.co;2

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Citations (28)