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 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.

Prey competition between sympatric Steller sea lions (Eumetopias jubatus) and northern fur seals (Callorhinus ursinus) on Lovushki Island, Russia

2012 ◽  
Vol 90 (1) ◽  
pp. 110-127 ◽  
Author(s):  
J.N. Waite ◽  
V.N. Burkanov ◽  
R.D. Andrews
Keyword(s):  
Interspecific Competition ◽  
Russian Far East ◽  
Far East ◽  
Callorhinus Ursinus ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
Sea Lions ◽  
Fur Seals ◽  
Northern Fur Seals ◽  
Atka Mackerel

Approximately 1 000 Steller sea lions ( Eumetopias jubatus (Schreber, 1776); SSL) and 14 000 northern fur seals ( Callorhinus ursinus (L., 1758); NFS) breed sympatrically on Lovushki Island in the Russian Far East, creating the potential for interspecific competition for prey. An additional 13 000 – 14 000 juvenile NFS are present during the breeding season. The diets of breeding SSL and both breeding and juvenile NFS were examined through analysis of scats and spews collected during the breeding seasons of 2003, 2005, and 2007–2008. There were significant overlaps in the prey species and size selection of SSL and juvenile NFS. There were significant differences between the diets of SSL and breeding NFS. SSL and juvenile NFS fed primarily on Atka mackerel ( Pleurogrammus monopterygius (Pallas, 1810)), while breeding NFS fed on cephalopods, salmon (genus Oncorhynchus Suckley, 1861), Atka mackerel, and northern smoothtongue ( Leuroglossus schmidti Rass, 1955). The partitioning of resources between breeding animals has allowed both species to coexist within the same region and likely reflected differences in foraging abilities and provisioning strategies of the adults and the fasting abilities of their pups. However, continued growth of the NFS population may lead to the exclusion of SSL owing to interspecific competition for prey.

The effects of El Niño on the foraging behavior of lactating California sea lions (Zalophus californianus californianus) during the nonbreeding season

2008 ◽  
Vol 86 (3) ◽  
pp. 192-206 ◽  
Author(s):  
S. R. Melin ◽  
R. L. DeLong ◽  
D. B. Siniff
Keyword(s):  
Foraging Behavior ◽  
El Niño ◽  
Prey Species ◽  
El Nino ◽  
Zalophus Californianus ◽  
California Sea Lions ◽  
Sea Lions ◽  
Nonbreeding Season ◽  
San Miguel Island ◽  
Lactating Females

We compared the nonbreeding-season foraging behavior of lactating California sea lions ( Zalophus californianus californianus (Lesson, 1828)) at San Miguel Island, California, during El Niño conditions in 1993 and non-El Niño conditions in 1996. Lactating females were instrumented with satellite-linked time–depth recorders between January and March in 1993 (n = 6) and 1996 (n = 10) and data were collected through May in each year. Females foraged northwest of the colony, up to 367 km from it and 230 km from the California coast. Mean dive depths ranged from 19.5 to 279.3 m, but most females achieved dives deeper than 400 m. Most females fed exclusively in the offshore habitat, traveled farther from the colony, spent more time traveling, made deeper and longer dives, and terminated lactation earlier during the 1993 El Niño. The results suggest that prey were concentrated in the offshore habitat and located farther from the colony and deeper in the water column during El Niño. Females did not change their foraging direction, foraging-trip duration, foraging effort, or prey species consumed.

scholarly journals THE ROLE OF DOMOIC ACID IN ABORTION AND PREMATURE PARTURITION OF CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS) ON SAN MIGUEL ISLAND, CALIFORNIA

2009 ◽  
Vol 45 (1) ◽  
pp. 91-108 ◽  
Author(s):  
Tracey Goldstein ◽  
Tanja S. Zabka ◽  
Robert L. DeLong ◽  
Elizabeth A. Wheeler ◽  
Gina Ylitalo ◽  
...  
Keyword(s):  
Domoic Acid ◽  
Zalophus Californianus ◽  
California Sea Lions ◽  
Sea Lions ◽  
San Miguel Island
Sign in / Sign up

Export Citation Format

Share Document