Project Description
Six cohorts of Steller sea lion pups have been tagged and branded at rookeries in northern California and southern Oregon beginning in 2001. Three cohorts totaling 667 individuals were branded at Rogue Reef in 2001, 2003, 2005 and 2007. Two cohorts totaling 370 individuals were branded at St. George Reef, California in 2002 and 2004. Branded pups at both rookeries have been monitored by conducting brand-sighting surveys from land or vessel and remotely with video systems at the rookeries provided by SeeMore Wildlife Inc. Brand sighting surveys conducted from 2001-2007 indicate a general northward dispersal of Steller sea lion pups and juveniles from the rookeries in the fall to haul out sites as far north as Washington and southern Vancouver Island, British Columbia, Canada. Remote video cameras will be installed in 2008 at Rogue Reef, Oregon. Additional brand sighting surveys will be conducted on hauling areas in northern California, Oregon, Washington and British Columbia.
Issues & Justification
Vital rate parameters for Steller sea lions are being assessed range wide for this species. The survival rate data collected from this study will provide these data from one of the southernmost rookery sites of the species and allow comparisons to other locations.
Goals
- Assess survival rates of Steller sea lions in Oregon and California from rookeries at St. George Reef and Rogue Reef.
- Assess the age of first reproduction and natality rates of females from these sites.
- Assess the distribution and dispersal of branded Steller pups and juveniles from these rookeries.
Methods
Remote video camera systems will be installed in April or May at Rogue Reef before the pupping season. The video feed will be monitored daily to record the presence of marked sea lions. Bimonthly brand sighting surveys will be conducted from March - October from northern California north to Vancouver Island, British Columbia to record the distribution of juvenile and young of the year sea lions. Initial survival rates for pups marked since 2001 will be determined for each cohort.