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Behavior is an important mechanism of evolution and it is paid for through energy expenditure. Nevertheless, field biologists can rarely observe animals for more than a fraction of their daily activities and attempts to quantify behavior for modeling ecological processes often exclude cryptic yet important behavioral events. Over the past few years, an(More)
Are pelagic species such as sharks and tuna distributed homogenously or heterogeneously in the oceans? Large assemblages of these species have been observed at seamounts and offshore islands in the eastern tropical Pacific, which are considered hotspots of pelagic biodiversity. Is the species distribution uniform at these hotspots or do species aggregate at(More)
In the final phase of their spawning migration, Pacific salmon use chemical cues to identify their home river, but how they navigate from the open ocean to the correct coastal area has remained enigmatic. To test the hypothesis that salmon imprint on the magnetic field that exists where they first enter the sea and later seek the same field upon return, we(More)
Mark-recapture techniques can be used to estimate white shark (Carcharodon carcharias) population abundance. These frameworks are based on assumptions that marks are conserved and animals are present at the sampling location over the entire duration of the study. Though these assumptions have been validated across short-time scales for white sharks,(More)
Understanding smolt migration dynamics is a critical step in the preservation and conservation of imperiled salmonids in California’s Sacramento River system. Late-fall run Chinook salmon yearling smolts were acoustically tagged and tracked during their outmigration through California’s Sacramento River and San Francisco Estuary during 2007–2009. Migration(More)
Sharks segregate by sex and size, but few studies have attempted to explain such behaviors. To address this, we examined aggregations and the foraging ecology of whale sharks in Bahía de La Paz (BLP) with aerial and ship surveys and direct observation. Zooplankton abundance and composition, and hydrographic conditions were analyzed in relation to whale(More)
Attachment of towed, floating satellite tags to large marine organisms has provided scientists with a wealth of information on the movements of these species. These tags generally are not programmed to detach at a particular time, yet are often prone to detachment by natural means after only a few days or weeks. It is important to be able to distinguish(More)
Acoustic and geolocating archival tags were deployed on steelhead kelts to study their post-spawning migrations, diving behavior and thermal habitat. Fourteen reconditioned steelhead kelts were surgically implanted with LAT2510 archival and V7-2 L acoustic tags, and released from Coleman National Fish Hatchery. An array of acoustic receivers in the(More)
We used ultrasonic telemetry to describe the movement patterns of late-fall run Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (O. mykiss) smolts during their entire emigration down California’s Sacramento River, through the San Francisco Bay Estuary and into the Pacific Ocean. Yearling hatchery smolts were tagged via intracoelomic surgical(More)
The release of hatchery reared salmonid smolts is a common management tool aimed at enhancing depleted wild stocks and maintaining fisheries throughout Northern California and the Pacific Northwest. In the Sacramento River watershed, smolts must migrate through the river, delta and estuary in order to successfully reach the Pacific Ocean. Migration success(More)