MEPS 372:253-264 (2008)  -  DOI: https://doi.org/10.3354/meps07706

ABSTRACT: Knowledge of how animals move through heterogeneous environments is essential to understanding the ecological functions they fulfill in each habitat and their responses to environmental change. Upper trophic level organisms exert structural influences through the food web, so information on their range, migration and foraging strategy is necessary to understanding ecosystem function. Recent technological advances have enabled researchers to follow individual animals over seasonal and multi-year timescales, revealing long-distance migrations in a variety of taxa. We used satellite telemetry to monitor female salmon sharks Lamna ditropis and remote sensing to characterize their environment. Salmon sharks ranged throughout the entire eastern North Pacific Ocean during a seasonal migration cycle. During long-distance migrations, quantitative movement analyses of speed, path straightness and first passage time (FPT) revealed area-restricted search (ARS) behaviors in northern and southern regions, with transiting behaviors at mid-latitudes. Individuals migrating to a highly productive southern region displayed more ARS behaviors than those moving to a low productivity region. The combination of multi-year time-series of animal behavior with synoptic environmental data reveals factors influencing migration and indicates that different life history functions are fulfilled in each habitat.

KEY WORDS: Migration · Behavior · Habitat selection · Landscape ecology · Oceanography · Foraging behavior · Reproduction · Elasmobranch · Lamna ditropis