Where Do Giants Go in the Deep Blue Sea? Ecology Using Satellite Tags

Intensive hunting in the 18th and 19th centuries decimated most great whale populations. After a global moratorium on hunting enacted in 1986 the populations have begun to be recover but the offshore distribution and long range-migrations of many species have precluded a more complete investigation of the physical and biological processes influencing whale ecology. However, in the last 15 years technological advances in data logging devices have revolutionized the field of animal telemetry, and satellite-linked electronic tags are becoming a viable tool to track whales over great distances. Coupled with observations of habitat variables available from oceanographic satellites and ship measurements, tracking data have great promise to advance our understanding of whale migration, environmental associations, and resource selection at various spatial and temporal scales. We present results from tagging studies on humpback, blue, sperm and gray whales in the Northeast Pacific, the Northwest and Southwest Atlantic, and the Gulf of Mexico. These studies have revealed their migration routes and destinations with unprecedented detail and have provided new insights into how whales navigate through vast areas of the open ocean. They also have shown that movement patterns and ranging can vary within and across ocean basins in relation to habitat characteristics and resources available. Analysis of movement behavior from tracking data has revealed the characteristic scales of individual home ranges while on the foraging grounds and their relationship to the time spent searching within foraging patches. At the smallest scales, data from digital tags have revealed a complex and flexible use of the water column while foraging depending on prey density, time of day and tidal state.