It's hard to study a creature when you only catch fleeting glimpses of it. Up until recently, that was one of the big stumbling blocks for marine biologists and ecologists, but advances in electronic tracking technology have allowed them to peer farther across, and deeper under, the surface of the oceans than ever before.
Satellite tracking systems and acoustic sensors are giving researchers insights into the behavior and lifestyles of some very elusive animals in the ocean, including the fabled white shark.
Researchers from several institutions, including Stanford University, have joined their efforts in a Census of Marine Life project called Tagging of Pacific Predators (TOPP). Since the project began in 1999, they have attached more than 3,000 tags to sharks, seals, whales, tunas, squids, turtles, albatross and more. For the first time, these TOPP researchers are getting a glimpse of a pelagic ecosystem from the California Current to the North Pacific at daily, seasonal and yearly time scales.
Along with the white shark, the TOPP researchers also have been studying the routes and habits of two cousins of the white shark: the salmon shark, whose range extends from the glaciers of Alaska down to Baja California, where it crosses over the white sharks' territory along the continental coast, and the mako shark, which resides along the continental shelf off California. The team also has tagged thresher sharks and blue sharks.
Sharks are a vital part of oceanic ecosystems. As the top predators in the food chain, they regulate the populations of the species below them. If shark populations get in trouble, it can trigger a cascading effect all the way down the food chain. The TOPP team has used several distinct tag technologies to get a simultaneous view of how these sharks divide up the ocean turf.
Salvador Jorgensen, a postdoctoral researcher at Stanford University's Hopkins Marine Station and the Monterey Bay Aquarium,
|Contact: Louis Bergeron|