The "White Shark Café" is a region of the Pacific Ocean, roughly the size of New Mexico, which lies halfway between Hawaii and Mexico’s Baja Peninsula. Data obtained from two decades of satellite tagging indicate that each spring, white sharks which spent the fall and winter months just off the western coast of North America aggregate here, in a region where scientific exploration has been limited.

Once thought to live exclusively near shore, the electronic tracks of tagged white sharks show that they migrate offshore for up to six months of the year, to an oceanic region known as the North Pacific Subtropical Gyre. The ocean is less productive in this region, so there is less food then at the coast. The surface well-lit layers (epipelagic) are oligotrophic (low in food) relative to coastal habitats, but deeper midwater depths (mesopelagic) are rich with life. Diving records from the sharks indicate they move into this twilight zone over 400-500m below the surface on a regular basis. The research team aboard the R/V Falkor will use sophisticated oceanographic techniques and equipment – including underwater robots – and molecular biology in an effort to learn what draws the sharks to these midwater environs that are some of the least known habitats on the planet.

Led by Stanford University Professor Barbara Block and Sal Jorgensen of the Monterey Bay Aquarium, the research team includes marine and molecular biologists and oceanographers from Stanford, the Monterey Bay Aquarium Research Institute (MBARI), the University of Delaware, and the NOAA Office of Exploration.

To carry out their month-long investigation, the researchers are utilizing a variety of cutting-edge ocean exploration tools to document the physical and biological characteristics of the White Shark Café. These include a remotely operated vehicle from the Falkor, the ROV SuBastian, which can dive to depths of 4,500 m and record high-resolution video; University of Delaware’s Slocum Glider, a free-swimming, torpedo-shaped robot carrying instruments to measure temperature, oxygen and salinity, through the water column; and two newly-developed robotic platforms called Saildrones. Saildrones are steered remotely and powered by the wind, and can scan beneath the surface to 500m with sonar, picking up schools of fish, shrimp and other marine prey swimming at depth. The Saildrones will help identify areas of interest and the scientists will use a traditional trawl net to census what animals are there possibly providing forage for the white sharks in the open sea.

The group will also use environmental DNA technology to help identify the community of animals using these waters. To find the exact location of individual sharks present at the Café during the expedition, the researchers will rely on data provided by the satellite and acoustic tags they put on the sharks during the fall and winter of 2017 off the California coast. The Pop-up Satellite Archival Tags, built by Wildlife Computers, are programmed to release from the sharks, float to the surface, and report their locations between April 23 – at the start of the Falkor’s journey -- and May 11. The team has equipped the Saildrones and Slocum Glider with acoustic listening devices, specially designed to hear the coded “pings” emitted by 75 active acoustic tags currently on white sharks. These acoustic tags will report the animals’ locations when they pass by a listening station – like a Saildrone or a Slocum glider – and the information is uploaded in real time to an Earth orbiting Iridium satellite and sent to the ship.

In addition to notifying the scientists to the presence of a shark when they detach from the sharks, the satellite tags will provide rich data sets on the environment as the sharks dive down into the water column. Tags will record temperature and depth, providing the scientists with the preferred water temperatures and swimming behaviors. The team will also seed the ocean with buoys carrying underwater baited video cameras and acoustic receivers that uplink data to Earth orbiting communications satellites, to try and document sharks or other pelagic animals in the region.

Over 35 sharks individual are carrying the satellite tags, and if all works as planned, some of these sharks should release their pop-up tags in the vicinity of the Café during the period of the research operations, providing researchers with targets around which they will focus their oceanographic and biological surveys.

The researchers hope to integrate all data from the shark tags, from shipboard instrumentation and from the robots – to generate a detailed 3-D view of the Café environment. This will tell scientists where the white sharks are, and also document the oceanographic conditions and the prey surrounding them. By documenting the physical, chemical, and ecological conditions throughout the entire region – a section of the Pacific Ocean the size of New Mexico – the researchers hope to better understand how and why this oceanic region serves as an annual hot spot for white sharks, which return to it year after year.