WHOI biologist Simon Thorrold holds a pop-up satellite archival transmitting (PSAT) tag used to collect information on sharks and other elusive fish. The tag, placed just below the dorsal fin, measures temperature, depth, and light levels of the waters the fish swims in. After several months it releases from the fish, floats to the surface, and sends data to a satellite, which relays the information to labs onshore.
It's just another day in the Dubai fish market in the United Arab Emirates. The demand for shark fins for soup threatens many species. Tens of millions of sharks are killed annually. (Simon Thorrold, Woods Hole Oceanographic Institution)
Dr. Jorge Fontes at the Institute of Marine Research at the University of the Azores dives toward a whale shark to affix a tag that will record and relay data on the shark’s movement to scientists. The tags open new windows on the habits and habitats of fish. (Nuno Sá)
The first of three views of a whale shark. Little is known about the movements of these mammoth creatures, on a daily basis or over years. Placing PSAT tags on the sharks will begin to provide that information to reveal how they live. (Pedro De La Torre)
The whale shark is not eating these fish. Whale sharks are primarily planktivorous: They open their mouths wide to engulf swaths of plankton. Fish congregate around the shark's mouth, probably to take a share of the planktivorous bounty. (Nuno Sá)
Photographed from below, the whale shark's mammoth white underbelly eclipses sunlight streaming down from the surface. (Nuno Sá)
A flurry of Chilean devil rays (Mobula tarapacana), many of them at least eight feet long, swim through waters near Ambrosia Seamount off the island of Santa Maria in the Azores. (Nuno Sá)
WHOI scientists have launched a new program called TOTEM, in which they tag large fish such as sharks, rays, tuna, and swordfish. The tags record the movements of these large, but rarely seen, creatures. TOTEM stands for "Tagging of Oceanic Teleost and Elasmobranch Megafauna." Teleosts are bony fish such as tuna and swordfish. Elasmobranchs are cartilaginous fish such as sharks and rays. (Nuno Sá)
PSAT tags have revealed movements of large fish that have never been known before. Scientists have now tracked large devil rays in the Atlantic diving to 2,000 meters, swimming down at 12 to 14 miles per hour, presumably to feed. (Jorge Fontes, Institute of Marine Research at the University of the Azores)
To apply tags to large fish, the first thing you have to do is find one, which can be hard to do in the open ocean. Divers then swim down to the fish to place a tag near the dorsal fins of fish, or the tops of rays. (Jorge Fontes, Institute of Marine Research at the University of the Azores)
Photographer Nuno Sá captured this image of the underside of an 8-foot-long Chilean devil ray (Mobula tarapacana) on Ambrosia Seamount off the island of Santa Maria in the Azores.