Food competition is tough for Hawaiian monk seals in the protected waters of Hawaii's remote northwestern islands.
Scientists suspected that fish were serious competitors of the seals, which are listed as endangered under the U.S. Endangered Species Act.
So they attached small cameras—called Crittercams—to 42 monk seals to see if they could document the seals' interactions with fish.
Crittercam is a National Geographic Society-patented research tool attached to wild animals that combines video and audio recording with environmental data. (National Geographic News is part of the National Geographic Society.)
The Crittercams caught 69 hours of footage—including scenes of jack fish and sharks stealing prey—such as eels and octopi—that were uncovered by the seals.
"We saw seals swimming along, flipping rocks, and then jacks would swim up ahead and wait at the next rock," said NOAA biologist Frank Parrish.
(See an underwater video of the seals hunting.)
"It was pretty clear that if the fish had figured it out, we had better catch up."