November 5, 2026 — An app tells beachgoers in Massachusetts and Maine if a shark has entered the area. Fishermen in Delaware check their phones to avoid accidentally catching endangered Atlantic sturgeon. Dwindling American shad, once cut off from their spawning grounds by dams, are returning in droves.
Each of these stories became possible in part because of tiny “acoustic telemetry” tags and a vast network of researchers deploying them along the East Coast of the U.S. With acoustic telemetry technology, each tag emits a unique, ultrasonic “ping.” Along the Eastern seaboard, thousands of electronic receivers are listening for those pings, ready to detect any tagged animal that swims within about half a kilometer.
Researchers in the Atlantic Cooperative Telemetry Network, or “ACT” for short, have been tagging animals for over two decades. Now managed by the Smithsonian Environmental Research Center, the network unites scientists from over 120 organizations from Maine to North Carolina. Together, they’ve tagged more than 17,000 animals and 92 species. By sharing data from all of their receivers, they’re making discoveries about animal movement no single team could have made on their own.
“Many fish migrate long distances,” says Matt Ogburn, a senior scientist at the Smithsonian Environmental Research Center (SERC). “The ACT Network supports researchers by making it easy and efficient to exchange data across projects as the fish they tagged move along the coast or even across oceans.”
This fall the network published a new paper, its first to highlight how acoustic telemetry is shaping real-world conservation. From sturgeon to sharks (a lot of sharks), here are six fish the ACT scientists and their tags are helping preserve.