Since 1955, someone has sat on a wooden tower over an Alaskan river with a hand-clicker, counting salmon in 10-minute bursts around the clock. That single number — how many fish "escape" upstream to spawn — decides whether a fishery opens or closes, whether a season is made or lost. It is one of the most consequential counts in conservation, and for seventy years we have made it by eye and by hand. That's changing fast. In this ReThink History series, we follow the technology now learning to watch the river for us: solar-powered "drone-in-a-box" units that launch themselves over Bristol Bay, computer-vision models trained to pick a single sockeye out of glare and shadow, acoustic "cameras" that see fish in pitch-black glacial water, and Indigenous-led AI built straight into traditional fishing weirs. Each new way of seeing does more than count faster — it reveals a little more of a life spent hidden underwater and thousands of miles out to sea, and it quietly changes who gets to decide what a shared resource is worth. Across eight episodes we go from the counting towers to the salmon's own secret life cycle; from drones and neural networks to imaging sonar and the elegant "echogram" that lets a cheap computer count fish where there's no internet; from First Nations weirs on the British Columbia coast to the hard questions underneath it all — a warming climate, the Pebble Mine at the headwaters of Bristol Bay, and who owns the count. It's a story about salmon, about the technology learning to see them, and about the remote Alaskan places whose summers ride on the count — like the Naknek cannery, where the run peaks on the Fourth of July and the bears watch from the fence. New episodes in order. Subscribe: youtube.com/@LetsRethinkHistory?sub_confirmation=1 Episodes The Number That Runs a Fishery — escapement, the counting towers, and why one number rules a fishery The Secret Life of a Sockeye — the salmon lifecycle we're actually trying to count The Drone in the Box — Bristol Bay's self-launching aerial fish-counter Training the Electronic Eye — how a machine learns to see a salmon Seeing in the Dark — imaging sonar and the acoustic cameras that count in the black The Echogram — the compression trick that counts fish off the grid The Weir and the Network — Indigenous-led AI and who controls the count The Digital Escapement — climate, Pebble Mine, and the future of the salmon run #History #SalmonCounting #ReThinkHistory