Wired mag has an interesting article on microscopic fish tagging. Cool stuff.
The US government’s fish-tagging operations used to be a lot like its intelligence-gathering: slow, imprecise, and occasionally responsible for the torture and death of innocent subjects. No more. The Fish and Wildlife Service now uses AutoFish, a mobile system that employs sensors, cameras, and computer algorithms to inject microscopically coded tags into 60,000 fish a day—without removing them from the water. Each $1.3 million automated rig is part of a program to ID-tag the millions of hatchery-raised fish that the US releases into the Great Lakes every year. The tags will provide fishery managers with comprehensive data that’ll help them boost low populations, avoid overstocking, and even satisfy Native American treaty obligations.