The electrofishing boat, which biologists once used to find out which fish species were present in a body of water, is becoming outmoded now that identification is possible through fish DNA present in the water itself.
Instead of trying to capture tagged fish again and again to track their movements, biologists can now use passive sonar detectors that register each time a tagged fish passes by.
The age-old problem of fish losing their tags can now be circumvented by injecting rice-grain-sized electronic tags under a fish's skin and using an electromagnetic wand to detect and read it.
Taking a tiny snippet from a fish's fin now allows biologists to examine its DNA and identify which regional strain of a species it represents.
In much the same way that wildlife biologists track radio-collared bears, fisheries biologists can track individual fish by attaching tiny radio tags to them.