“Counting fish is like counting trees, but the trees are invisible and constantly on the move,” says The Atlantic, explaining the often unreliable science behind marine population estimates. To get more accurate numbers, marine scientists are putting artificial intelligence, autonomous submarines, and drones to work.
For decades, researchers have relied on flawed counting systems like handwritten reports from fishermen, which are inherently skewed because fishermen congregate where there are the most fish. A species’ population may be suffering in other parts of its natural range. In the U.S., the National Oceanic and Atmospheric Administration provides information on rock-dwelling fish like scallops by trawling the sea and counting what comes up in the net. But many species live in areas that are too craggy to trawl. Or they’re migratory, like tuna, and spend most of their time in open water, where a trawl can’t catch them.
New technology is trying to give scientists the upper hand. For example, a camera, called the Habitat Mapping Camera System, or HabCam, floats five or six feet above the sea floor, snapping six overlapping images a second – providing researchers with footage from areas they could never reach with a trawl. For fish swimming closer to the surface, such as sardines, scientists are turning to broadband sounds systems capable of picking up fish noises in the water. By linking the frequencies together, scientists can create a 3-D underwater picture of where the fish are.
Tuna are a special case, since they travel vast distances and their numbers are hotly contested. Researchers believe they can use sound frequency data to learn where tuna are located and in what numbers, while getting a sense of their size from pictures taken by drones when the fish come near the surface.
Because some species are sensitive to light or “camera shy,” scientists generally agree that these new methods —all of which are in their infancy — will need to be combined for best effect with old techniques, says The Atlantic. And in the end, the fish will likely always evade a perfect tally.