Consider: Salmon do not plow through chaotic water. Instead, when swimming upstream, they conserve energy by using vortices, or miniature whirlpools, that form where the water flow is disturbed by rocks, branches, or other objects. As the vortices form on alternating sides of an object, the fish curve their bodies from side to side and glide between the pockets of turbulence. (See diagram.) Some schools of fish use the vortices created by the fish swimming in front of them, effectively riding in their wake. The fish can even take advantage of the turbulence created by their own bodies!

Researchers hope to borrow from the salmon’s efficient swimming style to harvest energy from slow-moving water. Traditional hydropower equipment usually generates electricity in water flowing at a rate of about five knots (5.8 miles per hour [9.3 km/​h]) or faster. Now a prototype using vortex-induced vibrations can generate electricity from water creeping along at only two knots.a The technology, however, is nowhere near the level of sophistication found in such fish as salmon. Professor Michael Bernitsas of the University of Michigan, U.S.A., admits: “We are not as smart as fish at this point.”