In order to breed, many salmon species swim upstream, facing turbulent waters along the way. How are they able to endure a grueling journey without succumbing to exhaustion? Instead of being overwhelmed by the rough water, these fish actually take advantage of it. How?

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. 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.”