A: It's a cold November day, barely above freezing. A steady rain beats upon the rushing water. A rainbow trout stirs deep in the river, her red band dark in the depths. Fierce river current pushes her to cliff's edge, and she falls — over Horseshoe Falls — to the plunge pool 170 feet (50 m) below. Luckily it's Horseshoe (where 90% of the river water falls). No rocks greet her, only a pool whose bottom is 150 feet deep. She plunges into the air-bubble cushioned pool, bobs up and swims slowly away, stunned but alive.
About 90% of fish swept over Niagara Falls survive, estimates Niagara River expert Wes Hill, who pulled about 400 human bodies from the river over the course of his 76-year life. Fish bodies, unlike humans, are built to withstand great underwater pressures, so such a fall is survivable, for a fish.
Yosemite Falls, however, is a far greater fall — one of the highest in the world. Fish don't make it down alive. Yosemite Creek cascades over a 2425-foot (739-m) cliff to form Yosemite Falls. The water descends in three thundering falls:
"I have seen fish in Yosemite Creek, above the falls," says photographer Dave of Log Cabin Wilderness Camp, a Boy Scout camp that offers backpacking trips through the Yosemite Wilderness Area. Dave's never actually seen any fish go over the falls, but thinks they well could. "If fish were to go over, they would surely die," he emails. Upper Falls ends at a rock shelf that "would instantly kill any fish." If any fish "miraculously" survived the first big fall, the jagged rocks at the base of Lower Falls would end its life. No fish could survive both falls.
(Answered Nov. 12, 2007)