We're going over that?
I visited Yosemite National Park in California
recently where I saw rivers that poured over cliffs, becoming thousand-foot-tall
thundering waterfalls before continuing on their courses at the bottoms of valleys. Do fish get carried over these waterfalls? Or do they know to stay away
from the edge??? Juliet, Toronto, Canada
Do fish go over Niagara Falls? Do they live?
Yosemite Falls, the sixth highest in the world, according to Wikipedia.
Photo courtesy of Kevin Eldon and Wikipedia.
It's a cold November day on the Niagara River, 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 currents push her to cliff's edge,
and she falls to a pool 170 feet (50 m)
below. Luckily it's Horseshoe (where 90% of the water falls). No
rocks greet her, only a pool whose bottom is 150 feet
down. 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 far greater — one of the highest in the
world. Fish don't make it down alive. Yosemite Creek cascades
over a 2400-foot (730-m) cliff to form Yosemite Falls. The water descends
in three stages:
- 1430-foot (425-m) Upper Falls
- 675-foot (205-m) Cascades (a series of smaller plunges)
- 320-foot (97-m) Lower Falls.
"I presume fish avoid the falls, but sometimes go over," emails
Daniel R.
Dawson, director of the Sierra Nevada Aquatic Research
Laboratory in response to my question, "but I really don't know the answer."
"I have seen fish in Yosemite Creek, above the falls," says photographer
Dave Fant of Log Cabin Wilderness Camp, a Boy Scout camp that offers backpacking trips
through Yosemite's Wilderness Area. Dave has 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. Water thundering over Upper Falls
crashes into 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.
Further Reading:
Log Cabin
Wilderness Camp
Yosemite Fall Facts
World waterfalls database
(Answered Nov. 12, 2007)
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