Paddlefish
For additional information visit the USGS
Upper Midwest Environmental Science Center web site.
Scientific Name: Polyodon spathula
Common Names: paddlefish, spoonbill, shovelnose
Paddlefish Interesting Facts
In 1997 Missouri designated the
paddlefish as the state's official aquatic animal.
The paddlefish is the only species of
family Polyodontidae in North America.
Paddlefish eggs, or roe, are a popular
caviar.
Because they are filter-feeding
planktivores, paddlefish cannot be caught by conventional fishing
techniques. In states where it is legal, snagging has become
a popular method of catching paddlefish.
Paddlefish are a long-lived fish,
surviving over 30 years in some cases. They also mature
later than most fish, sometimes at 10 years or older.
Paddlefish can attain sizes of over 7
feet long and more than 200 pounds.
Paddlefish Distribution and Identification
In Ohio, paddlefish are native to Lake Erie and the Ohio River and
its tributaries. Although population densities have declined,
paddlefish can still be found in the Ohio River and some of the major
tributaries. Paddlefish have a very distinctive appearance, with
the presence of a long snout, deeply forked tail, and are gray in
color. The paddlefish's genus name, Polyodon, comes from
a Greek word meaning "many tooth", and refers to their gill
rakers (Texas
Parks and Wildlife). Their extensive gill rakers are used
for filter feeding. Although paddlefish can reach large sizes
(over 100 pounds), they feed primarily on plankton. The
paddlefish's species name, spathula, is derived from a Latin
word meaning "spatula" or "blade".
Paddlefish Biology
The function of the paddlefish's unique rostrum (paddle) has long
been debated. Lon
Wilkens, at the University of Missouri, St. Louis, conducted
research that documented how the paddle functions. With the
paddlefish reaching such large sizes, it is obvious that it must be
very efficient at capturing mass amounts of food. Being
primarily a river dweller, the paddlefish lives in a murky, harsh
environment. Paddlefish are known to have poor eye sight, so to
thrive in river environments their other senses must be extraordinary.
The results of Lon Wilkens' research shows that paddlefish most likely
use their long snout to detect prey.
For additional information visit the Tennessee
Aquarium web site.
Paddlefish feed on plankton, such as the water flea (Daphnia),
that have been found to emit weak electrical signals. It appears
as though the rostrum is a highly developed electro-receptor that can
detect signals of less than 1/100th of one 1-millionth volt per
centimeter. Laboratory studies verified that juvenile paddlefish
will strike at electrodes placed in the water that emit currents
similar to currents emitted by plankton. The response was
verified by conducting the experiments in the dark, proving that the
strike was not visually triggered. It was concluded that the
paddlefish's rostrum is a highly sensitive "antenna" that
aids the fish in not only feeding, but also navigation. When
metal objects were place in the swim path of paddlefish, they
routinely avoided them. However, when plastic objects were
placed in their path, they usually collided with them.
For more information about paddlefish, see these interesting pages:
Paddlefish Article By
Travis Hartman, Fondriest Environmental, September 2001
All websites referenced have direct hyperlinks to the original source.
