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There are five species of Carp that can or will be a concern to Iowa's
anglers and outdoor enthusiasts.
Common Carp
The Common Carp has been well established in Iowa for over 100 years. Carp were origianlly
brought over from Europe where they were a prized food fish. These fish
are found in almost all water bodies in the state. They are extremely tolerant
of poor water quality, which has contributed to its spread. Carp feeding
activity can cause poor water quality, due to their habit of rooting the
bottom and stirring up sediment in search of food. The aggravation of bottom
sediments reduces visiblility for predatory fish and limits light penetration
for plant growth.
Common carp are prolific spawners and can quickly overrun a body of
water. With their large size, they can also dominate the total fish biomass
of a body of water, leaving little room for more popular game species.
Grass Carp
The grass carp is a herbivorous (weed eating) species from Asia. It
was brought into the United States for nuisence aquatic vegetation control.
In controlled situations the grass carp has proved a valuable tool for
managers to use for weed control. Grass carp need long river stretches
for spawning and incubation of young. Some grass carp have made their way
to the Mississippi River and spawning has been documented in the lower
portions of the Upper Mississippi River (below Iowa's border). To the best
of our knowledge grass carp have not been found naturally spawning in Iowa's
portion of the Mississippi. Numerous adults however have been found free
roaming in the Mississippi and these are believed to be escapees from inland
lakes and ponds. The grass carp could prove to be a problem fish if they
became established in wetland areas. Since grass carp consume vegetation,
they could destroy areas which ducks and other wildlife use for food and
shelter.
Bighead Carp
The bighead carp is a plankton eater (microscopic algae) native to Asia.
They were introduced into the Mississippi River when private hatchery ponds
were washed out in the state of Missouri. They quickly began spawning in
the Mississippi and populations spread to other Iowa Rivers. These carp
have also been found in the Chariton, Iowa, and Des Moines Rivers.
In fact, bighead carp were quite numerous in the Chariton River below Rathbun
Dam. Netting studies in the Mississippi River conducted by the Illinois
DNR have found that bigheads school with paddlefish and may compete with
the paddlefish for food. Since bighead eat microscopic food, it is feared
they will also compete with young larval native fishes for food. They can
get quite large, with individuals over 60 lbs. having been collected.
Silver Carp
The silver carp, like the bighead carp, eats microscopic algae and plankton.
It was introduced into Arkansas in 1973 from Asia. The silver carp has
not yet been found in Iowa, but it has been collected in Illinois, Missouri,
and throughout Arkansas. However, successful natural reproduction has not
been documented in any of these states. In its native range, the silver
carp spawns in larger rivers where it requires long streches of warm water
(around 75 F.), which means there is potential for this species to start
spawning in the Mississippi River. Like the bighead carp, the silver carp
eat microscopic food and can compete for food with young larval native
fishes. Individuals weighing in at 60 lbs. have been collected.
The identification of both the silver carp and the bighead carp is quite
easy. It is the only fish with extremely small scales, and the eyes are
low (below midline) of the fish. If you believe you have collected either
of these species, please report it to your local fish management office.
Black Carp
Not much is known about the black carp. It is known to eat zebra mussels
and some want to introduce this species to attempt as a controling zebra
mussel expansion. The Iowa DNR response to is -NO-. As you can see, we
have enough exotics fish to worry about already. As with other exotics,
black carp could compete for food and space with our native fishes.
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