Crayfish
Crayfish Facts
Identification, Range, and
Biology
Crayfish, also called crawfish,
crawcrab, crab, stonecrab, crawdad,
creekcrab, and other local names, are
native to fresh waters on all continents
except Africa, where they have been widely introduced. There are over 400
species in the family Astacidae worldwide,
and approximately 300 species
in the United States.
In size, shape, and color, the variation is extremely wide
among species. The detailed life histories
and habits of all species of crayfish
are beyond the scope of this handbook.
PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994
Cooperative Extension Division
Institute of Agriculture and Natural Resources
University of Nebraska - Lincoln
United States Department of Agriculture
Animal and Plant Health Inspection Service
Animal Damage Control
Great Plains Agricultural Council
Wildlife Committee
Crayfish are economically important in
a number of states for use as fish bait
and for human consumption. In Louisiana,
the crayfish is a major economic
crop and comprises the second largest
aquaculture industry in North
America. Over 130,000 acres (56,000
ha) are devoted solely to crayfish
culture.
Damage
Most damage associated with crayfish
is the result of crayfish burrowing in
home lawns. Burrows created by
burrowing species of crayfish are damaging
to turf areas and may be hazardous
to mowing machinery. Newly
planted rice fields may be damaged by
foraging crayfish where local populations
are high.
Crayfish populations in commercial
baitfish ponds can reduce reproduction
by feeding on the eggs of the
baitfish as they are deposited on
spawning mats. During pond harvest,
crayfish caught in the nets injure and
destroy baitfish as they are being harvested
for market.
Unwanted populations of crayfish
have been established in the wild
because of the release of bait crayfish.
Some populations have reached
extremely high levels. Crayfish can
reduce game fish populations by preying
on eggs and fry. They also can
degrade habitat by destroying aquatic
vegetation.
Legal Status
Crayfish may be protected by law in
some states. Harvest of crayfish may
also be regulated by state wildlife conservation
agencies. In areas where
damage occurs, control measures are
generally unrestricted. Check with
your local agricultural or wildlife
authorities before initiating control.
Unwanted populations of crayfish
have resulted in regulations against
the use of crayfish as bait in some
northern lakes.
Damage Prevention and
Control Methods
Cultural Methods
Deep cultivation helps reduce burrowing
crayfish populations in rice fields
and other grain crops. Drainage of rice
irrigation canals and fallow fields during
fall and winter is also helpful in
reducing crayfish populations in these
areas.
High populations of crayfish are
generally associated with years of high
rainfall. Unseasonably dry weather
conditions usually reduce crayfish
numbers.
Rapid drainage of baitfish ponds during
early spring helps eliminate crayfish
by exposing them to predators
before burrowing activities begin.
Principal predators include snakes,
racoons, mink, otter, skunks, bass,
catfish, ibis, and herons.
Toxicants
There are no General Use Pesticides
registered for crayfish control. In some
states, however, Special Local Needs
registration under section 24(c) of
FIFRA have been established for certain
insecticides for burrow treatment.
Toxicants, where legal, may be used at
any time of the year when crayfish are
active, but best results are obtained in
early fall when adults are in their burrows.
To be effective, applications of
toxic chemicals must reach the water
in the burrows. Additional treatments
may be necessary where burrows in
dikes or dams open at the bottom into
a pond or stream.
Fumigants
None are federally registered for crayfish
control. Check with your local
wildlife or agricultural agency for
Special Local Needs registrations.
Trapping
Wire cage traps baited with fish,
chicken, or other meat can be used to
capture crayfish, but they are not cost effective
in damage control situations.
*The above information was taken from a University of Nebraska Web site with
express permission of Stephen Vatassel, wildlife damage project coordinator.
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