"Sunrise at Valley Forge, Valley Forge National Historical Park, 2015." by U.S. National Park Service , public domain
![]() | Valley ForgeRusty Crayfishes |
Brochure about Rusty Crayfishes at Valley Forge National Historical Park (NHP) in Pennsylvania. Published by the National Park Service (NPS).
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The Rusty Crayfish
The rusty crayfish is considered a non-native,
invasive species in the park and throughout
Pennsylvania. Originally from the Ohio River
Basin, this crayfish has been introduced into 19
states where it never occurred before over the
last 30-40 years (Figure 2). It has been
transported from one place to another primarily
by bait fishermen, but also through biological
supply houses, aquaculture, and the pond and
aquarium trade.
Rusty crayfish were
first documented in
Pennsylvania in the
1970’s and now occur
in the Delaware,
Potomac, Schuylkill,
and Susquehanna
River watersheds.
From large rivers they
are able to invade the
countless small
streams that feed into
the rivers, such as
Valley Creek.
What does invasive
mean?
An invasive, non-native
species is one that, once
introduced, is able to
out-compete native
species for needed
resources such as food,
space, water, and shelter.
In extreme cases, native
species may be totally
eliminated from the
ecosystem.
The rusty crayfish is bigger, more aggressive,
and eats up to twice as much as native crayfish in
Valley Creek. They are able to eliminate ALL
other crayfish species through direct
competition for food and shelter and increasing
the susceptibility of native crayfish to predators
as they are chased from under protective rocks
and move more to find food. Rusty crayfish also
may reduce the amount of aquatic vegetation,
reduce aquatic insect populations, and
ultimately negatively effect large predators such
as trout.
National Park Service
U.S. Department of Interior
Valley Forge National Historical Park
King of Prussia, Pa
Stewards of Native
Diversity at Valley Forge
Introduced Populations
Native Range
Figure 2. Distribution of rusty crayfish in the United States,
including their native range and areas where they have been
introduced and are considered non-native.(From
http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=214).
For additional information on
rusty crayfish please visit*:
http://www.invadingspecies.com/Invaders.
cfm?A=Page&PID=4
http://www.seagrant.umn.edu/ais/rustycray
fish_invader
http://nas.er.usgs.gov/queries/FactSheet.as
px?speciesID=214
* Information contained within this brochure was obtained
from the sources above.
2010
Did You Know?
It is illegal to use rusty crayfish as fishing bait in
Pennsylvania and no live bait of any kind can be
used in Valley Creek within the park. These
regulations exist to prevent the introduction of
additional non-native species into Valley Creek
and to control the spread of rusty crayfish across
the state.
www.nps.gov/vafo
Funding contributed by the National Park Service
Volunteer-In-Parks Program
What is the Crayfish Corps
In 2008, the rusty crayfish (Orconectes rusticus)
invaded Valley Creek in Valley Forge National
Historical Park. Valley Creek is considered an
“Exceptional Value” waterway, Class A Wild
Trout Fishery, and one of the park’s most
important natural resources. The rusty crayfish
is a highly aggressive, non-native species that
poses a significant threat to the continued
health of the stream ecosystem.
Rusty crayfish claws are grayish– green to
reddish-brown with dark black bands on the
tips (b). The
claws, when
closed, have
an oval gap
in the
middle. The
moveable
claw is
smooth and
S-shaped (c).
NPS Photo
Members of the
What is a Non-Native
Crayfish Corps will
Species?
join NPS staff in the
Non-native species are
battle to suppress
those that occur in an
rusty crayfish
area as the result of
populations by
deliberate or accidental
physically removing
human activities.
them from the stream
ecosystem. Our goal is to maintain a ratio of 1
rusty crayfish or less for every 4 native crayfish
present in Valley Creek.
(b) Black bands on tip of claw
Join the Crayfish Corps
Crayfish Corps is active between May and
August in order to catch the most rusty
crayfish and allow the stream time to rest.
Crayfish removal is accomplished using hand
nets and participants should be prepared to get
in the stream and get wet!
All ages are welcome and park staff will
provide necessary training and equipment
including nets and a limited number of hip
boots. Participants should wear their own
close-toed water
shoes if possible.
(b)
(c)
Receive a Crayfish
Corps button the first
time you participate
and earn a Crayfish
Corps t-shirt after
participating only
three times.
To become a member of the Crayfish
Corps, visit our volunteer website :
Rusty Crayfish Identification
http://www.nps.gov/vafo/supportyourpark/
volunteeropportunities.htm
Rusty crayfish are most easily identified by the
presence of rust-colored spots located on both
sides of the carapace behind the claws (a)
(Figure 1).
(a)
These patches
may be less
pronounced on
crayfish from
different areas.
Illustration by Marian Orlousky
NPS Photo
(a) Rust-colored spot on carapace
Figure 1. Rusty crayfish illustration showing key identifying
characteristics: (a) rust-colored spots, (b) black bands on tip
of claws, and ( c ) S-shaped moveable claw.
NPS Photo
Crayfish Corps volunteers Ajena and Kaylen Rogers