MalheurAquatic Health |
Aquatic Health at Malheur National Wildlife Refuge (NWR) in Oregon. Published by the U.S. Fish & Wildlife Service (USFWS).
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Common carp have negatively impacted the aquatic health ofMalheur
National Wildlife Refuge - we need your help to bring the birds back.
alheur National Wildlife Refuge is one of the jewels of
the National Wildlife Refuge System. It is a premier site
for birds and birding as it provides invaluable migratory
stopover and breeding habitat along the Pacifi c Flyway.
Over the last 60 years, these habitats have been significantly
altered by a non-native species, the common carp. As a result,
refuge waters can produce only a fraction of the waterfowl and
waterbirds they once did.
u. s. Fi5h c~ IVj ldl!fo Savicei Duvl! Mmh!
Malheur National Wildlife Refuge supports a good number
of migratory ruddy ducks on the Pa cific Flyway. Ruddy and
other diving ducks rely on sago p ondweed - an abundant
subm erged aquatic p lant found on healthy lakes.
Malheur, M ud and Harney Lakes are m agnets for colonial
nesting waterbirds, or birds that gather in large assemblages
during nesting season. Ref uge waters support white-faced
ibis, as well as grebes, pelicans and egrets.
A Disastrous
e
The common carp is a member oJ
the minnow family with resilient
characteristics: it can resist wide
temperature ranges, low water clarity
and high water turbidity, and has
{{ wide-ranging diel and breeds
prolifically. Tn the Hamey basin,
common carp eat all the same foods
as birds and native fish.
us. Fish &J VildIife Service
~ ommon carp were introduced in the 1920s
~ as a desirable sustenance fish in many
places across North America, and in the 1950s
carp became established in Malheur National
Wildlife Refuge waters. Since then, carp have
severely depleted migratory bird food resources
and diminished water quality. With over 7,2 million
pounds of carp currently in refuge waters, bird
productions numbers will remain dramatically
decreased.
Why are Carp
a Problem?
The greatest impact of carp is their bottom feeding
behavior: carp eat invertebrates, uproot vegetation and
disturb the muddy bottom. As carp populations explode,
food staples for waterfowl and waterbirds disappear.
The damaging impacts of
common carp have
seriously handicapped
the refuge and its ability
to fulfill its mission to
provide feeding, nesting
and rearing habitat for
migratory birds. Currently,
the ecological collapse
caused by carp has
reduced waterfowl
production to about
2-7% of its former
capability,
Malhear is one of the largest lake systems west
ofthe Rockies. [t is a very dynamic system
with water levels changing every year. The
interconnectivity of the lakes and wate/ways
makes carp control an on-going battle.
For the Birds
Historically, Malheur Lake was home to
large colonies of nesting waterbi rds, host
to tens of thousands of nesting waterfowl
and a resting stop for migratory shorebirds.
In 1908, President Theodore Roosevelt
established the Lake Malheur Reservation
"as a preserve and breeding ground for
native birds." The reservation encompassed
over 80,000 acres around Malheur, Mud
and Harney Lakes for migratory waterfowl.
Today, it is known as Malheur National
Wildlife Refuge, and protects over 187,000
acres of habitat, including wetlands, riparian
areas, meadows and uplands.
Hi'lOrically, abolll 35%
oJ the Pacific Flyway's
canvasback duck
population used Malhellr
Lake. In Jact, the lake
produced approximately
400, 000 ducks, 75,000
geese and 3,500 swans, and
ranked as One of the most
productive waterfowl areas
in NOl1h A merica.
us.Fjsh &.. IVild/{e Service
In 1908, William Finley
photographed a white pelican
breeding colony on Maiheur
Lake. Finley - and his photos
- were instrumental in early
recognition of the importance of
the lakes, riparian streams and
marshes in the Hamey basin
to shorebirds, warerbirds and
wateifowl.
A refuge fish biologist and a University
of Minnesota researcher place a radio
telemetry tag in a carp specimen. With
tagging, scielllists can develop population
estimates as well as locate carp willlering
and spawning areas.
u. s. Fish &,. Wildlifi: Serl'ice
A Goal
for the
u ure
~Challenge
of carp control is not insurmountable.
{
National Wildlife Refuge is working to
restore the basin's aquatic health in order to fulfill its
mission of providing feeding, nesting, and rearing habitat
for migratory birds. This will be accomplished by working
with partners to develop an efficient and sustainable carp
control program for the entire basin using the best
available science.
;:;~lheur
Current Carp
Control Techniques
Refuge staff have been conducting carp control treatments since 1955.
Since then, ongoing efforts to improve aquatic health on Malheur
National Wildlife Refuge have included the use of chemicals, fishscreens,
traps and barriers, and water draw downs. While all of these treatments
have been effective, carp populations rebound within a few years without
a basin-wide solution.
In order for carp control to be a success, continuing studies on carp
populations and their effect on aquatic food supplies will need to be
completed. Complete eradication of common carp will not be possible in
all waterways, but huge strides can be made in control.
u.s.
FISH & WILDLIFE
SERVICE
A juvenile pied-hilled grehe swims alone on a
wetland. Grebes feed heavily on insects, small
fish and crustaceans hy diving below the surface.