U.S. Fish & Wildlife Service

What is the winged

mapleleaf?

The only reproducing

population of winged mapleleaf

is found in the St. Croix River

along the Wisconsin and

Minnesota border. Winged Mapleleaf

The winged mapleleaf is an endangered species. Endangered species are

animals and plants that are in danger of becoming extinct. Threatened

species are animals and plants that are likely to become endangered in the

foreseeable future. Identifying, protecting and restoring endangered and

threatened species is the primary objective of the U.S. Fish and Wildlife

Service’s endangered species program.

Scientific Name - Quadrula fragosa

Appearance - Winged mapleleaf grow up to four inches long. They have

thick shells that are greenish brown, chestnut, or dark brown in color. Their

shell, like that of a few other native freshwater mussel species, has several

rows of bumps running from the hinge (umbo) to the edge of the shell. The

patterns of these rows of bumps, or tubercles, help biologists differentiate

this from other, similar mussel species. Faint rays are visible in small shells.

Range - The range of the winged mapleleaf once included 13 states where it

was found in large rivers and streams that flow into the Mississippi River

and in one river that flows into the Missouri River. Today it is found in the

St. Croix River in Minnesota and Wisconsin, the Ouachita and Saline Rivers

in Arkansas, and the Bourbeuse River in Missouri. The St. Croix River

contains the only population known to be reproducing.

Habitat - Winged mapleleaf are found in riffles with clean gravel, sand, or

rubble bottoms and in clear, high quality water. In the past, it may also

have been found in large rivers and streams on mud, mud-covered gravel,

and gravel bottoms.

Feeding Habits - To feed, the winged mapleleaf siphons in water and filters

out food particles. It is thought that most of the particles that are actually

used as food are phyto- and zooplankton – tiny organisms that drift with

river currents.
Why is the winged

mapleleaf

endangered?

What is being done to

prevent extinction of

the winged mapleleaf?

What can I do to help

prevent the extinction of

species?

Updated September 2004

U.S. Fish & Wildlife Service

1 Federal Drive

Fort Snelling, Minnesota 55111-4056

612/713-5350

http://midwest.fws.gov/endangered

What is the winged

mapleleaf? (cont’d.)

Reproduction - Winged mapleleaf reproduction is similar to many other freshwater

mussels. The males shed sperm into the water. Eggs on the gills of females are

fertilized when sperm is collected as the female siphons in water. After fertilization,

the females store the developing larvae (glochidia) in their gills until they’re expelled

into the river current. These glochidia must attach to the gills or fins of a fish to

complete development. Glochidia can only develop on certain species of fish which are

called host fish. Known host fish for the winged mapleleaf are channel and blue catfish.

 Glochidia continue growing on the fish and transform into juveniles, then they drop off

and land on the river bottom where they mature into adults. The lifespan of the winged

mapleleaf is not known, but the oldest known individual in the St. Croix is 22 years old.

Catastropic Events - Only one population is known to be reproducing. Therefore, a single

catastrophic event in the St. Croix River could effectively eliminate the species, leaving

only remnant, unviable populations remaining. Examples of catastrophic events are

toxic spills, severe drought, or disease.

Zebra Mussels - Zebra mussels are an exotic species of mussel that threaten

freshwater mussels in the Mississippi River watershed. Zebra mussels were

inadvertantly introduced into North America during the late 1980’s and became

established in the lower St. Croix River in 2000. They attach to any hard surface and

breed so prolifically that they smother or otherwise harm native freshwater mussels. It

is essential to the conservation of winged mapleleaf that zebra mussels are not allowed

to invade this species’ sole reproducing population.

Land Use Changes - The remaining reproducing population of winged mapleleaf is near

the major metropolitan area of Minneapolis and St. Paul, Minnesota. As sprawl from

this urban area continues, more and more of the St. Croix River watershed will be

developed, which could result in increasing levels of contaminants and sediments in runoff that drains into the river. In Missouri and Arkansas, agriculture and industry are

abundant in the watersheds where winged mapleleaf are present. These activities can

destabilize river corridors and increase runoff of harmful pesticides, chemicals, and

sediment.

Listing - The winged mapleleaf was added to the U.S. List of Endangered and

Threatened Wildlife and Plants on July 22, 1991. It is illegal to harm, harass, collect, or

kill the mussel. Permits can be obtained from the U.S. Fish and Wildlife Service for

scientific studies or take that is incidental to an otherwise legal activity.

Recovery Plan - A recovery plan has been prepared that identifies and prioritizes

actions that are necessary to recover this species.

Habitat Protection - Xcel Energy, which operates a dam just upstream of the only known

reproducing population of winged mapleleaf, is coordinating with the Minnesota and

Wisconsin DNR’s and the U.S. Fish & Wildlife Service to insure instream flow levels

that protect this mussel. In addition, the National Park Service, the states of Minnesota

and Wisconsin, the U.S. Army Corps of Engineers, and others are cooperating with the

U.S. Fish and Wildlife Service to keep zebra mussels out of habitat occupied by winged

mapleleaf in the St. Croix River.

Learn - Learn more about the winged mapleleaf and other endangered and threatened

species. Understand how the destruction of habitat leads to loss of endangered and

threatened species and our nation’s plant and animal diversity. Tell others about what

you have learned.

Join - Join a conservation group; many have local chapters.

Protect – Protect water quality by minimizing use of lawn chemicals (i.e., fertilizers,

herbicides, and insecticides), recycling used car oil, and properly disposing of paint and

other toxic household products. If you boat, do whatever you can to prevent spreading

zebra mussels within or between water bodies.