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A dozen or so small grey fish next to a ruler.
Information icon Adult saltmarsh topminnows. Photo by Ronald Paille, USFWS.

Service Coastal Program improves Louisiana marshes to benefit at-risk topminnow

A narrow stream cuts through a marsh with spiky grasses
Typical tidal creek in marshes near Sabine Lake. Photo by Ron Paille, USFWS.

The saltmarsh topminnow, a rare little fish that grows to about three inches long, is only found along marshes on the northern Gulf of Mexico coast. The U.S. Fish and Wildlife Service is researching the species, with the intention of possibly deciding whether it needs to be protected under the Endangered Species Act.

In the meantime, the Service is working on the topminnow’s favored habitat in Louisiana. If the habitat can be improved enough, the species may increase on its own without protection.

Service biologist Ronny Paille of the Lafayette, Louisiana, Ecological Service Office, has been working on two Service Coastal Program projects to construct tidal creeks in marshes on Sabine National Wildlife Refuge where the little fish likes to live. The Army Corps of Engineers created these marshes through their beneficial use of the dredged spoil program.

Construction of these tidal creeks will improve access to many acres of marshes currently not accessible and will provide over nine acres of tidal creek habitat for the topminnow.

This work has been aided by fish sampling in natural tidal creeks conducted by Paille and Service biologists Kevin Roy, John Savell, and David Oster to document the presence of the topminnow in tidal creeks where no prior records of the topminnow existed.

Dozens of small grey minnows in a white net
Topminnows and other small fish captured in a narrow tidal cree, Photo by Kevin Roy, USFWS.

The biologists were able to determine that the creeks which supported the highest density of topminnows and other marsh resident fishes were 3 to 8 feet wide, 2 feet deep or less (shallower during low tide), and dead-ended in the marsh such that they were not bayous having continuous through-flow. Using this as a template for the design of artificially constructed tidal creeks, several Section 404 permits have been received for creek construction and several additional projects are also in preliminary stages of development.

Currently, five projects are nearing construction in which over 66,000 linear feet of tidal creeks would be constructed on Sabine National Wildlife Refuge. In addition to providing habitat for the at-risk topminnow, these creeks would also provide nursery habitat for commercially and recreationally important species such as brown shrimp, white shrimp, blue crab, red drum, spotted seatrout, flounder, and others. The proposed creeks are proposed in areas where the created marshes are of lower elevation. Spoil placement and spreading would raise the adjoining marsh surface and provide habitat for rails, seaside sparrow, and other wildlife species which utilize higher elevation marshes. Spoil placement may also provide additional habitat for the black rail.

A small fish next to a ruler measuring 4 inches with a light red belly and black spots along its side
Juvenile red drum captured in a tidal creek. Photo by Ron Paille, USFWS.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. For more information on our work and the people who can make it happen, visit fws.gov. Connect with the Service on Facebook, follow our tweets, watch the YouTube Channel and download photos from Flickr.

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