There are more than 600 species of crayfish worldwide and Tennessee is home to more than 90 different species. The Nashville crayfish (Faxonius shoupi) is the only animal whose entire range is located only in the greater Nashville area, as it is only found in Mill Creek and its tributaries (this includes the stream that flows through Nashville Zoo, although they aren’t found in this part of the stream).
Nashville crayfish are usually found under flat slabs of limestone and other rocks in free-flowing streams. They eat algae, leaves, insects, worms, fish eggs, snails and mussels. Crayfish play a valuable role in their ecosystem, as they are an important source of food for more than 240 other species, including their main predators, which are other species of crayfish, raccoons, fish and reptiles. Their burrows are also used as a refuge by other animals like the crawfish frog, snakes, salamanders and small rodents.
The Nashville crayfish grows to be a rather large crayfish, up to 7 inches long as an adult. Like all crayfish, it has four pairs of legs and two pinchers. Nashville crayfish can be distinguished by its elongated pinchers with orange and black coloration on the tips and a light-colored “saddle” on its mid-back that extends down the sides toward the head.
Nashville crayfish are the only federally protected crayfish in Tennessee and one of four federally protected crayfish in the United States. Nashville crayfish are currently classified as Endangered by the IUCN Red List. About half of all crayfish species are considered endangered or imperiled. One of the main threats to this species is habitat degradation. More than half of Mill Creek’s 27.9 miles are considered “impaired” by the state because of development, siltation, pollution, agricultural run-off and invasive species. Despite being listed as federally endangered in 1986, the Nashville crayfish is doing well and Mill Creek remains a relatively healthy creek thanks to the efforts to reduce these threats.
Surveying wild Nashville crayfish population
Measuring a wild Nashville crayfish
HERE AT NASHVILLE ZOO
In collaboration with the Tennessee Department of Environment and Conservation (TDEC), Tennessee Wildlife Resources Agency (TWRA) and the U.S. Fish and Wildlife Service (USFWS), Nashville Zoo initiated the Nashville Crayfish Project in 2009, which focuses on involving the community in Mill Creek’s revitalization and protection of the crayfish habitat. Project leaders also organized the Mill Creek Watershed Association, which leads cleanups of Mill Creek and has stenciled “No Dumping” on storm drains in the watershed.
In 2011, Nashville Zoo entered a cooperative agreement with the USFWS to develop and implement long-term population monitoring protocols for Nashville crayfish. Zoo staff also monitor water quality in Mill Creek, as determining long-term population trends and monitoring water quality are fundamental first steps in creating a successful conservation program for crayfish. This population study will continue indefinitely, showing trends in the wild population over time.
In addition to population monitoring, Zoo staff are also developing a captive breeding program for the Nashville crayfish using a surrogate species known as the bigclaw crayfish (Faxonius placidus). Once captive care proves to be repeatedly successful, we may begin working directly with Nashville crayfish in captivity. So far, two complete generations of crayfish have been hatched from the surrogate species (with offspring produced in 2012, 2015 and 2018). Nashville Zoo is writing a husbandry manual for this species that would serve as a guide for other institutions that want to work with endangered crayfish.
HOW YOU CAN HELP
Avoid using chemical fertilizers and pesticides in your yard and garden, because those chemicals have the potential to get into nearby streams or rivers. Wash your car on grass and not in the driveway to avoid having the run-off go into storm drains.
Donate to conservation