The U.S. Fish and Wildlife Service is proposing to list the Miami cave crayfish (Procambarus milleri) as a threatened species with an accompanying section 4(d) rule under the Endangered Species Act.  

Using the best available science, the Service has determined the Miami cave crayfish fits the definition of “threatened” as it is at risk of becoming endangered in the foreseeable future. This species cannot survive in saltwater, yet the threat of saltwater intrusion into the Biscayne Aquifer is increasing from sea level rise, more frequent tidal flooding, and growing storm intensity.  

The Miami cave crayfish is a tiny pale subterranean crustacean found seven to 36 feet deep below ground only within the Biscayne Aquifer along the Atlantic Coastal Ridge in southern and central Miami-Dade County, Florida. The crayfish moves through the limestone, devouring organic matter that is filtered from the surface.   



The limestone layers along the Atlantic Coastal Ridge are extremely porous, providing an interconnected network for the crayfish to travel and shelter from threats; the enhanced groundwater flow provides high water quality and ample food.   

Critical habitat for the Miami Cave crayfish will be proposed at a later date. 

For threatened species, section 4(d) of the ESA allows exceptions for incidental take when the actions benefit the conservation of the species. The exceptions proposed for the Miami cave crayfish include construction and maintenance to prevent saltwater intrusion into the Biscayne Aquifer and restoring coastal wetlands to improve water quality or infiltration into the Biscayne Aquifer. 

Listing under the ESA provides immediate protection, promotes recovery, and generates greater public awareness about the threats and conservation opportunities. It also inspires actions by diverse partners, including federal, state, Tribal, local agencies, industry, conservation groups, and individuals.   

Targeted protections:  Under the ESA, federal agencies must ensure actions they approve, fund or carry out do not jeopardize the continued existence of a listed species or destroy or adversely modify its habitat. In addition, the ESA protects listed species and their habitats by prohibiting “take” and interstate or international trade in listed species (including their parts and products), except under federal permits. Take is defined by the ESA as “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect or attempt to engage in any such conduct.”  Harm is defined as “an act which actually kills or injures wildlife.”  Such an act may include significant habitat modification or degradation where it kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding, or sheltering.  

Recovery efforts:  The ESA also requires the Service to develop and implement recovery plans for the conservation of threatened and endangered species. Recovery plans outline actions that are needed to improve the species’ status, so they no longer require protection under the ESA. The Service develops and implements these plans in partnership with species experts, federal, state, and local agencies, Tribes, non-governmental organizations, academia, and other stakeholders.   

Comments on the proposed rule must be submitted by November 20, 2023. Using the Federal eRulemaking Portal, search for docket number FWS-R4-ES-2023-0103. Comments submitted electronically must be received by 11:59 p.m. Eastern Time. The agency must receive requests for public hearings in writing at the address shown below by November 6, 2023.  

For more information contact Lourdes Mena, Classification and Recovery Division Manager, 904-731-3134, Florida Ecological Services Office, 7915 Baymeadows Way, Suite 200, Jacksonville, FL 32256-7517.  Persons who use a telecommunications device for the deaf (TDD) may call the Federal Relay Service at 800–877–8339.