programs Natural Resources

Alligator Snapping Turtle Distribution

(Macrochelys temminckii)


The alligator snapping turtle is the largest freshwater turtle in North America. In 2016, federal agents caught poachers attempting to sell a turtle from Texas weighing 171 pounds. Records from across the turtle’s range, which covers 15 states from Florida to Texas and as far north as Illinois, include weights over 200 pounds.

Until the mid-20th century, alligator snapping turtles were commercially collected and populations were in decline in river basins across the southeast. Now, all states within the species’ range have prohibited commercial harvest, and recreational harvest is only allowed in Louisiana and Mississippi. The Texas Parks and Wildlife Department (TPWD) listed the species as threatened in the state; thus, any harvest or possession of the species is illegal without the proper scientific permit.

Despite the legal risk in many states, poaching is still believed to be common. In November 2021 the U.S. Fish and Wildlife Service proposed listing the species as threatened with a proposed a Section 4(d) rule under the Endangered Species Act citing threats from “harvest/collection, nest predation, habitat alteration, and bycatch (hook ingestion, entanglement, and drowning) associated with commercial and recreational fishing.” For more information, see the FWS Fact Sheet under Resources.

Research Description

Although the species is easy to identify by its size and the distinct ridges running down its back, many questions remain about the species in Texas. To fill in these gaps in knowledge for the species in Texas, the Texas Comptroller of Public Accounts contracted with the Environmental Institute of Houston (EIH) at the University of Houston – Clear Lake in fall 2020. Over the next two years, EIH researchers will characterize abundance and demographic parameters to understand viability, assess population genetic structures in Texas and coordinate with stakeholders to provide a basis for future long-term monitoring efforts.

In addition to contributing to a baseline understanding of the species for resource managers and regulators, EIH researchers will provide survey training to stakeholders across Texas to enable long term monitoring and more effective conservation for the species.

Deliverables Due at Contract End, March 31, 2023

  • Data from all surveys, including GPS coordinates
  • Report and analysis of results to estimate:
    • Baseline demographic information
    • Genetic structure across the range in Texas
  • Formal stakeholder trainings to provide tools for future monitoring efforts
  • Contribution to a publicly accessible web platform to inform future monitoring

Why This Research Matters

The status of the alligator snapping turtle in Texas is relatively unknown. A listing decision could result in uncertainty for project permitting in multiple watersheds. More information on the species is needed in order to effectively manage habitat for the alligator snapping turtle in Texas.

This work is a part of the Comptroller’s East Texas Initiative, aimed at accomplishing two goals. First, the Natural Resources program will facilitate regular communication between East Texas stakeholders and USFWS so both have the information they need to operate. Second, the program will incorporate further discussions within East Texas communities to identify the priority gaps in knowledge needed to characterize species status. The Natural Resources program can fund research to address these gaps and develop the science-driven tools stakeholders need for long-term ESA compliance.

Based on stakeholder interest, the Natural Resources program formed a public working group on East Texas aquatic species to coordinate research and provide updates through this initiative. The aquatic ecosystem working group focuses primarily on the East Texas mussels, alligator snapping turtle, and western chicken turtle.