Alligator Snapping Turtle (Macrochelys temminckii) Research in Louisiana in Support of the Species Status Assessment and Listing Decision by the U.S. Fish and Wildlife Service

Science Center Objects

WARC researchers are investigating individual movement, growth, and population dynamics of alligator snapping turtles in a southwest Louisiana creek.

The Science Issue and Relevance: The alligator snapping turtle (AST) has experienced declines across their historic range, primarily because of overharvesting, but also habitat loss and environmental pollution. These notable declines along with the persistent threats have led to the species currently being under U.S. Fish and Wildlife Service review for federal protection. Commercial harvest of ASTs was banned in Louisiana in 2004, making it the last state to end such practices. Individuals with a valid fishing license can still harvest the animals with a bag limit of one AST per person, per vehicle, per day with no size limit. Recently, the USGS Amphibian and Research Monitoring Initiative (ARMI) has expanded its scope to pre-listing science, including research on non-amphibians like ASTs. Our goal is to collect data that will inform the Species Status Assessment and assist management in conserving this iconic species.

 

Alligator Snapping Turtle

Alligator snapping turtle (Photo by Brad M. Glorioso)

 

Methodology for Addressing the Issue: Between 2015 and 2016, the Louisiana Department of Wildlife and Fisheries (LDWF) released 53 head-started ASTs in a southwest Louisiana creek. In 2018, we initiated a trapping survey in collaboration with LDWF at the release sites to recapture those prior AST releases. We used baited hoop nets of various sizes and trapped each release site along the creek for a week. We measured and marked each turtle captured, including non-ASTs. We successfully recaptured several head-started ASTs as well as some ASTs native to the creek. In 2019, we sampled sites in south-central Louisiana where ASTs have been recorded in the past as well as sites where presence of ASTs was unknown, with the goal of updating known occupancy as part of a multi-state analysis.

 

 

 

Turtle hoop net

Turtle hoop net used to capture alligator snapping turtles (Photo by Brad M. Glorioso)

 

Using similar trapping survey methods to our 2018 effort, we caught, measured, and marked ASTs at four out of the eight field sites. In 2020, we are shifting focus to a capture-mark-recapture study at one of those four sites where we had the highest success in capturing ASTs. Using these data, we plan to investigate individual movement, growth, and population dynamics of ASTs.

 

Future Steps: We plan to continue trapping at the capture-mark-recapture site in 2020 and beyond to capture marked ASTs and mark new individuals.