Meeting Abstract

P1-152   -   Nothing but Net: A Mark-Recapture Study of Diamondback Terrapin (Malaclemys terrapin) Populations in the Barataria Estuary Gray, KD*; Clay, TA; Nicholls State University Department of Biological Sciences; Nicholls State University Department of Biological Sciences kgray13@nicholls.edu

The Diamondback Terrapin (Malaclemys terrapin) is a brackish water turtle with a range spanning Cape Cod, Massachusetts through Corpus Christi, Texas. Although well-studied along the Atlantic portion of its range, Gulf Coast terrapin study is lacking. To further expand the knowledge of Louisiana’s Diamondback Terrapins, a long-term mark-recapture study was initiated at two locations in the Barataria Estuary, Elmer’s Island Wildlife Refuge and the barrier island East Grand Terre. This study employed an open sampling design that spanned one field season, March 2021 to August 2021, with surveys occurring monthly. Unbaited single lead fyke nets were set in tidal channels at both locations and checked once every 24 hours. Sex, age class, and carapace, plastron, and head morphometrics data were recorded from all captured terrapins. To identify previously captured individuals, each terrapin was PIT tagged and uniquely marked by filing triangular notches in the marginal scutes. POPAN and Pradel Recruitment Jolly-Seber model simulations were run in R to estimate population parameters of abundance, survival, capture probability, probability of entry, and recruitment. Survey efforts resulted in the capture of 81 individual terrapins and two recaptures. Terrapin captures at East Grand Terre and Elmer’s Island populations produced respective sex ratios of 3:5 and 2:3, both favoring females. Overall, adult females were significantly larger than males in all morphometrics. Delta AICc values determined that East Grand Terre data was best fit to a time-varied probability of capture model under both POPAN and Pradel Recruitment parameterizations. Conversely, Delta AICc determined that Elmer’s Island data was best fit to a time-varied probability of entry model under the POPAN parameterization and a time-varied recruitment under the Pradel Recruitment parameterization.