Somatic Growth and Maturity for Four Species of River Cooter Including Pseudemys concinna suwanniensis, P. nelsoni, P. peninsularis, and P. texana

Abstract

Pseudemys is a genus of commonly occurring freshwater turtles with limited growth information across their long lifespans. We used 11,361 mark-recapture events to estimate the somatic growth rates of P. nelsoni, P. peninsularis, P. concinna suwanniensis, and P. texana from freshwater springs and developed a Bayesian growth model to estimate the species-specific, site-specific, and individual effects on growth. We corroborated evidence for fast juvenile growth and slower adult growth in Pseudemys but found uncommonly fast growth rates, with turtles doubling or tripling in size in the first year. P. texana males had the smallest average maximum size (L∞, 243 mm), while P. c. suwanniensis females had the largest (423 mm). Environmental conditions at springs had significant effects on k, the growth coefficient, but not L∞. We derived, using a ratio of length at maturity to L∞ (71.7% and 87%, males and females), that females matured 1.15–1.57 times older than males except for P. c. suwanniensis, which matured three times older. Given the local abundance declines in many Pseudemys from anthropogenic impacts, this study provides important baseline life history information for Pseudemys species for use in ongoing conservation efforts and presents a novel hierarchical modeling approach using a long-term mark-recapture dataset.