Meeting Abstract

S3.11  Sunday, Jan. 4 15:00  Evidence of determinate growth in American alligators (Alligator mississippiensis) based on long-term recaptures RAINWATER, TR*; WOODWARD, AR; WILKINSON, PM; U.S. Fish and Wildlife Service

Debate exists as to whether crocodilians exhibit determinate or indeterminate growth. Long-term mark-recapture studies appear to be the best method of determining long-term growth patterns in crocodilians, but because of the inherent difficulties in conducting decades-long mark-recapture studies on wild, long-lived species, only a few such studies have been successfully undertaken. However, each of these investigations has documented cessation of growth well before senescence in the species examined, thereby supporting the concept of determinate growth. In this study, we examined growth (total length) in a population of wild American alligators (Alligator mississippiensis) in coastal South Carolina over a period of 32 years (1980-2012). To ensure adequate time had passed for discernible growth to occur between the most recent recapture and the previous or initial capture, we included in our analysis only those alligators that were at least slightly below approximate minimal adult size at the previous/initial capture and recaptured >10 years later. No discernible growth was observed for 22 animals during the study. Discernible growth occurred in 34 alligators examined, but these animals were all well below asymptotic size when initially captured. These results provide evidence that alligators in the study population reach asymptotic linear length during the mid-part of their adult life and continue to reproduce for an extended period of time after reaching that point. Overall, this investigation complements findings of similar studies on other crocodilian species and further suggests that lineal growth in some, if not all, crocodilians is determinate.