Growth rates and body condition factors of Alligator mississippiensis in coastal Louisiana wetlands: A comparison of wild and farm-released juveniles

Abstract

1. 1. Growth rates and body condition factors for native wild and captive-raised juvenile alligators ( Alligator mississippiensis) that had been released to the wild were studied using tag-recapture methods for 274 alligators over a 4-year period. Alligators were grouped by sex, size class, source (farm-released vs native wild) and as to whether they had overwintered or not. 2. 2. In most groups, the farm-released alligators grew significantly better than wild alligators matched for sex and size; in the remaining groups the post-release alligators grew as well as their counterparts, though not better. 3. 3. Overwintering tended to slow growth rates in both groups, but farm-released alligators still demonstrated superior growth over native wild alligators even after overwintering. 4. 4. Males tended to grow faster than females, though this trend was not always significantly greater. In no matched group did females grow faster than males. 5. 5. Growth rates diminished with increasing size in native wild alligators (smaller alligators grew faster), but growth rates of farm-released alligators remained accelerated even at the larger size classes. 6. 6. Growth curves were constructed using known recapture data with three growth models (von Bertlanffy, Gompertz and logistic); the calculated maximum attainable length and growth parameters were significantly larger ( P < 0.01) for farm-released alligators than wild using all three models. 7. 7. Body condition factors were not different in captive-raised post-released alligators than native wild alligators.