Characteristics of a Historically Harvested Alligator Snapping Turtle (Macrochelys temminckii) Population

Following perturbations like commercial harvests, turtles are susceptible to population declines because of life history characteristics such as long generation times, low recruitment rates, delayed maturity, and slow growth rates. Prior to gaining state-wide protection in 1993, the Alligator Snapping Turtle (Macrochelys temminckii) was commercially harvested in Arkansas. We conducted a mark-recapture study from 2005-2007 on a population of M. temminckii known to have been harvested in the East Fork Cadron Creek, a slow-moving stream in central Arkansas and part of the Mississippi River drainage. Captured turtles were marked, measured, weighed, and sexed. We compared observed characteristics to what would be expected if this population did not exhibit any evidence of past commercial harvest. We caught few large adults and approximately one adult for every juvenile. The adult sex ratio was highly female biased (6 F:1 M). Population density (18 turtles/km stream reach) was slightly lower than expected. The apparent survivorship for males (0.96), females (0.88), and juveniles (0.80) appear to be as expected for a large freshwater turtle. Whereas high survivorship rates may ameliorate the effects of historical commercial harvest, slow growth rates, low reproductive success, and long generation times have assured these effects to be long lasting and still present within our study population. We also suggest that there are factors impeding recovery of this population, such as life history characteristics and incidental catch by fisherman.