Effects of Density and Food Availability on the Growth of Captive-Reared Eastern Hellbenders

Nascent captive rearing programs often lack empirical data to inform the development of husbandry practices. This lack of data, especially for density and food availability recommendations, can lead to suboptimal husbandry standards that can impair growth or survival. We conducted two experiments with captive-reared Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) to explore the effects of husbandry conditions on growth. In the first experiment, we examined growth after 7 months when reared at three densities (low, medium, or high). We found no differences in growth among the treatments. In the second experiment, we examined the interactive effects of density and food availability on growth over 8 months. The experiment was a 3 × 3 factorial design with three densities (low, medium, and high) and three food availability treatments (low, medium, and high). We found a significant effect of food availability on growth during the experiment, but no effect of density or interactive effects. Averaged across the density treatments, we found that growth was 26%-46% greater in the high food availability treatment compared to the low and medium food availability treatments. This work suggests that food is the major factor limiting captive-reared Hellbender growth and that increasing rearing density to the tested levels does not negatively impact growth. Implementing these changes may result in larger, more robust Hellbenders and increase the success of reintroduction programs.