Influence of Hoop-Net Trap Diameter on Capture Success and Size Distribution of Comparatively Large and Small Freshwater Turtles

Abstract

We investigated the influence of hoop-net trap size on number and size of captures for comparatively large (Chelydra serpentina [Snapping Turtle]) and small (Chrysemys picta [Painted Turtle]) freshwater turtle species. We trapped turtles at 32 ponds throughout West Virginia in the summers of 2016 and 2017, with each pond sampled for 5 consecutive days using five 0.91-m–diameter and five 0.76-m–diameter baited hoop-net traps. We captured a total of 98 and 283 unique Snapping Turtles and Painted Turtles, respectively. Larger-diameter traps captured more Snapping Turtles and smallerdiameter traps captured more Painted Turtles. Mean carapace length was greater for both species in larger-diameter traps, but this result was possibly influenced by the ability of the smallest Painted Turtles to escape through the mesh of the larger traps. Our results indicate that hoop-net–trap diameter can substantially influence both number and size distribution of captures, and thus, trap size is an important sampling design consideration for freshwater turtle research and monitoring using hoop-net traps.