Can color alone reduce terrapin bycatch in commercial crab traps, without the need for bycatch reduction devices?

Holly Funkhouser (Biology) and Jessica Wood (Christopher Newport University)  

 

Prior research has demonstrated that red bycatch devices (BRDs) inserted into the funnels of crab traps exclude terrapin bycatch and enhance the capture of preferred male blue crabs. We tried a trap modification for which no BRDs were installed; instead, we painted the funnels of the traps red, to test whether the effect observed with red BRDs would be similar with red funnels without BRDs. We fished baited crab traps in two tidal creeks during summer 2017, using 4 traps with black funnels and 4 traps with red funnels in each creek. Total legal crab catch was not significantly different between traps with red and black funnels (411 and 379, respectively), nor was there a significant difference in crab male:female sex ratio (red 22:1; black 25:1). Further, terrapin bycatch was not significantly different between traps with red and black funnels (26 and 27, respectively). Reduction in terrapin bycatch cannot be achieved using funnel color without reducing the size of the funnel opening, i.e., by installing a bycatch reduction device. The general absence of a color effect on the relative capture of male and female crabs may have been a result of ongoing biofouling of the trap funnels that over time obscured their colors. Chronic cleaning of the funnels was required to maintain full coloration.