Location, Location, Location: The Importance of Cull Ring Placement in Blue Crab Traps

Abstract

Wire-mesh crab traps capture both legal- and sublegal-sized blue crabs Callinectes sapidus. The likelihood of injury and subsequent mortality of small crabs when confined with larger conspecifics increases as the time of confinement lengthens. While the installation of cull (escape) rings has reduced the entrapment of sublegal crabs, the capture of undersized blue crabs continues. In most states, there are no regulations requiring placement of cull rings in a specific location on a trap wall. Since blue crabs tend to crawl along the floor of the upper chamber of crab traps, we tested escape efficiency for sublegal blue crabs in traps with cull rings that were flush with the upper chamber floor. Placement of cull rings flush with the upper chamber floor or partition increases the odds of escape within 4 h of capture by 39 times over traps with cull rings placed higher on the trap wall. A reduction in the entrapment and potential injury or mortality of undersized blue crabs can be realized by proper placement of cull rings within crab traps.