Configuring escape gaps in recreational rectangular traps to improve size selection for eastern rock lobster, Sagmariasus verreauxi

Abstract

The utility of escape gaps in rectangular traps for improving the size selection of eastern rock lobster, Sagmariasus verreauxi was assessed during two experiments in an Australian recreational fishery. In experiment one, compared to conventional traps (no escape gaps), those comprising one (57 × 500 mm) or three (each 57 × 200 mm) escape gaps along their sides maintained legal catches of S. verreauxi, but did not significantly affect undersized (<104 mm carapace length; CL) catches; although there were fewer (mean catch reduced by 35%) in the latter traps. In experiment two, three escape gaps all located either on the sides or corners of traps significantly reduced catches of undersized S. verreauxi by up to 82%, with no effect on legal catches, and when catches were pooled between treatments, produced a 50% CL at selection of 102 mm with a selection range of 10 mm. Notwithstanding the inter-experimental differences—which possibly reflected relative catches and density-dependent escape rates—escape gaps should be enforced in recreational traps targeting S. verreauxi as a means for reducing discarding.