Other methods effectively used to limit escape of crabs from pots are sloping the funnel entrances upwards, installing separate chambers or parlors to increase retention, or placing triggers, shutters or other non-return devices in the entrances to prevent escape (Thomas, 1956; High, 1976; Miller, 1979a, 1980, 1990). Currently, there are no trigger designs that can be installed on collapsible pots (Wyman, Neptune Marine Products Inc., personal communication).