Jul 03, 2002 · The crab population at each site was sampled using pitfall traps and three 15-min crab fishches Ashton, 1999, Ashton et al., 2002. The pitfall traps were made from PVC pipe 16 cm in diameter by 20 cm deep. Polypropylene mesh (3 mm mesh size) was attached to the bottom of the trap to allow normal tLIMAal water-level fluctuations.