Are the Wild Young Crabs appearing once you stomp on the hole? I’m not sure if just stomping on the holes advances the requirement for the quest, or not.
‘Stomp on crab holes, which will spawn Wild Young Crabs. Catch them and bring them to Bram Dawnrazer or Anroov, or walk into the rock circle (enclosing the domesticated crabs) while holding one.’
http://wiki.guildwars2.com/wiki/Teach_quaggans_how_to_raise_crabs
