Hey,
Thanks for the feedback. Unfortunately this is a tough issue to solve, as once the sand crabs 'pop up', there is no way of identifying them as your own. Luckily, this shouldn't happen very often, especially in spots which are more out of the way (e.g. crab claw isle spots). Also, if this does happen, the sand crabs should despawn after around 2 minutes, so this shouldn't significally impact exp/h. If you are finding this happening often, i'd highly recommend picking a spot which is less busy; that way you hopefully won't experience this again.
Cheers
Sure - cooking trial started (let me know if that's not the script you wanted)
Sure - trial activated!
-Apa