Shellfish traps don't produce enough and eat the shellfish

So i put out a shellfish trap and i come back to it several hours later. (Irl hours) And the fish traps work fine. I look in the shellfish traps and 2 are empty. One and 2 shrimp in it and one has lobster in it and when i close it and open it back up the lobster is gone. It had a lot of time left on it but it was just gone.

Shellfish traps suck.