Its a long and boring job mate.......as a friend just drop them off at my place and I will do them for you hehehehe
Seriously, I'd use salt water from where you cauight them, (sometimes i will add a handfull of salt on top of this) .....bring water to boil and place them into the water. After a few minutes they will start to float. I generally allow a further minute or so and them remove them from the boiling water and straight into an icy cold slurry. Lip smacking good.
Shane