In a bowl combine together the garlic, pepper, soy sauce, orange juice, tomato ketchup, chopped parsley and lemon juice.
Take the shark steaks and place them in a shallow baking dish and pour the sauce you have just made over them.
It is important that you turn the steaks over to ensure that all sides of them are coated in the sauce, which you are going to be marinating them in.
Now cover the dish and place in the refrigerator for 2 hours.
When it comes time to cook the shark steaks make sure that the grill on the barbecue has been lightly oiled first to prevent them from sticking to the surface.
As soon as the barbecue has heated up remove the steaks from the marinate and place them on the grill keeping any left over marinate in the dish for use later.
Grill the shark steaks over a high heat for 6 minutes on each side or until when tested with a fork the fish flakes easily.
Throughout the time the shark steaks are cooking make sure that you baste them regularly with the remainder of the sauce you marinated them in earlier.