Fish them slower than you would a spinner for kahawai and give them a bit of action with a few stops and jiggles. You will find that blue cod will eat Gulp softbait like an ordinary bait. The only problem I have had with them is the habit they have of holding on to the tail till you bring them in and then spitting it after you get a look at them. I have found 4 and 5ins baits in natural colours to work well. Try New Penny and Watermelon colours in the Gulp range.