If it had a really rough sort of tail it was most likely a Skate, since there is only really two types of Rays that could be caught around the area you’re fishing, and neither have and bumps etc on their tails. Also I think skates and rays are a different family of fish.
I also went out to Wakanui for just under an hour to fish. After catching a constant supply of dogfish I gave up and headed home. I definitely wont be going surfcasting again any time soon. Might try the Wharf at Timaru or the Pier once the Red cod show up.