Yeah there is some massive rays in Caroline bay saw one in the harbour last year would have been at least 60-70kg. Havent really tryed hooking them though as landing them on the rocks would be kinda hard. You would have to fish off the beach.
And yes finding good berley/bait in Timaru is dam hard all you can buy at supermarkets is squid. I have seen bonito at one Fishing shop but it was way to expensive.