I know a guy who does quite a bit of trolling [I haven’t done it myself] and he thought the salmon might be spooked by the bright yellow paravane, he uses a downrigger to get his down[or a darker couloured paravame?], he also uses jelly lures, they are pretty realistic
Because the salmon have yet to enter fresh water they will still be feeding, so a lure that represents what its feeding on would be the go, e.g. the common sprat is most likely atm, I have seen tonnes of them down at the wharf so somthing that imitates one of them would be the go I reckon
And go down to elios gun shop in south Dunedin, its left along King Edward street from National bank, it is open from 9am-till 5:30pm weekdays, and 10am-1pm on saturday, closed on Sunday.
The guys down there will be sure to help you out.