Short answer is yes, during winter it's any beach between the flags (the lifesaving flags that is), Cottesloe main beach, between Swanbourne and Floreat if the red flag is displayed at the Swanbourne barracks (you can see it from the beach), south of Cott at Dutchies you need to be a WAKSA member and display your WAKSA tag. I think there is also a section directly in front of Scarborough, just go south 200m to Brighton or north 100m to Contacios. there's also some no go zones at Pelican Point and some safety controls in place at Melville.

Check out kiteboardingwa.org.au/ for beach recommendations and location info.