this does digress from Perth Zoo so apologies in advance.
Perhaps a marine rescue centre similar to those in many other parts of Australia (are some around Perth like AQWA does,, this could be a major 'hub' for focused on) - what Kanyana in eastern hill outskirtts of Lesmurdie in Perth does for land based wildlife but for marine animals instead.
But very big (huge in fact, like some of biggest in the world) deep pools and huge tanks of natural flowing seawater, so if medium/small cetaceans, pinnipeds, sea-turtles, sea snakes, sea birds, fish and other marine animas can be rescued legitmately and rehabilitated, and can also be some experience for visitors to see them, it could be a worthwhile not-for-profit venture if a 'Mr Monopoly' sort of wealthy philanthropist(s) would fund the establishment of such a place in south-west WA.
Maybe established in the Fremantle/Rockingham/Mandurah coatal area somewhere. Its not 'competition' for AQWA, but a(nother) legitimate facility about helping marine life in a similar but slightly different (and always more needed) way, rescue-rehabilitate-rewilding marine-sanctuary on the edge of the Indian Ocean.
That was extremely sad what happened to Echo, Mila and Rajah the bottlenose dolphins in 1999 hey.
*is a ''yeah dream on'' idea, but if had big financial backing, would be a very worthwhile thing to exist.