If you are new to fishing or just not sure where to fish then yes, fishing will probably turn out to be as fun as watching paint dry. In fact it can be downright frustrating, especially if you try fishing during this winter months in the Swan River anywhere from Heirrison Island near the Causeway, Riverside Drive, Barrack Street Jetty, near the bridge near Millpoint Road all the way to Mosman Bay.
For one, you can forget about catching marine fish such as tailor, herring, trevally, flathead, whiting or maybe even bream during the winter months up until maybe around October. The reason being is most of the Swan River, especially if you are fishing from the shore, is fresh water. Yes, one interesting fact about our Swan River is that there is a seasonal change to the salinity of the river. During the winter months when there is a bit of rain, the flow of the water pretty much prevented most of the sea water from entering the system making the Swan River mostly fresh water.
Another thing that you can be sure to always be around when fishing in those areas is the plague number of blowfish/pufferfish, or what is locally known as the blowie.
I know many of those who fish hate the blowie, but it is not only cruel to leave it to die on the shore when you catch them but it also creates a risk for pets like dogs and cats as they are extremely poisonous and could kill our four legged friends.
So please release them instead of leaving them to die on the shore. Their numbers are naturally controlled by the amount of food available in the river.
But ... all is not lost, there are many good places you can go to fish, one of them is at Fleet street, Fremantle.
You can see the picture by going to Google Street. There is ample parking and also decent public amenities such as toilets. It is also great to be able to spend time out with the family, especially on a nice sunny day.
But anyway go to this link google map and on the map, click the button street view. Then put Fleet Street, Fremantle in the search box next to the image google map Australia and click search map. A map of the area will be seen and just click on Fleet Street on the map and see a 3D view of the area.
You can catch trevally quite easily there by using prawn as bait and a size 4 hook with a running ball sinker heavy enough to chuck the line about 30-40m. Please note however that there is a size and bag limit for trevally in Perth, namely, at least 25cm and maximum of 8 fish per person for silver trevally.
For complete guide please refer to the "Recreational Fishing Guide for West Coast Region" from the department of fisheries.