Interestingly, while tests have been conducted on Yarra fish and turned up low levels of PCB and heavy metals, there is nothing to say that Port Phillip Bay caught fish are any safer, since there are no tests to confirm this to be the case. The industrial pollutants in the Yarra have been washing into Port Phillip Bay for 150 years, so it is probably safe to assume that contaminant levels in fish there are about the same as the Yarra. Also, fish like bream, mullet, mulloway and snapper regularly travel between the bay and the metro rivers. If you catch a bream or Mulloway at St, Kilda or Elwood, for instance, how are you to know whether it has spent most of its life in the Yarra or Maribyrnong? In fact there is no way to know. So if you have eaten fish from the bay, you may well have already eaten fish from the lower Yarra without even knowing it. And likewise, if you catch fish from the bay, it is folly to think that contaminants from the river have not entered the food chain there too.