As a fisherman with a science background having worked as an analyst at CSIRO as part of a heavy metals in fresh water study, the studies of the Dioxin contamination were of interest to me.
Many years ago I found and had a look at the papers on which recommendations were based and to me the numbers of samples and the range of results were only borderline statistically valid. The sample sizes of fishes tested were small and the result range varied greatly for each type of fish.
Further, their only survey seemed to be a one off event in that year (I think 2004?) rather than a regular sample program over the course of a year or years which may have better included fishes movements.
I think I recall another study in maybe 2017 that was done that gave similar results to 2004 for 20 fish of 20 species….. again think it was a single event study.
Do I eat fish from West of the bridge, yes I do. However I’m primarily a Luderick fisherman and they’re mainly vego’s as well as being a species that migrate in and out of estuaries for spawning.
Would I eat bream or flatties from further upstream, possibly not.
In my mind the ‘Harbour Bridge’ demarcation point was used cos it’s a bloody obvious spot, rather than for any science based reason.
Anyway, that’s just my 2c worth everyone needs to make their own decisions on whether they eat fish from Sydney Harbour.