�We�d love to see any people responsible held to account and prosecuted,� Recfishwest chief executive Andrew Rowland said.
Last Friday, there was no proof the deaths of at least 250 large, breeding snapper, and about 500 whiting, flathead and other species found badly decomposed on Sound beaches were linked to pollution or a human cause.
�And it�s not heavy metals because they generally accumulate over time, and this happened suddenly,� Mr Rowland said.
The public first reported the deaths to Fishwatch at 6.58am on November 19, but strong easterly winds in the days near and after the report may have blown the fish from any source of the kill.
�And all that weekend there were kids playing in Rockingham, and at the other beaches,� Mr Rowland said.
Recfishwest�s website reported no current evidence of algae blooms or disease, the ChemCentre had not identified significant chemicals, and the Department of Environmental Regulation had found no links to industry outfalls, but not all companies had replied.
But a fish examined by the Department of Fisheries had an abnormal liver and kidney.
After the deaths, Kwinana titanium feedstock maker Tronox said it had recently analysed its process, confirmed all its materials were �accounted for�, and there had been no loss of containments.
A spokeswoman for nearby Alcoa said there was nothing to suggest its operations were connected to the fish deaths.