Authorities in Western Australia are working to find out why more than 1,000 dead fish washed ashore on a beach south of Perth on Wednesday morning.
Pictures show the Rockingham foreshore littered with the fish on a 500-metre stretch of beach, around the Palm Beach and Rockingham Yacht Club jetties.
Brad Tilley from WA's Department of Primary Industries and Regional Development (DPIRD) said only one species of fish, the scaly mackerel, was killed in the mysterious event.
"The numbers of fish were estimated to be more than a thousand," he said.
"A report from the public on site was that dead fish could be observed in the shallows up to a kilometre towards the Kwinana bulk cargo terminal."
Mr Tilley said tests would now be undertaken to determine the cause of the deaths.
"The fish samples have been delivered to DPIRD Aquatic Diagnostics, and the water samples to the Department of Water and Environment Regulation's phytoplankton ecology unit."
Other fish and dolphins unaffected
Witnesses said other fish were swimming freely around the dead mackerel.
"What was quite strange to me was it was this one particular type of fish that was washed up," said Johann Maree, who was at the beach this morning.
"The dolphins actually came past and turned around and swam back up the shoreline, everything else seemed fine."
Mr Maree said a local tour boat arrived while he was down there and staff on board advised him the fish kill was not a normal occurrence.
"It looked like clear water, there were actually lots of schools of small fish as well, but the water was dead still," Mr Maree said.
"Not even a funny smell, everything seemed fairly normal except for the dead fish."
DPIRD said fisheries officers would continue to monitor the area, and any additional species, in case of further fish deaths.
