Abrolhos coral spawn kills fish

Large schools of dead fish were found dead at Jurien Bay and the Abrolhos Islands last week.

Experts have attributed the death to coral spawns and a resulting lower oxygen level.

Pearl farmer Pia Boschetti said there were large numbers of dead fish in the water at the Abrolhos Islands.

She said there was coral spawn everywhere and that it was caused by the Leeuwin current, which passed through at this time of year.

The Leeuwin current flows southwards near the Western Australian coast and is characterised by a rise in the water temperature.

Ms Boschetti said from the affect on fish stocks, it appeared the water temperature had been warmer than previous years.

“Not to say this is an abnormality or a result of climate change, but just that we don’t have data from previous years to compare it to,” she said.

Department of Fisheries senior fish pathologist Dr Brian Jones said the advent of coral spawning at the Abrolhos Islands had sapped oxygen from the water causing the fish to die.

He said while the water temperatures remained high, the natural phenomena would continue.

“Fish are cold-blooded, so when the water gets either too hot, or too cold, they suffer,” Dr Jones said.

Ms Boschetti said it would be an anxious wait to see if the oysters and pearls in her pearl farms had been affected.

“We have made the decision to put off handling the shell for three to four weeks to allow it to relax in order to avoid losses,” she said.

With the Abrolhos Island rock lobster season opening tomorrow, fishers have been advised to store their catch in appropriate conditions to prevent mortalities.

“Fishers should take precautions against coral spawning by storing their catch in deeper, well flushed water during the spawning period,” Dr Jones said.

There were also reports of a million dead fish in a Southern Californian marina this week.

The unusual event was deemed to be from natural causes, allegedly caused by a lack of oxygen in the water.

JESSICA MILLWARD