THE death of about 200 starfish at South Beach earlier this week has the Fisheries department working to unravel the mystery.

Fisheries received reports that between 100 and 1000 dead starfish washed up at South Beach on Monday and Tuesday, but marine officers said there were less than 200 when they went down to assess the situation.

Samples were collected and sent to the Fish Health Unit for analysis, but the department says results may take some time.

• Dead starfish still litter CY O Connor beach. Photo by Meagan Barrett

Concerned beach-goers on Facebook also reported seeing dead starfish at CY O’Connor and Coogee beaches.

An EG Ocean Science report published in 2012 by T.H Rose, D.A Smale, and G. Botting found it was not unusual for invertebrates like starfish to die in large numbers around Autumn as water temperatures rose, and the Herald noted weekend temperatures before the sightings were a couple of degrees above average.

The death of an estimated 2100 fish, eel and starfish in Cockburn Sound last November was put down to algal blooms cutting off oxygen in the water; although some experts said they couldn’t rule out pollution.

Fisheries says people shouldn’t collect or handle any fish in fish kill areas, should stay out of the water, and report mass fish deaths to the FishWatch 24-hour hotline.