DEATH after mating or recent rough weather may be to blame for many dead starfish on Cottesloe Beach being investigating by the Department of Fisheries since last Thursday.
“Some aquatic animals perish when they are reproductively active and this is part of their natural lifecycle,” a department spokesman said.
“Also, animals such as these can be washed ashore when swells increase or change and when there are storms.”
Perth had high winds and strong swells four days before about 60 of the starfish were reported on the beach.
Fisheries officers collected samples, but saw less than 30 dead starfish, and no other dead aquatic animals.
The spokesman said the starfish appeared to be the sand sea star found in WA and the Whitsunday Islands in Queensland, and the deaths would continue to be monitored.
Fish kills should be reported to FishWatch on 1800 815 507.