Thousands of dead fish have washed up in the area in recent weeks but authorities have yet to determine what caused the deaths. DPAW officers took the penguin to Perth Zoo where staff performed an autopsy.
Senior wildlife officer Rick Dawson said preliminary results indicated the penguin's death was a natural occurrence. "It's probably a normal event, one of the young [penguins] that's fledged from the Penguin Island area or Garden Island and hasn't been able to make it, and as a result starved," he said."Unfortunately it's been dead for a fair few days so although it looked in tact on the outside, it was actually quite decaying inside."
"The chances of us getting meaningful results from the inside of the penguin, as a result of what it may have eaten, are quite remote."
Photos of the penguin have been shared widely on social media. The penguin weighed 550 grams, which is about half the average weight of one kilo for a bird of its age.
Mr Dawson said it was common for juvenile penguins and other wildlife such as pelicans not to survive their first year. "Those that have the skills to be able to hunt and survive in the wild do and those that don't unfortunately perish," he said. Mr Dawson said no adults penguins had washed up dead in the area.
The Department of Fisheries is continuing to investigate what caused the fish kill but said tests to date pointed to an, as yet, unknown natural event. The public is still being encouraged to report anything unusual to authorities.