Wildlife officials are investigating a suspected dog attack in Tasmania, after 58 penguins were found mauled to death.

A member of the public alerted rangers to the dozens of penguin bodies strewn across a beach on the north coast of Australia's island state.

This is the second dog attack in months on the little penguins - the smallest penguin species - according to reports.

Authorities said dog owners must take responsibility for their pets and earlier warned of hefty fines.

"We would like to remind dog owners of the need to take responsibility for their animals at all times as dogs have the capacity to do a lot of damage to penguin colonies in a short period of time," Tasmania's department of parks, water and environment said in a statement.

It said all reports of alleged unlawful harming of wildlife would be taken "extremely seriously" and encouraged anyone with information to come forward.

According to a local wildlife expert, the birds attacked earlier this week were returning to their nests for the start of breeding season.

"This will have a catastrophic impact on the colony," BirdLife Tasmania convenor Eric Woehler told the Australian Associated Press. "It's going to take a long time, years, for those breeding birds to be replaced."

In June, a dozen of little penguins - locally called fairy penguins - were found killed in an apparent dog attack on a nearby beach at the Low Head Conservation Area.

Little penguins in the wild grow up to around 30cm (12inch) in height, and live to around six years. They are not a threatened species but are protected under wildlife legalisation.