Two headless seals have been found on a beach in South Australia’s Lower Eyre peninsula.

Authorities are investigating the discovery on Thursday of the New Zealand fur seals, an adult and a juvenile, which were washed up on a beach about 3km north of Louth Bay, near Port Lincoln.

The juvenile seal was badly decomposed, a Natural Resources Eyre Peninsula spokeswoman said on Monday.

New Zealand fur seals, native to Australia as well as to their namesake, are a protected species.

The maximum penalty for killing a fur seal is two years’ jail or a $100,000 fine.