The Department of Conservation is pleading for help from the public, after a sea lion pup was killed on the Otago Peninsula.

The sea lion known as Rua was just 11 months old when her body was discovered at a beach near Portabello on Saturday.

The pup's body has been sent to Massey University's Veterinary, Animal and Biomedical Sciences institute to try and find out how she died.

DOC Coastal Otago operations manager Annie Wallace said both they and the Peninsula residents are gutted.

She said Rua was a healthy female pup, and one they were hoping would join the breeding population within the next four years.

Wallace added that to have one of just 11 pups born on the peninsula shot is just tragic.

Anyone with information is being to contact the Department of Conservation.