A mother sea lion's been found shot dead - just 100 metres from where her pup was found killed last month - in the Southland's Caitlins

A local found the decomposing body on Tuesday, riddled with about 50 shotgun pellets.

DOC's Aaron Fleming says the shot will be forensically tested for a match with pellets found in her pup.

Only seven pups were born in the Southland sealion population this year, with only 12 breeding females in the local area.

The NZ Sea Lion Trust is offering a 6000 dollar reward for information leading to a successful prosecution.