Three Australian fisherman have been captured clinging on to a chilly bin after their boat capsized off the south coast of Western Australia.

ABC have reported authorities say without an EPIRB (an emergency beacon), the men may have died at sea.

Friends of the men reportedly reached out to authorities, saying the men could be in trouble because they were due to return home but hadn't yet.

Sea rescue coordinator Chris Johns told ABC without the EPIRB and being alerted to the situation by the men's friends, the rescue team would have had "no idea" where to begin their search.

"In seas like this at the moment, it would be really difficult," he said.