An endangered southern resident killer whale known as J17 has been spotted in improved condition several months after researchers feared the worst.

The Center for Whale Research in Washington State says in an update today that the 42-year-old orca was seen swimming with the J Pod in the northern Haro Strait on Friday.

Researchers say her breath was awful but her condition appears to have improved since her last sighting at the beginning of the year, when she was suffering from a condition called peanut head, a sign of starvation in orcas.

They add they remain cautiously optimistic that she will survive.