The photographer from Ramsgate is the president of marine charity Whale Wise, which has undertaken the research in an area where a port development has been proposed.
“It’s important to know what’s in the area and be able to advocate for the whales now that we know that they’re here year on year,” she told BBC Radio Kent.
Douglas said the experience had been “very emotional”.
The whale song was captured by underwater microphones deployed over the year, with the researchers having an anxious wait to see if anything had been picked up.
“That moment of release and relief when it’s there, I can’t describe,” said Douglas.