A beluga whale seen living in the River Thames for three months last year has almost certainly headed home, according to the Port of London Authority (PLA).
"Benny the beluga" was first spotted off Gravesend on 25 September and regularly fed in sheltered areas along the Kent stretch of the river.
Crowds gathered on the bank to catch a glimpse of him and local businesses cashed in with Benny souvenirs.
Martin Garside said the last confirmed sighting was just before Christmas.
"We're fairly confident he went early in the new year.
"He didn't leave a thank you card for all the fish he ate," the PLA spokesman said.
There were numerous possible sightings in November and December, with one of the last in the Cliffe area, east of Gravesend.
However, Mr Garside said it would have become increasingly difficult to see if he was still in the Thames during the winter months because he would only surface for three to four seconds, and could easily be confused with a wave during rough weather.
"We did fear something bad had happened, but he would have washed up in that case.
"He almost certainly came in for the fish stocks, but they do move around and change so it's fairly possible he would have swum out with the fish.
"Whales are not stupid and will move if they can't get food."