Hope they stay.....Headed there in 3 days, will be there during the full moon. But won't be disappointed if we do not see them, we were lucky enough to see them on a dive trip to Roatan a few years ago as a total surprise.
different people will tell you different things but my experience on utila has been that whaleshark sightings are most common in the 10 days leading up to the full moon and then start up again a couple of days after the full moon.