Yes pelicans swallow the fish alive when they eat the fish.
The pelican swallows the live fish whole without chewing the fish or breaking the fish down and the whole fish goes into the pelicans stomach.
A pelicans throat pouch can hold more fish than the pelicans stomach can so the fish is swallowed whole by the pelican.
Most Pelicans eat around 4 to 5 lbs of fish per day depending on how hungry they are.
So that could be that the Pelican eats 1 fish that weighs 4 lbs or they may eat 2 fish that weighs less than 4 lbs.
The smaller the fish the more fish the Pelican will eat to get it's fill up to 4 to 5 lbs of fish per day.
If the pelican can get a larger fish to eat then they will get full sooner and will not need to eat anymore fish until the next day or when they become hungry.
Pelicans eat fish by moving their heads forward to remove excess water and then they swallow the fish.
The Pelican is a very social bird and lives in large colonies composed of several hundreds of pelican birds.