The website on the link above also has information on duckling/gosling care if you need it.
I released my ducks onto my island when they were 9 weeks old. They stayed on or very close to it for about a 2 weeks untill they started gradually venturing farther out into the pond.
Monty is right, after a short while the ducks will learn to attack the fish pellets. My favorite method of keeping them away is either throwing tennis balls at them or shooting at them with a paintball gun (be sure it is tuned down to below 250 feet per second). They learn quickly to avoid the feed ring when anyone with a good aim is near but move in as soon as you turn your back.
-Scott
