While I can't imagine a small amount would hurt (people feed kelp meal to ducks as a supplement), I'd worry about the amount of salt and iodine. That's just me though. I can't find any information on how much iodine is too much for a duck.
Hi I am Michael and I have two twin Muscovy Drakes I have been feeding them cooked shrimp small pieces of course a couple times a week as a treat, and they adore it. When they see me approaching on shrimp days they start a dance that is so cute. So yes you can feed shrimps to your pet ducks Thank you