How big are your ducks? Are you around often? To some extent hawks won't go for anything bigger than they are. If you provide lots of shelters for your ducks to run to, you may only lose a few. Once the others see 1 of their own taken out, they'll learn to be remarkably wary. This may not be an acceptable option for you. We've kept 3 big goofy Muscovy hens on our pond, with island and shelters, near the house for a year. The back side is predator heavy. In the spring some 4 juvenile hawks circle above screaming. I've seen an owl dive at 'em. The trail cam and prints in the mud indicate a red fox visiting the shoreline now and then.
There was a duck lady across from a restaurant we regularly ate at. Occasionally I'd drop by to talk if I saw her outside. She'd keep 20-30 ducks on her 1-acre pond with trees along the bank. She suggested as long they weren't white; she'd only lose about 1 a year. Last fall she moved to Idaho (from Alabama) leaving her about 25 ducks on her pond. Her relatives in close by homes take care of her property but neglect the ducks. In the past 9 months we've observed the flock tick down to 2.
It's possibly doable, but it's either risk of some acceptable loss, or unacceptably high risk.