Eagle wings have several adaptations for the eagle's fishing life.
Shape: Long, broad wings like an eagle's take a lot of energy to flap, but are wonderful for riding effortlessly on thermals. Like all birds, eagles must minimize the energy they need for flight over long distances.
"Fingers" or slotted primaries: This provides more lift with less weight--important for birds that ride thermals
Size: Eagle wings are big enough to carry the weight of the eagle PLUS the weight of a fairly large fish. And if the fish is too heavy to pull out of the water, the eagle can use its long wings to paddle to shore!
Color: The pigment that makes an eagle's wing feathers black also makes those feathers stronger, which is important when feathers hit the water while fishing and when flying.

http://www.learner.org/jnorth/images/graphics/d-e/EagleAdaptationsWing.gif