Puzzled by Army medals for Navy sub crew in WW2

[DeepSix]

Don't know where else to ask this, but this seems a somewhat logical place.

In Silent Victory, Blair says that Mike Fenno and Trout were assigned to a special mission to Corregidor shortly before that island fell to the Japanese. Upon arrival, Trout needed ballast, and the Filipinos needed to evacuate gold and silver. Trout carted a large amount of gold and silver back to Pearl Harbor - as ballast! - and then Blair says that Fenno was awarded the *Army* DSC and his crew was awarded the *Army* Silver Star.

I'm puzzled. Why Army medals instead of Navy medals?

Thanks.