I'm willing to bet a skilled EWO operator will find debris before the eye of an observer will.
EWO? I'm assuming you mean an EO operator?
You'd think that EO would be able to pick up debris first, but it rarely happens like that. Using EO is like looking down a drinking straw, it's very good for seeing large objects that are far away, once you are queued on by either Radar or AIS. Once acquired, the object can be held in view to the on top. Even using the wider fields of view it is very difficult to acquire smaller objects, observers usually see the smaller objects first, either on the flight deck or in the observer stations. EO will be used for the search, as it is an extra set of eyes, but the MK1 eyeball is hard to beat.