There is no such thing as involuntary lockup on a raptors foot,, any
raptor.
The mechanism is the same for any bird in that in the hallux longus
tendon there is a ratchet that holds the tallons closed as long as the
leg is bent, and the tendon is being pulled,this is the reason that
birds do not fall of their perch when they roost,also sitting on one
foot increases the pressure on the tendon increasing lock,and
relaxing the muscles, the pressure is proportional to the degree of
bend. The bird simply has to straighten the leg for the "lock" to
release the toes can be closed and opend by the extendor muscle on
the front fo the leg. So "lockup" is a mental attitude and not
physical I believe. Raptors are killers/preditors. and hunting is
very expensive in energy costs so they mean to hang on to the catch.
Birds catching fish too heavy for a lift, might swim or bounce the
fish ashore, if this is too far out then the bird might die from
exhausion, In deep water a fish can go down and this should let the
bird straighten its leg and release.
In shallow water, possibly a fish cant go anywhere and the Osprey
might hang on till its exhausted.
Not too sure of the baiting story though they are certainly not shy
and do get quite close to human habitation,
Finally in Alan poole book` Ospreys` , there is a picture , actually
a good picture of a bird taking a lure in 1914 (Staten Island)
Hope this helps
http://www.birdforum.net/showthread.php?t=33000&highlight=carron+valley+osprey