Many thanks for your comments. At 300mm the 70-300VR's max aperture is 5.6; the shot was made at f9.0. At the latter as well as at f10 my lens is very sharp at 300mm (IMO). Your statement regarding sharpness and detail is a problem I've always encountered with the "wet" turtle; can't explain it.
Blown highlights, yes; low in contrast??
Thanks a lot for you time and comments,
Jacobo