  We introduce an operational discord-type measure for quantifying nonclassical
correlations in bipartite Gaussian states based on using Gaussian measurements.
We refer to this measure as operational Gaussian discord (OGD). It is defined
as the difference between the entropies of two conditional probability
distributions associated to one subsystem, which are obtained by performing
optimal local and joint Gaussian measurements. We demonstrate the operational
significance of this measure in terms of a Gaussian quantum protocol for
extracting maximal information about an encoded classical signal. As examples,
we calculate OGD for several Gaussian states in the standard form.
