  The gauge invariant electromagnetic Wigner equation is taken as the basis for
a fluid-like system describing quantum plasmas, derived from the moments of the
gauge invariant Wigner function. The use of the standard, gauge dependent
Wigner function is shown to produce inconsistencies, if a direct correspondence
principle is applied. The propagation of linear transverse waves is considered
and shown to be in agreement with the kinetic theory in the long wavelength
approximation, provided an adequate closure is chosen for the macroscopic
equations. A general recipe to solve the closure problem is suggested.
