  It is shown that, in the presence of a moderately strong C_4 symmetry
breaking (which could be produced either by lattice orthorhombicity or the
presence of an electron nematic phase), a weak, period 4, unidirectional charge
density wave ("charge stripe") order can reconstruct the Fermi surface of a
typical hole-doped cuprate to produce a small electron pocket. This form of
charge density wave order is consistent with that adduced from recent high
field NMR experiments in YBCO. The Fermi pocket has an area and effective mass
which is a rough caricature of those seen in recent high field quantum
oscillation experiments.
