  OH maser emission at 1.67 GHz is known to be associated with regions of
intense star formation within ULIRGs. As these galaxies are formed through
violent mergers, studying the co-moving density of OH maser galaxies across
cosmic time will allow the merger rate of the Universe to be determined in an
independent way. This merger rate is an important parameter in galaxy formation
and evolution scenarios. The sensitivity, wide field of view and spectral
coverage of both APERTIF on the WSRT and ASKAP will allow for the first time
all-sky blind surveys for OH maser galaxies to be carried out to redshift 1.4.
We describe the prospects for such surveys, including the expected number of OH
maser galaxies that will be discovered, and what limits can be placed on the OH
maser luminosity function, and hence the merger rate out to redshift 1.4 with
various survey strategies.
