  We present the high-energy-neutrino follow-up observations of the first
gravitational wave transient GW150914 observed by the Advanced LIGO detectors
on Sept. 14th, 2015. We search for coincident neutrino candidates within the
data recorded by the IceCube and ANTARES neutrino detectors. A possible joint
detection could be used in targeted electromagnetic follow-up observations,
given the significantly better angular resolution of neutrino events compared
to gravitational waves. We find no neutrino candidates in both temporal and
spatial coincidence with the gravitational wave event. Within 500 s of the
gravitational wave event, the number of neutrino candidates detected by IceCube
and ANTARES were three and zero, respectively. This is consistent with the
expected atmospheric background, and none of the neutrino candidates were
directionally coincident with GW150914. We use this non-detection to constrain
neutrino emission from the gravitational-wave event.
