  We have performed three searches for high-frequency signals in the solar
neutrino flux measured by the Sudbury Neutrino Observatory (SNO), motivated by
the possibility that solar $g$-mode oscillations could affect the production or
propagation of solar $^8$B neutrinos. The first search looked for any
significant peak in the frequency range 1/day to 144/day, with a sensitivity to
sinusoidal signals with amplitudes of 12% or greater. The second search focused
on regions in which $g$-mode signals have been claimed by experiments aboard
the SoHO satellite, and was sensitive to signals with amplitudes of 10% or
greater. The third search looked for extra power across the entire frequency
band. No statistically significant signal was detected in any of the three
searches.
