An earlier study examined the effects of exposure to seismic air guns on the hearing of three species of fish from the Mackenzie River Delta in Northern Canada [Popper et al. (2005). "Effects of exposure to seismic airgun use on hearing of three fish species," J. Acoust. Soc. Am. 117, 3958-3971]. The sound pressure levels to which the fishes were exposed were a mean received level of 205-209 dB re 1 microPa (peak) per shot and an approximate received mean SEL of 176-180 dB re 1 microPa(2) s per shot. In this report, the same animals were examined to determine whether there were effects on the sensory cells of the inner ear as a result of the seismic exposure. No damage was found to the ears of the fishes exposed to seismic sounds despite the fact that two of the species, adult northern pike and lake chub, had shown a temporary threshold shift in hearing studies.