Lightning flashes result from charge separation caused by colliding ice particles. They are particularly prevalent in continental convection but also occur over oceans, where their frequency correlates with maritime shipping emissions. In 2020, the International Maritime Organization (IMO) restricted ship fuels to much lower sulfur concentrations. We use this abrupt perturbation to study the response of oceanic lightning to aerosol, cloud, and convective properties. In principle, a reduction in aerosols should lead to a decrease in lightning over shiptracks relative to unpolluted regions. However, we find only one of the two investigated shipping lanes displays this sensitivity. Using the spatiotemporal sensitivity of lightning flash rate to hydrometeor size, we estimate the sensitivity of cloud water path to cloud number concentration. The results offers insights into both the role of aerosols in generating oceanic lightning and the mechanisms of aerosol-cloud interactions in deep convection.