During an investigation on the effects of bottom trawling, we found that otter boards which keep nets open bury surface sediment at a few centimeters of sediment depth. This is also done by animals living in the sediment (bioturbation), a process that is considered very important for sediment ecosystem integrity. We try to differentiate between the two and estimate that natural bioturbation is much more likely than otter board sediment reversal in our investigation area.