catches as the 8- and 10-mm treatments may have elicited much of the required tactile stimuli not just from the 4-mm chains, but potentially a hydrodynamic influence of the floats. More specifically, the flow of water around the floats would have meant at least some was displaced downwards which, although speculative,might have stimulated school prawns. The same theory supports using angled cups on the leading edge of dredges to displace water and evoke an escape response among great scallops (Pecten max-imus) described by Shepard etal. (2009). Assuming comparable effects, any reduction in the size of floats in the soft-brush ground gear might require a concomitant focus of water displacement.