I think I might be on the edge of my abilities to give you a good answer. I think he's probably right in that there are extreme tidal currents, not transport currents, and back-and-forth sloshing tidal currents in this very complex area known as the Broughtons.
I think that probably we're looking at about eight or 10 days from hatch to the infective stage. In that time, those animals could have moved quite far from the farm of origin. But I don't think that's an important issue. They're adding to the overall pool of infective stages in the area, and therefore if there is or was a farm contribution, it doesn't have to take place right beside the farm. It could take place downstream or upstream.
Just to repeat something I said earlier, it's quite a fascinating biological mystery how these infective planktonic stages, tiny little things, manage to find their hosts so effectively. They do find them. But when you take a plankton sample and try to sample them from the plankton with a fine mesh net, I think as Brian said in one of his reports, you're looking at one or two larvae in a volume the size of a living room. We don't know quite how they manage to do it, but they do it.