Fishing for Mussels (?)

I caught 2 small boats out in the estuary with one man in each. All I could initialy see was that they each had a very long pole and seems to be poking the bottom . When I got my zoom working I noticed that they had this sort of rake thingy on the end. I can only imaging that they are dragging the bottom for mussels.

spot the opportunity for Frankie Howard impressions in that lot!!!