The arms are hinged to the rock staff and are kept in position while fishing with a wooden spreader called the headboard.
Fishermen wade out at low tide with lave nets on their shoulders to the fishing grounds, with the water up to their waists.
The last lave net fishermen in Wales promote the fishery as a tourist attraction at Black Rock, Portskewett, with the aim of maintaining its history and tradition.
Demonstrations of lave net fishing can be watched on certain days from the picnic site at Black Rock.
In the 1990s the fishery declined because the fishing stations silted up, claimed by the fishermen to be a result of slower tides caused by the construction of the Second Severn Crossing.