The metal box scraper can be used for gathering mussels from smooth, vertical surfaces. The data gathered are mostly for qualitative use, but can be quantitative if the area of removal is calculated.
Metal box scraper
A metal box scraper can be constructed from a medium-sized metal box, with the top and bottom removed. Drill holes along the bottom and sew on a mesh net bag using any heavy or nylon thread. (The mesh on the net is effective in the 1/4-to 1/16-in. range.) File one of the top edges of the box to sharpen it and firmly attach a long pole to the other side of the box. Lower the metal scraper box below the surface and scrape firmly so that the mussels become dislodged and fall into the mesh bag if they are attached to the area.