Fish are often caught on shores and in rivers by causing them to pass between converging walls of stakes or basket work, until they enter an enclosure, the floor of which is covered by a net. When the fish have gathered in the enclosure, the net is pulled up. The simplest form of inshore fishery is that for periwinkles, in which they are simply picked off the rock. Mussels live on the sea bottom, on the lower half of the foreshore. They generally attach themselves to a stone by a thread. They are usually collected at low tide by hand or, when submerged, are raked from the bottom. The rake is from 2 to 3 ft. wide, and is furnished with teeth 10 ins. long, the back of the rake being covered with netting. Sometimes the mussels are submerged even at low water and then a short rake is used. Cockles live about an inch or so below the surface of the sand, and maintain a connection with the water above by means of small tunnels in the sand. They occur abundantly in many places between high and low watermark. When the cockles are abundant they are raked out of the sand, the rake being from 10 ins. to 1 ft. wide, with teeth 1 in. long. The cockles are riddled, the small ones being rejected. When the cockles do not exist in such large numbers, they are obtained by means of a “jumbo.” This is essentially a block of wood, 3 or 4 ft. long, and 1 ft. wide, furnished with two upright handles. The jumbo is rocked to and fro on the surface of the sand, with the result that the cockles are gradually worked up to the surface. CHAPTER IV THE HERRING FISHING INDUSTRY Herrings abound in the waters round the coast of Great Britain. Ordinarily they are widely scattered in deep water, but at certain times of the year they come together in shoals in the warmer water near the surface for the purpose of spawning. It is at this time that they are of greatest value for food purposes and, being gathered together in shoals, are most economically caught.