In certain areas of the western United States and Canada, particularly off the coast of British Columbia, the seine fishing method introduced in the late 1950s and used only in those areas is drum seine fishing. A drum seine uses a horizontally mounted drum to pull and store a net instead of a power block. The net is drawn into a pulley that spans the stern and passes through a spool with an upright pulley. A spool mechanism moves left and right on the stern, allowing the net to be guided and tightly wound onto the drum. Drum Calf has several advantages over Power Block. The net can be retracted very quickly. He on the power block is more than twice as fast and doesn't have to handle the net overhead, which makes the process safer. The most important advantage is that the drum system can be operated by fewer crews. However, the use of calf drums is illegal in Alaska. The combinations of these blocks and advances in hydro-hydraulics, and new large synthetic nets have changed the character of purse seine fishing. The original Puretic power block was powered by an endless cable from the twist head of the winch. Today, power blocks are typically driven by hydraulic pumps driven by the main or auxiliary engines. Their speed, traction, and direction can be controlled remotely. Power block wading requires at least 3 people. Skippers, skiff operators, and cork line stackers. In many operations, the 4th person stacks the leader her line and often the 5th person stacks the web. The Danish seine, sometimes called an anchor seine, consists of a conical net with two long wings and a bag in which the fish gather. A trailing line extends from the wing and is long enough to encircle the area. The Danish Wade resembles a small troll, but the wire chain is much longer and there are no otter planks. A seine boat pulls the warp and net in a circle around the fish. The movement of the warp drives the fish into the central net. Danish seine vessels are usually larger than purse seine vessels but are often accompanied by smaller vessels. Towing lines are often stored on drums or wound onto decks by winders. Colourful buoys anchored as 'markers' serve as fixed points for calf rolling. A power block, usually attached to a jib or slewing crane, pulls the seine. Danish trawling is best suited for (shallow water) bottom fish that are scattered or clustered on or near the seabed. They are used when there is a flat but rough seabed that cannot be crawled on. It is especially useful in northern regions but less useful in tropical to subtropical regions. The net is deployed from a main vessel, a dragnet, or a small support vessel attached at one end to an anchored dun (marker) buoy. A towline is paid out, followed by networking. When the dragnet makes a large circle back to the buoy, the deployment continues with the dragnet and the remaining wing, ending with the remaining towline. This way you can enclose a large area. The dragline is retracted using a rope winder until the collection bag is secured. The Seine method was developed in Denmark.