In the Chesapeake Bay, catching crabs required skill and knowledge of where they were found, and watermen relied mainly on trotlines and crab pots. In the early 1980s the Bay produced more than half of all crabs harvested in the United States, but by 2000 its share had fallen to 28 percent as catches decreased and North Carolina and the Gulf of Mexico captured more of the market. Until 1943 most watermen used trotlines, made by knotting bait such as eel, chicken necks, and bull lips onto lines up to two-thirds of a mile long, stringing them between marker buoys on the Bay bottom, and pulling them over a roller while scooping up crabs with a dip net. Crab pots, patented in 1928, caught more crabs and were easier to use, trapping crabs continuously after being baited and dropped into the water, but they were not legal in Maryland until 1943 and were initially subject to strict limits, including a maximum of 50 pots and a requirement that a user have been a waterman for two years; by 1960 the limit was 100, in the late 1960s the state removed all limits, and today a typical waterman sets 300 on average. In the 19th century, crabbers down the Bay used scrapes towed by boats to catch peelers and soft-shell crabs, and in the early 20th century these molting crabs were abundant in aquatic grasses close to shore, including Parrish Creek, where they were said to be plentiful enough to pluck from the grasses. Watermen also harvested molting crabs by hauling a seine through the shallows by boat.