Fishing trawling is a commercial fishing method in which a large net is dragged along the seafloor to catch fish. It is one of the most common methods used by commercial fishermen to harvest fish, and is especially effective for catching bottom-dwelling species such as cod, haddock, and flounder. Trawling is also used to catch shrimp, squid, and other types of seafood. The net is usually towed behind a boat, and the catch is then brought back to shore for processing and sale.