fishermen in many parts of the world to keep fishing nets, as well as longlines or droplines afloat. Weights and anchors The Cucuteni–Trypillia culture, BC to 2750 BC in Eastern Europe, created ceramic weights in various shapes and sizes which were used as loom weights when weaving, and also were attached to fishing nets. Despite their ornamental value, dog conches are traditionally used by local fishermen as sinkers for their fishing nets. Production Fishing nets are usually manufactured on industrial looms, though traditional methods are still used where the nets are woven by hand and assembled in home or cottage industries. Environmental impact Fisheries often use large-scale nets that are indiscriminate and catch whatever comes along; sea turtle, dolphin, or shark. Bycatch is a large contributor to sea turtle deaths. Longline, trawl, and gillnet fishing are three types of fishing with the most sea turtle accidents. Deaths occur often because of drowning, where the sea turtle was ensnared and could not come up for air. Cubs of endangered Saimaa ringed seal also drown to fishing nets. Fishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, whales, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, restricting movement, causing starvation, laceration and infection, and, in those that need to return to the surface to breathe, suffocation. Miscellany Divers may become trapped in fishing nets; monofilament is almost invisible underwater. Divers often carry a net cutter. This is a small handheld tool carried by scuba divers to extricate themselves if trapped by a fishing net or fishing line. It has a small sharp blade such as a replaceable scalpel blade inside the small notch. There is a small hole at the other end to for a lanyard to tether the cutter to the diver. Gallery See also Fish trap Fishnet (material) Miraculous catch of fish Notes References Fridman AL and Carrothers PJG (1986) ''Calculations for fishing gear designs" (FAO fishing manual), Fishing News Books. Klust, Gerhard (1982) Netting materials for fishing gear FAO Fishing Manuals, Fishing News Books. . Download PHP (9MB) Prado J and Dremière PY (eds.) (1990) Fisherman's workbook FAO, Rome. . von Brandt A (1984) Fish catching methods of the world Wiley-Blackwell. . External links Basic net design: Gill nets !