A vertical net curtain is used to surround the school of fish, the bottom of which is then drawn together to enclose the fish, rather like tightening the cords of a drawstring purse. Purse-seine fishing in open water is generally considered to be an efficient form of fishing. It has no contact with the seabed and can have low levels of bycatch (accidental catch of unwanted species).”  Unless you use it incorrectly. Why would you ever use anything incorrectly on purpose. That is so odd to me.