a giant net that turns the ocean into a drawstring bag, closing beneath the fish.
means a wall of netting that encircles a school of fish, then cinches shut at the bottom like a drawstring purse so nothing swims out underneath.
from named for the action, not the object: after the net rings the school, a cable through rings along the bottom pulls closed exactly like tightening a coin purse, a technique refined by new england and mediterranean fishers in the 1800s and mechanized hard in the 20th century.
eastern pacific tuna fishery — purse seines here once killed hundreds of thousands of dolphins yearly before 1990s reforms.
norwegian herring seiners — use massive purse seines to land herring by the thousand tons each season.
fad fishing — floating fish aggregating devices lure schools straight into purse seine range.