Purse-seine Fishing
Purse-Seine Fishing © John Surrick, Chesapeake Bay Foundation, Marine Photobank.

The purse-seine net is used to catch dense, mobile aggregations of pelagic fish which shoal in mid-water or near the surface (such as sardines, mackerel, anchovies, herring and some species of tuna). Aggregations of fish are surrounded by a large net, with an upper line (head-rope) attached to floats ensuring the net remains on the surface. Rings along the bottom edge of the net, through which a cable (the purse-line) extends, allow the fishermen to fully enclose the fish, preventing them from escaping downwards. After closure of the net by hauling in the purse-line, the net is slowly hauled aboard using a power block. As space within the net is gradually reduced the captured fish become more densely packed and are then taken aboard using a pumping system. Depending on the fishery, a purse-seine net can be several kilometres long and more than 200m deep. 

The primary environmental concern surrounding purse seine fishing is the pressure the use of large nets can place on fish stocks. Incidental catch of non-target species (i.e. bycatch) is also of concern. Sharks are not generally targeted in purse-seine fisheries, although due to the non-selective nature of the gear, pelagic sharks can be taken as bycatch.

Related Links:

Fisheries and Aquaculture Organisation (FAO) website