Fishing consist of several methods.  You could use the traditional method of a pole and a line with a baited hook at the end or cast a net into the sea from shore and pull it in.  What I'm going to tell you about is the more important methods of large scale commercial fishing.. These activities are carried out in the open sea on good fishing grounds where the waters are not too deep- over 200 meters, in cold waters- where bacteria growth which competes with plankton for food is minimize, in locations where the warm and cold ocean current meets and where there are off shore winds- both bringing nutrient salts needed by the plankton from the seabed to the surface.

Purse-Seining

This is the larger version of casting a net into the sea from the shore.  This method is used to catch pelagic fishes such as mackerel and herring.  The net is used to encircle the fishes, then the fishes which are trapped are sucked onboard with a special fish pump or scooped out with the power operated net.

Drifting

This method is also used to catch pelagic fishes.  The fishes are enwited by their own gills in the mesh of the net.

Trawling

This efficient method is used for catching demersal fishes like cod, plaice and sole, near the smooth seabed.  Floats at the top and weights at the bottom keeps the mouth of the trawl net open.  The sides are kept open by the 'otter boards'.  The net is towed along the seabed  by a vessel called a trawler.

Long-Lining

This is another method to catch demersal fishes on a rough seabed which may damage the trawl net.  A long-line, consisting of up to 2000 baited hooks suspended from the it, is buoyed.  The line is then hauled up by a team of fishermen.

With the advancement of technology, man is now affecting the eco-system of the fishes.   Find out the ways man affects it.