Seine/Net

History

Archaeological evidence suggests that humans learned the art of fishing with nets (or seines, which are weighted nets that fold inward to enclose fish) very early in man’s history. Based on large prehistoric mounds of discarded mollusk shells, man’s first attempt at foraging meals from the water involved simply grabbing these creatures (such as clams) from the shallow waters of oceans, lakes, and rivers. However, as any small child standing ankle-deep in a stream can tell you, the reach-and-pluck method is not very effective in capturing more mobile aquatic creatures such as fish or shrimp. Thus, other techniques were developed, such as using nets.

At first nets were small and used exclusively in lakes and rivers, but a number of different factors spurred the development and range of net usage. One was the introduction of boats, which allowed man to venture further and further out into areas of the ocean that were rich with marine life. Another was the development of storage techniques that prevented the need to immediately consume caught fish, such as salting, smoking, drying, and fermentation. These advances, combined with the dietary needs of an expanding population, made it necessary and economically viable to catch fish in large numbers. Collective, large-scale fishing with nets was born.

Examples of the early use of nets for large-scale fishing abound in history. The Black Sea fisheries were an important part of the economies of both ancient Greek and Phoenician cultures, and by the Middle Ages herring was being caught in large numbers in northern Europe. The development of large-scale commercial fishing paralleled the development of industrial technology, with steam ships replacing sailing ships, only to be replaced with more and more powerful internal-combustion engine vessels. And at every stage the catch of these largely net-hauling ships increased dramatically, to the point that the current worldwide catch of fish averages more than 100 million tons per year.

Another major historical advancement in fishing with nets occurred after WWII when man-made fibers such as nylon and polyester began to replace older vegetable or animal fibers that were prone to rotting.

Types of Nets

Most people’s first (and perhaps only) experience with a fishing net is eagerly fumbling a dip net over the side of a boat to prevent the loss of a hooked bass, trout or crappie. But there are several other types of nets and seines employed in fishing throughout the world. The three basic categories of nets are:

1.      Drift nets-These sometimes long (up to 40 miles in length) nets can either drift freely or remain attached to a fishing craft. They are set in the water vertically with floating devices suspending the top and weights holding down the bottom. Often dropped into the water after sunset (so the fish cannot see its presence), they remain drifting all night. Fish become entangled in the net as they try to swim though it, either by a section of twine slipping under their gill cover (in what are called gill nets) or by becoming trapped in pockets between multiple layers of meshing. The nets are then hauled up, either by hand or by hydraulic engines, and the entangled fish are removed from the nets. These types of nets are commonly used to catch salmon, herrings, flatfish, sturgeon, and different shellfish, such as king crabs.

2.      Surrounding nets-These nets do just what their name implies, they encircle or surround the fish so that it cannot escape. There are two main varieties of surrounding nets, the seine and the trawl, with two subgroups of seines, the beach (or drag) and the purse. The beach seines are used right off shore with the fish hauled right up onto the beach. The purse seines are operated from boats in deep waters, usually with one end of the net towed around the school of fish while the other end remains fastened to the main vessel. They have a steel cable that runs through rings at the bottom that is pulled upwards, preventing fish from escaping by diving downwards. They are used primarily for fish that school near the surface and can operate from a single boat or by two vessels. Fish that are commonly caught with purse seines are sardines, cod, mackerel, salmon, tuna, and herring, and more fish are caught worldwide with purse seines than any other method. Trawls are another form of surrounding net that are quite effective in catching large numbers of fish. Pulled behind specialized boats called trawlers, they are large, funnel-shaped nets that trap fish in the rear of their netting. It is attached to the boat by two long cables and near the net’s opening are two boards (called otter boards) that are forced downward and sideways by the force of the water to hold open the net. The older models of trawlers launched and recovered the net from the side of the vessel but most modern trawlers launch it from the stern (back). Trawls can be placed at many different depths, from scraping along the seabed to just below the surface, and catch many species of fish and shrimp. They are second to only the purse seine in total catch world-wide.

3.      Trap nets-Trap nets are stationary nets that are staked at the bottom of bodies of water. Usually cylindrical in shape, they form a labyrinth-like series of chambers that are easy for aquatic life to enter (through funnels) but from which they cannot escape. The catch can then be emptied out by pulling the drawstring that opens the tail of the net. This type of net is popular for catching catfish, salmon, trout, and eels.

Other Methods

Besides the methods listed above, there are a number of other interesting methods for catching fish with nets.

1.      The lift method-This method employs nets with a square metal frame around the four sides with four lift lines running from the frame’s corners to a central point known as the lift rope. The lift net is set into the water and either bait is thrown in the water above it or light is used to attract fish or crustaceans. When the prey swims over it the lift net is pulled up out of the water with the prey inside of it. These nets are great for catching bait such as minnows. This method can also be employed on a grand scale by large, mechanically operated lift nets off of beaches or vessels.

2.      Recovery nets-Recovery nets are long, rectangular nets primarily used to collect fish at hydroelectric dams for mortality studies. The fish are collected in a live box at one end of the net.

3.      Veranda nets-Waters where flying fish and shrimp gather are stirred up, then this specialized net is used to catch them in the air.