Netting and Trawling Seining

SEINING, NETTING AND TRAWLING. From re mote antiquity fish have been taken by spear, line, trap and net.

At the present day nets are by far the most important fishing implements employed, although certain deep water fish (for instance halibut) are still taken mainly by long lines. Fishing nets, although of innumerable kinds, fall naturally into two main groups, namely, stationary nets and nets used in motion. The former group contains the most primitive nets, though nets of great complexity are now included in it ; and the simplest fixed nets, themselves derived probably from dams of rushes or stones so placed as to lead fish in to a "pound" or enclosure, may with some confidence be considered as the ancestors of the great otter trawls now shot and towed daily from powerful steamers on fishing grounds more than a thousand miles from the market they work to supply. The more primitive fixed nets are of far less importance than movable nets (except in the capture of certain particular species), owing to the fact that they are necessarily confined to very shallow water. The main types of movable nets may therefore be treated first.

All nets are constructed in accordance with what is known of the habits of the fish they are designed to capture; and as fishes may be roughly divided into those spending at least the greater part of their lives on or near the sea-bottom and those spending a great portion of their lives near the surface, two lines have been followed in the development of nets, some being designed to work on the bottom, others to work near the surface. The most important nets used in the capture of "demersal" or bottom living fishes are trawls; the most important pelagic nets are drif t-nets. The word trawling was at one time applied to more than one method of fishing, but has, at all events in Europe, now become restricted to the operation of a flattened conical net or trawl, dragged along the sea-bottom. There are two trawls in common use, the beam-trawl and the otter-trawl. They differ in the method adopted for extending the mouth of the net. The original form is the beam-trawl.

The beam-trawl may be described as a flattened conical net whose mouth is kept open when in use by a long beam preferably of elm supported at the ends by iron runners, the trawl-heads.

Trawl-heads are of various shapes, but usually take the form of a loop, the curve being in front and ending in straight bars which meet at a point behind. One of these bars, the "shoe" lies along the sea-bed when the trawl is in use, and is usually of double thickness, in order to withstand wear. A square socket is bolted to the top of the head, to receive the beam, and ring-bolts are fitted at the front of the curve and in the angle of the "heel" for attaching the towing ropes and the "ground rope" to which the lower lip of the net is lashed.

The Net.

The top lip of the net is lashed along the beam, but the ground rope, being much longer than the beam, when the trawl is towed forms a deep curve between the trawl-heads, the centre or "bosom" thus being considerably behind the beam. Ac cordingly, when the fish on the sea-bed are disturbed by the travelling ground rope, the roof of the trawl is above them, and the way of escape has already passed and is moving steadily on: a great number of them therefore ultimately pass over the ground rope into the net. The net narrows gradually until the last few feet are reached : this terminal portion is cylindrical and is called the "cod-end." It is closed by a line rove through the terminal meshes, the "cod-line." The fish taken mostly collect in the cod-end, and as their weight increases friction with the bottom, it is protected by pieces of old netting laced across its under side. The fish not taken from the cod-end are found in the "pockets" the pockets are made by lacing together the upper and under sides of the net. They are wedge shaped, the points lying at the sides of the net, at about the level of the bosom, the broad ends at that of the entrance to the cod-end. At this level the lumen of the net thus is divided into three : a fish enters by the central passage, which is furnished with a valve-like curtain, the "flapper," and then either stays in the cod-end or works back along the sides into the pockets. Some species, particularly soles, are frequently found in the pockets.