What are drift nets, drift fishing

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Drift fishing is fishing carried out by drifters - fishing vessels. The ship drifts with the current and wind along with a very long network, the so-called drifter order, or floating networks, making up a single system. The length of networks can reach 50 km. These nets catch moving fish. The need for drift nets arose in connection with the need to catch certain types of fish that are kept sparsely. In this way, they fish for tuna, salmon, mackerel and herring.

Features of networks

Drift (or smooth) nets are a net cloth, which the fish does not regard as an obstacle, therefore it pulls the meshes tightly, tightly entangled in them without the possibility of escaping. Rectangular separate nets 10-12 m high and 30 m long are interconnected in a single drifter order, the basis of which can be a leader rope, and buoys and floats support this system at a given depth. Drift nets are used for industrial fishing from drifters.

Materials used

Catchability of gear depends on manyfactors, including the material and thickness of the thread, the size of the cells, coloring, landing of the fabric on the rebounds. If vegetable threads were previously used, including cotton from twisted thread, now more durable and catchy fishing nets of nylon, as well as nylon, amylan and similar ones made of artificial fibers are most often used.

Fishing nets made of monofilament (fishing line), the so-called vein nets, demonstrate high efficiency. The main advantage of these gears is their transparency. Even in daylight, catchability in clear water is very high, while well-colored nets made of other materials can scare away fish. In addition, they have a higher rigidity than twisted threads, which keeps the meshes straightened and prevents the nets from becoming tangled and dirty. Although the rigidity makes them a little more difficult to work with and increases the volume, requiring more space on the deck.

Constructive types of nets

According to their structure, fishing gear can be single-wall gill, double-walled or three-walled. The last two species are also called "putanki". The most effective are three-walled fishing nets, consisting of three net cloths. Outside, there are large-mesh canvases called cut (ryazhy, cut), and in the middle there is a smaller particle (del). All three canvases are planted on the same rebounds, but the part has a large length and is located between the outer layers with significant slack. Passing through the cut, the fish gets entangled in the particle, falling into the net bag. Double-walled ones consist of two canvases with different mesh sizes and are effective when it is known exactly which side the fish is coming from.

For drift fishing, kapron fishing nets made of monofilament or nylon monofilament are most often used. Rebounds are also taken kapron. Three-wall smooth nets are the most effective.

Types of construction of drifter orders

Networks can be connected to each other in different ways. Three main types can be distinguished: simple, with an upper or lower leader. Small, simple formations can be used in the coastal strip, but on the high seas, a more reliable design is needed, therefore formations with leaders are used to ensure the integrity of the order and increase reliability.

Easy order

For a small drifter order, sometimes several separate networks are simply connected in series with each other by lower and upper lugs. This is how a simple drifter order is obtained. It is used in lakes and sea coastal areas by small boats. Most often, it includes only 15-20 networks, but when they take more, they generally do not exceed 1-1.5 km.

Buoys are attached to the buoy lines, which keep order afloat. The desired horizon is set by adjusting the length of the lines. From below, the net is weighted by placing the load in the lower selection. On both sides of the order there are also ottuga. They are attached in front with a stop end - a rope that goes directly to the ship, and behindconnected to the beacon end - a rope attached to the beacon. This beacon (lantern or pennant attached to a weighted buoy) shows where order ends.

It is easy to organize such an order, but it is not suitable for long networks, and even more so for use on the high seas. The tension of the nets during the drift is very high, therefore, with such an organization, order can be torn off the ship or it will be destroyed.

Appointment of leader

To significantly reduce the risk of breakage, the so-called leader is used - a thick rope to which order is attached along the entire length. Fishing involves the integration of up to 100-150 nets. The drift tension is on the reliable leader, not on the nets themselves. Separate nets are attached not only to each other, but also to the leader, which also strengthens the structure.

The leader itself can be divided into three parts: the leader itself, the stop (parking) end for connecting to the vessel and the beacon end for attaching the beacon. It turns out that it is the leader that is attached to the ship, which holds the net. The parking end is made as strong as possible. Its length can reach 200-500 m, which depends not only on the depth to which the order sinks, but also on the state of the sea and the strength of the wind.

When selecting nets, the thrust is carried out for the leader. This allows you to mechanize the production process. In addition, automatic devices are used that control the tension of the leader, if necessary, bleed it to reduce excess tension.

Features of the leader

BDepending on the fishing technique and the type of vessel itself, the required length of streamer lines is set to make it convenient to choose drift nets: the leader is selected through the malgoger, and the net must reach a certain place on board, the streamers should just provide the right distance. On small vessels, it is only 1.5-2 meters, and on large vessels it can reach 10 m.

Due to the fact that the tension of the leader decreases with distance from the vessel to the lighthouse, the leader is often made composite, reducing the thickness of the rope. Additionally, this reduces the cost of the order and reduces the weight of the order. But in order to avoid sagging towards the end of the network due to a decrease in tension, sometimes floating anchors are added to the lighthouse or the distances between the buoys are changed.

Order with bottom leader

To organize order with the lower leader, separate drift nets are connected into a single whole also for the upper and lower lugs, but at the same time, the leader goes under the nets throughout the order. It is connected to the nets by leader lines with the help of quick-untying knots. The order is kept afloat by buoys, which are attached with streamer lines at the junctions of the nets or to the upper selection. The depth of immersion of the nets depends on the length of the lines. Additional weights below are not required, since the leader himself serves as a load, stretching the nets.

Apply this order for shallow depths, immersing nets at 30-40 m. It is convenient to operate. For marking and when choosing an order, you have to work only with leader lines, without the hassle of sinkers.

Top orderleader

If it is necessary to fish at great depths, the order with the upper leader is more often used. In this case, it passes over the networks. Buoy snoods are attached to it, sometimes reaching a length of more than a hundred meters. Between themselves, the buoys are connected by a conductor rope for ease of sampling. The leader lines are connected to the top line or the lugs of the nets. On the lower rebounds, you have to add loading in the form of cast-iron sinkers.

Working with this order is more difficult than using the lower leader, since it is necessary to organize the loading, and the buoy guide requires additional attention. However, such drift-net fishing is a must when fishing at great depths. In this case, the lower leader can, when hauling or even pulling, wind the nets around itself, therefore it is not used. In addition to the advantages of the upper leader, you can also add damping of jerks from buoys, so the nets will be calmer. The downside is the risk of separation of the buoy itself in large waves.

In fact, different depth orders are sometimes used to determine exactly where this or that fish is located. To do this, often create combined types of orders.

Harm from the use of drifter nets

In some regions commercial fishing with drift nets is prohibited. So, it is not used in the North Pacific Ocean in order to preserve the stocks of some fish species. Large-scale drift net fishing is prohibited by the UN General Assembly in the open waters of the oceans. Scientific fishing is allowed with such nets, but thisopportunity is often misused. There is no complete ban on drift-net fishing yet, but reduced deadlines and some restrictions on this type of fishing have already been established.

Drift nets often end up with marine mammals and seabirds, which are killed in the process. The numbers are simply daunting. So, only in the Far East in the Russian economic zone, more than 100 thousand birds and 2.5 thousand mammals die annually because of this. And the salmon populations themselves are declining.

Another serious threat is the attitude of the fishermen themselves. Often sockeye salmon is caught this way - the most valuable of salmon, while the rest of the fish, including sockeye salmon juveniles, other salmon species, pink salmon and chum salmon, are simply thrown overboard. Such re-grading destroys a huge number of fish aimlessly, which is a violation of fishing rules.