Technology of Fishing Methods PDF

Faculty of Fisheries and Fisheries Technology Aswan University Technology of Fishing Methods By : Dr / Ola AbdElHady Lecturer of fishing methods Faculty of Fisheries and Fish Technolo...

Faculty of Fisheries and Fisheries Technology Aswan University Technology of Fishing Methods By : Dr / Ola AbdElHady Lecturer of fishing methods Faculty of Fisheries and Fish Technology Aswan University  What the goal of studying fisheries science? We note that the global exploitation of fish resources is constantly increasing, as the catch increased from 19 to 92 million tons in the period from 1950 to 2024, and in the Mediterranean fishery in Egypt, production increased from 40 thousand tons in 1991 to about 84 thousand tons in 2024, meaning that fish production doubled in just 17 years. This remarkable progress may have its drawbacks, as the increase in the catch was at the expense of fish groups that almost disappeared or perhaps disappeared one after the other from some water bodies, leaving collapsed fish groups that are no longer able to appear in the catch again due to many wrong practices in fisheries and the emergence of many internationally prohibited fishing crafts. Because fisheries are a living, exploited state, they are renewable resources. The exploitation of fisheries in an unfair manner, especially since they are the common property of many countries, and in many cases the fisheries are available without controls and without specifying fishing licenses, which leads to the unfair biological and economic exploitation of these fisheries. Some fisheries may continue for a long time under the maximum exploitation level, especially inland fisheries, due to several reasons, including primitive fishing methods, a shortage of fishing equipment, and the lack of distribution markets, etc. However, in recent years, aquatic life has become an important source of protein in many countries, and thus fisheries in these countries have clearly suffered from overfishing and are in dire need of reorganizing fishing operations. Therefore, the goal of studying fisheries science is to identify fish stocks and those available for fishing while maintaining the catch on an ongoing basis, as well as to shed light on the current status of fisheries and the technology used in fishing, whether safe or harmful, and to develop appropriate solutions and policies for managing and organizing fisheries. Fisheries science alone cannot treat all these cases, however, it provides optimal management solutions to restore fish stocks to their natural state. Stages of development of the fisheries industry : Although the fishing profession is one of the ancient professions and is one of the important processes for fish production and fishing methods differ according to the fishing areas and the depths of the water in which they work, it did not become an industry until the beginning of the nineteenth century after going through three important steps: 1- Mechanization of fisheries where diesel was used as a driving force by English fishermen, and thus fishing boats became more capable of navigating the high seas. This also helped in the use of winches to pull nets and travel long distances with trawling nets and move freely without relying on the strength and direction of the wind. Diesel power is considered the beginning of a huge industry represented by marine fisheries. The fishing vessel industry has also become more advanced and can store huge quantities of fuel sufficient for several days in the catch. In many of these cases, effective fuel savings can be achieved by staying longer in the fishing area, especially when a large part of the day is wasted moving to and from the fisheries. For example, if trips could be completed in two days instead of one, the catch over those two days would be spent on fuel on one return trip instead of two. This would effectively reduce the cost of travel to and from the fishing grounds per kilogram of fish caught by up to 50 percent. On-board storage and preservation of fish is an important development in fisheries. In small-scale fisheries, the trend is to restrict the length of a fishing trip to a single day, often due to a lack of on- board storage facilities or to long-term stable patterns that are not typical of large fishing vessels. However, there are often serious obstacles that make increasing the autonomy of the vessel extremely difficult, especially extending fishing trips beyond a single day. The vessel always needs an isolated holding area, and the selling price of the fish must be able to justify the additional investment in the holding area and the daily cost of ice, which must also be available at the port of departure. The crew must be prepared to spend nights at sea, which they may not be accustomed to.  What Using radar and echo sounders (sonar)? This helped to link fishing fleets together and also detect fish gatherings instead of relying on human expertise or using primitive means represented by the rope that the fisherman drags behind the boat ending with a weight to rub against the fish and according to the number and strength of its vibration in the fisherman's hand, the size of the fish gathering is determined. The sonar device is a sensor that uses sound waves to determine the locations of objects under the surface of the water; it is also called a marine probe. Fishing vessels use sonar to determine the locations of schools of fish. As for ship recovery companies, they use it to find the wreckage of sunken ships. This device is used in aircraft and warships to determine the locations of enemy submarines. It is also used in regular ships to determine the depth of the water.  How does a sonar device work? Seminar Lab Bliss A sharp sound pulse similar to the sound made by a table ball Figure How does a sonar device work? Sonar works by sending a sharp sound pulse similar to the sound made by a table ball (Figure (1). This pulse bounces back when it hits an object. The object is then calculated by measuring the time it took for the sound to return. The speed of sound in water is estimated at about 1500 meters per second. If the sound returns after two seconds, it will have traveled a distance of 3 thousand meters, 1500 of which were to reach the object and 1500 to return. This method of challenging distances is called echo sounding. The emergence of synthetic fibers: - Synthetic fibers (Figure 2) were used in the manufacture of fishing nets instead of natural fibers, as they are characterized by the following: 1- Light weight compared to natural fibers, as they do not get saturated with water. 2- Do not require dyeing and periodic maintenance. 3- Transparent, so fish cannot see them. 4- High quality and stability of the knot. 5- Easy to store and has a long lifespan. 6- Can be manufactured in the required colors.  Fisheries Technology Fisheries technology refers to the fishing fleet and the equipment and devices it includes to serve the fishing process, the infrastructure necessary for fish production (fishing port equipment and coastal services related to the fishing mechanism such as repair and maintenance workshops for marine motors, refrigerators and means of transporting fish. The choice of the type of fishing equipment used is often dictated by the species of fish targeted, the material conditions for investment in this field as well as the environmental conditions of the area (type of bottom, currents), weather conditions and the type of vessel. The combination of these factors often means that only one type of fishing equipment can be used. However, in net fishing, especially in small-scale coastal fishing, it is sometimes possible to use double-net fishing vessels instead of the traditional single-net fishing vessel. Double-net fishing can lead to a reduction in costs compared to fishing with a single net. The use of navigation devices equipped with satellite means and echo sounders has become more widespread in fisheries after this technology became not only cheaper but also easier to carry, especially satellite navigation devices). Navigational aids of this type can contribute to achieving many gains. This equipment can not only help the captain to easily identify fishing areas, but it can also identify new areas and contribute to increasing navigational safety. The fishing fleet and means are the foundations on which the development of fisheries is built. Fisheries can be divided according to the technology of the fleet and fishing means into: 1 - Artisanal fisheries (small-scale fisheries): These are regional fisheries with small and usually undeveloped fishing units. These fisheries are of global importance as they contribute to the production of more than a quarter of the world's catch, and half of the fish used for direct human consumption. Two types of fishing units can be used in these fisheries at present: A - Sailing vessels The use of sails is not common today by any means. The use of sails requires very specific conditions in terms of weather conditions, the design of the fishing vessel, as well as the position of the crew and their knowledge of using the sail. The use of sails imposes additional requirements on the vessel in terms of the stability of the deck. Small fishing vessels may need additional weight or an external weight rig to improve their stability and the performance of the sail in the face of the wind or in its direction. The sails on any fishing vessel are a hindrance to its operation, and the mast and rigging occupy space on the deck that would otherwise be open. Sailing is a skill in itself, and to be effective sailors must be skilled and prepared - there is often a great deal of hard work involved in setting sails, especially on large vessels. It is a simple fact of life that it is always easier for sailors to forget about sails and just use the engine. However, sails can lead to significant fuel savings, depending on the strength of the wind, the direction of the wind relative to the course to and from the fishing grounds and the length of the voyage. This depends greatly on the sailor's ability to use the sail, the shape of the hull and the conditions and design of the sail. There are many different sail rig designs that have been developed in fisheries around the world. The use of sails can be combined with the technology of motorized rigging and it is important in this case that the sail design of the fishing vessel should be simple, safe and practical, with a minimum of fixed and moving rigging and rigging. In smaller vessels, a single sail rig is preferred, which can be easily and space -efficiently reduced. Sails as a secondary form of propulsion contribute greatly to the safety of the vessel.