Fishing is a type of hunting where people catch fish for nutrition, sport, or trade. Fishing, which has been one of the ways of providing food for many societies such as the people living in coastal areas throughout history, continues to be important today. Moreover, the increasing use of seafood in the industry has increased and spread this importance. Although angling usually comes to mind when it comes to fishing, fishing without hooks actually corresponds to a much larger part of the sector.
Fishing without hooks means simply fishing via fishing nets. This phenomenon is called the seine fishery. There are mainly two methods used in seine fishery, namely purse seine fishing and trawling. These two methods where fish get caught without using a hook, have similarities as well as differences. Purse seine method is used to catch fish that live in the middle layer of water, where trawling is used for fishing near the bottom of the sea. Let’s explore more about these two fishing methods without hooks together!
Fishing Without Hooks: Categorization of Fishing Nets
There is a wide variety of fishing nets. Not all fish are caught with every net. We can group fishing nets as trammel, trawl, surrounding, cast, and fixed nets. Let’s take a brief look at these now.
- Trammel Nets
These types of nets are single-layered and consist of a lead and a cork collar, both remnants, and a net called tor. Usually between 2-20 m, depending on the depth of the water reservoir and the fish species to be caught; and their length can be 50-300 m or more. The lead collar sinks to the bottom because it is heavy, the cork collar remains on the surface because it is light, and in this way, the net remains stretched in the water. Tor’s eye-opening varies between 20 mm and 80- 90 mm, depending on the type of fish to be caught. The fish approaching the net strikes the tor and is caught by its gills while trying to cross the other side. These nets are mostly used for fishing fish such as pike, crane, and catfish.
Entangling trammel nets also have a lead collar and a cork collar and a small mesh net called tor in between. In addition, these nets have a mesh at a wider aperture, which is attached to either side or one side of the net. The length and depth of these nets also vary according to the fish species caught and the depth of the water reservoir. The fish approaching the fishnets left in the water, when they want to go to the opposite side, get caught in the tor, and the fish can pass into the eye of the fan and form a bag and the fish cannot leave the net.
The trammel nets can be released into the water in different ways. It is usually left perpendicular to the direction of movement of the fish and the shore. There must be a distance of at least 50 m between the two nets.
Method 1: It is usually left perpendicular to the direction of movement of the fish and the shore. There must be a distance of at least 50 m between the two nets.
- Method: If too many nets are to be used and if the nets are at different mesh openings, they should be placed perpendicular to the shore with 50 m intervals.
- Method: Here, unit nets are placed perpendicular to the shore at 50 m intervals. In the next nets, it is left in the water perpendicular to each other.
- Method (Labyrinth System): Nets with large and small apertures are used together. Nets with small meshes are placed perpendicular to the shore at 50 m intervals. Large mesh nets are left to turn their ends.
In hunting with nets, the nets are left in the evening and pulled out the next day in the morning. Fish are taken out of the nets and taken into boxes; they are stacked so that the net is washed and thrown away again. It has been used in monofilament networks in recent years. These are knotless networks. In the experience, it has been observed that it gives more prey than polyphyletic (knotted) nets.
- Trawling Nets
They are bag-shaped nets that are pulled from the shore or from a boat by driving the bottom. With its general structure, it consists of a bag in the middle and 50 m to 75 m long wings on both sides of the bag. Also, these have lead collars and mushroom collars.
Placement of Trawling Net in Water Goes as follows:
The rope tied to the end of one of its wings is left on the shore and sailed to the lake by boat. First, the wing is poured into the water, then the bag is dropped into the water and the second wing is poured into the water and approached the shore. The rope at the tip of the wing is taken to the shore, a situation in the form of a half-moon occurs. 3 or 5 people from each of the ropes are hung up and pulled to the shore and the fish in the bag are taken.
- Surrounding Nets
These nets are used in the middle parts of the lake and deep places. They are also called purse seiners. It has a cork collar on the top and a lead collar on the bottom. The fish flock is wrapped up, when the flock enters the net, the two ends of the net are joined and taken to the boat by human or motor power. In addition, the bottom of the net is collected with a rope passed over the lead collar in the Pearl Mullet hunt and the fish are kept in the net.
- Cast Nets
It is the most widely used and very simple to use nets group in inland fishing. Usually, Carp and Trout are caught with these nets. Cast nets come in various forms. Generally in streams, a fixed pocketed sprinkling net is used. This network is thrown from the edge of the stream. While the fish want to escape from the net, they get caught in the pockets on the sides. Fish cannot go out even when the lead collar is merged by pulling the net or the net is open.
Another method of use in cast nets is the use of shrunken sprinkling net used in lakes and shallow waters. In use in shallow waters, the bottom contact of the net is essential. Intense hunting flocks are sought in lakes. The net is left on the fish, it is expected to collapse for a while, and the net shrinks by pulling the ropes quickly. As the net shrinks, the top of the shrinking part becomes a bag.
- Fixed Nets
The most important fixed net used in the seas is crayfish baskets used in crayfish fishing. Two types of crayfish baskets are used today. Double-entry crayfish basket (old type crayfish basket) consists of two-mouthed, four-wire hoops side by side. Each wire is covered with a net and is connected from the first circle in the mouth to the second circles inside it with a truncated cone narrowing inward. Single entry crayfish (new crayfish basket) two funnels one after the other and 3 mm. thick plastic-coated, made of 5 wire hoops.
The lower part of the first hoop is made flat for the pinter to rest on the ground. The straight edge of this circle, which looks like a semicircle, is 45 cm long and 35 cm in height. The other 4 circles have a diameter of 27 cm. The length of the baskets is approximately 125 cm and the intermediate stretching is 175 cm. In order to keep the stretch used between two baskets tight in water, cork on top and lead on the bottom are tied. The Mesh size of the mesh used in these baskets is 30 mm.
Crayfish fishing is done with or without forage in single or double-entry baskets. Forage hunting is generally done in double-entry baskets with bait and single-entry baskets. The crayfish baskets are thrown perpendicular to the movement direction of the crayfish in the water, and after a day or two, the caught crayfish are collected. Since the movements of the crayfish are parallel to the shore, the longer the crayfish baskets are thrown perpendicular to the shore, they give more prey.
Fishing Without Hooks: Purse Seine Fishing
Purse seine nets are bottom-shrinking surrounding nets. Surrounding nets are fisheries fishing equipment that allows fish to be caught by circling them and trapping them in the net. Purse seine nets can be classified as purse seine nets used in anchovy fishing, purse seine net used in acorn fishing, purse seine nets used in tuna fishing, and other purse seiners. This kind of hunting is mostly done for commercial purposes.
With this hunting, pelagic and small fishes are caught in flocks. Fish such as anchovies, sardines, mackerel, bonito, bluefish, and tuna are target species. Purse seiners can be done with a single boat or two boats. This type of hunting is referred to as flip nets. In principle, nets of a certain length and length are left in the flock. At the bottom of these nets, there is an additional rope called a stacking rope. This rope is placed in the harness. After the flock is surrounded by a net, the two ends of the stacking ropes are brought together and gathered and shrunk in the form of a bag. As a result, a six indoor pool is obtained. The catch is slowly pulled into the boat from the top ropes and the fish remaining in the pool is gathered in the boat.
During this operation, generally illuminated systems are used. Since fish such as anchovy feed on plankton, they tend to light by showing sensitivity to light. In this way, the herd inevitably enters the hunting area. Purse seine nets are produced from synthetic materials as in many other net makings. Synthetic materials, which are much more durable than cotton yarn, are also longer lasting in terms of use. The aperture used varies according to the size of the target species. By calculating the length according to the eye-opening, the lead cork collars are equipped with the net.
It is usually produced 150 meters in length and 25-50 meters in height and this network feature varies according to the length and power of the boat. Especially in tuna fishing, net lengths and widths are very large. There is special equipment developed for purse seiners. These are tools that aim to bring the net to the deck and are used to unload the prey remaining in the bag. Cranes, net drums, and net harvesting reels are used to take the net onto the boat, while fish pumps draw the catch from the water and discharge it to the deck. Large ladles can be used in small-scale purse-seiners.
While the upper parts come with 5-8 floaters (net corks) per meter, the lower parts are also equipped with sinkers, ie net leads. This type of hunting, which can be done on a small scale without any of these, can be easily collected by double boats. The catch is shared by pulling half of the net to one boat and the other half to the other boat. Sheet and wooden boats can be preferred for purse-seine fishing. Boats with an average engine power of 250-500HP are used.
The Subtleties of Purse-Seine Fishing
In contrast to trawling, which is one of the important methods of fishing with trawl nets, purse-seine fishing is mostly used for hunting species that live in the upper middle part of the water body and are called pelagic fish. Purse-seiners, equipped with highly advanced technological devices to detect fish living in herds and wandering in large masses in open seas, can be described as a medium-sized factory with the hunting, processing, and storage tools they have today.
These ships, which have VHF and public band radios in terms of communication and security, are also equipped with surface radar in order to determine the direction in foggy weather and to prevent any accident. Purse-seiners use devices called Sonar and Echo-Sounder, which are called fish finders, to detect the fish they will hunt. Although these are originally similar based devices, they have different transducer structures designed to obtain data in horizontal and vertical directions.
With the help of these devices, after the fish shoals are detected, the fishing operation can be started for those who are suitable in terms of quality and quantity. For this purpose, the mother ship comes to a position close to the herd, one end of the net is taken to the auxiliary boat and the herd is surrounded by the boat that moves rapidly thanks to its very powerful engine. Immediately afterward, the lead collar of the purse-seine net remaining in the lower part of the water is pulled with the help of a steel rope and contracted, thus obtaining an extremely large net pool. Considering that the cork collar is on the water surface, it is no longer possible for the fish to go out of the pool and therefore escape.
After this stage, the machines of the auxiliary boat and the mother ship, in cooperation, reduce the net pool and compress the fish as much as possible. In this operation, which is carried out on the side of the ship, the fish that are compressed in the shrinking volume is either taken to the deck with the help of suitable ladles or are pulled into the ship with the water with fish pumps. For the last remaining part, the net is lifted with the help of a crane and unloaded to the deck and thus a net throwing process called “break” is completed.
Currently, many ships equipped as purse-seiners of various sizes are operating licensed in the world. Among these, there are a considerable number of examples that have a height of over or around 50 meters and can actually be described as a factory. Anchovy, horse mackerel, bonito, bluefish, sardines, mullet, and tuna are fished by purse seiners and contribute to the economy.
Despite the current fishing depth rule of 24 meters for purse seiners, the limitation of the net depth of 90 fathoms, and many other prohibitions, the species living in the seas are under severe predation pressure due to the low selectivity of purse seiners and unconscious hunting. Although it is necessary to carry out various studies in order to raise the awareness of fishermen in terms of fishing prohibitions, what should be essential is to increase the adequate and effective control opportunities. Ensuring this would be a beacon of hope for the species whose existence is endangered in the seas.
Fishing Without Hooks: Trawling
Trawl nets are hunting tools used in the fishing of various fish, mollusks, and shellfish living on or near the ground. As its importance in fisheries is understood, many different types of trawl nets have been developed. These are mini models that can be towed with very small boats, as well as those with a mouth opening reaching 30-40 meters and large ones that can be towed with 500-3000 HP powerboats.
In trawl fishing, the amount of catch is proportional to the size of the net. Heavy and modern trawl nets are used for economical hunting. Trawling needs to be well planned for the search for prey to be found and an efficient operation. Today, three main types of trawl nets are used such as bottom trawl, mid-water trawl, and combined trawl.
- Fishing with Bottom Trawl
They are the advanced types of deep dredges. It is used for fishing fishery products that live on the ground or near the ground. The larger the mouth opening and the screened area, the more possible prey. Nowadays, doors are used to increase the mouth opening. The methods to be applied to increase the mouth opening depend on the type of prey. For example, it is necessary to increase the horizontal clearance for flatfish, shrimp, and living creatures close to the ground, and to increase the vertical clearance for fish such as herring and cod haddock that live at a certain height from the ground.
Previously, vertical rods were tied between the lower and upper edges of the mouth to keep the vertical opening constant. Later, considering that these rods scared the fish, other methods were found. The most important of these is the flotation and lead weight applications used in trawl nets today. The higher the buoyancy of the floaters, the higher the mouth opening relatively. However, increasing the lifting power further is inconvenient as it will cause the trawl net to lift from the ground during towing. In addition, large floaters increase the resistance of water.
Other applications are mushroom collars lifting parts and kite applications. Doors are widely used today to increase the horizontal clearance of trawl nets. Trawl doors, which can reach several square meters in size and can be of different types, keep the network open by working with hydrodynamic principles by splitting the water outward. The most suitable place for the doors is 1,3 of the rope length starting from the ends of the wings.
The most suitable door angle for active fish fishing is 20-26 °, and in bottom trawls, it is 40-50 °, closer to the wings. Apart from these applications, bottom trawl nets generally show a common structure. It has an all-around conical mesh pouch. Behind the body, there is a section where fish gather and a second thicker net surrounding the net to increase resistance. The turbidity that occurs as a result of the friction of the doors to the bottom during the pulling of the net allows the fish caught between the two doors to head towards the bag.
Trawls, which show different structures according to the type of fish to be caught, can be towed with a single ship or with two boats. The speed of trawl nets pulled from the bottom varies according to the fish species to be caught. While 1.5-2 mph speed may be sufficient for slow swimming species, 4-5 mph/hour shooting speed is suitable for fast swimming fish. Pulling the trawl net too slowly causes the doors to close together and the muzzle is insufficiently opened and the hunting capacity decreases. On the other hand, too fast pulling causes the net to take off from the ground and not to hunt.
On boats that use the side operation bottom trawling method, the deck is designed to keep the front wide for operation. The wheelhouse and engine room are located at the stern. In front of the wheelhouse, there are usually 2 winch drums on which trawl ropes are wound. Two davits made of stainless material are mounted on the side of the boat, one on the front and the other on the side of the boathouse. There is one pole in the front where the pulleys are hung, and in some types, two poles.
In the stern operation bottom trawl method, all activities related to fishing are carried out behind the boat. This method, which is widely used in our country and in the world, differs from side-operated trawls in terms of some features. Although different methods are used in collecting and wrapping the net, technical equipment and hull layout are similar to ships with side operations.
It has two major advantages over the side-operated system. The boat can sail on a straight route while the operation is carried out on the stern. The pulling force occurs in the direction of movement. For this reason, most of the time, the boat can turn directly towards the wind and wave and continue hunting even in harsh sea conditions. Thus, proportionally more time is allocated for hunting.
- Fishing with Mid-Water Trawl
The mid-water trawl is used for fishing fishery products at different depths between the ground and the surface. While a few hours of fishing is done at a time in a wide area with the bottom trawl, a 10-20 minute catch is enough to catch a specific fish herd with the midwater trawl. Thus, the fishing efficiency of the boat increases. Successful midwater trawl fishing depends on the use of a variety of electronic aids. Tools such as the Echo sounder and sonar are essential for both finding the herd and managing the ship while hunting.
In addition, the net should be kept at the desired depth, and the boat should be able to be kept on a fixed route through which the net will pass. Due to the density of the herd, the amount of fish caught in each shoot is more than the bottom trawl. This ratio is about 10/1. On the other hand, the bottom trawl can be used in 18 out of 24 hours, while the middle water trawl can take 3-6 shots at the same time. Both single and double hull method can be applied in the mid-water trawl. It is suitable to be towed with small boats with low engine power in shallow waters, especially with double boats.
In addition, there is no problem for fish to be scared due to the steel ropes passing through the flock. The startling of the fish due to the passage of the ropes before the net approaches the flock leads to a decrease in fishing efficiency in the single boat method. midwater trawl nets have a more conical structure than bottom trawl nets. Many different types are used in practice. midwater trawl nets are made of very light material, as they are not well connected to the ground except for shallow waters. Thus, it is possible to tow a larger mid-water trawl with the same boat.
If a trawler boat with side operation is used, usually a pair of blocks are suspended after the davits. These blocks, linked with the crane, allow both ropes to be pulled from this point. Both strands pass through a pair of pull blocks and pull one side of the net. The other boat pulls the other side and the mooring rope is transferred to the leader boat at the end of the operation with the help of a guide rope. During the gathering, the net is taken from the stern by passing the mooring ropes to the boat through the guide blocks located behind and winding the winch reels. With this arrangement, only the lower moorings are lifted, the upper ropes are pulled by hand.
Fishing Without Hooks: Trawl or Purse Seine?
The increase in production as a result of fishing with nets followed a horizontal course until the 1980s, the rapid development of technology since the early 1980s, the introduction of the new import regime, and the increase in fishing fleet and fishing power in the fleet made it increase 2-3 times. In addition to the effects of many factors on this increase, the biggest factor started with the use of fish finders (sonar and echosounder), which can determine the location, quantity, and even type of fish, and the formation of large fishing equipment.
With the lack of stock management and the uncontrolled use of developing technology in fishing, our rapidly increasing fishery products production has entered a downward trend in recent years and has started to decrease gradually. Besides the decrease in total production, some species have reached almost extinction. One of the most important factors causing this decrease in production is the non-compliance with all kinds of hunting bans. Our fish stocks are about to disappear now. Because fish are hunted without spawning for a new generation. Everyone knows the cause of the problem, but nobody takes responsibility for their own interests.
Trawling is at the top of the above-mentioned hunting bans. This is our main subject here. For years, the harms of trawling have always been told, both in the universities and through the media. Indeed, trawling is one of the biggest factors in the extinction of the fish population in the seas. Because as a result of trawling fishing, fish nests and eggs are destroyed, and especially by the blind net at the back of the trawl net, the juveniles are completely destroyed. In spite of the damages of trawling, is fishing with purse seiners really innocent? Is there no harmful side to purse-seine hunting?
I will explain purse seine fishing and trawl fishing with an example below. However, I leave you the interpretation of which one is more harmful. The purse seine nets used in the seas have an average length of 800 fathoms (1200 meters) and a depth of 80 fathoms (120 meters). Purse seine nets are available that are smaller than this and have a greater depth and length. The mouth width of the trawl nets used in the seas is approximately 5 m and the height of the mouth is around 2 m. Behind this, there is a bag part, which is made of net, which is generally called a blind net and allows the fish to gather together.
For example, if we consider that a purse seine net with a length of 1000 m and a depth of 120 m is opened in a full circle and released to the sea, a cylindrical area will be formed here. Inside this cylindrical area, there will be fish of all sizes and even breeds. If we calculate the volume formula of the cylinder, we see that this area is 10,000,000 m3 (ten million cubic meters). In other words, a purse seine net with the above dimensions can catch all fish, large and small, in a volume of 10,000,000 m3 in one shot. This process can be done in as little as 2-3 hours. If we consider that larger fish such as bluefish or horse mackerel were caught here with an anchovy net and fishing in shallower waters with a purse seine net with a depth of 120 m, we can clearly see how dire the result is.
If we calculate that a trawl net with a mouth width of 5 m and mouth height of 2 m and an area of 10.000.000 m3 will be scanned by the distance the trawl net is pulled; The result will be a distance of 1000 km. How many days can a trawler dredge this 1000 km distance? As a result, as it can be understood from the above account, purse-seine fishing is not innocent at all unless the rules and prohibitions are followed. Because the trawler can only do what a purse does in a few hours in a few days. If a net with an eye-opening suitable for the fish to be caught is not used; It is obvious that we will hunt the fish not always, but once. The future of fishing cannot go further than throwing the net empty and pulling it empty.
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