RU2171573C2 - Sorting system for trawl - Google Patents

Abstract

FIELD: fish industry. SUBSTANCE: sorting system has additional selective members made from netted fabric with square cells. Selective members are stitched into netted patches of rhombic cell trawl sack by known methods providing complete opening of square cell. System may be equipped with sorting member formed as rigid grid-type insert defined by longitudinal and transverse rope binders with intersection points rigidly fixed by known methods, or formed as rigid grid of V-shaped separating wall. System is further provided with netted board adapted for guiding caught fish to sorting member. Construction of sorting system allows young fish of valuable kinds of fish to be sorted in cases when, according to catching conditions, usage of rigid grids is impracticable, or usage of such systems is insufficient for high-quality sorting of young fish due to increased specific content of such fish in fish catching region. System is fabricated from soft flexible materials, is intrinsically incorporated into netted enclosure of trawl sack patches, does not reduce hydrodynamic characteristics of trawl and facilitates decrease of hydrodynamic head within trawl sack. Sorting system provides release of small-sized species or young fish from trawl net. EFFECT: increased efficiency and simplified construction. 5 cl, 10 dwg

Description

 The invention relates to the fishing industry, in particular to trawls equipped with devices for the production of small fish or juveniles.

 Currently, it has become a vital necessity to introduce resource-saving technologies in the field.

 This is due to the acute problem of by-catch of juveniles in almost all areas of cod distribution, with a decrease in raw materials, with seasonal migrations of large fish. Even when using varietal systems with rigid lattice by-catch in such conditions exceeds the permissible limit.

Known trawl with a device for the release of small-sized fish (juvenile) ("Trawl with a device for the release of small-sized objects of fishing" VM Glukhov, S. F. Lisovsky, RF patent A 01 K 73/02 MKI ⁵ , N 2098957, s. N 95106067; application. 04/18/95; publ. 12/20/97, bull. N 35).

 The device contains a sorting and guiding elements, a through hole for large fish inside the trawl bag, as well as additional selective elements in the form of a series of selective rigid gratings of small size, which are sequentially fixed to the trawl bag in the form of a buffer belt, alternating with net inserts acting as a net shell trawl bag.

 In addition, such a device can be additionally equipped with selective rigid gratings, which are fixed between the buffer belt and the device for releasing fish on the net shell of a trawl bag.

 All these devices contribute to improving the quality of sorting juveniles, as well as improving the hydrodynamic characteristics of the trawl.

 The known design has several advantages over other similar systems: almost before approaching the sorting element of the device, juveniles located near the shell of the trawl bag are filtered through the gratings of the buffer belt, as it passively follows the direction of the water flows exiting through the gratings, which will be more powerful than flows around them. Further, the separation of juveniles occurs (in the entire thickness of the water-fish mixture moving inside the trawl bag) using sorting elements. A buffer belt of selective elements allows to reduce hydrodynamic backwater inside the trawl bag and creates favorable conditions for active large fish to fall into the trawl heap, and juveniles to selective elements, as underwater observations have shown.

 The disadvantage of this device is a sufficiently large number of elements that have a certain rigidity, which complicates the work when lowering and raising the trawl in adverse conditions, creates some inconvenience during its storage.

 It is especially difficult to work with trawls equipped with grading systems made of hard elements in stormy conditions, that is, in autumn, when the fishing situation is further complicated by the fact that fish accumulations contain 50% and more young fish due to the seasonal migration of large fish to other areas. Almost at this time, by-catch contained juveniles in quantities exceeding those allowed by the Fisheries Rules, which leads to undermining of the raw materials of valuable commercial fish species.

 The proposed system allows, while retaining all the advantages of the prototype, to use elastic network materials and cable ties for the manufacture of selective elements without reducing the strength and selective characteristics of the trawl.

 Additional selective elements are made of a mesh web with a square mesh. The elements are sewn into the net fabric of the trawl bag with a rhombic mesh using known methods that ensure the completeness of the opening of a square mesh, for example, by combining the elements in such a way that an integer rhombic number is formed per square mesh.

 This will maximize the selective surface of the trawl bag without using additional rigid elements, as well as reduce the hydrodynamic support inside the trawl bag, similar to the action of the buffer belt. The “soft” system fits more organically into the design of the trawl and does not violate its strength, hydrodynamic and selective characteristics.

 With a significant content of juveniles in the fish gathering, it is necessary to use the most efficient sorting systems. Such systems, as a rule, contain rigid sorting gratings.

 In difficult fishing conditions, when the use of rigid gratings becomes impossible due to safety requirements, and sorting is carried out practically due to the selectivity of the net trawl web, which is not enough, the proposed system provides for the use of an insert similar to a rigid selective grating made of longitudinal and transverse cable ties the intersections of which are rigidly fixed by known methods (for example, by punching). If there is a guide element in the form of a net springboard fixed on the bottom of the bag in front of the sorting insert, which provides a change in the direction of movement of the water-fish mixture inside the bag towards this insert, the juveniles are sorted with good results.

 Working with a trawl equipped with such a system is as safe as with a conventional trawl, since all its elements are made of "soft" elastic materials.

 In the event that the fishing conditions allow the use of V-shaped dividing walls, the use of which guarantees the release of 80-90% of juveniles when they are kept in the harvested collection of up to 40-50%, but the proportion of such fish in by-catch still exceeds the permissible fishing rules, from - due to the high specific content of juveniles in the cluster, the proposed system provides for equipping the trawl with a V-shaped dividing wall with a rigid selective and guide elements, with a guide net springboard, a combination of which with selective elements Net mesh with mirror mesh significantly increases sorting efficiency.

 All parameters of the selective and sorting elements — the number and relative position of additional selective elements, their cell sizes, the distance between the bonds of the sorting element — are set based on the fishing conditions and the requirements of the Fishing Rules.

 The higher the specific content of juveniles in the fishing cluster, the greater should be the surface area of additional selective elements. Due to the fact that the sorting capabilities of the insert, similar to the lattice of the V-shaped dividing wall (in cases where its application is impossible due to safety requirements), is lower than that of the rigid wall lattice, such a system is equipped with a large number of additional selective elements which can be located not only before the sorting element, but also after it.

 The location of the selective elements can be, depending on the behavioral characteristics of the fishing object, different: for pelagic fish, seeking to exit in the upper part of the trawl bag - in the upper part and on the sides, for bottom ones - in the lower and on the sides closer to the lower part.

The invention is illustrated by drawings, where
in FIG. 1, 2 depicts a single cut trawl, side and top view;
in FIG. 3, 4 - embodiment of the trawl with two selective elements, side view and top;
in FIG. 5 is a section I in FIG. 2;
in FIG. 6 is a section II in FIG. 4;
in FIG. 7, 8 - embodiment of the trawl with 3 selective elements, side view and top view;
in FIG. 9, 10 - embodiments of a two-track trawl with selective elements, plan view.

 The trawl with a selective system contains additional selective elements 1 made of a square web mesh web sewn into a net with a rhombic mesh of the trawl bag layers 2 3. The sorting system has a guiding element 4 made in the form of a net springboard and mounted on the bottom plate of the trawl bag 3 in front of the sorting element 5, made, depending on the fishing conditions, in the form of an insert of rope ties 6, the intersections 7 of which are rigidly fixed, or a rigid sorting lattice of a V-shaped section tion wall 8.

 The system operates as follows.

 The flooded water-fish mixture moves inside the trawl bag 3. Large fish with sufficient physical strength, encountering obstacles in the way in the form of a net web, hydrodynamic backwater, at the beginning of the path have the opportunity to get out of the trawl, changing the direction of movement. A weaker fish moves passively with the water flow of water, so it is necessary to stimulate its movement to exit through selective elements. With a significant specific content of juveniles in the catch, this is especially necessary, since even the most efficient sorting systems with rigid lattices do not always cope with this task: juveniles fall into the trawl heap without having to pass through the lattice or bypassing it.

 Additional elements from the canvas with a square mesh allow gradually, as the water-fish mixture moves inside the trawl bag, due to the fact that water flows through the sections that are more open than the rhombic mesh of the bag are formed, to help change the direction of movement of passively moving juveniles to exit through square mesh element along with the flow.

 First of all, the young will leave the trawl, which moved in close proximity to the surface of the net shell of the trawl bag 3 and selective elements 1 with a square mesh.

 The remaining fish will proceed to the guide net springboard 4, which will change its direction of movement towards the sorting element 5, made in the form of a similar rigid grid sorting insert of rope ties 6, 7 or a rigid lattice of a V-shaped dividing wall 8. The young get the opportunity to get out of the trawl through the holes of these elements 5, and all fish that did not pass through the sorting element 5 will go to the trawl heap if the system does not provide selective elements 1 located after the sorting element 5. that the presence of such elements 1 juvenile receives a final opportunity to leave the trawl (if it will allow its size).

 The proposed design of the selective system allows one to achieve good results of sorting juveniles of valuable commercial fish species in cases where, according to the fishing conditions, it is impossible to use rigid sorting devices or the presence of such systems is insufficient for high-quality sorting of juveniles due to the large specific content of such fish in the fished pool.

 A sorting system made of “soft” elastic materials and organically “blended” into the net shell of the trawl bag layers not only does not worsen the hydrodynamic characteristics of the trawl, but also reduces the hydrodynamic backwater inside the trawl bag due to the presence of square mesh inserts, performing in this case the role of the buffer belt.

 The stable full opening of the square mesh of the inserts and holes between the rigidly fixed bonds of the sorting elements ensures effective sorting of juveniles.

 In the case when all elements of the system are made in the “soft” version, the trawl is especially easy to operate and practically does not differ from ordinary trawls.

 The manufacture of systems does not require large expenditures and can be carried out from any FOL.

 For the manufacture of selective elements of the system, new types of network materials can be used, for example, such as the Knotless Del Cross Ultra Spectrum type.

 It is possible to use such systems in two-track trawls (Figs. 9, 10).

Claims (5)

 1. A sorting system for a trawl containing a guide, sorting elements, a through hole for large fish inside the trawl bag and additional selective elements, characterized in that the additional selective elements are made of a mesh cloth with a square mesh and sewn into a mesh cloth with a rhombic mesh layers trawl bag through techniques that ensure the completeness of the disclosure of a square mesh.  2. The sorting system for the trawl according to claim 1, characterized in that the sorting element is made in the net layer of the trawl bag from the web with a rhombic mesh in the form of an insert similar to the sorting grid formed by longitudinal and transverse cable ties, the intersections of which are rigidly fixed by known methods.  3. The sorting system for the trawl according to claim 1, characterized in that the sorting and guiding elements are made in the form of a V-shaped dividing wall.  4. The sorting system for the trawl according to claim 1, characterized in that the system is equipped with a guiding element in the form of a net springboard fixed in front of the sorting element.  5. The sorting system for the trawl according to claim 1, characterized in that the number and location of additional selective elements, their mesh size, and also the distance between the bonds of the sorting element are established based on the behavioral characteristics of the target, the specific content of juveniles in the fishing cluster, conditions fishery and the requirements of the Fisheries Rules.

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