RU2239998C1 - Trawl for fishing in bottom zone - Google Patents

Abstract

FIELD: fishing; trawls.

SUBSTANCE: proposed trawl consists of pelagric net trawl and towed acoustic concentrator of rotary type. Concentrator forms extended fish barrier-acoustic field in water by means of acoustic radiator. Field is periodically interrupted and is changed after each pause in spectral composition. Field encloses upper half of trawl net and corresponding sector of water space before trawl. Lower part of trawl net is periodically covered by short-time acoustic pulses, part of which getting in ground causes bottom reverberation. Spectrum of re-reflected acoustic signals from and out of ground makes fish separate from bottom and rise to zone of fishing of net trawl where fish is held from dispersing by acoustic field enclosing upper part of trawl net.

EFFECT: provision of effective fishing at sea bottom, even on complex submarine relief.

3 dwg

Description

The invention relates to the field of fishing equipment, in particular to devices for trawl fishing.

Trawl systems are known, consisting of a network trawl and a rotary-type acoustic concentrator towed behind it, which creates in the aquatic environment by means of an acoustic emitter controlled by a program unit an extended, traveling in the form of a circular cone, fish-blocking acoustic field covering the network trawl and the area in front of the trawl, and thereby Concentrating fish stocks at the rate of movement of the trawl, RF patents [1, 2, 3, 4].

The prototype of the claimed device can serve as a trawl system (hereinafter referred to as trawl) with an acoustic fish concentrator according to the patent of the Russian Federation [4]. Distinctive features of such a trawl are:

- the fish-blocking acoustic field emitted by the concentrator is periodically interrupted, and after each pause it changes in spectral composition; periods of emissions and pauses are in the order of units of minutes;

- there is a device for the rapid reconfiguration of the hub to change the geometric shapes of the acoustic field for different types of trawling: pelagic, surface, bottom-bottom.

From the description of the prototype it follows that with bottom-bottom trawling, only the upper, relatively horizontal plane, passing through the longitudinal axis of the network trawl, the 180 ° sector of the water space is voiced, which raises no doubt about the suitability of such a configuration of the acoustic field for use with the bottom trawl. But when the trawl has no contact with the ground, and the area between the lower net trawl selection and the ground is not protected by the acoustic field, this configuration of the acoustic field is not suitable for trawling in the bottom zone. (Zone within 10 m from the bottom (author's note)).

Considering that fishing with bottom trawls violates the ecological structure of the bottom of the seas and can be banned everywhere in the future, the aim of the invention is to create a new type of trawl that does not have contact with the ground and at the same time allows for efficient fishing in the bottom zone, including and bottom fish species on difficult terrain.

This goal is achieved by the fact that a trawl for fishing in the bottom zone, consisting, for example, of a pelagic net trawl and a towed acoustic fish concentrator of a rotating type, which creates in the aquatic environment by means of an acoustic emitter controlled by a program unit, periodically interrupted by pauses and changed after each pause in spectral composition, an extended fish-boring acoustic field, covering the network trawl and the area in front of the trawl in the upper, relative to the horizontal plane Coinciding with the longitudinal axis of the trawl network 180 ° -th sector of the body of water; the program block is supplemented by a program that generates control signals, under the influence of which the concentrator periodically emits short-term acoustic signals covering the network trawl in the lower 180 ° sector of the water body and at the same time sounding the bottom soil, the bottom reverberation resulting from this causes separation of fish accumulations from the ground and rise them into the area of fishing net trawl.

Figure 1 shows a diagram explaining the operation of the proposed trawl on the example of two operating cycles of bottom trawling; figure 2 shows a cross section along aa fragment of the active site of the trawl; figure 3 shows an exemplary timing diagram of two operating cycles of bottom trawling, depicted in figure 1.

Figure 1 shows: a trawler 1, towing a network trawl 2 with an acoustic concentrator 3, rotating around its longitudinal axis due to the oncoming flow and swivel with the end part of the network trawl; acoustic fields 4, 5 (in a stylized form) with various spectra of acoustic signals, covering the upper half of the network trawl 2 and the area in front of it (indicated by a different slope of the hatch); periodic short-term acoustic signals 6, 7 (shown by dash-dotted rays), covering the lower half of the network trawl 2 and simultaneously sounding the bottom soil 8; short arrows 9 indicate bottom reverb signals; L1, L3 — trawl advance distances with the acoustic hub turned on; L2, L4 — trawl advance distances with the hub turned off (pauses); clusters of fish are indicated by a mass of dots above the soil image: 10 - before the start of trawling, 11 - during the trawling process.

Figure 2 shows a section along aa (figure 1): acoustic field 4; voiced sections of the water space with periodic short-term acoustic signals 6 and bottom soil 8. Pos. 12 shows the perimeter and the area of the mouth of the network trawl.

Figure 3 shows the temporal distribution of the acoustic signals emitted by the hub: in the upper row - continuous radiation, alternating with pauses, after which the frequency spectrum of the signals changes (4, 5), in the lower row - an approximate distribution of periodic short-term acoustic parcels with a frequency spectrum corresponding to in each working cycle, the spectrum of signals in the upper row.

The number of duty cycles with acoustic signals that are not repeated over the frequency spectrum is determined by the number of programs contained in the program block of the acoustic hub.

Work of the trawl in the bottom zone

Upon detection by the fish finders of the trawler accumulations of fish 10 in the bottom layer (Fig. 1), the concentrator circuit switches to the trawl mode in the bottom zone, which is carried out by means of a switch located on the carrier body (not shown in Fig.). Next is the setting of the trawl. At a certain depth, a hydrostatic device (not shown in FIG.) Connects the hub circuit to a power source.

When the trawl enters the bottom zone, the operating towing speed is established and the trawling process begins. The acoustic concentrator 3 creates in the aquatic environment an extended fish-boring acoustic field 4, covering the upper half of the net trawl 2 and the area in front of it. The lower half of the network trawl 2 is periodically covered by short-term acoustic signals 6, 7. Some of these signals, falling into the ground 8, cause bottom reverb [5], in which there is random sound scattering by the unevenness of the bottom soil and its structural components, which is symbolically represented by short arrows 9 The spectrum of reverberation signals contains low frequencies, which enhances their effect on fish accumulations at the bottom.

In the process of advancing the trawl, the signals of bottom reverb 9 coming from and from the ground cause separation from the ground and the rise of fish 11 (Fig. 1) into the fishing area of the net trawl, where they are kept from being scattered by the acoustic field 4, thereby achieving effective bottom fishing and bottom fish species, including those living on difficult terrain soils.

The duration of active acoustic impact on the accumulation of fish in the working cycle is of the order of units of minutes, which excludes the adaptation of fish to these signals. During this time, the trawl passes the distance L1 (L3), at the end of which the hub turns off. The concentrator is switched on again after a pause, the duration of which is also in the order of units of minutes, and the trawl passes the distance L2 (L4) during this time.

Figure 3 shows an approximate ratio of the time of action of the acoustic fields 4, 5 and signals 6, 7. The number of acoustic parcels 6, 7 is determined by the accepted durations of working cycles. It is advisable to reduce the duration of pauses in comparison with the duration of duty cycles.

In cases of prolonged trawling, sequences of duty cycles with different frequency spectra of acoustic signals are automatically repeated an unlimited number of times.

In the process of trawling, it is advisable to periodically change the horizon of the trawl within the bottom zone in order to obtain the maximum efficiency of the bottom reverb signals, while the result is evaluated by the readings of the trawl control device, which, as a rule, is available on each operating trawler.

Thus, the proposed trawl for fishing in the bottom zone is a new type of fishing gear for fishing bottom and bottom species of fish, eliminating the violation of the ecological structure of the bottom of the sea.

The application materials are based on the results of experimental tests of trawls using an acoustic fish concentrator.

In conclusion, it should be noted that the proposed trawl system does not violate the selective qualities of the network trawl used, since during the work cycles lasting several minutes, continuous acoustic radiation covers only the upper half of the network trawl, while the lower part of the trawl is covered by rather rare short-term acoustic bursts, designed mainly for the formation of bottom reverb signals, which does not impede the exit of small fish from the net trawl. At the end of each working cycle, there is a pause during which the acoustic radiation is completely removed.

Sources of information

1. Trawl for fishing. RF patent №2007077, 1994.

2. Device for trawl fishing. RF patent No. 2048095, 1995.

3. Device for trawl fishing. RF patent No. 2134508, 1999.

4. Acoustic hub for trawl fishing. RF patent №2169465, 2001.

5. Stashkevich A.P. Acoustics of the sea. Publishing house "Shipbuilding", 1966, p.175-182.

Claims (1)

A trawl for fishing in the near-bottom zone, consisting of a net trawl and a rotary-type acoustic concentrator towed behind it, creating in the aquatic environment by means of an acoustic emitter controlled by a program unit periodically interrupted by pauses and changing after each pause in spectral composition an extended fish-blocking acoustic field covering net trawl and the area in front of the trawl in the upper relative to the horizontal plane passing through the longitudinal axis of the net trawl, 180 ° sector of the water of space, characterized in that a program generating acoustic signals is additionally introduced into the program block of the acoustic concentrator, under the influence of which the concentrator periodically emits short-term acoustic signals covering the network trawl in the lower 180 ° sector of the water space and simultaneously sounding the bottom soil, causing This bottom reverb, leading to the separation of accumulations of fish from the ground, and their rise in the area of fishing net trawl.

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