SU1316613A1 - System for studying migration of fish under natural conditions - Google Patents

Abstract

The invention relates to ichthyology, is used to study the migration of fish in natural conditions and is aimed at. increasing the range in the marine iKbu ;. the possibility of studying the effects on fish of short-term stimuli and providing a more detailed study of the behavior of fish in natural conditions. The system contains a hydroacoustic tag for fish in the form of a sealed enclosure containing two sources of 2, 3 sound waves operating at different frequencies, a receiving sound antenna 4 with indicators of azimuth and tilt, two filters 5, 6, two amplitude detectors (.AD ) 7, 8, two logarithmic amplifiers (LU) 9, 10, adder (C) 11, inverter 12. linear amplifier 13, range indicator 14. The inputs of filters 5 and 6 are connected to antenna 4, and their outputs are connected to the AD inputs 7 and 8, the outputs of the AD 7 and 8 - with the inputs of the LU 9 and 10. The output of the LU 9 is connected to the first input C 11, the output The dLU 10 is connected to the second input C 11 via an inverter 12. The output C 11 is connected to the input of the linear amplifier 13, and the output of the latter is connected to the range indicator 14. 1 sludge. ) (L with Ci С5 СО

Description

The invention relates to the field of ichthyology, namely to systems for studying the migration of fish under natural conditions using sonar tags.

The purpose of the invention is to increase the range of the system in sea water, thereby studying the effect on fish migrations of short-term stimuli and providing a more detailed study of the behavior of fish in natural conditions.

Increasing the range of the system is important for underwater biotelemetry and the study of the behavior of a hydrobiont under natural conditions, depending on its physiological state and environmental factors, and the use of the information obtained to increase the intensity of commercial fishing.

The drawing shows the structural scheme of the proposed system.

The system for studying fish migrations in natural conditions contains a sonar tag 1 installed in fish in the form of a sealed, streamlined hull, in which sources of 2 and 3 sound vibrations operating at different sound frequencies, spatially directed sound antenna 4 with indicators of azimuth and elevation are mounted , the first 5 and second 6 filters, the first 7 and second 8 amplitude detectors, the first 9 and second 10 logarithmic amplifiers, the adder 11, the inverter 12, the linear amplifier 13 and the range indicator 14.

An example of a specific system implementation can be the Biont system, w, and a tag for fish containing two sources of sound waves with filling frequencies of 19.7 and 50 kHz, launched synchronously every 0.01 s, and a receiver with two broadband hydrophones located with a view to obtaining a spatial directivity at a distance of 0.2 m from each other and installed in the slide-out device of the Bream. The output of one of the hydrophones is loaded onto the resonant amplifier of the “Halibus” sonar recorder, and the output of the other - to the similar amplifier of the “Sonch” sonar recorder. The audio outputs of each of the amplifiers are loaded on amplitude detectors, which, in turn, are loaded on the same diode-resistive approximators with transmission coefficients that are measured logarithmically depending on the level of the signal at the outputs of the amplifiers. The output of one of the approximators is loaded onto the resistive adder directly, and the second through the inverter. The output of the adder through a linear voltage amplifier is connected to the M265M millizoltmeter, which

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used as a range indicator.

The system works in the following way. The hydroacoustic mark 1 installed on the fish simultaneously emits two sound bursts from sources 2 and 3. Both sound bursts spread in the aquatic environment, and at the sound antenna input each of them creates sound pressure,

which, taking into account the attenuation on the path between the tag and the antenna, is determined by the following relation:

p, -. pjf

(one)

where RO is the sound pressure generated by each of the sources at a distance of Go 1 m;

P 0.036f - attenuation coefficient of 0sonic energy in the aquatic environment

at a frequency of radiation equal to f. From the output of the sound antenna 4, electrical signals proportional to the sound pressure generated by the corresponding signal from the sources 2 and 3 of the sound vibrations in the tag are fed to the inputs of filters 5 and 6. The pa outputs of filters 5 and 6 separate the signals with frequencies , they are the frequencies of sources 2 and 3, which are fed to amplitude detectors Q tori 7 and 8. The transmission coefficients of amplitude detectors are chosen so that at equal sound pressures at the input of the sound antenna from sources 2 and 3 at a distance of th amplitude The signal voltages at the outputs of the detectors 7 and 8 were the same. In this case, at a distance r, the ratio of the output voltages at the outputs of the detectors 7 and 8, taking into account expression (I), is determined by the following relation

40

  - jioO P h)

(2)

where p2 is the attenuation of the energy of sound vibrations from a source with a radiation frequency h,

PI is the attenuation of the energy of sound oscillations from a source with a radiation frequency fi.

From relation (2), the expression for the distance between the fish tag and the receiving sound antenna is defined as

one

55

2 (R 2-p i) K (lgU, - IgUa),

(lgU, -lgU2)

(3)

where k

one

2 (p

Thus, to determine the distance r, it is necessary to perform operations corresponding to the expression (3). For this purpose, the first 9 and second 10 logarithmic amplifiers, inverter 12, adder 11, linear amplifiers 13 serve. The signal from the output of the first amplitude detector 7 is amplified by a logarithmic amplifier and fed to the adder I. The signal from the output of the second amplitude detector 8 is amplified by a second logarithmic amplifier 10 and is fed to the same adder 11 through the inverter 12. At the output of the adder 11, a signal is generated that is proportional to the difference in the logarithms of voltages from each of the sound signals emitted by sources 2 and 3 in the body of the labels and. The resulting difference is amplified using a linear amplifier 13 K times, after which the voltage corresponding to the distance r between the fish tag and the receiving sound antenna 4 is fed to the range indicator 14.

With the help of the proposed system, the reaction of fish to light stimuli was investigated. Using it made it possible to study the peculiarities of the effect of short-term light stimuli on fish migration. In particular, it was possible to fix fish reactions in the form of throws at a distance of up to 10 m with a duration of 0.05–0.1 s with the receiving equipment located at a distance of more than 100 m from the tagged fish under study.

The receiving equipment is removed from the fish, therefore it does not affect the natural behavior of the latter, which increases the purity of the experiment.

Claims (1)

Invention Formula A system for studying fish migrations in natural conditions, containing a sonar tag for fish in the form of a sealed enclosure containing two oscillation sources, one of which is a sound oscillation source, a filter, an amplitude detector, a range indicator, and a spatial directional receiving sound antenna with azimuth and tilt angle indicators connected through a filter to an amplitude detector input, characterized in that, in order to increase the range of the system in seawater, it is possible studying the effects of short-term stimuli on fish and providing a more detailed study of the behavior of fish in natural conditions, it is equipped with a second filter, a second amplitude the detector, two logarithmic amplifiers, an inverter and a linear amplifier, and the second source of oscillations used a source of acoustic oscillations operating at a frequency different from the frequency of the first source of acoustic oscillations, while the input of the second amplitude detector is connected the first and second amplitude detectors are connected respectively to the inputs of the first and the second logarithmic amplifiers, the output of the first logarithmic amplifier is connected to the first input of the adder, the output of the second logarithmic amplifier is connected via an inverter to the second input of the adder, the output of which is connected to the input linear amplifier, and the output of the latter is connected to the range indicator.