SU1282835A1 - Method of concentrating fish - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to the field of fish farming, in particular to methods of concentrating fish. It can be used to control the movement of fish when catching ponds. The aim of the invention is to reduce the cost of the method, ensuring the concentration of fish near the surface of the water and thereby simplifying its catch from the reservoir. In order to achieve the goal, a trichodermin empirical formula is introduced into the water as a substance having repellent properties in concentrations from 30 to 50 mg / l.

Description

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The invention relates to fish management, in particular to methods of concentrating fish, and can be used to control the movement of fish when fishing in lakes for the next time they are populated with highly productive fish species.

The aim of the invention is to reduce the cost of the method, to ensure the concentration of fish near the surface of the water and to simplify its height from the reservoir. The use of the proposed method makes it possible to completely catch unwanted fish from the reservoir and, moreover, since time to ascend from individual fish species to the surface differently, the sorting of the fish is accelerated.

The fish concentration method is carried out as follows.

Trichodermin in a concentration of 30-50 mg / l is introduced into a reservoir intended for the subsequent cultivation of valuable fish species. Trichodermin is applied directly to the reservoir by spraying it on the surface of the water using a standard sprayer

After some time (during the day) the fish rises to the surface of the water, where it can easily be caught (removed from the reservoir) with any known fishing gear.

Trichodermin is an antibiotic that is a product of the vital activity of the fungus Trichodern virida l. Its empirical formula)

To ensure a complete ascent of fish, it is necessary to bring trichodermin in concentrations of 30–50 mg / l, since at lower concentrations the fish of its zone of action only drifts to the side, but does not float, and at higher concentrations, an unnecessarily high consumption of trichodermin will be observed and the effect of the ascent of the fish does not increase.

Trichodermin, having repellent properties, has no toxic effect on food invertebrates, in particular, on zooplankton.

The absence of pathological changes in fish found in clear water for three days after exposure to trichodermin, and the favorable results of the organoleptic studies of these fish make it possible to use the caught fish for food. The danger of any undesirable consequence of the consumption of these fish for food is excluded due to the well-known mass distribution in nature of the fungus producing Trichodermin, as well as the widespread use of Trichodermine in agriculture as a fungicide in doses exceeding the above. However, no adverse effects on the body of warm-blooded animals have been identified.

PRI me R 1. Experiments were performed on three types of fish: perch, carp and trout. Ten individuals of different-age perch, 10 carp yearlings and 10 trout fingerlings were placed in separate aquariums, which were filled with lake water. The fish were kept in this water for adaptation during the day. Then live water was added to the Trichodermin culture. At the same time, 8 series of experiments were conducted with different concentrations of the drug: 10, 20, 30, 40, 50, 60, 70 and 80 mg / l. A total of 24 aquariums were used simultaneously. The repetition of experiments in each series was threefold. Water temperature in all aquariums was equal. At the same time, the control groups of perch, carp and trout of corresponding ages were placed fe clean lake water in three aquariums. The observation was carried out for three days.

The average results for a series of experiments with perch are given in Table. 1, and with a carp and a trout - in tab. 2

It can be seen from the above data that, at a trichodermine concentration of 30 mg / l and above, all types of fish float to the surface of the water during the day. As expected, the trout's reaction to the drug was faster than that of perch and carp.

Example 2. In the Pond with a total area of 29 m, with an average depth of 0.7 m, the temperature of the water before treatment with Trichodermin was 50 perch, 30 hooks, 25 copies. roach, 25 year old carp and 25 year olds sang di. Then the pond was treated with trichoderm at a concentration of 40 mg / l.

The results of processing the pond showed that the ascent of fish occurred in the following sequence: first the hooks and yearlings sang di, then after 3 hours the perch, after 3-5 hours of roach, and last (after 5-8 hours) yearlings of carp.

Thus it was found that the rate of ascent of certain species of fish to the surface of the water is different.

PRI me R 3. Determine the reversibility of processes after the action of trichodermin. The experiments were conducted on trout fingerlings, carp yearlings and perch x of different ages. In the experiments used aquariums: 150 l. Five fish samples were placed in each aquarium. DP adaptations were carried out in lake water during the day. Then, trichodermin was introduced into the water at a concentration of 50 mg / l and the fish ascended to the surface of the water. For each fish species, 5 aquariums were used. Total used 15 aquariums. The repetition of the experience is 3 times. In order to establish the reversibility of the processes of fish that floated to the surface of the water, they were transferred to clean water from some aquariums - 24 hours after ascending, from others - after 36 and from third - after 48 hours. Observations were made for 3 days after transplanting fish into clean, no running water in a 150 l aquarium,

In the control aquariums, the fish were left in a solution of trichodermin. V. these aquariums at a concentration of 50 mg / ltrocadramine fish of all species died after 48 hours of exposure.

The results of observations of fish transferred to clean water are given in table. 3

Presented in table. 3 data indicate that trout fingerlings are more sensitive to trichodermin compared to other fish species. It should be noted that on the ground day after the transfer of fish to clean water, they react poorly to external stimuli (sound and mechanical effects). At the subsequent time after transferring them to clean water, the response of the surviving fish did not differ from the control

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Organoleptic studies on these fish showed that the consistency and taste of the fish did not change compared with the controls.

Thus, studies have shown that the caught fish can be transplanted into another body of water or, after being held in clean water for 72 hours, be used.

PRI me R 4. Toxicity of trichodermine for feeding invertebrates. Experiments were carried out in 1 l glass beakers. Water was taken from natural reservoirs. Ten glasses of Daphnia (Daphnia magna Straus) were placed in glasses. Then the preparation was applied at a concentration of 30, 50, 80, 100 mg / l. Water temperature 16 s, pH 7.8. Control served as water in aquariums without the drug. Experiments were performed in 2-fold repetition. The observations were carried out for 10 days after the application of the drug according to the Lesnikov method.

The results are shown in Table. four.

Given in Table. 4 evidence suggests that trichodermin, even at a concentration of 100 mg / l, does not have a negative effect on feeding invertebrates, in particular daphnia.

Example 5. The stability of the biological activity of trichodermin in fish on perch of different ages, as an ichthyological test object, highly sensitive to different validates, was tested. pesticides. The experiments were carried out in laboratory conditions. In 12 aquariums with a capacity of 150 l, the preparation was applied at a concentration corresponding to its upper boundary, i.e. 50 mg / l. In each experiment 5 fish were used. In 6 aquariums, the fish were placed immediately after the application of the preparation, in 6 others - ten days after the application of Trichodermin. Temperature

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The observed fish before and after their stay in clear water for 72 hours showed the following: in individuals, before they were transferred to clear water, the swim bladder and intestines were swollen. In fish that remained alive, after 72 hours of being in clean water, no pathological changes were found.

a group of fish in three aquariums with clean water were placed control fish. The repetition of all experiments is threefold.

All fish placed in the aquarium 5 immediately after the application of the preparation, floated to the water surface during the day. Two days later the fish remained alive. After four days, the contents of these fish in an acgroup of fish in three aquariums with clear water were placed in control fish. The repetition of all experiments is threefold.

All fish placed in the aquarium immediately after the application of the preparation, floated to the surface of the water during the day. Two days later, the fish remained alive. After four days of keeping these fish in ak5128283

Variumah with trichodermin, they died. In experiments in which fish were placed in aquariums 10 days after the preparation was removed, the fish retained their normal swimming ability. When keeping these fish for 10 days. all fish remained alive and responded normally to various external stimuli. The behavior of experimental fish placed in aquariums after 10 days. after making 10

parata, did not differ from the behavior and reactions of the controls.

These experiments showed that the ichthyotoxic activity of trichodermin at a concentration of 50 mg / l

disappears completely due to its introduction into the water.

10 days after

Claims (1)

Invention Formula The method of concentrating fish by introducing into the pond a substance possessing repellent properties, characterized in that, in order to reduce the cost of the method, to ensure the concentration of fish near the surface of the water and thereby simplify its catch from the reservoir, trichodermin is used as a repellent substance, which is introduced into the reservoir at concentrations of 30-50 mg / l. Table 1 table 2 Control thirty 50 80 100 1282835 10 Tables a- 4 75 87 85 80 70