Control method of omnivorous fish and application thereof

Abstract

The invention relates to an omnivorous fish control method and application thereof, and belongs to the technical field of water ecological restoration. The invention provides a control method for omnivorous fishes. The control method comprises the following steps: putting carnivorous fishes into a small water body containing the omnivorous fishes; the mass ratio of the carnivorous fishes to the omnivorous fishes is 1: (1-3). According to the method, carnivorous fishes with a specific proportional relation are put into a small water body containing omnivorous fishes, so that the biomass of the omnivorous fishes can be remarkably reduced, a cascade effect is triggered, the predation of the omnivorous fishes on zooplankton is reduced, the biomass of the zooplankton is increased, the predation of the zooplankton on planktonic algae is increased, and the survival rate of the zooplankton is increased. Furthermore, the disturbance of omnivorous fishes to the bottom mud can be reduced, and the total suspended matter concentration is reduced, so that the effect of repairing the water quality is achieved.

Description

Technical Field

[0001] This invention relates to the field of aquatic ecosystem restoration technology, and in particular to a method for controlling omnivorous fish and its application. Background Technology

[0002] Fish in small aquatic bodies are typically benthic omnivorous fish such as crucian carp and common carp. These fish live at the bottom of the water, and their foraging activities reduce the number of large zooplankton, leading to insufficient phytoplankton feeding pressure. Furthermore, their benthic omnivorous nature greatly disturbs the bottom sediment, causing water turbidity, increased nutrient release, and water quality deterioration. These fish are highly resilient (e.g., tolerant of low temperatures and low oxygen levels), have high reproductive capacity, and adapt to various habitats (e.g., aquatic plant areas, open water areas), making them difficult to remove. Existing artificial capture methods can only maintain their effectiveness for a short period, are unsustainable, and are costly in terms of manpower and resources.

[0003] Based on this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling omnivorous fish and its application, so as to solve the problem of water quality deterioration in small water bodies caused by benthic omnivorous fish in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for controlling omnivorous fish by introducing carnivorous fish into a small body of water containing omnivorous fish. The mass ratio of carnivorous fish to omnivorous fish is 1:1~3.

[0006] Preferably, the omnivorous fish include one or more of crucian carp, carp, tilapia, and loach.

[0007] Preferably, the small body of water includes one of ponds, lakes, and ditches.

[0008] Preferably, the carnivorous fish includes one or more of catfish, mandarin fish, and snakehead.

[0009] This invention provides the application of the control method described above in improving water quality.

[0010] This invention provides the application of the control method described above in increasing the biomass of zooplankton in aquatic bodies.

[0011] This invention provides the application of the control method described above in reducing the biomass of phytoplankton in aquatic bodies.

[0012] The present invention has the following technical effects and advantages: This invention introduces a specific ratio of carnivorous fish into small bodies of water containing omnivorous fish. This significantly reduces the biomass of omnivorous fish, triggering a cascade effect that decreases the predation of zooplankton by omnivorous fish, thereby increasing zooplankton biomass. This, in turn, increases zooplankton predation on phytoplankton, inhibiting phytoplankton growth. Furthermore, it reduces disturbance to bottom sediment by omnivorous fish, lowering the total suspended solids concentration, thus achieving the effect of water quality restoration. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the embodiment scheme; Figure 2 For the experimental design scheme diagram; Figure 3 The results show the determination of total nitrogen, total phosphorus, solid particles and chlorophyll α content in water samples from different treatment groups; Figure 4 The results show the biomass measurements of zooplankton, phytoplankton, and benthic omnivorous fish in different treatment groups. Detailed Implementation

[0014] This invention provides a method for controlling omnivorous fish by introducing carnivorous fish into a small body of water containing omnivorous fish. The mass ratio of carnivorous fish to omnivorous fish is 1:1~3.

[0015] In this invention, the omnivorous fish include one or more of crucian carp, carp, tilapia, and loach.

[0016] In this invention, the small body of water includes one of ponds, lakes, and ditches.

[0017] In this invention, the carnivorous fish includes one or more of catfish, mandarin fish, and snakehead.

[0018] This invention provides the application of the control method described above in improving water quality.

[0019] This invention provides the application of the control method described above in increasing the biomass of zooplankton in aquatic bodies.

[0020] This invention provides the application of the control method described above in reducing the biomass of phytoplankton in aquatic bodies.

[0021] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0022] Example

[0023] The schematic diagram of this embodiment is as follows: Figure 1 As shown, the specific solution is as follows: The experiment was conducted in six cement pools on the shore of Taihu Lake in Dongshan County, Suzhou. Each cement pool was 3m long and 3m wide, and 2.5m deep. Two months before the experiment, each cement pond was drained, cleaned, and left to dry for half a month to remove any remaining fish eggs. Two weeks before the experiment, a large plastic frame (2m long, 1.5m wide, 0.15m high) was placed at the bottom of each cement pond. A 10cm thick layer of sediment (taken from surrounding ponds, sieved, mixed, and then packaged) was placed in the frame. To simulate a real pond environment, a 2mm mesh wire was tightly nailed to each frame, maintaining a 5cm distance from the sediment. A 2m long, 85mm wide, 18mm thick wooden board was also nailed to the frame for placing artificial aquatic plants. Artificial aquatic plants resembling *Vallisneria natans* were selected (to provide cover for carnivorous fish such as mandarin fish, which hunt by ambush and need to hide in grass or crevices between rocks) (maximum plant height 1m, single plant area 0.01m²). 2 The plants were evenly fixed onto each wooden board at a density of one plant per square meter. Then, sieved (3mm mesh) Taihu Lake water was added until it reached a height of 1.5m from the bottom of the cement pool. The specific experimental design diagram is shown below. Figure 2 As shown. One week before the experiment (June 22), 4500 transparent Daphnia magna were added to each of the six cement pools. Daphnia hyalina The fish (caught from East Taihu Lake) were allowed to reproduce and grow for a week (June 29th), after which 40 crucian carp (2.44g / m³) were added to each of the six cement ponds. 2 The fish was 4.50±0.12cm long and weighed 0.55±0.06g, forming a food chain of "crucian carp-Daphnia hygroscopica-plankton".

[0024] Six cement ponds were divided into two groups: three ponds for mandarin fish and three ponds for the control group. On June 29th, one new-age mandarin fish (11.23±0.52 cm in total length and 11.27±1.21 g in weight) was added to each of the three mandarin fish ponds in the control group, ensuring a mandarin fish to crucian carp weight ratio of 1:2 (based on the survey ratios of other carnivorous fish in 36 lakes in the middle and lower reaches of the Yangtze River). No fish were added to the three control ponds. The experiment lasted 21 days, with mixed water samples collected every three days to measure total nitrogen (TN, in mg·L⁻¹). -1 Total phosphorus content (TP, in mg·L⁻¹) -1 ), the content of solid particles (TSS, in mg·L) -1 ) and chlorophyll α content (Chl-α, in μg·L -1Concentration. At the end of the experiment, zooplankton and phytoplankton samples were collected, stained with Lugol's solution, counted under a microscope, and the biomass was calculated. All water in the cement tanks was drained, and benthic omnivorous fish (crucian carp) were captured, weighed, and their biomass was calculated. The biomass calculation method is as follows: Biomass = Mass / Area; The mass refers to the mass of zooplankton, phytoplankton, or benthic omnivorous fish (crucian carp); The area refers to the bottom area of ​​the cement pool.

[0025] The results of the determination of total nitrogen content, total phosphorus content, particulate matter content and chlorophyll α content in water samples from different treatment groups are as follows: Figure 3 As shown in the figure, the red line represents the control group, and the blue line represents the mandarin fish group. The horizontal axis represents the number of experimental days, and the vertical axis represents the content. The biomass of zooplankton, phytoplankton, and benthic omnivorous fish in different treatment groups are shown in the figure. Figure 4 As shown.

[0026] according to Figure 3 and Figure 4 The results showed that the total nitrogen, total phosphorus, particulate matter, and chlorophyll α content in the mandarin fish group were lower than those in the control group. The biomass of crucian carp and phytoplankton was significantly lower in the mandarin fish group, while the biomass of zooplankton was significantly higher. This indicates that the introduction of mandarin fish reduced the biomass of crucian carp, triggering a strong cascade effect that increased zooplankton biomass, thereby inhibiting the growth of phytoplankton. Simultaneously, the predation of crucian carp by mandarin fish reduced the disturbance of bottom sediment by crucian carp, lowering the total suspended solids concentration. In summary, stocking mandarin fish at a weight ratio of 1:2 to crucian carp effectively suppressed the crucian carp population and mitigated its negative effects on water quality.

[0027] As can be seen from the above embodiments, the present invention provides a method for controlling omnivorous fish and its application. The present invention introduces carnivorous fish in a specific proportion into a small body of water containing omnivorous fish. This significantly reduces the biomass of the omnivorous fish, triggering a cascade effect, reducing the predation of zooplankton by the omnivorous fish, increasing zooplankton biomass, thereby increasing zooplankton predation on phytoplankton, inhibiting phytoplankton growth, and also reducing disturbance of bottom sediment by the omnivorous fish, lowering the total suspended solids concentration, thus achieving the effect of water quality restoration.

[0028] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling omnivorous fish, characterized in that, Introduce carnivorous fish into small bodies of water that already contain omnivorous fish; The mass ratio of carnivorous fish to omnivorous fish is 1:1~3.

2. The control method according to claim 1, characterized in that, The omnivorous fish include one or more of the following: crucian carp, common carp, tilapia, and loach.

3. The control method according to claim 1, characterized in that, The small body of water includes one of the following: pond, lake, and ditch.

4. The control method according to claim 1, characterized in that, The carnivorous fish include one or more of the following: catfish, mandarin fish, and snakehead.

5. The application of the control method according to any one of claims 1 to 4 in improving water quality.

6. The application of the control method according to any one of claims 1 to 4 in increasing the biomass of zooplankton in aquatic bodies.

7. The application of the control method according to any one of claims 1 to 4 in reducing the biomass of phytoplankton in aquatic bodies.

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