A method for constructing a fish feeding ground for river fish

Abstract

The application discloses a method suitable for creating a fish baiting field in a river, and comprises the following steps: S1, preliminary investigation; S2, selection of a location for creating the baiting field; S3, arrangement of ecological ditches; S4, bottom transformation; S5, microhabitat creation in a river bank zone: a group of submerged dams are arranged in an array on a gentle slope beach on one side or both sides of the target river section, the submerged dams are in a C shape, in the same submerged dam group, all the openings of the submerged dams are directed to the river bank close to the submerged dam group, and the adjacent two rows of the submerged dams are staggered; and S6, plant community restoration. The application has the advantages of simple structure, convenient construction, interception of local area non-point source pollution, reduction of pollution load into the river, better promotion of protection and maintenance of fish resources, and contribution to formation of a good river water ecological system.

Description

Technical Field

[0001] This invention relates to the field of aquatic ecosystem restoration technology, specifically to a method for creating feeding grounds for fish in rivers. Background Technology

[0002] Feeding grounds are important places for fish to gather, feed, and fatten up. They are generally distributed in wetlands along river and lake shores, sandbar wetlands, river confluences, and river mouths into lakes (reservoirs). These areas have wide water surfaces and slow currents. Due to the constant flow of water over the years, they bring rich nutrients from upstream and surrounding areas, with high organic matter and food biomass, which can meet the needs of fish to gather, fatten up, and grow. If the water quality, water flow, and bottom conditions in this area are good, it can also attract juvenile fish to swim upstream to feed.

[0003] Under natural conditions, topography, bottom sediment, flow velocity, riparian vegetation, aquatic plants, and water quality are all important factors affecting fish feeding grounds. With rapid economic development, human activities such as pollution discharge, sand dredging, silt removal, aquatic plant clearing, dam and revetment construction, riverside roads, and river channel management have adversely affected the aquatic ecological environment. Fish habitats for feeding are damaged or lost, and the quantity and diversity of aquatic biological resources decrease. Therefore, given the decline in the quality of fish feeding habitats and habitat shrinkage, taking certain ecological restoration measures to restore the structure and function of fish feeding and habitats is particularly important. This is also a realistic choice for protecting natural fish resources in the context of the deepening development of rivers and lakes.

[0004] There is relatively little research in my country on the restoration and creation of fish feeding grounds. In recent years, as the concept of aquatic ecological protection has gradually gained popularity, some researchers have begun to focus on the field of fish habitat restoration and have carried out the research and development of applicable technologies, resulting in some good technical solutions. For example, the invention "A Vertical Slit Fishway with Small Foraging and Overwintering Ground Functions" (Chinese Patent Application No. 202110331261.1) invented a vertical slit fishway with small foraging and overwintering ground functions, constructing the fishway into an open small water area suitable for fish foraging and overwintering, which can not only cultivate a long-term stable habitat, breeding and migration space for local fish, but also extend the usage time of the fishway; the invention "A Composite Ecological Slope Protection for Restoring Habitat for Fish Laying Sticky Eggs in Rivers" (Chinese Patent Application No. 202110263173.2) invented a composite ecological slope protection for restoring habitat for fish laying sticky eggs in rivers, solving problems such as the creation of microenvironment for fish spawning, temporary shelter, and convenience of egg protection behavior in terms of slope protection material, shape, growth of submerged plants, and convenience of microbial biofilm formation; the invention "Method for Constructing Multi-morphic Habitat for Fish in Composite Plant Patches" (Chinese Patent Application No. 20210331261.1) 110933124.5) divides the area for constructing fish habitats into multiple grid units by dividing the area into grids. Different densities of aquatic plant communities are planted in each grid unit, and the improved water flow pattern makes it closer to the natural state familiar to fish, thereby effectively ensuring the survival and migration of fish. "Slope Protection Method for Improving Biodiversity and Stability of Habitats in High-Velocity Rivers" (Chinese Patent Application No. 201810106700.7) proposes to use reinforced concrete for foundation fixation, set up suitable fish habitat modules, and restore the healthy state of river biodiversity. "Method for Restoring Fishery Habitats in Tidal Flats of the Yangtze River Estuary" (Chinese Patent Application No. 202210677202.4) proposes to restore fishery habitats in suitable areas of the Yangtze River Estuary by using a combination of "planting + three-dimensional floating beds" to achieve the restoration of ecological functions such as spawning grounds, feeding grounds, and migration channels of regional fishery organisms.

[0005] The aforementioned technologies each have their own characteristics in the research and development of fish habitat restoration techniques, providing good technical ideas for fish habitat restoration. Feeding grounds are an indispensable part of the important "three grounds and one passage" habitat for fish. At present, there is still a lack of mature technical solutions for the restoration and creation of fish feeding grounds, and further technical research and development is needed. Summary of the Invention

[0006] Based on the above-mentioned prior art, the present invention provides a method for creating river fish feeding grounds. This method is simple and easy to construct. It can intercept local non-point source pollution while creating fish feeding habitats, reduce the pollution load entering the river, better promote the protection and maintenance of fish resources, and help form a good river aquatic ecosystem.

[0007] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows:

[0008] A method for creating feeding grounds for river fish includes the following steps:

[0009] S1. Preliminary Investigation:

[0010] Conduct a fish resource survey in the target waters to determine the fish population size, community structure, feeding habits, and existing feeding ground distribution, and identify the main target fish populations for feeding ground creation; S2, Selection of feeding ground creation sites:

[0011] The feeding grounds are selected and created in the target river section with suitable riverbed topography, bottom sediment, hydrology and light conditions for the target fish population to produce food. The target river section has gentle slopes on one or both sides.

[0012] S3. Layout of ecological ditches:

[0013] Ecological ditches extending along the shoreline are laid on the upper edge of the gentle slope beach on one or both sides of the target river section. The length of the ecological ditches is longer than the length of the target river section. The ecological ditches have a drop, and the collection area at the lowest point of the ecological ditches is within the target river section. At least one discharge outlet is set on the side of the ecological ditches facing the gentle slope beach, so that non-point source pollution flows into the corresponding gentle slope beach after being collected and purified by the ecological ditches.

[0014] S4. Substrate Improvement:

[0015] A subgrade layer is laid on one or both sides of the gentle slope of the target river section to modify the bottom sediment;

[0016] S5. Creation of riparian microhabitats:

[0017] A group of submerged dams is arranged in an array on the gentle slope beach on one or both sides of the target river section. The submerged dams are "C" shaped. In the same submerged dam group, all the openings of the submerged dams face the riverbank that is closer to the submerged dam group. The submerged dams in adjacent rows are staggered.

[0018] S6. Plant Community Restoration:

[0019] Plant vegetation on the gentle slopes and sandbars on one or both sides of the target river section.

[0020] Furthermore, the slope of the gently sloping beach is less than 5°.

[0021] Furthermore, if there are river embankments on the upper edge of the gentle slope beach on one or both sides of a natural river channel, ecological ditches shall be set outside the corresponding river embankments.

[0022] Furthermore, the ecological ditch is a permeable dry structure, with a filler layer and a vegetation layer inside. The filler layer consists of a gravel layer, a volcanic rock layer and a peat soil layer laid from bottom to top, and the vegetation layer consists of native herbaceous plants planted on the peat soil layer.

[0023] Furthermore, the cross-section of the ecological ditch is parabolic, with a side slope of 1:3 and a longitudinal slope of no more than 1%.

[0024] Furthermore, the submerged dam group is located between the highest and lowest water levels of the corresponding gentle slope beach.

[0025] Furthermore, within the same group of submerged dams, the same row of submerged dams is located on the same contour line.

[0026] Furthermore, the edge of the submerged dam is enclosed by multiple wooden piles whose lower ends are buried in the corresponding gentle slope beach, and the space enclosed by the wooden piles is filled with pebbles.

[0027] Furthermore, the gentle slope beach is provided with multiple tree roots arranged at equal intervals along its waterfront edge, with the roots of each tree root facing the water flow.

[0028] Furthermore, the vegetation species are local native plants, selected from one of the following: Bermuda grass, bullwhip, cattail, ryegrass, and vetiver.

[0029] Compared with the prior art, the beneficial effects and advantages of the present invention are as follows:

[0030] 1. This invention can create diverse river habitat structures, effectively improving problems such as the homogenization and hardening of river habitats caused by the construction of hard revetments, sand mining, and dams. Through artificial near-natural habitat creation, suitable foraging grounds can be provided for fish growth, feeding, and fattening, significantly improving the quality of fish habitats and mitigating the impact of water-related engineering construction on the aquatic ecosystem.

[0031] 2. This invention can determine the scale and area of ​​feeding grounds based on the resource quantity and feeding needs of different types of fish, combined with the location of fish spawning grounds, and manage and protect the feeding grounds, which can effectively increase the resource quantity of fish, promote the effective operation of fishery production, and better maintain the sustainable utilization and protection of fish resources.

[0032] 3. The method of the present invention is simple and easy to construct. By setting up ecological ditches, on the one hand, it can collect and intercept non-point source pollution in rivers to a certain extent, reduce the pollution load entering the river, protect the water quality of the river, and improve the river's aquatic ecological environment. On the other hand, it can promote the conversion of nutrients in non-point source pollution into feed organism productivity, avoiding the need to input feed organism productivity through other means. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the layout of the feeding area constructed according to the present invention.

[0034] Figure 2 This is a schematic diagram of the submerged dam structure.

[0035] Among them, 1-Target river section: 101-Gentle slope beach; 2-Ecological ditch; 201-Outlet; 3-Submerged dam: 301-Wooden pile, 302-Pebble; 4-Tree root; 5-Highest water level line; 6-Lowest water level line. Detailed Implementation

[0036] To make the objectives, technical solutions, and features of this invention more prominent and easier for those skilled in the art to understand, the method of creating a feeding ground for scraping fish such as yellowtail gudgeon and benthic fish such as catfish in a tributary of a reservoir is described in detail.

[0037] Example 1

[0038] Yellowtail gudgeon and catfish are important fish species in a large reservoir. Yellowtail gudgeon inhabit the lower water layer, scraping organic debris, sludge, surface residue, and foam containing euglena, as well as riparian diatoms such as feathery diatoms, bislit diatoms, birchalcedony diatoms, and oscillation algae. Catfish typically inhabit the bottom water layer, feeding on invertebrate larvae, aquatic insect larvae, mayflies, dragonfly nymphs, and chironomid larvae. Due to human activities such as hard revetment, agriculture, and sand mining, the reservoir area has a high non-point source pollution load, leading to a gradual shrinking of fish habitats and a year-on-year decline in fish populations. By implementing feeding ground creation measures in the reservoir area, favorable foraging conditions and food sources will be provided for fish, thereby increasing the resources of yellowtail gudgeon and catfish.

[0039] The specific method for creating the feeding grounds in this reservoir area is as follows:

[0040] 1. Preliminary investigation:

[0041] An investigation was conducted into the fish resources of the reservoir and the foraging habitats of yellowtail catfish and tilapia.

[0042] 2. Site selection for baiting area construction:

[0043] Based on the suitable riverbed topography, sediment, hydrology, and sunlight conditions required for the production of bait for yellowtail gudgeon and catfish, the starting point for establishing a feeding ground is located 5 km from the reservoir entrance at the end of the upstream river channel or the end of its tributary. The feeding ground has a shoreline length of 300 meters. This river section for establishing the feeding ground is designated as target river section 1. The right side of target river section 1 is the riverbank zone, such as... Figure 1As shown, the riverbank zone has gently sloping beaches with a gradient of less than 5° 101. This riverbank zone has a certain drop in elevation, and there are other suitable habitats for fish such as yellowtail gudgeon and catfish, such as spawning grounds and overwintering grounds, nearby. This is conducive to the construction of a complete set of habitats for fish such as yellowtail gudgeon and catfish, and to the improvement of the fish population of yellowtail gudgeon and catfish.

[0044] 3. Layout of ecological ditches:

[0045] An ecological ditch 2 is constructed along the upper edge of the gentle slope beach 101 of the target river section 1. The ecological ditch 2 extends along the shoreline, with its length determined by the terrain, generally not less than 1000m. The ecological ditch 2 is higher on both sides and lower in the middle. Seven outlets 201 are installed on the middle side of the ecological ditch 2 facing the gentle slope beach. Non-point source pollution is collected and purified through the ecological ditch 2 before flowing into the gentle slope beach 101. The main function of the ecological ditch 2 is to collect non-point source pollution from a local area of ​​the target river, introducing the preliminarily purified pollution into the foraging area, promoting the conversion of nutrients in the non-point source pollution into forage biological productivity.

[0046] Ecological ditch 2 is a permeable dry structure, containing a filler layer and a vegetation layer. The filler layer is 20-30cm thick and consists of a gravel layer, a volcanic rock layer, and a peat moss layer laid from bottom to top. The vegetation layer consists of native herbaceous plants planted on the peat moss layer, using a combination of manual planting and grass seed sowing.

[0047] The cross-section of ecological ditch 2 is parabolic, with a side slope of 1:3 and a longitudinal slope of no more than 1%. The width of ecological ditch 2 is 30-80cm, and the depth is 30-50cm.

[0048] 4. Substrate improvement:

[0049] A subgrade layer with a thickness of 30–50 cm was laid on the gently sloping beach 101 of the target river section 1 to improve the bottom sediment. The subgrade layer has good permeability and is generally composed of matrix materials such as large gravel, pebbles, and sand, of which large gravel and pebbles (long diameter ≥ 5 cm) account for no less than 60%.

[0050] 5. Creation of riparian microhabitats:

[0051] A group of submerged dams is constructed on the gentle slope 101 of the target river section 1, located between the highest water level 5 and the lowest water level 6. The group consists of multiple rows of submerged dams 3, the number of which can be determined based on the terrain conditions. For example... Figure 2 As shown, the submerged dam 3 is C-shaped, with an inner diameter of 80-150cm and a width of 10-80cm.

[0052] Submerged dams 3 in the same row are located on the same contour line. The spacing between submerged dams 3 is determined according to the terrain conditions, generally 200-500 cm. The submerged dams 3 in adjacent rows are staggered, and the openings of all submerged dams 3 face the riverbank that is closer to the submerged dam group.

[0053] The submerged dam 3 is enclosed by multiple wooden piles 301 whose lower ends are buried in the corresponding gentle slope beach 101. Each wooden pile 502 is buried at least 100cm into the gentle slope beach 101, and the portion extending beyond the surface of the gentle slope beach 101 is generally 20-50cm. The space enclosed by the wooden piles 301 is filled with pebbles 302, the diameter of which is 5-20cm.

[0054] Multiple tree roots 4 are arranged at equal intervals along the waterfront edge of the gently sloping beach 101, with the roots of each tree root 4 facing the water flow. The placement of tree roots 4 can create diverse habitats and at the same time mitigate the erosion of the riverbank by the water flow.

[0055] 6. Plant community restoration:

[0056] Vegetation was planted on the gentle slopes and sandbars of the target river section 1. This vegetation provides attachment sites for prey organisms and microorganisms, as well as a habitat for fish to forage, grow, and fatten. It also promotes the conversion of nutrients into prey organism productivity and water purification. The vegetation should consist of native species, with terrestrial and wetland plants generally recommended, such as Bermuda grass, purslane, cattail, ryegrass, and vetiver.

[0057] 7. Effectiveness Monitoring:

[0058] After the foraging area is constructed, underwater cameras are deployed to monitor the gathering of fish in the area. At the same time, manual fishing and acoustic detection methods are used to monitor changes in fish species, resource quantity, and fish density in the waters, and the effectiveness is evaluated.

Claims

1. A method for creating a fish feeding ground in a river, characterized by It comprises the following steps: S1, preliminary investigation: Carrying out fish resource investigation in the target water area to determine the size of fish population, community structure and diet in the target water area, and the distribution of existing foraging ground, and determine the target fish population for foraging ground construction; S2, selection of foraging ground construction site: The foraging ground is constructed in the target river section with suitable riverbed topography, bottom material, hydrology and light conditions required for the production of bait for the target fish population, and the target river section has a gentle slope on one side or both sides; S3, ecological ditch layout: An ecological ditch extending along the coastline is laid out on the upper edge of the gentle slope on one side or both sides of the target river section, the length of the ecological ditch is greater than the length of the target river section, the ecological ditch has a drop, and the lowest part of the ecological ditch is in the target river section, at least one more than one outlet is provided on the side of the ecological ditch facing the gentle slope, so that the non-point source pollution flows into the corresponding gentle slope after being collected and purified by the ecological ditch; The cross section of the ecological ditch is in the shape of a parabola, the slope is 1:3, and the longitudinal slope is not greater than 1%; The ecological ditch is a permeable dry structure, and the ecological ditch is provided with a filler layer and a vegetation layer, the filler layer is composed of gravel layer, volcanic rock layer and grass charcoal soil layer from bottom to top, and the vegetation layer is indigenous herbaceous plants planted on the grass charcoal soil layer; S4, bottom material modification: A cushion layer is laid on the bottom material of the gentle slope on one side or both sides of the target river section to modify the bottom material; S5, riparian zone microhabitat construction: An array of submerged dam groups is provided on the gentle slope on one side or both sides of the target river section, the submerged dam group is located between the highest water level and the lowest water level of the corresponding gentle slope; The submerged dam is in the shape of "C", in the same submerged dam group, the same row of submerged dams is located on the same contour line, and the openings of all the submerged dams are directed towards the river bank closest to the submerged dam group, and the adjacent two rows of submerged dams are staggered; S6, plant community restoration: Vegetation is planted on the gentle slope and beach on one side or both sides of the target river section.

2. The method for creating a river fish feeding ground according to claim 1, wherein: The slope of the gentle slope is less than 5°.

3. The method for creating a river fish feeding ground according to claim 1, wherein: If the upper edge of the gentle slope on one side or both sides of the natural river section is provided with a river embankment, the ecological ditch is arranged outside the corresponding river embankment.

4. The method for creating a river fish feeding ground according to claim 1, wherein: The edge of the submerged dam is surrounded by a plurality of lower end embedded wooden piles in the corresponding gentle slope, and the space surrounded by the wooden piles is filled with pebbles.

5. The method for creating a river fish feeding ground according to claim 1, wherein: A plurality of equidistantly arranged tree roots are arranged on the water edge of the gentle slope, and the root hairs of each tree root are directed towards the water flow.

6. The method for creating a river fish feeding ground according to claim 1, wherein: The vegetation type is local indigenous plant, and the vegetation type is selected from one of Cynodon dactylon, Imperata cylindra, Typha angustifolia, Lolium multiflorum and Helichrysum.

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