Detailed Explanation of the Code of Practice for Organic Food Fish Farming in Large and Medium-Sized Reservoirs

Code of Practice for Organic Food Fish Farming in Large and Medium-Sized Reservoirs

1 Scope of Application

The "Code of Practice for Organic Food Fish Farming in Large and Medium-Sized Reservoirs" specifies the requirements for site selection, farming and fishing techniques for organic food fish farming in large and medium-sized reservoirs.

2 Normative Reference Documents

The "Code of Practice for Organic Food Fish Farming in Large and Medium-Sized Reservoirs" is formulated with reference to GB/T19630 "Organic Food", GB11607-89 "Water Quality Standard for Fisheries", GB18 406.7 Fishery Water Bottom Sediment and other documents.

3 Definition of Organic Food

Organic food from large and medium-sized reservoirs refers to all agricultural and sideline products that come from organic farming systems, are farmed and processed in accordance with organic certification standards, and have been certified by a qualified independent certification body.

4 Selection of Farming Site

The water quality of the fishery waters shall comply with the provisions of GB11607-89, and the bottom sediment of the fishery waters shall comply with the provisions of GB18 406.7. There shall be no industrial waste or domestic garbage, no large plant debris or animal carcasses, no abnormal color or odor, and the structure shall be natural.

5 Farming Management

5.1 Selection of Fish Fingerlings

(1) Selection principles. The source must be clear; the fish fingerlings shall have smooth body surface and abundant mucus, pure, uniform and glossy body color, no stray colors or spots, intact fins and scales, no injury or disease, rapid swimming, active and vigorous swimming against the current, no deformities or injuries; fingerlings of the same batch shall be uniform in size with very small differences among individuals; the data for total length, body length, head length, body depth, body weight and other measurements of various sizes shall conform to the indicators stipulated in relevant national regulations.

(2) Use conventional fish fingerlings. The use of transgenic fish fingerlings bred through triploidy, parthenogenesis, genetic engineering and other technologies is prohibited.

(3) Fish fingerling species. Applicable species include grass crab, red tail, huluzi, silver carp, jihua, crucian carp, laotouyu, common carp, catfish, yellow catfish, makou, qinggen, qinglinzi.

5.2 Stocking of Fish Fingerlings

Organic food fish farming in large and medium-sized reservoirs requires low investment, no feeding, no fertilizing and no medication; the fish mainly rely on feeding on aquatic organisms. Reservoir fish farming should take into account the types and quantities of natural food in the water, so that the quantity and species of stocked fingerlings are adapted to them.

(1) Stocked fish species. Large and medium-sized reservoirs have abundant plankton, and filter-feeding fish have relatively rich natural food. Among filter-feeding fish, silver carp grows the fastest, has a large individual size and a wide source of fry, making it the main stocking target.

(2) Stocking size and quality. The fingerlings should be large in size and robust in constitution; this is the basis for high yield. Silver carp: 16-18 cm. Quality shall conform to the principles for selecting fish fingerlings.

(3) Stocking density. Stocking density: about 675 fish/hm2 per year. The stocking density shall be adjusted according to the growth rate and annual yield of various fish.

(4) Stocking time and location. Stocking is carried out on October 5, when the water temperature is 6-10 °C. The release sites are mostly chosen in the wind-sheltered, sun-facing upper reaches of the reservoir and along the banks where natural food is relatively abundant, with multi-point release.

(5) Stocking operations. Before entering the reservoir, the fingerlings shall be disinfected to prevent disease. Soak the fingerlings in 25-40 g/L salt water for 5-10 min. The temperature difference between the salt water and the reservoir water shall be less than 3 °C to benefit the health of the fish. After disinfection, slowly release the fingerlings into the reservoir. After the fingerlings enter the reservoir, the stocking personnel stand at the reservoir edge or on a boat and gently tap the reservoir water with oars to encourage the fingerlings to swim toward the larger water area.

(6) Precautions for release. Stocking shall be carried out on clear, warm days. When the fingerlings enter the water, they shall be poured in slowly, allowing them to swim freely into the water, and an aerator shall be provided.

5.3 Routine Farming Management Code

(1) Strengthen fishery administration. The core work of fishery administration is to properly handle the relationship of interests between the reservoir management agency and the people in the reservoir area. Fishery administration agencies in the reservoir area shall strengthen contact with village and township organizations in the reservoir area, rely on these units to educate workers and villagers to abide by the law, and regularly dispatch full-time personnel to patrol, stopping fish theft, electrofishing, fish poisoning and fish bombing in the reservoir, so as to ensure the steady development of reservoir fishery farming.

(2) Strengthen escape prevention management. Improve escape prevention facilities, regularly inspect fish-blocking facilities, and repair them promptly when damage is found. Especially during flood discharge in the flood season, management of fish-blocking facilities shall be further strengthened to minimize fish escape.

(3) Effectively prevent fish diseases. In large and medium-sized reservoirs, as long as high-quality, large-size fingerlings are strictly selected and used, and disinfection before the fingerlings enter the reservoir is carefully carried out, fish diseases generally rarely occur, and no chemicals are used to prevent fish diseases.

(4) Patrol the reservoir regularly. Patrol the reservoir every morning and evening, observe reservoir dynamics, and strictly control water quality. During patrols, observe whether the fish show warning signs, whether they swim alone away from the group, swim rapidly, or appear restless. When the fish are living normally, the water surface is calm and they are generally not easy to see. If abnormal activity is found, take measures promptly.

(5) Do a good job of reservoir cleaning and sanitation. Remove debris in the reservoir at any time to maintain a good reservoir environment. If dead fish are found, remove them promptly and do not discard them randomly, so as to avoid the spread of pathogens.

(6) Keep farming logs. The contents of the farming log include: fingerling stocking, fishing situation, water quality management, and income and expenditure.

6 Control Code for Inputs

The fish farmed at the base, Xingxing Reservoir, grow naturally, and no inputs are added (no feed, no fertilizer, no medication); the fish mainly rely on feeding on aquatic organisms.

7 Adult Fish Fishing Code

7.1 Commonly Used Fishing Gear

(1) Gillnet. A gillnet is a fishing gear formed by connecting several rectangular net pieces into a long belt-shaped net. When fishing in reservoirs, a 3-layer gillnet is used, that is, 2 layers of large-mesh netting with 1 layer of small-mesh netting sandwiched in between. The net piece length is 50 m, and the height can be determined according to the depth or shallowness of each part of the reservoir. Generally 10 m, 15 m or 30 m. The gillnet is set vertically on the migration channels of fish. When fish migrate or flee in fright, they become caught in the mesh or entangled in the net and are captured.

(2) Blocking net. Used to intercept fish schools and close off waters. It is a long belt-shaped net piece, with each section 50 m long, total length 2 times the widest part of the reservoir, and height determined by reaching the reservoir bottom.

(3) Stationary trap net. The trap net is set, according to the living habits of fish, in the reservoir spillway or other fish migration channels. Relying on the impact of water flow or artificial driving, fish swimming near the net mouth are forced into the net and captured. The stationary trap net is sewn from a bottom net, wall net, splayed net and cover net, forming a dustpan shape. Length 50 m, width 15 m, height 10 m-30 m. Mesh sizes are 3 cm, 5 cm, 8 cm, 12 cm, 16 cm, knotted from 43 strands/10×3-15×3 polyethylene twine.

7.2 Fishing Methods

Establish a skilled professional fishing team. According to the topography, landforms and fish activity patterns of the reservoir, use the combined fishing method of "driving, blocking, gilling and trapping" to catch adult fish. Process: haul in the net - lift the fish - place into the live fish boat - come ashore. The market size shall be based on market demand, with rational fishing, catching the large and leaving the small.

Because the water depth of the reservoir varies, using only one type of fishing gear results in a very low catch rate, and some fish species may not necessarily be caught. Using several types of fishing gear in combined operations gives better fishing results. The operation method is called the "driving, blocking, gilling and trapping (or pulling)" combined fishing method. "Driving" means driving with a 3-layer gillnet or towing a white board with a motorboat. Its purpose is to guide fish schools into the fishing area through frightening and driving. The order of driving fish is from inside to outside and from shallow water to deep water; floating gillnets and sinking gillnets are used alternately, advancing in turn toward the driving direction. Nets are set both horizontally and vertically, with the nets perpendicular to the reservoir bank, set in parallel every 50 m, cutting across the water surface. Drive 1-2 places each morning or each afternoon. Whenever all the gillnets have been set, immediately set the blocking net along the edge of the last gillnet to isolate the area that has already been driven from the area that has not yet been driven. "Blocking" means using the blocking net to block the fish within the fishing area. As the gillnets continue to drive forward, the blocking net also continues to advance. "Gilling" means using 3-layer gillnets to hang gillnets inside and outside the fishing area to catch fish that have not been driven into the trap net. "Trapping" or "pulling" means setting the trap net in the fish-catching area in advance, waiting for the fish to enter the net and then catching them, or using a seine net to catch all the fish in a small area in one haul. Trap nets are generally set in the evening and hauled in the next morning. Operating principles: unified command, clear division of labor; set nets according to fish, aim and catch; block at the front and drive from the rear, keep the fish passage open; where there are many fish, use dense nets, and fight a quick battle.