From 2005 to 2006, the author conducted wild-breeding experiments on the surface of Wugou River in Guangming Village, Dagang Town, Yandu District, Yancheng City. The project yielded significant economic returns and is now being shared with detailed insights into the experimental process.
**I. Experimental Conditions**
The test site was a former waste river, characterized by a calm environment and easy management. The river was 15 to 21 meters wide and extended for 600 meters, with a water area of approximately 15 mu at normal water levels. The water quality was free from industrial and agricultural pollution, meeting the standards outlined in NY5051-2002. The embankments were solid, not prone to flooding, and the riverbed was relatively flat. The annual water level fluctuation was less than 0.5 meters, and during the breeding season, the water depth ranged between 1.5 to 2 meters with a slow flow rate of up to 5 cm/s. Before stocking, the levees were reinforced, and black-leaf algae and water hyacinths were planted, covering about 50% of the water surface. One end of the river had a levee, while the other end featured a barrage equipped with floating gates that could be manually adjusted.
**II. Source of Fingerlings and Stocking**
The fingerlings were collected from natural waters in early May, with sizes ranging from 30.5g to 45g per fish, averaging 40g. They were healthy, disease-free, and robust. A total of 10,000 fingerlings were stocked, along with an additional 3,000 fish of larger size (about 100g each), mainly consisting of squid species.
**III. Feeding Practices**
During the early breeding phase, fresh small fish were the main feed, supplemented with animal offal, cocoon, cockroach, and compound feed. In later stages, frozen sea fish were used. The daily feeding amount varied depending on fish type and water conditions. From May to June, the feeding rate was 5%, rising to 9% from July to August, then dropping to 5% in September, and staying between 0.5% to 4% from October to April. Summer and autumn were critical periods for growth, so maintaining a steady feed supply was essential.
**IV. Routine Management**
A dedicated staff member monitored the estuary. Special attention was given to checking fence facilities during early stocking and near harvest time. The floating doors of the netting were kept about 0.5 meters above the water surface. Adjustments were made during weather changes or floods, and debris in front of the fences was regularly removed to ensure smooth water flow. Although the ecological conditions were favorable, disease prevention measures were still necessary. Seedlings were soaked in a 10 mg/L potassium permanganate solution for 5 minutes before being placed in the river. Precautions such as bait bagging were taken before the epidemic season.
**V. Adult Fishing**
Adult fish were caught using various methods, including hook fishing, cage trapping, and large nets. In this experiment, the fish were sent directly to a processing plant. Fish were first caught in the net in late March and then harvested by draining the pond using a dam. Due to the fish's tendency to burrow in mud, multiple captures were needed. The caught fish were temporarily stored in cages or buckets before being shipped, with smaller sizes sorted out first.
**VI. Test Results**
1. A total of 3,298.4 kg of Chinese wolfberry were harvested, with an average weight of 0.62 kg per fish and a survival rate of 53.2%. Polycultured pupae reached 3,283.2 kg, averaging 1.2 kg per fish, with a survival rate of 91.2%.
2. Total output value amounted to RMB 61,900, with RMB 48,156.64 from Uzbek (RMB 14.6/kg) and RMB 13,789.44 from other production (RMB 4.2/kg).
3. Total costs were RMB 34,500, including RMB 5,200 for fish species (Uzbek: RMB 4,000; other species: RMB 1,200).
4. Net profit was RMB 2.74, with an average income of RMB 1,826.67 per mu and an input-output ratio of 1:1.79.
**VII. Summary and Discussion**
1. The experiment demonstrated that semi-open channels can effectively mimic wild breeding conditions for blackbirds, especially when sufficient feed is available. This method shows promise for wider application.
2. The low survival rate of 53.2% was attributed to injuries during capture, handling, and transport, as well as the strong wild traits of the fish, which led to high mortality due to fungal infections. It is recommended to use self-bred fish to improve survival rates.
3. Aquatic plants, both submerged and floating, are essential for improving water quality and providing shade during hot seasons. Planting should begin around the Qingming Festival, starting at 10% of the water surface and gradually increasing to 40% as temperatures rise. In winter, coverage should be reduced to around 10%.
This comprehensive approach highlights the potential and challenges of river-based aquaculture, offering valuable insights for future projects.
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