Anesthesia Breathing Circuit Sterilizer Anesthesia Breathing Circuit Sterilizer,Hydrogen Peroxide Disinfection Machine,Hydrogen Peroxide Sterilizer,Anesthesia Machine Ventilator JIANGSU JIANLAIBANG MEDICAL EOUIPMENT CO.,LTD , https://www.jsjlbmed.com
Subsequent investment seedlings develop large-scale river crab technology
Traditional crab farming methods typically involve stocking crabs one at a time, with uniform size specifications. However, over the past few years, practical experience has shown that using split seedlings in natural water bodies can yield better economic returns. The results of this trial are summarized as follows:
The test site covered 158 acres of natural river gullies, with stable water flow and an average depth of 2.1 meters, with some areas reaching 3.5 meters deep and others just 1 meter shallow. About two-thirds of the area was shallow, with black loam as the bottom substrate.
Aquatic plants were introduced from August 2004 to May 2005, including 21 tons of algae. In early April 2005, 203 kg of *Albus* seeds were planted. Deep-water zones were seeded with goldfish algae, while shallow areas were planted with *Vallisneria*, achieving 70-80% coverage.
Snail populations were also enriched, with 36 tons of snails introduced between November 2004 and April 2005, including both native and 500 kg of added snails.
Due to the large scale and connection to surrounding waters, dry pond cleaning wasn't feasible. Instead, nets, gill nets, and osprey techniques were used to remove wild fish. In November 2004, 14 tons of quicklime were applied, followed by 6 tons of lime water in February 2005 to prepare the water for seedling release. Water clarity reached 1.5 meters, with a pH of 7.5–8.5.
Seedlings were sourced from the Sheyang Nursery in Jiangsu Province, imported via the Yangtze River system. Crabs were acclimated locally to reduce stress from long-distance transport. In August 2004, 50,000 crabs (400–500 per kg) were stocked, followed by 31,000 crabs (120–160 per kg) in July 2005, totaling 81,000 crabs across 512 acres on average.
In addition to crabs, 100 kg of young shrimp, 2,500 carp, and 1,500 carp fry were introduced in December 2004 and May 2005. Seedlings were treated with 3–5% saltwater for 10–15 minutes to eliminate surface bacteria and parasites.
Feeding began in mid-March with chilled fish and small amounts of formulated feed. From May to September, sufficient bait was provided to ensure good feeding, with 8% of body weight used daily, depending on crab activity. *Vallisneria* served as an indicator—when it was abundant, crabs had enough food; when leaves were eaten, feeding was increased. Twenty to thirty days before harvest, high-protein feed was used to improve crab quality and market value. A total of 52,000 kg of feed was used throughout the year.
Escape prevention was critical. Double-layered barriers were installed at inlets and outlets, with daily checks to ensure no crabs escaped, especially during rainy seasons when water levels rose rapidly.
Fishing started in late September, peaking in early October, using crab traps.
Economically, 8,714 kg of marketable crabs were harvested, with an average weight of 215 grams and a survival rate of 50.03%. Additional catches included 503 kg of carp, 8,493 kg of other fish, and 1,351 kg of green shrimp. Total revenue reached 955,000 yuan, with crabs contributing 802,000 yuan. Total costs were 3.8135 million yuan, resulting in a profit of 573.65 million yuan, or 3,631 yuan per mu.
Key lessons included the need to secure blocking facilities with stakes due to unstable water levels and frequent inflows. Patrols were intensified during rainy and flood seasons. Timely harvesting was essential to prevent escape and maximize yield.