Russian squid introduction techniques

The carp, which has existed on Earth for over 200 million years, is often referred to as a "living fossil." Known for its delicious taste and high nutritional value, the fish is also prized for its eggs, which are called "black gold." There are 27 species of carp worldwide, with 8 species found in China. In recent years, China has begun to cultivate trout, but this effort is still in the early stages of exploration and technological development. On October 29, 1999, Zhejiang Wenzhou Shengfa Aquatic Products Co., Ltd. introduced 1,200 Russian squid specimens for adaptive breeding. Later, on September 10, 2000, they imported 2,500 more for productive trials. After more than a year of careful farming, both trials were successful, marking the first such case in Wenzhou City. The project recently passed the technical acceptance by the science and technology department and received positive feedback from experts. Below are the key technical details of the introduction. I. Biological Characteristics (I) Morphological Features Russian squids have a spindle-shaped body, with the head making up 17% to 19% of the total length. The snout is short and blunt, measuring 4% to 6.5% of the total length. Four tentacles are located between the snout and the mouth. There are no cilia on the mouth, which is small and prominent. The body is covered with five rows of bony plates, appearing pale golden yellow. The dorsal fin ranges from 27 to 51 rays, while the anal fin has 18 to 33 rays. The back is dark gray or blackish green, the sides are gray-brown, and the belly is light gray or yellowish brown. Juveniles typically have a blue back and a white belly. (II) Behavior and Habitat Russian squids prefer brackish water with a salinity range of 0 to 30 parts per thousand. They feed primarily on benthic mollusks, crustaceans, and small fish like shrimp and crab. Their optimal growth temperature is between 5°C and 30°C, with the ideal range being 18°C to 24°C. Dissolved oxygen levels should be above 6 mg/L, and the water hardness should be between 5 and 8. II. Materials and Methods (A) Pond Design The ponds are typically outdoor cement structures, each covering an area of 48 to 50 square meters, totaling 1.2 acres. The corners of the pools are rounded, and the bottom is shaped like a pot with a slope of 1% to 2%. A drainage outlet of 1 to 2 square meters is placed at the center. During water flushing, the flow angle is set at 45°, allowing the pool to rotate and automatically transfer debris to the center for removal. The ponds are easy to drain and provide sufficient water supply for micro-flowing or continuous water farming. Shade structures are installed above the pools, with nylon film used for insulation in winter and black sunshades for cooling in summer to prevent overheating. (2) Water Supply Water is supplied through flowing water from nearby ravines or by pumping groundwater from downstream reservoirs. The water quality must remain fresh, with a temperature range of 8°C to 30°C. Approximately 40% of the water is changed daily, and the depth is maintained at 1.2 to 1.5 meters. Before stocking, each pond is disinfected with “strong chlorine” at 1.5 ppm. After stocking, disinfection with “dibromohydantoin” at 0.5 ppm is done once a week. After disinfection, 3 ppm of photosynthetic bacteria is added to improve water quality. (3) Equipment and Facilities Each of the three ponds is equipped with a 1.5-kilowatt blower-type air pump, and a total of four such pumps are used across all ponds. Each pond also has a 1.5-kilowatt two-phase water pump. Air is injected once daily at noon, and the oxygen pump runs from 1:00 PM to 8:00 AM. From 4:00 AM to 7:00 AM, the water pump is turned on to exchange water and maintain adequate dissolved oxygen levels. Throughout the aquaculture process, measures are taken to enhance automatic water exchange and increase self-drainage. Nighttime patrols and water quality monitoring are strengthened. During summer and autumn, more water is exchanged to lower temperatures and increase oxygen levels, typically around 60% to 70% of the total volume per day. In each pond, 3 to 4 feeding stations are hung to monitor the carp’s feeding behavior effectively.

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