Zinc steel balcony Guardrail Railing Xuzhou Guifeng Metal Technology Co., Ltd , https://www.guifengmetal.com
In recent years, many fishermen working in bay scallop ponds have experienced disappointing results. While climate change has played a role, the main issues are often related to technical practices. To improve the economic returns from raising seedlings in ponds, it's essential to focus on enhancing the quality and survival rate of the seedlings. Here are some key points to consider:
First, the pond bottom should be a soft mud area, and the edges need to be properly compacted. Otherwise, strong winds can cause the water to become murky, clogging the mesh of the seedling bags. The size of the shrimp pond must match the number of seedlings. If the density is too low, resources are wasted; if it's too high, there may not be enough food later on. Maintaining good water quality and proper fertilization can boost the growth rate of scallops, as well as their survival and maintenance rates. Typically, the water clarity should be around 40 centimeters, with a yellow-brown or yellow-green color. The main food sources should include species like *Chaetoceros*, *Dinobryon*, *Skeletonema*, *Cylindrotheca*, and *Chlorella*. If there's an overgrowth of dinoflagellates, it’s important to change the water or move the seedlings to a different pond.
Second, the timing of juvenile release should not be too early. Once the juveniles are placed in the pond, if the water temperature remains below 13°C for a long time and is unstable, their metabolism slows down, and growth becomes sluggish. If they detach, reattachment is difficult. During cold air events, the juveniles may close their shells, which negatively affects their growth and survival.
Third, selecting high-quality juveniles is crucial. It's important to inquire about the source, specifications, probiotics used, incubation time, cultivation conditions, drug usage, and feeding types. Combining microscopic examination, visual inspection, swing tests, and cooling tests can help assess attachment, feeding behavior, vitality, and size—key indicators of seedling quality.
Fourth, seedling bags should be placed in a low-light water layer between 30 cm and 40 cm deep. The mud inside the bags should be cleaned regularly to improve water exchange and ensure adequate food supply. Using a large tube brush or a long-haired stiff brush is recommended to thoroughly clean the bags and remove debris blocking the mesh. Traditional methods using soft brushes are often ineffective at cleaning the mesh. This lack of proper cleaning leads to poor water exchange, making it hard for the larvae to get enough oxygen and nutrients. Additionally, seedlings should be moved out of overcrowded bags to prevent stress and weakness. Prolonged storage in plastic pots can also lead to drying and make it difficult to reintroduce them to the seedling bags.
Fifth, starting from the third day after the juveniles enter the pond, water should be changed daily by about 10%, and later increased to around 20%. Water changes help maintain good water quality, stabilize temperature, and promote flow that enhances water exchange within the seedling bags. On rainy days, the pond level should be raised as much as possible, and seedling bags should be lowered to avoid sudden salinity changes that could harm the juveniles. In the first three days after release, more than 30% of the water should be exchanged to make the pond environment closer to natural seawater, improving the juveniles' adaptability before they are released into the sea.
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