Several Measures to Shorten the Farming Cycle of Scallops
Scallops, I think, are very familiar to everyone in daily life. Many people really enjoy eating scallops. Scallops are one of the most common and most frequently eaten seafoods, and their nutritional value is also very high. Their protein content is very high, so the market demand for scallops is quite large.
Several Measures to Shorten the Farming Cycle in Scallop Farming
1. Timely seedling separation and cage turning. Scallops have two suitable-temperature growth periods each year. To grow undulate scallop (Chlamys farreri) seedlings to adult scallops requires going through three suitable-temperature growth periods, so in production it is necessary to seize the time and separate the seedlings before the end of August of that year. In this way, by the end of the year the shell height of the seedlings can reach 2 cm to 3 cm. When turning the cages for grow-out in April of the following year, large and small seedlings should be separated. The large seedlings can be harvested by October to November of that year; the small seedlings can only be harvested by April to May of the third spring.
In addition, the timing of cage turning also has a great impact on scallop growth. Generally, when the water temperature rises back to about 5°C in the following spring, the cages should be turned in a timely manner. If the cage turning work can be completed around mid-April, the scallops can make full use of the two suitable-temperature growth periods of that year and grow to a shell height of 6 cm to 7 cm.
2. Timely adjustment of the farming water layer. In winter (water temperature below 5°C) and summer (water temperature above 25°C), scallops are sunk to the middle and lower layers of seawater for farming, so that they can safely overwinter and pass the summer; in spring and autumn (water temperature 10°C to 23°C), scallops are raised to a water layer of 2 m to 3 m for farming. In these two seasons, because the upper-layer water temperature is suitable and food is abundant, it is beneficial to scallop growth.
3. Timely removal of fouling organisms. In scallop farming, large amounts of fouling organisms attach, causing poor water flow and reduced food, seriously affecting the growth and survival of scallops. Methods for removing fouling organisms include: 1) In summer, during the peak reproduction period of fouling organisms in July and August, sink the rafts to avoid the fouling water layer; 2) timely brush the cages and turn the cages. The net cages should be washed and brushed once every 1 month to 2 months, and the cages should be turned once each in April and August every year. Turning the cages can thoroughly remove fouling organisms.
4. Adjust buoyancy. As scallops continue to grow, and with the attachment of fouling organisms, the load on the raft frame gradually increases. In order to maintain a reasonable water layer and prevent the raft from sinking, buoyancy should be adjusted in a timely manner. The number of floats can be increased or double-row hanging floats can be used. In daily management, it is also necessary to frequently check for phenomena such as detached floats, loosened hanging ropes, broken or opened net cages, and net cages tangling with each other, and solve problems promptly when found.
5. Implement scallop-kelp intercropping and scallop-kelp rotational farming. In scallop farming, in order to improve the utilization rate of the sea area and increase economic benefits, scallop-kelp intercropping and scallop-kelp rotational farming are also commonly practiced. The metabolic products of scallops provide organic fertilizer for kelp and increase the nitrogen content of the sea area; the carbon dioxide exhaled by scallops increases the raw material for photosynthesis in kelp. The oxygen released by kelp through photosynthesis is beneficial to the respiration of scallops; the kelp thalli floating in the water provide shading for scallops, which is beneficial to the feeding and growth of scallops. Therefore, the two are mutually beneficial. The main practices in production are intercropping between rafts and intercropping between ropes. The former means that for every 1 to 2 raft frames, 1 raft frame of kelp is farmed; the latter means that for every 4 to 5 ropes of kelp, 1 cage of scallops is farmed. Bay scallops can be farmed rotationally with kelp. After kelp is harvested in June, bay scallop seedlings can be temporarily cultured; in July the seedlings are separated into cages for grow-out; in October the kelp is put into the sea to culture seedlings (occupying only 10% of the farming sea area); in November the bay scallops can be harvested. After harvest, the kelp can be separated and grown, which can double the utilization rate of the sea area.
What Are Scallops
Scallops are bivalve mollusks. Their shells are fan-shaped, like a folding fan, hence the name scallop. It is one of the precious marine delicacies and is distributed along the coast of our country. In the past, most were obtained by harvesting natural resources. In recent years, artificial farming has been developed in coastal areas. The main farmed varieties include the original undulate scallop (Chlamys farreri), as well as the Ezo scallop (Patinopecten yessoensis) introduced from Japan and the bay scallop (Argopecten irradians) from the United States. Scallops are generally harvested throughout the year, but the quality is better in spring.
Scallop shells may be purple-brown, light brown, apricot yellow, red-brown or grayish white, etc. In the sea, scallops usually attach to rocks, gravel, shells, coral reefs or other objects by byssus threads, and some live with the lower shell spread flat on the sandy seabed. Their traces are found from shallow seas below the tide line to the deep sea at 5000 m. They like to live in groups, often with individuals linked to one another, one after another, and can form natural scallop beds. According to observations, ordinary scallops generally take about 3 years from spawning to growing into adults, among which Ezo scallops grow relatively quickly and take about 19 months, while the fastest-growing bay scallop can be grown and harvested for market in the same year.
Key Points of Scallop Farming Technology
1. Seedling selection: Select healthy, disease-free seedlings with a shell height of 0.5 cm. Use local seedlings as much as possible, as both quantity and quality are guaranteed. Using seedlings from other places will consume a large amount of the seedlings' physical energy due to long-distance transportation, causing large numbers of deaths.
2. Timely seedling separation: The attachment period of oysters is at the end of July. Therefore, try to delay the last seedling separation period as much as possible.
3. Living habits: Bay scallops are mostly distributed 3-10 m below the sea surface. They are relatively hardy, with a temperature tolerance range of -1-31°C. They stop growing below 5°C, grow slowly below 10°C, and grow faster at 18-28°C. When the environment is unsuitable, they can sever their byssus threads themselves and use the opening and closing of the two shells to strike the water for rapid movement. Under fully artificial farming conditions, low-density stocking grows faster than high-density stocking, and early seedling separation grows faster than late seedling separation.
4. Reproductive habits: Bay scallops are hermaphroditic. They grow and develop relatively quickly. Seedlings bred in spring, when farmed to autumn and reaching a shell height of about 5 cm, have mature gonads and can be used as parent scallops to collect eggs and breed seedlings. In the northern sea areas of our country, bay scallops have two major breeding peaks each year, in spring and autumn. Spring is from late May to June, and autumn is from September to October. After the autumn reproductive period, the abdomen is transparent and no sperm or eggs are present.
In the process of scallop farming, only by shortening the scallop farming cycle can more profit be obtained. Therefore, the scallop farming cycle is very important. Farmers should not only exchange ideas and learn from one another, but also continuously research and develop new technologies and methods.