CATDOLL : CATDOLL: How are oysters farmed?

How to farm oysters?

Oysters, also known as oysters, are a kind of marine shellfish with wide temperature and salinity. They are mainly caught in the ocean, and are less cultivated artificially. The oyster seedlings used for artificial cultivation are generally natural seedlings in the ocean. The main cultivation methods include: raft culture, longline culture, trellis culture, etc. 5 to 6 months before the oysters are harvested, the cement columns in the cultivation area are moved to the muddy beach with fertile water quality and fast flow rate for fattening.

Due to the different types of oysters and the different sea environments, the seedling collection seasons are also different; therefore, artificial breeding is mostly semi-finished product breeding. That is, wild seedlings are used and then artificially cultivated. The growth environment is basically the same as that of wild shellfish.

Oysters, also known as oysters, are one of the larger species. There are many breeding methods, among which there are 8 basic methods (with key points): 1. Raft culture, which is divided into two types: hanging rope and cage culture. It is necessary to ensure that the water depth is about 4 meters, and choose a river mouth with low salinity to breed near the river. 2. Sowing and raising seedlings on the tidal flats; the site should be selected with small waves, flat tides, and pollution-free inner bays. Sowing is more suitable from mid-March to mid-April. 3. Oyster and shrimp mixed culture. With silt or mud sand as the bottom material, the water depth is more than 1.3 meters, and the daily average water exchange rate should reach more than 50%. The sowing time is selected in early April. 4. Stone throwing culture. The rocks of the oyster seedling machine are used as cultivation equipment, and the baby's baby selling respect, plum blossom Zhongqiao Shen and determinant cultivation methods are adopted. 5. Bamboo cultivation. Arrange in a straight or oblique manner with gaps in the middle to allow smooth water flow. 6. Bridge culture. The stone bars used in the bridge seedling method are rearranged, with 6 to 7 bars in a group, the distance between groups is about 50 to 60 cm, and the distance between rows is 1 to 2m. 7. Vertical stone culture. This method is relatively simple. As long as the amount of seedlings collected is appropriate, it can be allowed to grow naturally. It is mainly used for the cultivation of pleated oysters. 8. Grid farming. The water depth is 2 to 4 meters, and a fixed grid is set in a calm place. Most oyster seedlings are raised on a wide locust grid frame with shells and cement tiles. Each string is 1 to 1.5 meters long, and the distance between strings is 0.5 to 1 meter. Note that the density should not be too high to prevent the bottom from being seen, so as to avoid being attacked by the natural enemies of benthic organisms.

What technology is needed to farm abalone?

1. Seedling conditions (1) Mature parent abalone: ​​healthy individuals without damage, with a shell length of more than 6 cm; the gonads are extremely full in appearance, covering most of the vertical part of the digestive glands, protruding from the edge of the shell, and the end becomes pure round due to being filled with sperm and egg cells. (2) Parent abalone temporary rearing ponds and juvenile abalone rearing ponds should be dark and covered with plastic sheets. (3) Collectors: mainly made of transparent organic glass, polyethylene plastic algae boards and films. (4) Collection frame: made of steel bars, wrapped with film, or made of thin bamboo and wood.

2. Process flow

Abalone breeding, artificial induction of spawning, screening of fertilized eggs, collection and cultivation of larvae (timely sparse breeding), and juvenile abalone farming.

In abalone breeding, bait is particularly important and must be prepared in advance. Before collecting the larvae, the collector must be attached with benthic diatoms or placed in a flat culture pool and soaked for several days. Then, the collectors with attached diatoms and unicellular algae are moved into the larval culture pool to collect the late larvae of the facial disc.

1. Abalone Overview

1. Biological characteristics

Abalone is widely distributed, while the wrinkled abalone is mainly produced in the Yellow Sea and Bohai Sea. It is an abalone with relatively high economic value and its production is also large, accounting for about 70% of the total abalone production. The wrinkled abalone shell is large and thick, with three layers of whorls, a suture line, and a blunt shell top. There is a row of protrusions on the edge of the shell, 4-5 openings at the end, which are tubular, and there is a groove parallel to the protrusions close to the outside of the protrusions. The shell surface is dark green-brown, with obvious growth lines, and no large folds. The shell is silvery white. Abalones live a crawling life, living in rock crevices and caves with abundant seaweed, clear water quality, and smooth water flow. They hide during the day and come out at night. Adult abalones are variegated animals, mainly feeding on brown algae, and also eating green algae, red algae, diatoms, seed plants, and lower plants and animals. The color of abalone shells is usually closely related to the bait they eat.

2. Economic characteristics

Abalone is listed as the first of the Eight Delicacies. It is delicious, tender and tasty, and rich in nutrition. Analysis of dry products shows that it contains 40% protein, 33.7% glycogen, 0.9% fat, and vitamins and other trace elements. In addition to being eaten fresh, abalone meat can also be made into collected dried products and various canned foods.

Abalone shell, also known as stone cassia, is a colorful pearl layer, which is a good raw material for excellent decorations and shell carving. More importantly, it has medicinal value. The pharmacological effects of abalone shell can calm the liver and clear away heat, nourish yin and strengthen yang, and abalone meat can lower blood pressure. The abalone Ⅰ and abalone Ⅱ contained in abalone meat can strongly inhibit the growth of cancer cells.

3. Current status of breeding

Abalones like to live in caves with clear water quality, abundant seaweed and smooth water flow. Therefore, the southern boundary of the wrinkled Haliotis discus is distributed in the Yellow Sea and Bohai Sea. The water depth near the coast of our city is not suitable for its growth, so the existing abalone farming method adopts tunnel farming, that is, artificially purifying seawater, taking advantage of the constant temperature of the tunnel, and intensive farming. Its main breeding site is Shuidao Village, Liandao Town.

4. Economic Analysis

Abalone farming requires high investment, high output, and high-efficiency aquaculture projects, and the farming cycle is long and the technical requirements are high, so the investment risk is high, but its high profit still attracts farming units. Take the tunnel farming of 1 million abalone as an example: 100 million tunnel farming abalone farm. The total investment is about 10 million yuan. Among them, the asset investment is more than 6.5 million yuan, the production cost is more than 3.6 million yuan, and the farming survival rate can reach 90%. The sales price is 400,000 yuan/T, then the sales revenue can reach 13.68 million yuan, and the total profit and tax can reach more than 8.7 million yuan, the sales profit and tax rate is 63.35%, and the investment recovery period is 2.56 years.

From the above, we can see that if the technical measures are appropriate and the disease is effectively controlled, the prospects for abalone farming in tunnels are still broad.

2. Abalone breeding technology

1. Seedling cultivation conditions

(1) Mature abalone: ​​healthy individuals without damage, with a shell length of more than 6 cm; the gonads are extremely full in appearance, covering most of the digestive glands, protruding clearly from the edge of the shell, and the end becomes purely round because it is filled with sperm and egg cells.

(2) Parent abalone holding ponds and juvenile abalone rearing ponds should be kept dark and covered with plastic sheets.

(3) Collector: Mainly made of transparent plexiglass, polyethylene plastic algae board and film, etc.

(4) Collection frame: Made of steel bars, wrapped with film, or made of thin bamboo and wood.

2. Process flow

Abalone breeding, artificial induction of spawning, screening of fertilized eggs, collection and cultivation of larvae (timely sparse breeding), and juvenile abalone farming.

In abalone breeding, bait is particularly important and must be prepared in advance. Before collecting the larvae, the collector must be attached with benthic diatoms or soaked in a flat culture pool for several days. Then, the collectors with attached diatoms and unicellular algae are moved into the larval culture pool to collect the late larvae of the veliger stage.

During the abalone breeding process, algae cultivation should be continuously strengthened. In addition to adding appropriate amounts of nutrients to the larval culture pond, light should be strengthened to promote the reproduction rate of benthic diatoms and maintain a balance between the reproduction number of benthic diatoms and the food intake of larvae or young abalone. To this end, fertilizers should be added continuously. If there is basically insufficient bait, additional bait should be added or the bait board should be replaced after changing the water to meet the larvae's food intake.

3. Disease prevention and control

Orphanosis: Symptoms: epithelial tissue of abalone feet falls off, and the diseased individuals are inactive. In severe cases, there is no response to mechanical stimulation. Active bacteria are found in the blood, the body fades, the palate is weak, the internal organs shrink, the feet retract, and abalones die persistently from metamorphosis to 1 cm, sometimes with a peak of death.

Pathogen: Red abalone is prone to bacteriophytosis when it is young. The biochemical characteristics of the isolated bacterium are close to those of Vibrio alginolyticus.

Time: The disease is more likely to occur under high temperature conditions or excessive oxygenation.

Prevention and treatment: Prevention: Young abalone should be raised in a suitable environment, and the wounds of injured abalone can be washed with medicine.

Treatment: 1) Soak in 25-50 ppm chloramphenicol seawater solution for 0.5-1 hour, or soak in 1% co-trimoxazole seawater solution for 5 minutes.

2) Apply a 5% seawater solution of chloramphenicol or co-trimoxazole to the wound.

The above drug treatment methods all require the abalone to be placed in the air for 10-15 minutes to allow the drug solution to fully penetrate the lesions, and then returned to the seawater for feeding. In addition, if necessary, the treatment can be repeated once the next day.

3. Abalone culture technology

1. Cultivation conditions

The quality of natural conditions in Pacific oyster farming areas is closely related to their cultivation.

(1) Terrain The aquaculture area should be located in a relatively flat tidal flat with a suitable bottom of mud and sand, which is convenient for the installation of scaffolding and floating rafts. It is ideal to choose a deep water location in an inner bay or reclamation area with an appropriate amount of fresh water inflow.

(2) The aquaculture area must have smooth tidal currents, good seawater exchange conditions, and calm winds and waves or be not easily attacked by strong winds and waves.

(3) Water quality: The seawater temperature should be within the suitable range of 5-30 degrees for Pacific oysters; the specific gravity of seawater should be around 1.005-1.025.

(4) The bait culture area must be a fertile area to facilitate the reproduction of plankton to ensure that there is abundant bait organisms required for oyster growth.

(5) Polluted aquaculture areas should be free from serious industrial and agricultural pollution.

2. Develop production process

Selection of aquaculture sea area → Determination of aquaculture method → ​​Preparation of aquaculture equipment → Setting up aquaculture facilities → Stocking of seedlings → Aquaculture management → Harvesting and processing

3. Introduction to the main development methods

(1) Direct cultivation method

Traditional breeding methods include stone throwing breeding, bridge breeding, stake breeding and bamboo planting breeding. The common feature of these breeding methods is that the seedling collector also serves as a breeding device.

(2) Seedling cultivation method

It includes various methods such as mudflat broadcasting, floating raft or longline farming and single-unit farming. Compared with direct cultivation, these farming methods can artificially control the farming density, effectively utilize the farming waters, have a short farming cycle and high yield, and are advanced methods of oyster farming.

4. Tidal flat culture: This is the simplest method of culturing Pacific oysters on tidal flats. The oyster seedlings are directly sown on the mudflat or muddy tidal flat at a certain density for cultivation.

Vertical farming is divided into:

1) Shed type: Use bamboo, wood or cement piles to build a shed in the breeding area, and hang the seedling attachment equipment on the shed for cultivation.

2) Floating raft type: A floating raft made of bamboo is set up in shallow waters, and the seedling attachment device is hung on the raft frame for breeding.

3) Longline method: A floating rope is set up in the shallow sea area, and the seed attaching device is hung on the floating rope for breeding.

4) Hanging cage type: The multi-layer net cages used for single-layer round cage culture of scallops can also be used for hanging oyster culture.

In addition, Pacific oysters can be cultured together with shrimps and intercultured with algae such as kelp and wakame.

Bait

It completely relies on natural bait organisms in natural sea areas, mainly unicellular algae.

Disease control

There are few diseases in the aquaculture and production of Pacific oysters. Carnosella disease has been reported abroad. The main hazards to domestic aquaculture come from predatory organisms. One type is competing organisms such as pleated oysters, barnacles, moss worms, lime worms, etc. that compete with them for attachment, food, and oxygen; the other type is cannibalistic organisms such as snails, crabs, clam beetles, scallop fleas, etc. The last type is the most serious and there is currently no effective prevention and control method.

4. Abalone Harvesting and Processing

1. Harvesting method

The harvesting method of abalone cage culture and factory culture is simple. It can be directly pulled out from the culture contract or culture corrugated board. The harvesting of abalone cultured in natural sea areas is generally arranged in the summer and autumn when the water temperature is higher, which is convenient for diving operations.

The standard for abalone is generally around 9 cm in size, and 20 pieces can weigh up to 1 kg.

2. Processing technology

Abalone is rich in nutrition, tender and delicious, and is in great demand. Currently, it is mainly exported. It can be cooked after being washed. It can also be processed into dried products or canned foods.

Processing of dried products: first remove the shells and internal organs of the fresh products, put them in a jar and add 7-8% salt. Take them out after overnight and scrub to remove the melanin and mucus around the feet. After washing, put them in a pot and add water to cook. Take them out, string them with thread and put them on a mat to dry.

Canning: In my country, the most common method is to boil the abalone in water, remove the shell, clean the head and internal organs, and then seal the can.