Method for breeding and culturing scapharca subcrenata fries

Abstract

The invention belongs to the technical field of culture and proliferation of shellfish, and relates to a scapharca subcrenata larva breeding and culturing method, which comprises the following steps: by taking local wild scapharca subcrenata in coastal area of Tangshan as seed scapharca subcrenata, transporting the seed scapharca subcrenata to a near-shore mud flat pond or an outdoor pond in coastal area of Zhejiang or Shandong for bottom sowing and temporary culture in the first ten days of April every year; then, in mid-to-late May, putting the seeds in a breeding workshop in the Zhejiang or Shandong coastal region for fattening and ripening, after gonads of the scapharca subcrenata are mature, performing induced spawning induction and seedling breeding, and then, performing seedling protection in a near-shore mud flat pond or an open sea area in the Zhejiang or Shandong coastal region to obtain large-specification scapharca subcrenata seedlings; after the larva protection is finished, the large-specification larva of the scapharca subcrenata is transported to the Tangshan coastal region for bottom sowing culture. According to the method, the relay type large-specification scapharca subcrenata larva breeding technology of bottom sowing and temporary rearing, indoor fattening and ripening promoting, indoor larva breeding and near-shore mud flat pond / open sea area larva protection is adopted, and the success rate of larva breeding, larva protection and breeding of scapharca subcrenata is remarkably increased.

Description

Technical Field

[0001] The invention belongs to the technical field of shellfish aquaculture, and particularly relates to a method for breeding and cultivating hairy clam seedlings. Background Art

[0002] my country is rich in shellfish resources, and multi-variety and multi-form shellfish farming has become one of the largest aquaculture industries in my country, occupying an important position in my country's fishery production. Among them, hairy clams, as a common shellfish, have become the main aquaculture species.

[0003] At present, most of the breeding and cultivation of razor clams adopts the method of breeding wild razor clam groups under local natural conditions. However, due to the long-term breeding and cultivation of razor clams in a single area, the resistance or adaptability of razor clams will decrease, affecting the reproduction rate of razor clam seedlings. On the other hand, the breeding environment under natural conditions may cause the reproduction rate of razor clam seedlings to be low and the growth to be slow due to factors such as water temperature, salinity, and predation by natural enemies. For example, the coastal mudflats of Tangshan are mostly muddy sea areas. During the breeding of razor clam seedlings, the seawater at the water inlet is turbid and difficult to settle. The salinity and temperature of the seawater are high, and there are many wild algae and protozoa in the sedimented seawater in the pond, resulting in a very low success rate of razor clam shellfish breeding. Summary of the Invention

[0004] The present invention aims to overcome the deficiencies of the prior art and provides a method for breeding and cultivating hairy clam seedlings.

[0005] The specific technical solutions are as follows:

[0006] A method for breeding and cultivating razor clam seedlings comprises: using local wild razor clam seedlings from the coastal areas of Tangshan as seedlings, transporting the razor clam seedlings to nearshore mudflat ponds or outdoor ponds in the coastal areas of Zhejiang or Shandong in early April each year for bottom seeding and temporary culture, then placing the razor clam seedlings in breeding workshops in the coastal areas of Zhejiang or Shandong in mid-to-late May for fattening and ripening, inducing spawning and breeding seedlings to obtain razor clam seedlings after the gonads of the razor clam seedlings mature, then cultivating the razor clam seedlings in nearshore mudflat ponds or open sea areas in the coastal areas of Zhejiang or Shandong for seedling conservation to obtain large-sized razor clam seedlings, and transporting the large-sized razor clam seedlings to the coastal areas of Tangshan for bottom seeding and culture after the seedling conservation is completed; the large-sized razor clam seedlings have a size of 600 to 800 grains per kilogram.

[0007] Preferably, the razor clams are Tangshan black-edged razor clams, and the seed clams are 2-3 years old, with complete shells and healthy and intact razor clams.

[0008] Preferably, the razor clams are collected from the coastal waters of Tangshan by manual excavation; manual excavation can reduce physical damage to the razor clams.

[0009] Preferably, the breeding workshop is an indoor breeding workshop

[0010] Specifically, before fattening and ripening, the clams are placed in coastal mudflat ponds or outdoor ponds in Zhejiang or Shandong coastal areas in early April for temporary bottom seeding. Before the seawater temperature in the coastal mudflat ponds or outdoor ponds (here, the natural temperature of the seawater, without external temperature control) rises to 27°C, that is, in mid-to-late May, they are placed in breeding workshops in coastal Zhejiang or Shandong for fattening and ripening. This operation ensures a high survival rate of razor clams during transportation, temporary breeding, ripening, spawning and sperm release.

[0011] Furthermore, bottom seeding and temporary rearing are carried out in nearshore mudflat ponds in the coastal areas of Zhejiang or outdoor ponds in the coastal areas of Shandong.

[0012] Preferably, during the fattening and ripening process, the density of the clams is 100 to 150 clams / m 2 The gonadal maturation of hairy clams can be promoted by increasing the feeding amount of unicellular algae, feeding marine red yeast and / or feeding cooked egg yolk.

[0013] Furthermore, during the induction of spawning, the molluscs can be induced to spawn and release sperm by drying in the shade and / or raising the water temperature. Alternatively, the molluscs can be fed cooked egg yolk and / or spirulina solution. The drying time, water temperature, and amount of cooked egg yolk and spirulina solution fed can be adjusted appropriately based on the molluscs' spawning and release status. The drying time is preferably 5-6 hours, and the water temperature is preferably raised by 2-3°C.

[0014] Furthermore, during the seed breeding process, when 40% of the larvae have eyespots and extended legs, an attachment base is placed to allow the larvae to attach and metamorphose into juveniles; the attachment base is preferably polyethylene netting and / or sea mud, and the polyethylene netting and sea mud are disinfected before use.

[0015] Preferably, seedlings are protected in nearshore mudflat ponds in the coastal areas of Zhejiang Province or in the open sea areas in the coastal areas of Shandong Province. Pests are regularly eliminated during seedling protection in ponds, and seedlings are regularly transplanted during seedling protection in the sea areas.

[0016] Furthermore, for seedlings bred in the coastal areas of Zhejiang Province, when the number of cultivated razor clam seedlings reaches 300,000 to 500,000 grains per kilogram, the razor clam seedlings are transported to the nearshore mudflat ponds in the coastal areas of Zhejiang Province for seedling preservation to 600 to 800 grains per kilogram, thereby obtaining large-sized razor clam seedlings; for seedlings bred in the coastal areas of Shandong Province, when the number of cultivated razor clam seedlings reaches 3 million to 4 million grains per kilogram, the razor clam seedlings are put into net bags and transported to the open sea areas in the coastal areas of Shandong Province for rope culture, where the seedlings are preserved to 600 to 800 grains per kilogram, thereby obtaining large-sized razor clam seedlings. In coastal Zhejiang, due to the low salinity and high temperature of the seawater, seedlings can reach 300,000 to 500,000 per kilogram (500 jin) in about 35 days of cultivation. During the seedling protection period, due to the high water temperature and suitable salinity (22-24) in the nearshore mudflats and ponds in coastal Zhejiang, and the abundant algae bait, large-sized seedlings can be obtained in about 3-4 months of cultivation. In coastal Shandong, due to the slightly higher seawater temperature and the proliferation of red tide algae in July, seedlings can reach 3-4 million per kilogram (500 jin) in about 20 days of cultivation. The shell length is about 1.0 mm. During the seedling protection period, large-sized seedlings can be obtained in about 5-6 months of cultivation.

[0017] Preferably, during the rope-hanging culture process, the hairy clam seedlings are transplanted every 20 to 25 days.

[0018] Preferably, during the transportation to the coastal areas of Tangshan, the razor clam seedlings are packed into nylon bags or insulated boxes and transported to the coastal areas of Tangshan by refrigerated trucks or iced vans; the temperature of the refrigerated trucks or iced vans is maintained below 10°C, and the transportation time is maintained within 30 hours, at which time the vitality of the razor clam seedlings is good.

[0019] Furthermore, bottom seeding is performed in the coastal shallow mudflats or ponds of Tangshan, where natural populations of razor clams are found. Preferably, seeding is performed in the early morning or evening when wind and waves are low to prevent the razor clams from being damaged or washed away by currents, thereby increasing their burrowing rate and survival rate. Preferably, pests are regularly removed before and after seeding.

[0020] Preferably, when bottom seeding is carried out in the shallow coastal mudflats of the Tangshan coastal area, the seeding density is 200 to 250 kilograms per mu. After about 12 to 15 months of cultivation, large-sized hairy cockle seedlings can grow to commercial size.

[0021] Preferably, bottom seeding aquaculture in nearshore ponds in Tangshan's coastal areas utilizes a polyculture model of shellfish and fish, or shellfish and shrimp / crab, with a seeding density of 250-300 jin (250-300 catties) per mu (approximately 1.5-1.5 ...

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The coastal mudflats of Tangshan are mostly muddy sea areas. During the breeding period of hairy clams, the seawater at the water inlet is turbid and difficult to settle. The seawater has high salinity and temperature. There are many wild algae and protozoa in the sedimented seawater in the pond, which leads to a very low success rate of shellfish breeding. The present invention uses wild hairy clams from the local coastal areas of Tangshan as breeding shellfish. Before the breeding season, hairy clams of 2 to 3 years old with complete shells and intact health are selected. They are transported to the coastal areas of Zhejiang or Shandong in my country for temporary breeding when the seawater temperature is low and the hairy clams' resistance or adaptability is reduced. The razor clam seedlings are obtained by breeding and protecting seedlings, and transported back to the coastal areas of Tangshan for bottom seeding culture. Since the sea areas in the coastal areas of Zhejiang or Shandong in my country are mostly muddy and sandy, the sea water is clear and easy to settle, and there are few wild algae and protozoa, the salinity is low (22-25), and the seedling water temperature does not exceed 32°C, on the one hand, it can significantly improve the success rate of razor clam seedling cultivation; on the other hand, it can significantly reduce the seedling cultivation, seedling protection and labor costs, and provide a large number of high-quality razor clam seedlings for the coastal areas of Tangshan in a short period of time.

[0024] (2) The present invention adopts a "relay-style" large-scale razor clam seedling cultivation technology that includes bottom seeding and temporary rearing, indoor fattening and ripening, indoor seedling propagation, and seedling protection in nearshore mudflat ponds / open sea areas. This significantly improves the success rate of seedling cultivation and seedling protection for razor clam, and the cultivation time for razor clam seedlings can be shortened by 2 to 3 months. The large-scale razor clam seedlings are transported back to the coastal areas of Tangshan for bottom seeding cultivation. The large-scale razor clam seedlings have strong adaptability and fast growth, and the survival rate of overwintering is significantly increased. Moreover, the razor clam can reach commercial specifications after about 10 to 15 months of cultivation. The method of the present invention shortens the cultivation time of razor clam by 4 to 6 months as a whole, and can realize the early listing of razor clam products. DETAILED DESCRIPTION

[0025] The following examples describe the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified. The first ten days of the month are from the 1st to the 10th; the middle ten days are from the 11th to the 20th; and the last ten days of the month are from the 21st to the last day of the month.

[0026] Example 1

[0027] On April 1, 2023, 200 kilograms of wild black-edged razor clams were collected from the coastal sea area of Heiyanzi Town, Tangshan City by manual excavation. The razor clams were transported to the cooperative shellfish hatchery in Laizhou, Shandong Province by van. The razor clams aged 2 to 3 years with complete shells and intact health were selected as clams. After disinfection and cleaning, they were spread on the bottom of outdoor ponds for temporary breeding on the same day. On May 15, before the seawater temperature in the outdoor pond rose to 27°C, the razor clams with large individuals and well-developed gonads were selected and brought into the indoor breeding workshop for fattening and ripening on the same day. The clams were cultured at a density of 100 to 150 pieces / m 2 The feed for the clams is primarily composed of golden algae, Chaetoceros algae, Nitzschia crescentii, and Pseudomonas triangularis, supplemented by Platyphylla, Spirulina, and marine red yeast powder. The feed rate is 500,000 to 800,000 cells / ml, and is distributed eight times daily. The feed rate is adjusted appropriately based on the clams' feeding and development. The water is changed twice daily, morning and evening, with 50% to 70% of the water changed each time. If the feed concentration and feces in the culture pond are high, the water is changed by inverting the pond. During this period, the development of the clams' gonads is continuously observed and recorded, and samples are taken to measure indicators such as the gonad index and fatness.

[0028] Dissection and microscopic examination revealed mature gonads in the scaly clams, and they were subsequently induced to spawn and rear seedlings in an indoor breeding facility. Shade-drying for six hours combined with a 2°C increase in water temperature induced spawning and semen release. Spirulina solution (2 ppm) and two cooked egg yolks were simultaneously sprayed into the pond. Within one hour of entering the water, the scaly clams began spawning and semen release. Furthermore, disturbances were minimized during the spawning process to prevent human disturbances from disrupting spawning and semen release. Male clams were promptly removed during spawning, and semen density was controlled by egg washing. The fertilized egg density was adjusted to 35-40 eggs / mL by dividing the ponds. During incubation, the fertilized eggs were slightly aerated, and the water in the incubation pond was agitated once an hour to prevent the eggs from sinking and clumping. After approximately 24 hours of incubation, the fertilized eggs develop into D-larvae. Siphoning is used to screen the pelagic larvae. D-larvae are then screened using a 300-mesh silk screen and transferred to new rearing tanks at a density of 8-9 cells / mL. D-larvae are fed a diet consisting of Isochrysis galbana, supplemented with Chaetoceros muelleri, with a daily feeding rate gradually increasing from 10,000 to 50,000 cells / mL. This is fed six times daily, with water changes performed in the morning and evening, each with a 30% to 50% water change. After approximately seven days of rearing, D-larvae reach the apical stage, the tank is drained and rearranged at a density of 4-5 cells / mL. Water changes are performed in the morning and evening, each with a 50% to 70% water change. Apical larvae are fed a diet primarily consisting of Chrysophyte and Chaetoceros, supplemented with Chlorella and Platymonas, with a daily feeding rate gradually increasing from 50,000 to 100,000 cells / mL, each with a 50% to 70% water change. After 12–14 days of incubation, the shell-top larvae grew to 240–260 μm in length. Microscopic examination revealed that 40% of the larvae had eyespots and extended their legs. The pond was then inverted and re-filled with a density of 1.5–2.0 larvae / mL, and sterilized polyethylene mesh was added as a substrate. In the initial stage of placing the attachment substrate, change the water once in the morning and evening every day, with each water change of 70% to 100%. The bait is mainly golden algae and diatoms, with Chlorella and Platyphylla. The feeding amount is gradually increased from 100,000 cells / mL per day to 150,000 cells / mL, and it is fed 6 times a day; after the larvae have just attached and metamorphosed, change the water once in the morning and evening every day, with each water change of 80% to 100%. After 10 days of attachment, change the water 4 times a day, with a daily water change of 100% to 150%. The bait is mainly golden algae and diatoms, with Chlorella and Platyphylla. The feeding amount is gradually increased from 150,000 cells / mL per day to 300,000 cells / mL. Feed once every 4 hours before water change, and feed after water change during water change. After about 20 days of cultivation, the number of hairy clam seedlings reaches 3 to 4 million per kilogram (shell length is about 1.0 mm). The hairy clam seedlings are brushed off from the attachment base, pond bottom and pond wall, counted and then transported to the sea area for seedling preservation.

[0029] On July 10, the razor clam seedlings were put into net bags and transported to the open sea area of Changdao for rope culture to protect the seedlings. During the seedling protection period, the seedlings were divided regularly, every 20 to 25 days. Each time the seedlings were divided, the razor clam seedlings were transferred to net bags with larger meshes for further cultivation. In December, the razor clam seedlings grew to 600 to 800 grains per kilogram, and large-sized razor clam seedlings were obtained.

[0030] The large-sized razor clam seedlings are placed in nylon bags or insulated boxes and transported to the coastal areas of Tangshan within 30 hours using refrigerated trucks (maintaining the temperature below 10°C). They are then bottom-seeded in near-shore ponds in the coastal areas of Tangshan. The razor clam seedlings are evenly spread in the early morning or evening when the wind and waves are small, and pests are regularly removed before and after seeding. Bottom-seeding aquaculture adopts a shellfish-fish mixed farming model (ditches are dug in the breeding ponds to raise shrimps and crabs, and a fence is used in the middle of the pond to isolate and raise razor clams). The seeding density is 250 to 300 jin per mu, and the burrowing of the razor clam seedlings into the sand is observed by diving 3 hours and 24 hours after seeding. During the breeding period, water is changed, fertilized, and pests are removed regularly. In November 2024, the finished razor clam will grow to 50 to 60 grains per jin.

[0031] In this embodiment, the hairy clam larvae were transported to a cooperative hatchery in the coastal area of Shandong for temporary rearing before mid-April. The seawater temperature was slightly different from that in the sea area where the hairy clam was collected. The hairy clam was less damaged by the stress of drying and exposure during transportation. The survival rate of the hairy clam was high during the temporary rearing process. The egg quality and fertilization hatching rate after sexual maturity were both very high. This was ultimately reflected in the high attachment and metamorphosis rate of the hairy clam larvae, the high seedling emergence rate and the high seedling survival rate. The mortality rate of the hairy clam larvae after induced spawning was less than 10%.

[0032] Comparative Example 1

[0033] On June 9, 2023, 200 kilograms of wild black-edged razor clams were collected from the coastal waters of Heiyanzi Town, Tangshan City by manual excavation. The razor clams were transported to the Shandong Laizhou Cooperative Shellfish Hatchery by van. 2-3-year-old razor clams with intact shells and good health were selected as seed clams. After disinfection and cleaning, they were directly put into the indoor breeding workshop for fattening and ripening on the same day. The seed clams were cultured at a density of 100-150 pieces / m 2 The feed for the clams is primarily composed of golden algae, Chaetoceros algae, Nitzschia crescentii, and Pseudomonas triangularis, supplemented by Platyphylla, Spirulina, and marine red yeast powder. The feed rate is 500,000 to 800,000 cells / ml, and is distributed eight times daily. The feed rate is adjusted appropriately based on the clams' feeding and development. The water is changed twice daily, morning and evening, with 50% to 70% of the water changed each time. If the feed concentration and feces in the culture pond are high, the water is changed by inverting the pond. During this period, the development of the clams' gonads is continuously observed and recorded, and samples are taken to measure indicators such as the gonad index and fatness.

[0034] On June 22, dissection and microscopic examination revealed mature gonads in the scaly clams. Subsequently, induced spawning and seedling propagation were carried out in an indoor breeding facility. The scaly clams were induced to spawn and release sperm by drying them in the shade for six hours and raising the water temperature by 2°C. A 2ppm solution of Spirulina and two cooked egg yolks were simultaneously sprayed into the pond. Within one hour of entering the water, the scaly clams began spawning and releasing sperm. Furthermore, disturbance was minimized during the spawning process to prevent human disturbances from disrupting spawning and release. Male clams were promptly removed during spawning, and egg washing was used to control semen density. The fertilized egg density was adjusted to 35-40 eggs / mL by separating the spawning pools. During the incubation period, the fertilized eggs were slightly aerated, and the water in the incubation pool was agitated once an hour to prevent the eggs from sinking and clumping. After approximately 24 hours of incubation, the fertilized eggs develop into D-larvae. Siphoning is used to screen the pelagic larvae. D-larvae are then screened using a 300-mesh silk screen and transferred to new rearing tanks at a density of 8-9 cells / mL. D-larvae are fed a diet consisting of Isochrysis galbana, supplemented with Chaetoceros muelleri, with a daily feeding rate gradually increasing from 10,000 to 50,000 cells / mL. This is fed six times daily, with water changes performed in the morning and evening, each with a 30% to 50% water change. After approximately seven days of rearing, D-larvae reach the apical stage, the tank is drained and rearranged at a density of 4-5 cells / mL. Water changes are performed in the morning and evening, each with a 50% to 70% water change. Apical larvae are fed a diet primarily consisting of Chrysophyte and Chaetoceros, supplemented with Chlorella and Platymonas, with a daily feeding rate gradually increasing from 50,000 to 100,000 cells / mL, each with a 50% to 70% water change. After 12–14 days of incubation, the shell-top larvae grew to 240–260 μm in length. Microscopic examination revealed that 40% of the larvae had eyespots and extended their legs. The pond was then inverted and re-filled with a density of 1.5–2.0 larvae / mL, and sterilized polyethylene mesh was added as a substrate. In the initial stage of placing the attachment substrate, change the water once in the morning and evening every day, with each water change of 70% to 100%. The bait is mainly golden algae and diatoms, with Chlorella and Platyphylla. The feeding amount is gradually increased from 100,000 cells / mL per day to 150,000 cells / mL, and it is fed 6 times a day; after the larvae have just attached and metamorphosed, change the water once in the morning and evening every day, with each water change of 80% to 100%. After 10 days of attachment, change the water 4 times a day, with a daily water change of 100% to 150%. The bait is mainly golden algae and diatoms, with Chlorella and Platyphylla. The feeding amount is gradually increased from 150,000 cells / mL per day to 300,000 cells / mL. Feed once every 4 hours before water change, and feed after water change during water change. After about 20 days of cultivation, the number of hairy clam seedlings reaches 3 to 4 million per kilogram (shell length is about 1.0 mm). The hairy clam seedlings are brushed off from the attachment base, pond bottom and pond wall, counted and then transported to the sea area for seedling preservation.

[0035] On August 5, the razor clam seedlings were put into net bags and transported to the open sea area of Changdao for rope culture to protect the seedlings. During the seedling protection period, the seedlings were regularly divided, every 20 to 25 days. Each time the seedlings were divided, the razor clam seedlings were transferred to net bags with larger meshes for further cultivation. On November 21, the razor clam seedlings grew to about 3,000 grains per kilogram. In April of the following year, the razor clam seedlings grew to 600 to 800 grains per kilogram, and large-sized razor clam seedlings were obtained.

[0036] Large-sized razor clam seedlings are placed in nylon bags or insulated boxes and transported to the coastal areas of Tangshan within 30 hours using refrigerated trucks (maintained below 10°C). They are then bottom-seeded in nearshore ponds along the coast. The seedlings are evenly spread in the early morning or evening when waves are calm, and pests are regularly removed before and after seeding. Bottom-seeding utilizes a shellfish-fish polyculture model (ditches are dug in the ponds for shrimp and crabs, and netting is used in the middle of the ponds to isolate the razor clams). Seeding density is 250-300 jin (150-200 catties) per mu (approximately 1.5-1.7 kg) per mu (approximately 1.5-2.5 kg). Submersion of the razor clam seedlings in the sand is monitored by diving three and 24 hours after seeding. Water changes, fertilizer, and pest control are performed regularly during the culture period. As of November 7, 2024, the survival rate of razor clam ponds exceeded 70%, with the final razor clam yielding 50-60 clams per jin (approximately 1.5-1.7 catties) of clams.

[0037] Table 1 shows the growth indicators of the large-sized razor clams and the finished razor clams of this comparative example. According to Table 1, the wet weight of the finished razor clams of this comparative example is about 9.86g, the shell length is about 27.12mm, the shell width is about 21.35mm, and the shell height is about 16.27mm. However, because the razor clams were collected in June, which is a relatively late collection time, and they were not temporarily cultured, the mortality rate of the razor clams during the fattening and ripening process in the workshop was very high, and more than 80% of the razor clams died before spawning.

[0038] Table 1 Growth indexes of large-sized scaly clams and finished scaly clams of comparative example 1

[0039] Wet weight(g) Shell length (mm) Shell width (mm) Shell height (mm) Large-sized razor clams 0.63±0.21 12.97±1.02 7.54±1.65 9.97±1.13 Finished hairy clams 9.86±2.35 27.12±2.83 21.35±1.75 16.27±0.98

[0040] Comparative Example 2

[0041] On June 16, 2023, 200 kilograms of wild black-edged razor clams were collected from the coastal waters of Heiyanzi Town, Tangshan City by manual excavation. The razor clams were transported to the Zhejiang Qingjiang Cooperative Shellfish Hatchery by van. 2-3-year-old, healthy and intact razor clams were selected as seed clams. After being disinfected and cleaned, they were brought into the indoor breeding workshop for fattening and ripening on the same day. The seed clams were cultured at a density of 100-150 pieces / m 2. Due to the long drying time during transportation, the hairy clam larvae will soon lay eggs and ejaculate after entering the water. During this period, male hairy clams are selected in time, and the fertilized eggs are hatched in the spawning pond after washing. The hatching density is 25 to 30 / mL. The fertilized eggs hatch for about 24 hours and develop into D-shaped larvae. The siphon method is used to select the upper and middle layer D-shaped larvae. Finally, the hairy clam larvae are cultivated according to the hairy clam larvae cultivation technology in Example 1. During the cultivation of hairy clam larvae, the salinity of seawater is maintained at 22 to 24. When the water temperature exceeds 30 ° C, the larvae can develop normally and the development speed is faster. After 17 days of cultivation, the hairy clam larvae have eye spots and differentiated feet.

[0042] On August 6, 2023, when 40% of the larvae have developed eyespots and extended legs, they are transferred to a pre-stocked marine mud culture pond for attachment and metamorphosis. The marine mud is collected from nearby coastal mudflats and sun-dried, disinfected, crushed, sieved, and boiled for disinfection before use. After the larvae have settled, the pond water is directly exchanged with pond water, which contains sediment, benthic diatoms, and trace elements. This pond water is fertilized, conditioned, and treated before use. After approximately 35 days of cultivation, the larvae grow to 300,000 to 500,000 pieces per kilogram. These are then placed in nylon bags and transferred to a pond on the Qingjiang River nearshore for seedling preservation.

[0043] On September 10, 2023, the hairy clam seedlings (300,000 to 500,000 grains per catty) were transferred to the nearshore mudflat ponds for seedling conservation, with a seedling density of 20 to 25 catties per mu. The bottom soil of the nearshore mudflat ponds in Qingjiang, Zhejiang is suitable for hairy clam seedling conservation and breeding. The area is rich in bait organisms, the water temperature and salinity (22 to 24) are suitable, and the hairy clam seedlings grow fast. 300,000 to 500,000 grains per catty of hairy clam seedlings can reach 600 to 800 grains per catty in 3 to 4 months of growth. During the seedling conservation period of hairy clam seedlings, pests are regularly disinfected. On December 7, 5,000 kilograms of large-sized Tangshan hairy clam seedlings with 600 to 800 grains per catty were successfully cultivated. The large-sized hairy clam seedlings were transported to a cooperative company in the coastal area of Tangshan for bottom sowing and breeding. The transportation time by refrigerated truck was 20 hours, and the large-sized hairy clam seedlings were in good vitality. Bottom-seeding aquaculture of razor clams is carried out in shallow, nearshore areas with naturally occurring wild razor clams, muddy seabeds, and moderate currents. The razor clams are evenly distributed at a density of 200-250 jin (200-250 catties) per mu (approximately 1.5 tbsp) and a seeding size of 600-800 razor clams per jin (approximately 1.5 tbsp) ...

[0044] Table 2 shows the growth indicators of the large-sized scaly clams and the finished scaly clams of this comparative example. According to Table 2, the wet weight of the finished scaly clams of this comparative example is about 11.26g, the shell length is about 36.72mm, the shell width is about 28.52mm, and the shell height is about 23.23mm. However, because the scaly clams were collected in June, which is a relatively late collection time, and they were not temporarily cultured, the mortality rate of the scaly clams during the fattening and ripening process in the workshop was very high, and nearly 80% of the scaly clams died before spawning.

[0045] Table 2 Growth indexes of large-sized scaly clams and finished scaly clams of comparative example 2

[0046]

[0047]

[0048] Comparative Example 3

[0049] With reference to Example 1, the difference is that, hairy clam seed shellfish are collected in mid-to-late April for bottom sowing and temporary culture.

[0050] During the breeding process, it was found that the mortality rate of hairy clams during temporary rearing in ponds was nearly 30%, and after spawning, the mortality rate reached more than 70%.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for breeding and cultivating hairy cockles, characterized in that: The method comprises the following steps: using local wild razor clams from the coastal areas of Tangshan as seed clams, transporting the razor clams to nearshore mudflat ponds or outdoor ponds in the coastal areas of Zhejiang or Shandong in early April each year for bottom seeding and temporary culture, then placing the razor clams in breeding workshops in the coastal areas of Zhejiang or Shandong in mid-to-late May for fattening and ripening, inducing spawning and breeding fry to obtain razor clam fry after the gonads of the razor clams mature, then planting the razor clams in nearshore mudflat ponds or open sea areas in the coastal areas of Zhejiang or Shandong for seedling protection to obtain large-sized razor clam fry, and after the seedling protection is completed, transporting the large-sized razor clam fry to the coastal areas of Tangshan for bottom seeding culture; the large-sized razor clam fry have a size of 600 to 800 grains per kilogram.

2. The method according to claim 1, characterized in that The razor clams are Tangshan black-edged razor clams, and the seed clams are 2-3 years old, with complete shell shapes and healthy and intact razor clams.

3. The method according to claim 1, characterized in that In early April, the seed clams are placed in nearshore mudflat ponds in the coastal areas of Zhejiang Province or outdoor ponds in the coastal areas of Shandong Province for bottom seeding and temporary culture.

4. The method according to claim 1, wherein The hairy clam seedlings are planted in the nearshore mudflat ponds in the coastal areas of Zhejiang or the open sea areas in the coastal areas of Shandong for seedling protection.

5. The method according to claim 4, characterized in that For seedling breeding in the coastal areas of Zhejiang, when the number of cultivated razor clam seedlings reaches 300,000 to 500,000 per kilogram, the razor clam seedlings will be transported to the near-shore mudflat ponds in the coastal areas of Zhejiang for seedling preservation.

6. The method according to claim 4, characterized in that For seedlings breeding in the coastal areas of Shandong, when the cultivated razor clam seedlings reach 3 to 4 million grains per kilogram, they will be transported to the open sea areas in the coastal areas of Shandong for seedling preservation.

7. The method according to claim 6, characterized in that The seedling protection method is rope hanging culture.

8. The method according to claim 1, characterized in that Bottom seeding aquaculture is carried out in the nearshore shallow sea mudflats or nearshore ponds in the coastal areas of Tangshan.

9. The method according to claim 8, characterized in that There are natural populations of hairy clams distributed on the nearshore shallow sea mudflats in the coastal area of Tangshan.

Images