Detailed Explanation of Key Points in Artificial Breeding Technology for the Chinese Giant Salamander
Artificial Breeding Technology for the Chinese Giant Salamander
The realization of artificial breeding technology for the Chinese giant salamander marks the entry of giant salamander farming into an era of artificial controllability, creating extremely favorable conditions for its industrialized commercial farming
□Article by Zhong Xiaoqing, Guangdong Provincial Aquatic Technology Extension Station
I. Biological Attributes
The Chinese giant salamander, scientific name: andrias, in biological taxonomy belongs to Amphibia, Caudata, Cryptobranchidae, Andrias. The genus Andrias mainly consists of 3 species: the Chinese giant salamander, the Japanese giant salamander and the American giant salamander. Apart from the American giant salamander, the others are distributed in Asia and can be found in streams and ponds in China and Japan. As an amphibian, the giant salamander is a typical cold-blooded poikilothermic animal, with a maximum tolerable temperature of 24°C and an optimal growth temperature of 15-20°C. When the air temperature drops below 10°C, the giant salamander enters a state of hibernation.
Under natural conditions, the giant salamander can live 50-60 years, among which the Chinese giant salamander can reach a maximum body length of 1.8 m, the Japanese giant salamander a maximum body length of 1.5 m, and the American giant salamander a maximum body length of only 0.75 m. Their common features are a flattened and elongated body, very short limbs, 4 toes on the forelimbs and 5 toes on the hindlimbs, webbed toes, and a short and laterally flattened tail. Those who do not know it often mistake it for a fish, but it is actually an amphibian, meaning its physiological structure helps it survive both in water and on land. In water, it breathes with gills; on land, it breathes with its lungs and skin. Their skin has only mucous membrane and no scale covering.
The Chinese giant salamander is commonly known as the "baby fish" because its call resembles the crying of an infant, while the Japanese giant salamander is called the "pepper fish" because its body has a pepper-like odor. Giant salamanders especially like to inhabit remote, quiet and rarely visited deep mountains and old forests with poor transportation, living year-round in mountain streams with fresh water quality and rapid currents. They are accustomed to sleeping during the day and foraging at night, feeding mainly on fish and crustaceans. However, due to long-term life in a dark environment, their eyesight is poor, and they can only rely on pressure changes detected by sensory areas on the head and body to hunt prey.
During the mating and breeding season, they swim upstream. After the eggs are fertilized, the male guards the young salamanders for 6 months, until they are able to forage on their own.
II. Socioeconomic Value
The giant salamander has a very long history of survival on Earth, dating back 200 million years, when it once flourished. Because it is at a transitional stage from aquatic to terrestrial life, it holds a special position in biological taxonomy. To this day, it has high academic research value in disciplines such as physiology, genetics, evolution and ecology. In addition, as its living environment is deteriorating day by day and its numbers are decreasing, it has been listed by the state as a Class II aquatic wildlife protected animal. At the same time, the giant salamander also has certain medicinal and food functions and a certain commercial development value. According to traditional Chinese medicine theory, the medicinal value of the giant salamander is shown in helping the human body promote circulation and invigorate blood, moisturize the skin and nourish the complexion, comprehensively nourishing the body both internally and externally. In terms of food value, as a rare and precious meat, the giant salamander has characteristics such as crisp skin, fine meat, crisp bones and delicious taste. Although the giant salamander is a Class II aquatic wildlife protected animal, in line with the purpose of protection for better development and utilization, relevant state laws stipulate that adult giant salamanders whose parents are second-generation artificially bred individuals, or which have lost reproductive capacity, or have body deformities, or abnormal growth, may be used for commercial purposes upon obtaining administrative permission from the relevant state authorities. Things are precious when they are rare. At present, the market price of giant salamanders reaching commercial specifications has reached 1200 yuan/500 g. Some high-end restaurants and eateries in Guangzhou and even some large cities in the Pearl River Delta use the giant salamander as a main ingredient through traditional fine processing techniques to create a series of dishes to attract customers, and business is booming.
III. Experimental Demonstration Base
Driven by demand from all sectors of society, fishery authorities, research institutions and aquaculture enterprises in the native producing areas of China's giant salamanders, such as the Yangtze River and Pearl River basins, have successively established projects and invested large amounts of manpower, material resources and financial resources in tackling key problems in artificial breeding and high-yield, high-efficiency farming technology for the giant salamander, including the active efforts made for this purpose by the Shaoguan City Fisheries Management Bureau. Recently, at the invitation of the Shaoguan City Fisheries Management Bureau, the Guangdong Provincial Aquatic Technology Extension Station dispatched the author to visit the city on a special trip to investigate the situation on the ground. The relevant information is now organized as follows for reference, study and emulation by those interested in this field.
In October 2004, with strong support from the Guangdong Provincial Department of Finance, the Provincial Ocean and Fishery Bureau and relevant municipal government departments, the Shaoguan City Fisheries Management Bureau successively invested 4 million yuan to establish the Municipal Aquatic Life Conservation Base (hereinafter referred to as the "Base") at the foot of Chaisang Mountain and Huangshi Mountain in Longgui Town of the city, relying on the infrastructure and technical strength of the Municipal Aquatic Fine Seed Farm and the Municipal Fisheries Research Institute. At the same time, in order to increase its functions, it was additionally designated the "Municipal Special Aquatic Products Experimental Demonstration Base". The Base covers an area of 60 mu and is operated under lease with a lease term of 30 years. The Base is surrounded by green mountains on three sides, with luxuriant vegetation on the mountains and mountain springs and streams flowing through. In particular, groundwater resources are abundant, and the water quality is excellent, with a constant temperature (20-22°C) and a flow rate of about 720 cubic meters/hour. The flow is relatively smaller in winter, but this does not affect aquaculture production and domestic water use. The conditions in all respects are very similar to the natural living environment of amphibians such as giant salamanders and reptiles such as turtles and soft-shelled turtles, making it an ideal place for developing artificial farming of giant salamanders and turtles.
At present, the Base is divided by function into three relatively independent zones: 1. Farming zone, with 600 sq m of indoor giant salamander acclimation ponds, 1200 sq m of turtle conservation ponds, 300 sq m of Asian giant softshell turtle conservation ponds, 5000 sq m of fish conservation ponds and 1000 sq m of management and maintenance buildings; 2. Office zone, with 500 sq m of offices and meeting rooms, and the meeting room can accommodate 30-40 people; 3. Living zone, with 120 sq m of kitchen and dining hall, and relatively complete living facilities built for the Base's staff. Whether in terms of roads, water and electricity supply, flood control facilities, or purification, greening and landscaping, the Base has reached a new level. It is a relatively rare standard garden-style aquatic experimental demonstration base.
IV. Introduction, Acclimation and Breeding Trials
In the 5 years from 2004 to the present, the Base has successively introduced several batches of giant salamanders from Shanxi, Shaanxi, Hunan and other provinces as well as Huadu in Guangdong and other places, including both wild and artificially bred giant salamanders, in various sizes and specifications. The Base's technicians took acclimation as the breakthrough point in tackling key problems in artificial breeding technology for the giant salamander. Through long-term artificial acclimation, they helped it adapt to the artificial farming environment and conditions, thereby selecting parents and propagating the next generation.
Through long-term artificial acclimation, the Base's technicians gradually mastered the theoretical knowledge and technical requirements concerning the physiology, pathology and ecology of the giant salamander. First, due to long-term evolution, certain functions of the giant salamander have seriously degenerated, especially its eyesight; it is highly nearsighted, photophobic, and requires a dark and quiet living environment. Because its respiratory system is underdeveloped, it needs an adequate water source, excellent water quality, strong flow and high dissolved oxygen content to facilitate its oxygen intake needs. Second, the giant salamander mainly feeds on fish, and it is best to feed it silver carp, bighead carp and crucian carp of moderate size, as well as wild miscellaneous fish caught from mountain ponds and reservoirs. Compared with other amphibians such as frogs and toads, the giant salamander's metabolism is very slow, manifested in behavior as remaining motionless for long periods, so it is fed once every two days. When feeding, the giant salamander uses stillness to control motion and launches attacks very quickly; once it bites, it will not easily let go until the prey dies, and then it swallows it and slowly digests and absorbs it. Due to low energy consumption, thorough digestion and absorption, and a high feed conversion rate, the giant salamander grows very quickly, and its body weight can double in 1 year. In other words, the input-output ratio of artificial giant salamander farming is very high, and its feed conversion ratio can reach 1-2, giving it great commercial investment value. Third, because the artificial acclimation period has been relatively short and the density is relatively low, it has not yet been found what types of diseases the giant salamander is susceptible to. However, from the Base's farming production practice, as long as the water supply is guaranteed, the water volume is relatively large, the water temperature fluctuates little and the water quality is excellent, the giant salamander is not prone to illness, the survival rate is very high, and the farming risk is relatively low. But this conclusion still needs further observation and research analysis.
In 2009, the Base had 201 giant salamanders, among which the largest weighed 15 kg and the smaller ones 0.5 kg, as well as 400 turtles including Chinese pond turtles, yellow-margined box turtles and yellow pond turtles. In July 2008, after careful study and discussion, the leaders of the Shaoguan City Fisheries Management Bureau and the Base's technicians believed that the conditions for artificial breeding of the giant salamander were gradually maturing and decided to carry out artificial breeding trials. The technical cooperation unit for the trials was the Zhangjiajie National Giant Salamander Protection Center, and the trials were successful.
The trial parents were giant salamanders introduced from other places and acclimated by the Base 4-5 years earlier. The Base's technicians carefully selected 5 male and 10 female adult giant salamanders and used artificial hormone injection to hasten their sexual maturity, with males releasing sperm and females ovulating. Because these parents were all produced through artificial farming, their gonads were not yet fully mature, and this was the first artificial induced spawning and breeding, only 4 female giant salamanders successfully laid 150 eggs through artificial induced spawning, among which the eggs of 2 were absorbed because they missed the optimal timing for induced spawning. Like the eggs laid by frogs and toads, the eggs laid by the giant salamander are also like black beans, wrapped outside by an egg membrane, strip-shaped and floating in the water.
Key technical points for successfully hatching giant salamanders: First, it is necessary to master the optimal timing for artificial fertilization. The giant salamander undergoes external fertilization in water, and artificial fertilization must be completed within 20 seconds after the giant salamander lays eggs and releases sperm, otherwise the semen becomes ineffective and fertilization cannot be achieved. Second, after successful fertilization, place the fertilized giant salamander eggs in a hatching room at a constant temperature of 19°C, and ensure excellent water quality through a circulating filtration system. After 31 days of hatching, the young salamanders will break through the membrane and emerge. Through the above technical steps, the Base successfully hatched more than 60 young salamanders, with a hatching survival rate as high as 40%. Newly born young salamanders are like tadpoles, lively and active, swimming around, completely different from their parents. They first digest their own nutritional reserves, and begin feeding after 4 weeks. The initial feed is generally red worms and other zooplankton, and once they grow to a certain size, they can be fed small fish and shrimp.
V. Economic Benefit Analysis
In 2009, although the Shaoguan City Fisheries Management Bureau and its subordinate Municipal Aquatic Life Conservation Base, after 5 years of effort and a large amount of manpower and material resources, successfully hatched 60 giant salamanders, taking a big step forward, mastering the source, key and core technology of artificial farming, and successfully achieving artificial breeding of the giant salamander, marking the entry of giant salamander farming into an era of artificial controllability and creating extremely favorable conditions for developing industrialized commercial farming. At present, the market conditions for giant salamanders are: young salamanders at 300-400 yuan each, small salamanders at 500-600 yuan each, giant salamanders reaching commercial specifications at 800 yuan per jin, and restaurants and eateries selling them at more than 1000 yuan per jin. The Base's farming water is high-quality groundwater, with large flow, stable water temperature and excellent water quality, very suitable for the growth of giant salamanders. In addition, through introduction, acclimation and breeding trials, the Base has basically mastered the techniques and methods for artificial breeding, grow-out of adult salamanders, disease prevention and control, and routine management of the giant salamander, and can expand the scale of giant salamander breeding and farming at any time, creating extremely considerable economic and social benefits. At present, the Base has formulated a near-term development plan, planning to acclimate and cultivate 400 parent giant salamanders, breed 6000-8000 giant salamander seedlings annually, develop commercial giant salamander farming, and raise 2000-3000 annually, with an average of 5000 g per salamander. Calculated at 500 yuan per giant salamander seedling and 800 yuan per 500 g of commercial giant salamander, its development prospects are very attractive.
□Article by Zhong Xiaoqing, Guangdong Provincial Aquatic Technology Extension Station
I. Biological Attributes
The Chinese giant salamander, scientific name: andrias, in biological taxonomy belongs to Amphibia, Caudata, Cryptobranchidae, Andrias. The genus Andrias mainly consists of 3 species: the Chinese giant salamander, the Japanese giant salamander and the American giant salamander. Apart from the American giant salamander, the others are distributed in Asia and can be found in streams and ponds in China and Japan. As an amphibian, the giant salamander is a typical cold-blooded poikilothermic animal, with a maximum tolerable temperature of 24°C and an optimal growth temperature of 15-20°C. When the air temperature drops below 10°C, the giant salamander enters a state of hibernation.
Under natural conditions, the giant salamander can live 50-60 years, among which the Chinese giant salamander can reach a maximum body length of 1.8 m, the Japanese giant salamander a maximum body length of 1.5 m, and the American giant salamander a maximum body length of only 0.75 m. Their common features are a flattened and elongated body, very short limbs, 4 toes on the forelimbs and 5 toes on the hindlimbs, webbed toes, and a short and laterally flattened tail. Those who do not know it often mistake it for a fish, but it is actually an amphibian, meaning its physiological structure helps it survive both in water and on land. In water, it breathes with gills; on land, it breathes with its lungs and skin. Their skin has only mucous membrane and no scale covering.
The Chinese giant salamander is commonly known as the "baby fish" because its call resembles the crying of an infant, while the Japanese giant salamander is called the "pepper fish" because its body has a pepper-like odor. Giant salamanders especially like to inhabit remote, quiet and rarely visited deep mountains and old forests with poor transportation, living year-round in mountain streams with fresh water quality and rapid currents. They are accustomed to sleeping during the day and foraging at night, feeding mainly on fish and crustaceans. However, due to long-term life in a dark environment, their eyesight is poor, and they can only rely on pressure changes detected by sensory areas on the head and body to hunt prey.
During the mating and breeding season, they swim upstream. After the eggs are fertilized, the male guards the young salamanders for 6 months, until they are able to forage on their own.
II. Socioeconomic Value
The giant salamander has a very long history of survival on Earth, dating back 200 million years, when it once flourished. Because it is at a transitional stage from aquatic to terrestrial life, it holds a special position in biological taxonomy. To this day, it has high academic research value in disciplines such as physiology, genetics, evolution and ecology. In addition, as its living environment is deteriorating day by day and its numbers are decreasing, it has been listed by the state as a Class II aquatic wildlife protected animal. At the same time, the giant salamander also has certain medicinal and food functions and a certain commercial development value. According to traditional Chinese medicine theory, the medicinal value of the giant salamander is shown in helping the human body promote circulation and invigorate blood, moisturize the skin and nourish the complexion, comprehensively nourishing the body both internally and externally. In terms of food value, as a rare and precious meat, the giant salamander has characteristics such as crisp skin, fine meat, crisp bones and delicious taste. Although the giant salamander is a Class II aquatic wildlife protected animal, in line with the purpose of protection for better development and utilization, relevant state laws stipulate that adult giant salamanders whose parents are second-generation artificially bred individuals, or which have lost reproductive capacity, or have body deformities, or abnormal growth, may be used for commercial purposes upon obtaining administrative permission from the relevant state authorities. Things are precious when they are rare. At present, the market price of giant salamanders reaching commercial specifications has reached 1200 yuan/500 g. Some high-end restaurants and eateries in Guangzhou and even some large cities in the Pearl River Delta use the giant salamander as a main ingredient through traditional fine processing techniques to create a series of dishes to attract customers, and business is booming.
III. Experimental Demonstration Base
Driven by demand from all sectors of society, fishery authorities, research institutions and aquaculture enterprises in the native producing areas of China's giant salamanders, such as the Yangtze River and Pearl River basins, have successively established projects and invested large amounts of manpower, material resources and financial resources in tackling key problems in artificial breeding and high-yield, high-efficiency farming technology for the giant salamander, including the active efforts made for this purpose by the Shaoguan City Fisheries Management Bureau. Recently, at the invitation of the Shaoguan City Fisheries Management Bureau, the Guangdong Provincial Aquatic Technology Extension Station dispatched the author to visit the city on a special trip to investigate the situation on the ground. The relevant information is now organized as follows for reference, study and emulation by those interested in this field.
In October 2004, with strong support from the Guangdong Provincial Department of Finance, the Provincial Ocean and Fishery Bureau and relevant municipal government departments, the Shaoguan City Fisheries Management Bureau successively invested 4 million yuan to establish the Municipal Aquatic Life Conservation Base (hereinafter referred to as the "Base") at the foot of Chaisang Mountain and Huangshi Mountain in Longgui Town of the city, relying on the infrastructure and technical strength of the Municipal Aquatic Fine Seed Farm and the Municipal Fisheries Research Institute. At the same time, in order to increase its functions, it was additionally designated the "Municipal Special Aquatic Products Experimental Demonstration Base". The Base covers an area of 60 mu and is operated under lease with a lease term of 30 years. The Base is surrounded by green mountains on three sides, with luxuriant vegetation on the mountains and mountain springs and streams flowing through. In particular, groundwater resources are abundant, and the water quality is excellent, with a constant temperature (20-22°C) and a flow rate of about 720 cubic meters/hour. The flow is relatively smaller in winter, but this does not affect aquaculture production and domestic water use. The conditions in all respects are very similar to the natural living environment of amphibians such as giant salamanders and reptiles such as turtles and soft-shelled turtles, making it an ideal place for developing artificial farming of giant salamanders and turtles.
At present, the Base is divided by function into three relatively independent zones: 1. Farming zone, with 600 sq m of indoor giant salamander acclimation ponds, 1200 sq m of turtle conservation ponds, 300 sq m of Asian giant softshell turtle conservation ponds, 5000 sq m of fish conservation ponds and 1000 sq m of management and maintenance buildings; 2. Office zone, with 500 sq m of offices and meeting rooms, and the meeting room can accommodate 30-40 people; 3. Living zone, with 120 sq m of kitchen and dining hall, and relatively complete living facilities built for the Base's staff. Whether in terms of roads, water and electricity supply, flood control facilities, or purification, greening and landscaping, the Base has reached a new level. It is a relatively rare standard garden-style aquatic experimental demonstration base.
IV. Introduction, Acclimation and Breeding Trials
In the 5 years from 2004 to the present, the Base has successively introduced several batches of giant salamanders from Shanxi, Shaanxi, Hunan and other provinces as well as Huadu in Guangdong and other places, including both wild and artificially bred giant salamanders, in various sizes and specifications. The Base's technicians took acclimation as the breakthrough point in tackling key problems in artificial breeding technology for the giant salamander. Through long-term artificial acclimation, they helped it adapt to the artificial farming environment and conditions, thereby selecting parents and propagating the next generation.
Through long-term artificial acclimation, the Base's technicians gradually mastered the theoretical knowledge and technical requirements concerning the physiology, pathology and ecology of the giant salamander. First, due to long-term evolution, certain functions of the giant salamander have seriously degenerated, especially its eyesight; it is highly nearsighted, photophobic, and requires a dark and quiet living environment. Because its respiratory system is underdeveloped, it needs an adequate water source, excellent water quality, strong flow and high dissolved oxygen content to facilitate its oxygen intake needs. Second, the giant salamander mainly feeds on fish, and it is best to feed it silver carp, bighead carp and crucian carp of moderate size, as well as wild miscellaneous fish caught from mountain ponds and reservoirs. Compared with other amphibians such as frogs and toads, the giant salamander's metabolism is very slow, manifested in behavior as remaining motionless for long periods, so it is fed once every two days. When feeding, the giant salamander uses stillness to control motion and launches attacks very quickly; once it bites, it will not easily let go until the prey dies, and then it swallows it and slowly digests and absorbs it. Due to low energy consumption, thorough digestion and absorption, and a high feed conversion rate, the giant salamander grows very quickly, and its body weight can double in 1 year. In other words, the input-output ratio of artificial giant salamander farming is very high, and its feed conversion ratio can reach 1-2, giving it great commercial investment value. Third, because the artificial acclimation period has been relatively short and the density is relatively low, it has not yet been found what types of diseases the giant salamander is susceptible to. However, from the Base's farming production practice, as long as the water supply is guaranteed, the water volume is relatively large, the water temperature fluctuates little and the water quality is excellent, the giant salamander is not prone to illness, the survival rate is very high, and the farming risk is relatively low. But this conclusion still needs further observation and research analysis.
In 2009, the Base had 201 giant salamanders, among which the largest weighed 15 kg and the smaller ones 0.5 kg, as well as 400 turtles including Chinese pond turtles, yellow-margined box turtles and yellow pond turtles. In July 2008, after careful study and discussion, the leaders of the Shaoguan City Fisheries Management Bureau and the Base's technicians believed that the conditions for artificial breeding of the giant salamander were gradually maturing and decided to carry out artificial breeding trials. The technical cooperation unit for the trials was the Zhangjiajie National Giant Salamander Protection Center, and the trials were successful.
The trial parents were giant salamanders introduced from other places and acclimated by the Base 4-5 years earlier. The Base's technicians carefully selected 5 male and 10 female adult giant salamanders and used artificial hormone injection to hasten their sexual maturity, with males releasing sperm and females ovulating. Because these parents were all produced through artificial farming, their gonads were not yet fully mature, and this was the first artificial induced spawning and breeding, only 4 female giant salamanders successfully laid 150 eggs through artificial induced spawning, among which the eggs of 2 were absorbed because they missed the optimal timing for induced spawning. Like the eggs laid by frogs and toads, the eggs laid by the giant salamander are also like black beans, wrapped outside by an egg membrane, strip-shaped and floating in the water.
Key technical points for successfully hatching giant salamanders: First, it is necessary to master the optimal timing for artificial fertilization. The giant salamander undergoes external fertilization in water, and artificial fertilization must be completed within 20 seconds after the giant salamander lays eggs and releases sperm, otherwise the semen becomes ineffective and fertilization cannot be achieved. Second, after successful fertilization, place the fertilized giant salamander eggs in a hatching room at a constant temperature of 19°C, and ensure excellent water quality through a circulating filtration system. After 31 days of hatching, the young salamanders will break through the membrane and emerge. Through the above technical steps, the Base successfully hatched more than 60 young salamanders, with a hatching survival rate as high as 40%. Newly born young salamanders are like tadpoles, lively and active, swimming around, completely different from their parents. They first digest their own nutritional reserves, and begin feeding after 4 weeks. The initial feed is generally red worms and other zooplankton, and once they grow to a certain size, they can be fed small fish and shrimp.
V. Economic Benefit Analysis
In 2009, although the Shaoguan City Fisheries Management Bureau and its subordinate Municipal Aquatic Life Conservation Base, after 5 years of effort and a large amount of manpower and material resources, successfully hatched 60 giant salamanders, taking a big step forward, mastering the source, key and core technology of artificial farming, and successfully achieving artificial breeding of the giant salamander, marking the entry of giant salamander farming into an era of artificial controllability and creating extremely favorable conditions for developing industrialized commercial farming. At present, the market conditions for giant salamanders are: young salamanders at 300-400 yuan each, small salamanders at 500-600 yuan each, giant salamanders reaching commercial specifications at 800 yuan per jin, and restaurants and eateries selling them at more than 1000 yuan per jin. The Base's farming water is high-quality groundwater, with large flow, stable water temperature and excellent water quality, very suitable for the growth of giant salamanders. In addition, through introduction, acclimation and breeding trials, the Base has basically mastered the techniques and methods for artificial breeding, grow-out of adult salamanders, disease prevention and control, and routine management of the giant salamander, and can expand the scale of giant salamander breeding and farming at any time, creating extremely considerable economic and social benefits. At present, the Base has formulated a near-term development plan, planning to acclimate and cultivate 400 parent giant salamanders, breed 6000-8000 giant salamander seedlings annually, develop commercial giant salamander farming, and raise 2000-3000 annually, with an average of 5000 g per salamander. Calculated at 500 yuan per giant salamander seedling and 800 yuan per 500 g of commercial giant salamander, its development prospects are very attractive.