Crocodile turtles belong to the genus Crocodile of Reptilidae. It is an original specialized turtle among more than 230 kinds of turtles in the world. Also known as flat-backed turtle, meat turtle, snake snapping turtle and snapping turtle. Its shell is brown, each shield has a spinous process, and its trailing edge is serrated. The abdominal nail is small, cross-shaped and yellow, and the nail bridge is short and wide. The head is triangular and brown, hooked on the beak, and the head cannot be completely retracted into the shell. There are thorns on the neck. The limbs are grayish brown with developed webbed fingers and toes. The tail is very long, with 1 rows of thorns in the center. It is distributed in Argentina, Peru, Brazil, Venezuela, the United States and the vast areas of the Great Lakes in southern Canada. Among them, there are many species in the United States, including big snapping turtles and small snapping turtles, which are divided into four subspecies.
Crocodile turtles belong to aquatic turtles and live in freshwater lakes, rivers, swamps and pools. They can survive normally in the water temperature of 3-45℃, feed normally above 65,438+08℃, are most active in the water temperature of 20-33℃, grow fastest in the water temperature of 28-365,438+0℃, rarely move above 34℃, and lie in the water or mud for summer. Omnivorous, under the condition of artificial feeding, pork, beef, poultry viscera, apples, vegetable leaves and artificial compound feed can all be fed. It grows fast, and it usually takes three years to grow into a commercial turtle at natural temperature. The growth rate is twice as fast as that of soft-shelled turtle, and the average annual weight gain is 300-800g. However, under the condition of temperature control, people grow faster, with an average annual weight gain of 1.5-2.0kg, short sexual maturity cycle and high spawning rate. Generally, it takes three years for wild snapping turtles to mature and lay eggs, while artificially raised snapping turtles begin to mature and lay eggs and reproduce when they are 18 months old or grow to more than 1 1,000 grams. April-May and 9- 10 are natural mating periods, and April-July is the peak of spawning. A snapping turtle weighing 5500g can lay 70-80 eggs, and a snapping turtle weighing 3000g can lay 30 eggs (Tai, 2007). Crocodile turtles have small abdominal carapace, large exposed armpit and more meat content (Tai, 2007), which is much higher than turtles such as soft-shelled turtles. To sum up, snapping turtles have broad breeding prospects and economic benefits than other turtles.
First, the development of the snapping turtle market in China
1996 and 1997, snapping turtles were introduced as ornamental pet turtles in China, mainly including snapping turtles' seedlings and larvae. However, due to the single color of snapping turtles, people don't realize that snapping turtles have the advantage of fast growth, so the domestic market price is low, and each snapping turtle seedling only sells for 30-40 yuan.
During the period of 1998, some farmers and turtle lovers found that snapping turtles not only grew fast, but also had the characteristics of simple breeding technology and high meat content. In addition, at that time, the market and price of Trionyx sinensis fell, and some Trionyx sinensis farmers were looking for suitable similar breeding projects, but there were similarities in breeding methods and pond requirements between Crocodile Tortoise and Trionyx sinensis. Therefore, many turtle farmers in China turned to breeding snapping turtles to make them.
By 1999, after half a year's breeding, the snapping turtle seedlings weighed 900- 1000g, which benefited farmers a lot. In addition, with the promotion of various media, the price of snapping turtles has risen again, with snapping turtle seedlings reaching 100- 120 yuan and adult turtles reaching 500-560 yuan per kilogram, and the supply is insufficient.
In the spring of 2000, farmers, farms and even some state-owned aquaculture farms all over the country took snapping turtles as investment projects in 2000, which led to the shortage of snapping turtles in the market and the price of snapping turtles and cultured snapping turtles rose again. In July, 2000, each snapping turtle 150- 170 yuan, the cultured turtle reached 540-600 yuan per kilogram. The snapping turtle market in China is ups and downs. In the first few years, it was mainly the introduction of cultured turtles, and the price was higher. Later, snapping turtles were first tasted in Guangdong, Beijing and other places after being cultured. It feels delicious and has a high meat content. It is accepted by high-end restaurants and introduced at a high price. After CCTV focused on promoting snapping turtles, the whole country set off a craze for breeding snapping turtles. Since then, the Ministry of Agriculture has taken snapping turtle as one of the promoted varieties, which has made snapping turtle breeding take a new step.
Under the influence of macro-economy, snapping turtle seedlings entered a temporary trough in 2004, and the snapping turtle market rose again in 2005. At this time, with the gradual maturity of crocodile turtle breeding technology and market, commercial crocodile turtles are profitable, which has stimulated the rise of crocodile turtle seedling market again and again in 2006. Finally, each snapping turtle seedling was shipped to farmers in China at the price of 130 yuan in the United States.
In 2007, the price of snapping turtle seedlings declined slightly, but the decline was not significant. The price of each snapping turtle seedling to farmers is 1 00-10 yuan. The price of snapping turtle parents has slightly increased, and each snapping turtle that can only lay eggs is about 150 yuan/500g. At present, the market price of commercial snapping turtles, with specifications above 4.5kg, is basically stable in 55 yuan, which is used for breeding. Crocodile turtles were introduced to China from the United States at the end of last century. After the hard work of farmers and researchers and the correct guidance of government departments at all levels, they have taken root and sprouted in China. At present, its breeding technology is becoming more and more mature, and snapping turtles are welcomed by the market for their unique delicacies.
Two, several outstanding problems restricting the development of crocodile turtle breeding industry
The artificial breeding technology of turtles is immature.
Fishery-related scientific research institutions and turtle seedling breeding enterprises have studied many physiological characteristics and genetic traits of turtles and stone turtles, but little has been involved in other varieties. Although there are already artificial breeding and breeding technical data, it is not deep and systematic enough. The artificial breeding technology of turtles is still immature, so it is urgent to speed up the research.
The artificial fertilization rate (fertilization rate, hatching rate and survival rate) of snapping turtles is low. Specifically, the fertility of snapping turtles is low, and the fertility of mature females is low. Usually, only 50% of females lay eggs. In addition, the fertilization rate is low, less than 70%. The hatching rate is unstable, often below 80%, and the survival rate of young turtles in winter is low, less than 70%. Crocodile turtles have strict requirements on environmental conditions and strong regionality, which often seriously affects their reproductive ability because of the inadaptability of environmental conditions. The low fertility seriously restricts the large-scale production of turtle seedlings and the development of industrialization of crocodile turtle breeding.
Backward breeding technology and equipment.
At present, some units are still using earthen ponds to raise turtles, while others are using greenhouses to raise turtles. There is no technical transformation, and an "ecological" greenhouse with multi-function, automatic environmental monitoring, automatic recording and automatic control has not been built, which often cannot meet the growth requirements of snapping turtles.
Crocodile turtle breeding is not specialized and large-scale production is not enough.
At present, crocodile turtle breeding has not reached the level of specialization and scale, and there is no crocodile turtle breeding enterprise group integrating scientific research, breeding, processing and sales, nor can it rely on scientific and technological progress, modern management, large-scale production and intensive processing of crocodile turtles, and there is no reliable market network information.
The comprehensive utilization rate of snapping turtles is low.
At present, snapping turtles are mainly sold in restaurants or hotels, while commercial turtles are sold in bits and pieces. For medical research institutes, pharmaceutical factories, aquatic products processing plants and other units, it is impossible to collect a large number of fresh and cheap snapping turtle discards, but directly buy a large number of commercial snapping turtles to get their discards, because the cost is high and unbearable. The purpose of comprehensive utilization has not been achieved, and the value of snapping turtles has not been fully reflected.
Third, the development trend of crocodile turtle breeding
The economic value of snapping turtle can be compared with that of ostrich. In the United States, ostrich meat is $0/00 per kilogram, and crocodile turtle meat can reach $0/50-180 per kilogram. At the same time, it has high yield, large output value and high fertility. According to statistics, after more than 8 months of breeding, the average weight of each young turtle is 624g, and the net yield per unit area is 12.5kg/㎡/m2. According to the current market price, the output value is as high as 6,000 yuan /m2, which is much higher than that of ordinary aquaculture. Overseas 1998 has started large-scale breeding. International markets such as the United States and Canada have matured.
The crocodile turtle breeding industry in China has only experienced more than ten years from small to large, and only a few years from the peak of crocodile turtle breeding to steady development, with rapid development. At present, the price of adult snapping turtles is gradually decreasing, and some turtle breeding enterprises think that the development prospect of snapping turtle breeding industry is not optimistic. In fact, the price of snapping turtles is normal at present, and with the increase of snapping turtle production, the price of snapping turtles has a gradual downward trend, which is also normal. In the early stage of crocodile turtle breeding, the price will inevitably rise because of the small number of crocodile turtles, especially in the "crocodile turtle breeding fever" stage in previous years, which is an abnormal phenomenon. From the perspective of market economy, this phenomenon only exists in the initial stage of the development of crocodile turtle breeding industry. This primary stage is over.
Now the crocodile turtle breeding industry has entered the intermediate development stage. There is an urgent need to build a platform for the production and supply of improved varieties, the demonstration and promotion of healthy breeding technology and the processing, circulation and sales of commercial crocodiles, tap potential, integrate resources and improve infrastructure.
One is to speed up the breeding and supply the parents of improved snapping turtles, and the other is to expand the yield and improve the quality of snapping turtles, so as to solve the bottleneck problem of large-scale development of snapping turtle breeding. Third, through the business model of "company+base+agriculture and fishery", through the demonstration of healthy breeding of snapping turtles, we will provide technical services for snapping turtle farmers, extend the industrial chain through "seedling supply-technical guidance-products-sales-processing and utilization", improve the added value of products, promote healthy turtle breeding technology with farmers, and build a well-known brand. Increase farmers' income and enhance industrial competitiveness. Only in this way can aquaculture be gradually industrialized, standardized and scaled.
At present, the price of snapping turtles is normal, and with the increase of snapping turtle production, the price of snapping turtles is gradually decreasing, which is also normal. The primary profiteering stage of snapping turtles has ended.