Text/ Aquatic Frontier Chen Xiaoqing, Research Group of Murray Cod Introduction and Breeding Project of Ocean University of China
Photo/ Research Group of Murray Cod Introduction and Breeding Project of Ocean University of China
In the future, Murray cod may become the new favorite of china's factory high-density aquaculture. Recently, confirmed by the Ministry of Education's Science and Technology Inspection Workstation (L16), the large-scale artificial breeding technology of Murray cod cooperated by Ocean University of China with Qingdao Qihao Biotechnology Co., Ltd., Qingdao Colorful Spot Aquaculture Co., Ltd., and Jiangsu College of Agriculture and Animal Husbandry Science and Technology has been successful, which is a major breakthrough in the world's Murray cod research technology.
<b>Large-scale, all-artificial breeding technology on-site acceptance meeting of Murray</b> cod
Murray cod, also known as Australian dragon stripes, is native to the Meridaling River Basin in southeastern Australia and is one of australia's main artificially bred warm-water freshwater fish. Its tender flesh has few thorns, delicious taste and no fishy taste, and it has a faint fragrance, and the taste can be comparable to that of groupers and bamboo shoot shell fish. Because of this, the economic evaluation of Murray cod in Australia is extremely high, known as the "national treasure fish". At present, there are about three large-scale Murray cod breeding enterprises in Australia, with an annual output of about 500 tons.
Murray cod is well-known abroad and is also loved by consumers in China, and the adult fish market is in short supply. At present, the market price of Murray cod is about 40-50 yuan / kg, the market distribution is as many as more than 30 cities, and the sales volume reaches 300-400 tons per year. Australian cod has the characteristics of fast growth rate, strong disease resistance, large tolerance to water temperature, high conversion rate of artificial compound feed (feed conversion rate of 1.05), etc., which is suitable for intensive breeding in different breeding areas. At present, several companies, including Qingdao Colorful Aoban Aquaculture Company, are carrying out Murray cod aquaculture, with an annual output of hundreds of tons, and have basically mastered the breeding, frying and adult fish breeding of Murray cod, and the breeding mode includes outdoor earthen ponds, indoor cement ponds and factory circulating water aquaculture.
Murray cod was first introduced to China in 2001, but due to the constraints of its seed supply, it has been difficult to carry out large-scale promotion in China. Murray cod is sexually mature and old, the amount of spawning is small, and the breeding environment is demanding, so far it can only be cultivated by placing broodstock in the fish pond, constructing a fish nest, allowing it to mate naturally, laying eggs and fertilizing, retrieving the fertilized egg mesh curtain for incubation, which belongs to the semi-artificial nursery method of natural egg collection, and it is difficult to achieve a stable number, excellent quality and large-scale supply of commercial fry. Domestic large-scale culture of Murray cod still needs to import millions of fry from Australia every year to carry out aquaculture production. For more than a decade, many practitioners have not stopped exploring the breeding technology of Murray cod.
<b>Hanging net incubation</b>
Since 2011, ocean university of China and Qingdao Qihao Biotechnology Co., Ltd. have jointly carried out research on industrial aquaculture of circulating water, and made a major breakthrough, and the breeding density has reached the current international leading and domestic highest level of 150-200 kg/m3 water body. At the same time, Professor Gong Qingli of ocean university of China led the team to carry out scientific research on artificial seedlings, and successively introduced 5 million fry for breeding, from which epigenetic traits such as body size, body length, growth performance, disease resistance, body pattern, male and female individuals were screened, and after 8 years, more than 7,000 breeding groups suitable for broodstock were selected from millions of farmed adult fish. This group has become the world's largest group of broodstock, and the reserves of this broodstock group have laid a solid foundation for the explosive growth of China's Murray cod industry.
In 2015, the scientific research team began to explore the influence of external environmental factors on broodstock breeding and gonadal maturation.
In 2018, the influence mechanism of temperature, light and nutritional conditions on the development of broodstock gonads was basically clarified, and successfully induced labor and breeding, but due to the timing of induction and other factors, only tens of thousands of fry were obtained, and the scale target was not reached.
<b>Video: Hatchlings</b>
<b>Video: Fry after re-feeding</b>
In 2019, on the basis of the existing results, the scientific research team continued to conduct technical research on the monitoring of Murray cod gonadal development, the selection of oxytocin hormones, the timing of induction and the control of the oxytocind dose, the preservation and activation of Murray cod sperm, the fertilization method, the method of hanging nets of fertilized eggs, the technology of fertilized egg hatching and waterproof mold, the breeding conditions of hatchling piglets, the biotrophic enhancement of fry opening bait, the preparation of live bait re-export feed, and the water quality management of the nursery process, and developed a set of technical processes suitable for the full artificial reproduction of Murray cod. In 2019, a total of about 4 million fertilized eggs, about 800,000 hatchlings, and more than 500,000 commercial fry with a body length of 3-5 cm were successfully bred for re-export feed, so far, the large-scale artificial nursery technology of Murray cod has been successful.
<b>Fry after re-feeding</b>
It is reported that the scientific research team of the Ocean University of China and relevant partners will further improve the relevant technical routes and technical processes, rely on technological innovation and breeding of a huge group of broodstock, find capital docking, and create a billion-yuan large-scale seed industry of Murray cod.
As an emerging freshwater high-quality fish breeding species, Murray cod will surely have a broad space and market for development in China.