Prof. Pin NIE: Freshwater Aquaculture Should be Resource Saving and Environmentally Friendly  

Journalist Hong Wei 
Translated by MA Yun

Food and Agriculture Organization of the United Nations predicts that worldwide harvest output of aquatic products will be stagnant or decreased whereas the consumption of aquatic products will be increased at the speed of 1.0% to 2.9%. The increase of aquatic product output will mainly be attributed to the development of aquaculture. For a developing country, especially for a country with a large population and fast developing pace as China, aquaculture in the 21st century will not only face favorable developing opportunities but severe challenges as well.  

Recently, with approval of the Ministry of Science and Technology, the “973” project “Investigation of Crucial Scientific Issues in Intensive Aquaculture of Freshwater Ponds in China” will be launched. As far as China’s status and scientific prospect of aquaculture are concerned, Prof. Nie Pin, chief scientist and researcher of IHB was interviewed by Science Times.  

Science Times: could you introduce the status of China’s development of aquaculture, especially freshwater aquaculture and its role in national economy? What problems are we facing? 

Prof. Nie: Traditionally speaking, aquatic products are the major sources of protein that Chinese obtained from their daily diet. According to the statistic data obtained in recent 5 years, the consumption of aquatic protein accounts for 1/3 of the total consumption of animal protein. After China’s opening up to the outside world, compared with other agricultural industry, aquaculture took the initiative to open its market and the aquatic product output increases quickly. Since 1989, China’s aquatic product output has been in the first place of the world. At present, it accounts for 40% of the world’s aquatic product output, among which the aquaculture output accounts for 70% of that of the world. China thus becomes the only fishery country that aquaculture output exceeds fishing yield, with 9 billion US dollars of export volume which accounts for 30% of the total export volume of agricultural products. Export of aquatic products has enhanced China’s international competitiveness in the field of fishery, thus promoted the development of domestic aquaculture and aquatic processing.  

In 2006, China’s total output value of fishery reached 456.86 billion RMB. It is expected that by the end of the “eleventh five-year plan”, the total output value will have reached 570 billion RMB. Fishery has become an important part of China’s agriculture and agricultural economy, a new growth point for increasing rural labor employment and farmers’ income. At present, the number of people who are directly involved in fishery production exceeds 13 million. In 2007, per capita income of farmers reached 6,500 RMB, but by the end of “eleventh five-year plan”, it will have reached 7,200 RMB.  

Freshwater fishery enjoys a long history in China. From late 1950s to the early 1960s, the artificial propagation technology of the so-called “four major Chinese carps” i.e. black carps, grass carps, silver carps and bighead carps had achieved great breakthrough and promoted the development of freshwater fish aquaculture. In 2006, the freshwater aquaculture area was 60,200 hectares and the aquaculture output was 19.5 million tons which accounted for 97% of the total output of cultured fishes.  

Nevertheless, China suffers from a shortage of freshwater resources. The problems of shortage of water resources and water quality-induced water shortage become more and more prominent in China. The current fishery pattern costs a great deal of resources and we need to shift the fishery pattern to the resource saving and environmentally friendly orientation. This is not only a scientific issue but also a social issue. However, the current scientific development of fishery in China does not meet the transformation of fishery growth modes. This is the most prominent issue right now and here lies the aim of our project.  

Science Times: How to make aquaculture be shifted to the resource saving and environmentally friendly orientation? In order to realize this goal, what kinds of key scientific problems need to be solved? 

Prof. Nie: Simply speaking, in order to realize the goal of shifting to the resource saving and environmentally friendly orientation, intensive aquaculture mode will become the direction of China’s aquaculture.  

Intensive aquaculture usually signifies the culture mode with high investment, high output and high stocking density, and which can regulate water quality. Its strengths lie in high output on the condition of high density technology investment and in that it occupies less land and is much easier to control diseases. Its weakness or problems are that it cannot effectively utilize the ability of aquaculture ecosystem’s regulation on water quality, and cannot exert the mutual benefits between aquaculture organisms. Therefore, how to fully exert the role of freshwater ponds in China, and how to construct a relatively stable and high efficient aquaculture ecosystem become a scientific problem that we have to face.  

Our project will mainly focus on the research of grass carps, which are herbivorous fishes that only exist in China. Their output accounts for 20.4% of that of the freshwater fish aquaculture. We can use grass or low animal protein to feed the grass carps. However, the main factors that restrict the development of culturing grass carps in the ponds are serious diseases, low utilization ratio of feed and serious pollution from aquaculture.  

The first question that we must answer is that whether grass carps have different manifestations in genetics and nutrition physiology that deal with the process of growth, feed utilization and disease resistance ability. To solve this problem, we need to select and breed the species that grow quickly and has high feed utilization ratio and can resist against disease. Another key issue that we have to understand is the relationship between nutritional requirement, digestion and absorption, metabolic mechanism, feed utilization ratio and endocrine and immune system of grass carps in their different phase of growth. This issue can lay a theoretic basis for saving feed and reducing pollution from aquaculture water.  

Secondly, high density intensive aquaculture could cause epidemic disease easily, thus resulting in huge loss for aquaculture production. Therefore, revealing the pathogenesis of the main cause of disease under the circumstance of intensive aquaculture in ponds and setting the theoretic basis for vaccine construction and vaccination are the crucial scientific problem that this project needs to settle, and the important technology resources that can break through the obstacle of drug residue in exported aquatic products.  

Thirdly, based on the intensive aquaculture that is supervised by ecosystem, we aim at developing the aquaculture mode that can efficiently use energy, feed and water resources input by men, and maintain the stability of aquaculture water environment and relatively high fishery productive capability and that has no negative influence on peripheral waters. In order to achieve this goal, we should fully exert the function of different functional groups in the aquaculture system and by optimizing the structure of food web and strengthening the mutual benefits between organisms, especially strengthening the role of microorganisms played in material circulation in ponds, we can maintain the stability of water environment and construct a stable and high efficient aquaculture ecosystem that can keep a balance between production, decomposition and consumption so as to enhance the utilization efficiency of water resources and protect water environment.  

Science Times: what kind of accomplishment is this project expected to achieve? 

Prof. Nie: The main goal of this project is to set up a biological research approach that is most suitable for China’s intensive aquaculture in ponds and construct a relevant theoretic system so as to guide the development of intensive aquaculture in freshwater ponds in China and lead the future of China’s fishery science and technology as well as genetic industry of aquaculture.  

In the near future, as far as genetic breeding is concerned, we will fulfill gene mapping in the growth of grass fishes, feed utilization and disease resistant traits and establish breeding population of grass fish’s characteristics. As far as nutrition mechanism is concerned, we will reveal the nutritional requirement of aquaculture species and explain their mechanisms of digestion, absorption and transformation, the relationship between nutritional utilization and growth and disease resistant ability. In this way, we can lay the theoretic basis for high efficient feed that is environmentally friendly. As far as disease prevention is concerned, we will sum up the major pathogenesis of pathogeny and construct a theoretic and technical system for immunity and prevention of diseases. As far as aquatic ecology is concerned, we will reveal the function that different biological groups exerts in aquaculture ecosystem in ponds and the mechanism of their role in the regulation of water environment. Besides, we will maintain the stability of water environment and provide theoretic and technical support for conservation of water resources and the sustainable development of aquaculture so as to ensure the healthy development of aquaculture and quality safety of aquatic products.  

In the meantime, we hope that through this project we can attract and cultivate a great number of innovative talents that can be engaged in the research of intensive aquaculture so that China’s original innovative ability of fishery science and technology as well as intensive aquaculture can be promoted, and the aquaculture modes can be shifted from traditional pond aquaculture to new and sustainable aquaculture mode, thus accelerating China’s transformation from a fishery country to a mighty one.  

Prof. Nie Pin, chief scientist and researcher of IHB was interviewed by Science Times.