2. FRAMEWORK FOR AQUACULTURE DEVELOPMENT IN CHINA

2.1 China's Aquatic Resources

Inland water surfaces in China cover approximately 17 million hectares, i.e., about 1.8 percent of the national territory (Zhu De-Shan, 1980). They are composed of different types of water surfaces, including rivers (approximately 50 percent), natural lakes (30 percent), reservoirs (11.5 percent) and ponds² (8.5 percent). It is currently estimated that 5 million hectares, i.e., 29.4 percent of these inland water surfaces could be suitable for aquaculture. To this must be added 10 million hectares of irrigated paddy fields, where aquaculture could also be envisaged (Anon., 1980).

There are four main drainage systems running from west to east toward the Dong Hai and Nippon Hai (Figure 3): the basins of the Xi Jiang, Chang Jiang, Huang He and Heilong Jiang³. Some of the features of these basins and rivers are given in Table 1. They are usually very wide and their flow is heavy and this often causes disastrous floods. Since the Liberation in 1949, much construction development (dykes, dams, weirs) was done to regulate the flow and control the course of these large rivers (Tapiador, et al., 1977). The result was a considerable increase in aquaculture potential, particularly in the valleys and plains of the middle and lower courses of the Xi, Chang and Huang rivers. In this regard, special mention must be made to the vast delta plains of these rivers. The aquatic fauna of these basins is very diversified. There are several hundreds of different fish species (Table 1), the majority of which belong to the cyprinid family (Anon., 1980).

² This includes any water surface of less than 1 000 mu (67 ha) in area, whether natural or man-made
³ See Chinese-English glossary (page xiv)

The natural lakes of eastern China are found in the plain of the medium and lower reaches of the Chang Jiang (Figure 3), mainly in the provinces of Hubei, Anhui and Jiangsu (Section 9). In western China, there are many high altitude lakes in Xizang and Qinghai, which are fed by the surrounding mountain glaciers. In all, China has approximately 130 lakes which have a water area of 100 km² and which are found mainly in the Chang Jiang plain (Tapiador, et al., 1977).

Many reservoirs have been built in China, most of them dating from after the Liberation. There are at present (loc. cit.) more than 280 whose capacity exceeds 100 million cubic metres, 1 800 medium capacity (10–100 million cubic metres) reservoirs and more than 10 000 of smaller capacity (0.1–10 million cubic metres). In all, they cover an area of 2 million hectares, 66 percent of which is used for extensive fish culture (Section 10).

From the point of view of production of aquatic products, China's resources in terms of inland water surfaces, are sub-divided into five Regions (Table 2). The two most important are:

Region I, which includes the lower and middle courses of the Chang Jiang - especially the provinces of Hubei and Jiangsu, and
Region II, which is centred in the lower courses of the Xi Jiang and Zhu Jiang and in particular in their vast delta in Guangdong province.

In the three other Regions, aquacultural production may be somewhat lower due to the presence of negative factors, such as a mountainous topography (Region III), colder waters (Region IV) or unfavourable socio-economic conditions (Region V). The most significant fish culture activities are therefore carried out in the south-eastern part of China, in the plains of the large rivers and in the coastal areas.

2.2 Use of Inland Water Surfaces for Fish Culture

At the end of 1979, 2.74 million hectares of inland water surfaces had been developed for fish production by a variety of farming systems (Zhu De-Shan, 1980). Almost 28 percent of these surfaces are made up of fish ponds, while the remainder consist of larger water surfaces (lakes, reservoirs, channels and rivers), where less intensive farming methods are applied (Table 3).

Pond farming is carried out by the people's communes, either as a main activity (fish culture communes) or as a secondary one (agricultural communes). While in the former, fish production is fully integrated with other types of production (usually pigs and vegetables), in the latter, it is carried out side by side with cereals, livestock and various other crops.

However, farming in lakes (natural or man-made), channels and rivers varies according to whether they are state-owned or belong to a people's commune, a production brigade or both.

2.3 Fish Production

Total output of freshwater fish for consumption reached 1 115 900 t in 1979. Fish culture accounted for 813 300 t (73 percent) and semi-intensive fish culture in ponds produced approximately 670 000 t (60 percent) (Zhu De-Shan, 1980).

Table 1

China's main drainage systems

^a From van der Leeden (1975) quoted by Tapiador, et al. (1977)
^b Anon., 1980 (percentage of cyprinids in brackets)

Table 2

China's main aquacultural regions

Table 3

Freshwater areas developed for fish culture^a

^a Situation end 1979 according to official statistics (Song, pers. comm., 1980)

The production trend for fish culture on the continent of China is given in Table 4. Over the last 30 years, food-fish production has quadrupled as a result of various measures taken, of which the main ones were:

1. administrative organization;
2. distribution of resources;
3. the setting up of people's communes and the establishment of fishing communities;
4. the success of research on artificial spawning of Chinese carps in captivity (1958–61), and
5. dissemination of methodologies developed at the fish stations.

Fish culture, which in 1950 was practised in the lower reaches of the Xi Jiang and Zhu Jiang (Guangdong province) and the Chang Jiang (Jiangsu and Zhejiang provinces) - where large numbers of wild fry could be caught each season - has since spread well beyond these geographical limits and has become largely independent of wild fry fisheries (Section 5). Although these fisheries still continue¹, their results no longer strongly influence fish culture development. Almost 40 000 million fry are now produced and distributed annually, over 95 percent of them in specialized fish culture stations (Anon., 1980).

2.4 Fish Species

The waters of the Chinese continent contain approximately 700 species of fish. In fish culture, however, only 20 or so species are economically important and three of these have only recently been imported. Among them, we must still consider three groups whose significance from the point of view of volume of production is declining (Table 5).

The four major species form the group of Chinese carps which are familiarly termed the ‘family carps’: the grass carp, the black carp, the silver carp and the bighead carp (Figure 7). The species of the second group are usually reared in mixed culture with the first, with the exception of the Japanese eel, which is produced according to intensive monoculture techniques. The species of the third group are produced only in certain areas and on a relatively small scale.

Although they are not ‘carps’ in the strict sense from a taxonomical point of view, the four ‘family’ carps and the mud carp all belong to the Cyprinidae. However, while the ‘true’ carp (Cyprinus carpio) is classified in the Cyprinid sub-family, the grass carp and black carp are Leuciscinae and the silver carp and bighead carps are Hypophthalmichthyinae².

¹ The district of Xishui (Hubei province) produced almost 300 million fry in 1979, a third of which came from the Chang Jiang
² G.V. Nikol'skii's classification (1954), 1961

Table 4

Fish output in China 1950–79

Table 5

Economically significant species in Chinese fish culture

^a In brackets, English terminology used in China when it differs from that recommended by FAO
^b Syn. Tilapia mossambica and T. nilotica
^c De luxe predator species, little cultivated
^d Exotic species

Figure 7 The main species cultivated in southern China: from top to bottom and from left to right, H. molitrix (silver carp), S. mossambicus (tilapia), A. nobilis (bighead carp), M. amblycephala (Wuchang bream), C. idella (grass carp), M. piceus (black carp), C. molitorella (mud carp) and C. carpio (common carp). Photo F. Botts.

From a thermal point of view, Chinese carps inhabit relatively warm waters. Their lowest thermal limit for growth is usually considered as 15°C, since their appetite declines rapidly in colder waters. They cease feeding under 8°–10°C (Anon., 1980). There are, nevertheless, some particular variations. The mud carp, for example, is a typically sub-tropical species, which is very vulnerable to cooling of its environment and it dies at 5.5°C. The bighead carp prefers warm waters (30°–31°C) and growth slows down considerably under 20°C. On the other hand, although silver and grass carps prefer warm waters, they continue to grow relatively well in cooler waters (15°–20°C).

Chinese carps - and the mud carp in particular - withstand a low dissolved oxygen content relatively well. This should nevertheless be preferably above 2 mg/litre. Below this level the fish lose their appetite and cease feeding when it falls below 1 mg/litre. Death ensues when the oxygen content is less than 0.2–0.5 mg/litre (Anon., 1980).

The natural diet of Chinese family carps and the mud carp is given in diagram form in Table 6. From the time they are 6.7 mm long (approximately 3 days old), the young fry feed actively on microzooplankton. The size of the planktonic organisms ingested increases gradually until the fry reach a total length of 14–16 mm. Their diet then begins to differ depending on the species and gradually evolves toward the preferred diet of each species. This becomes apparent in the silver and bighead carps from the length of 3 cm, while the three other species must reach 10–15 cm. From the fish culture point of view, these diets may be summarized as follows:

Other species (Figure 7) are usually used in mixed culture with the major species (Section 6.1), e.g., Wuchang bream (macrophytic feeder), the common carp and the crucian carp (benthos feeders), as well as various ichthyophagous species (snakeheads and mandarin fish).

From a biological point of view, one of the other significant aspects of fish culture is the preference shown by different species for well-defined areas of the body of water in which they live. Choice of zone is made by Chinese carps mainly on the basis of diet (Table 7). This is why the plankton feeders prefer the upper layers of the pelagic zone, while the grass carp inhabits the coastal zone. Mud carps, black carps and common carps live in the deeper benthic zones.

2.5 Farming Systems and Yields

At present, different farming systems¹ are used in fish culture on the continent of China and they may be classified as follows:

1. semi-intensive fish culture in ponds: polyculture, organic fertilizers (integration), little supplementary feeding;
2. extensive fish culture in natural lakes and reservoirs: polyculture starting from fry in stock; usually little use of fertilizer and little supplementary feeding;
3. extensive fish culture in pens, rivers and channels: polyculture starting from fry in stock; usually little use of fertilizer and little supplementary feeding;
4. extensive fish culture in cages: mono or polyculture in lakes, reservoirs, rivers or channels; little supplementary feeding, and
5. intensive fish culture in pools: monoculture in warm water of eels for export.

Other farming systems are used, but these are in the experimental stages, i.e., intensive cage farming. Further details based on data obtained on the spot, are given in the following sections.

¹ The different fish culture systems, based on the diet given to the fish, are defined as follows: extensive (natural feeding); semi-intensive (supplementary feeding) or intensive (artificial feeds)

Table 6

Natural diet of major Chinese carps

		Silver carp	Bighead carp	Grass carp	Mud carp		Black carp
		copepod and rotifer nauplii
		micro-cladocera and rotifers especially cladocera			+	phytoplankton and organic detritus	copepods cladocera
							cladocera chironomids (benthos) detritus
		cladocera copepods (rotifers)	cladocera copepods rotifers phytoplankton	cladocera and copepods chironomids and benthic organisms
		phytoplankton increases gradually	zooplankton increases gradually	+ plant fragments	+	organic detritus phytoplankton	gradual increase of molluscs (gastropods)
		PHYTOPLANKTON zooplankton	ZOOPLANKTON phytoplankton	gradual increase  - soft aquatic plants - leaves + young shoots		gradual increase epiphytic algae
				- aquatic plants - soft land plants	epiphytic diatoms green filamental algae plant detritus (zooplankton)		BENTHIC MOLLUSCS
				HIGHER PLANTS		EPIPHYTIC ALGAE ORGANIC DETRITUS

Table 7

Environmental features of Chinese fish species

At national level (Table 8), average yield from extensive systems varied in 1978 from 90 kg/ha/year to 307.5 kg/ha/year, while in 1979, using the semi-intensive system in ponds, the yield exceeded 2 750 kg/ha/year.

Table 8

Average annual yields obtained with fish culture in China in different aquatic environments

(a) Semi-intensive in ponds
(b) Extensive, in lakes and reservoirs
(c) Extensive, in pens
(d) Extensive, in cages
(exp.) experimental

At the local level, however, yields vary not only with the type of farming system used, but also with the duration of the period of growth, which is dictated mainly by the local climate and the influence this has on the temperature of the water (Table 9). In southern China, carps grow practically all year long, while in the Chang Jiang basin, the period of growth is restricted to 7 or 8 months in the year. It becomes shorter as we move toward the north, where it is 5.5 months.

Table 9

Variation in duration of the growing period for family carps in China (Anon., 1980)

^a Period during which the monthly average temperature of the water is at least 15°C

A third factor which affects yields is the relative intensity with which the system is applied. This is particularly valid for the semi-intensive system in ponds, where the rates of stocking, fertilizing and supplementary feeding can vary widely in time and space and result in proportionally different yields (Section 6.1.5).

A few data provided by the technicians of the Xishui district (Hubei), allow us to compare the annual profits which can be obtained with the three most widely used systems:

Although we were not able to define ‘retail price’, it would appear from the opinions expressed by these technicians, that there is no doubt that fish culture can be considered one of the most profitable rural activities.

2.6 Main Factors Contributing to Fish Culture Development in China

Fish culture in fresh water has been a traditional activity in China for more than 3 000 years. The first known Chinese monography on the subject dates back to the Fifth Century B.C. (Table 10). Other later writings also describe extensive fish rearing in open waters.

Table 10

Summary of the historical development of fish culture on the continent of China
(Adapted from Anon., 1980, page 3)

Until early in the Seventh Century A.D., i.e., for at least 1 200 years, the attention of the Chinese fish culturists was focused solely on the common carp (C. carpio). This fascination with this single species ended abruptly during the Tang Dynasty (618–906 A.D.), when fate willed that the name of the Emperor be similar to the common name (li) of this species. Fishing, sales and consumption of all common carps was banned. Fish culturists therefore turned to other species of local fish. Since there was an abundance of wild fry of the four family carps, and since they could be easily fished in the large rivers (Chang Jiang and Xi/Zhu Jiang) and then reared together in ponds, they quickly became popular. Monoculture of the common carp was thus definitively replaced by polyculture of family carps, which is practised today.

Techniques for catching wild fry, transporting them, sometimes long distances and selling them, thus became part of the fish culture tradition (Table 10). For nearly 1 300 years, fish culture activities remained centred in the valleys of the Chang Jiang and Xi/Zhu Jiang, close to the source of eggs and fry. It is only since 1960, when artificial spawning of family carps was developed and brought into widespread use, that this close dependence gradually ceased (Section 5).

It is only over the past 30 years that fish culture techniques have developed rapidly, to the point where China has become the world leader in fish production. Several of the main reasons for this ‘leap forward’ have already been mentioned (Section 2.3), but the following have to be added to the list:

1. the close relationship between agriculture and fish culture, combined with the widespread development of controlled irrigation, which enables maximum use to be made of lands and water;
2. the spread of electricity in the rural areas, combined with the relatively low cost of electrical energy thus provided to the people;
3. decentralization of production scheme preparation to allow the people to participate and to encourage them to undertake responsibility;
4. the establishment of close links between education, research and practical application, by combining theoretical knowledge and practical experience, and
5. motivation of the masses by means of the widespread use of slogans and discussion campaigns designed to promote aquaculture development (Table 11).

Table 11

Examples of slogans used for promoting aquaculture

In its present stage of development, however, fish culture has not yet made a sufficient contribution toward a complete solution to the problem of providing fish for the population of China and average annual per caput consumption is only 5 kg. There are several reasons for this: the rate of utilization of freshwater surfaces is too low (less than 60 percent), yields are usually not high enough, research facilities are inadequate and there is a regional imbalance in production. Moreover, recent efforts in industrializing the country is resulting in increased pollution of the waters. In most ponds, rates of stocking, fertilization and feeding are low because fish culture inputs required to intensify the cultural systems are lacking.

In an attempt to increase production of aquatic products, current efforts are being directed mainly to increasing utilization of existing water surfaces and establishing new ponds (priority being given to the immediate outskirts of urban centres), as well as intensifying cultural systems, applying more advanced technology and developing scientific research.