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4.1 Productivity

4.1.1 Reservoirs and lakes

Total area of fresh water in China is usually given as about 20 million ha. About one third of this consists of small lakes, reservoirs and ponds. This estimate, however, was made before 1956 (Solecki, 1966). Since then there have been increases in water area available for fish culture. Active programmes for the construction of ponds and small to medium-sized reservoirs have continued. Thus, the 6.7 million ha of water area considered suitable for aquaculture at the time have probably been increased to 10 million or more.

The traditional “five lakes” of China are: Tungting, Poyang, Hungtze, Taihu and Chao. Together they make up nearly 1.4 million ha, and yield in the order of 70 000 tons of fish annually (estimated by the Mission at 50 kg/ha).

There are reported to be about 130 lakes larger than 100 km2. The 33 lakes over 100 km2 in size listed in van der Leeden (1975) total over 4 million ha. Of this area, 670 000 ha are salty.

The largest of the salt lakes, Koko Nor, has an elevation of 3 200 m above sea level. It is about one percent salt and supports a significant fishery of yellowfish and pike (Anon., 1974).

In Hupei Province, lakes, rivers and reservoirs make up some 70 percent of the 270 000 ha of water. The Mission was told that the average yield of lakes over 10 000 ha in size is 60 kg/ha. Those of medium size reportedly yield 225 kg/ha. Small lakes and reservoirs under 500 ha generally yield 1 000 kg/ha under intensive management.

The Chinese assume that reservoirs will produce about one third less than natural lakes of the same size. For small reservoirs and lakes, the national average is given as “several dozen jin/mu”. This is about one quarter to one third the figure given for Hupei.

Table 4 gives the reported productivity of some reservoirs and lakes of various sizes. Recent data on the deeper lakes and reservoirs of the hilly and mountainous areas are not available. It may be assumed that their productivity would be substantially less.

There are evidently still some parts of the country where the small reservoirs built for water storage are not used for fish production. The people in these areas have not been accustomed to eating fish. However, in most areas, the Mission was told, such reservoirs are now stocked and fished, following the national motto “wherever there is water there should be fish”. The required fish fry and fingerlings seem to be readily available in most parts of the country where pond production is possible.

4.1.2 Rivers and canals

Larger rivers are also fished. However, little attention appears to be given to their management for fishery purposes. Fishing here is usually carried out with traditional gear. The Mission noted the use of large lift nets, with 5 to 20 m2 of netting, in several places, and set nets and lines are reportedly also used.

Small rivers and canals in the delta regions of the Yangtse, the Pearl and other rivers are more intensively managed for fisheries. As at the Chen-tung Commune visited, some are divided off into sections (sometimes with guards whose duties are to maintain the fences and assist boats in passing). These areas are stocked (see section 5.3) and provided with additional food materials such as manure and grasses. Productivity reaches nearly 1 500 kg/ha.

Table 4
Productivity and Other Characteristics of Various Lakes and Reservoirs in China

NameProvinceSurface Area (ha)Average Depth (m)Productivity (kg/ha/year)Remarks
Ho Lung ReservoirKwangtung       2008.3     70(Present production; 200 kg/ha expected)
Tung Lake (East Lake)Hupei    1 4674–5   278167 ha not used for fish
Pai Tan LakeHupei       4002   730 
Miyun ReservoirPeking    9 300?   150 
Taihu LakeKiangsu226 0003     52 
Fan Li Lake (2½ li Lake)Kiangsu       3332   525Connected to Taihu Lake
Hsuan Wu LakeKiangsu        4501.51 100 
Tin Shan LakeShanghai    6 600?   151Also 450 kg/ha of snails and other molluscs
Lui Hwa LakePeking        3325 000(Report of Canadian Mission)
Liang tse LakeHupei    4 330?   1731953. In 1956 had been reduced to ½ by excess fishing. Anon., 1958

4.2 Management

4.2.1 Principles

Management programmes developed for lake and reservoir fisheries are basically an extension of the polyculture system so successfully used in pond culture. Reservoirs or lakes under 100 ha in size are managed for intensive production with supplementary feeding as well as heavy stocking.

At the other end of the scale, the large lakes (over 10 000 ha) like Taihu Lake in the Yangtse Basin are managed by a combination of techniques: stocking; protection of natural spawning sites as well as creation of supplementary spawning sites; regulation of fishing seasons and gear; and enclosure of suitable bays and coves for conversion to intensive fish culture.

Much attention appears to be given to watershed management to increase lake fertility. Conversely, additional resources of the lakes (fertile bottom mud, aquatic vegetation, snails, etc.) are utilized to increase agricultural production in surrounding areas.

Certain of the natural lakes, such as Pai Tan and Hsuan Wu once underwent large-level fluctuations owing to the periodic droughts and floods. Pumping stations and other control devices have now been installed to control the water level (see section 3.5).

Special attention is given to the small and medium-sized lakes and reservoirs near cities where the local facilities for both fish production and recreation are especially needed. The Mission was told that grass clippings from the parks and vegetable waste from the markets are utilized for supplementary feeding. Dikes and causeways provide walkways and mid-lake pavilions; but they also serve to separate the lake into different kinds of production units, as at East Lake (Fig. 2).

Fig.  2

Fig. 2 Causeway on East Lake separating lake into different basins

4.2.2 Special methods

There are five unusual aspects of the Chinese approach to lake and reservoir fisheries that merit detailed comment. These are:

  1. stocking
  2. fertilizing
  3. large-scale catching
  4. subdivision
  5. bottom grading and clearing.

Such policies are not unique. They are also followed in the U.S.S.R. for instance, though with less consistency. Elsewhere, they have often been regarded as not worth the high cost. These aspects are discussed below in relation to the special conditions that exist in China. Stocking

In Asia there are fewer native species of freshwater fishes than in North America, and many fewer than in South America or Africa. The Asian species are more typically riverine. Thus, the natural or spontaneous fish fauna of lakes and reservoirs does not not encompass the variety of feeding habits that is typical, say, of the faunas of most African water bodies. Mollusc, detritus, phytoplankton and plant feeders, and even zooplankton feeders adapted to open water, are often missing.

Thus, the practice of stocking a combination of grass carp (herbivore), silver carp (phytoplankton), black carp (mollusc eater) and bighead (zooplankton), along with such bottom feeders as mud carp and common carp, utilizes more of the natural production of the system. These species, however, do not reproduce naturally in the still waters of lakes and ponds and therefore stocking must be regularly repeated (“catch and stock in rotation”). This requires extra work and facilities, but the system does allow close control of stock size. Thus catches need not fluctuate from year to year as they do when dependent on wild stocks.

The Mission feels that relatively low labour costs, and species that do not require high protein foods, are the most important factors in the success of this technique in China. It is also significant that bulk or large-scale harvesting of the stocks (see section where this is practised, leaves time for other activities than fish catching. In China, it is the fishermen who usually also produce the fish to be stocked.

Usually, the Mission learned, about 1 500 individuals (10–15 cm in length) are stocked per hectare of lake (see section 5.3). These fingerlings are usually produced near the lake site (see sections 5.5 and 5.6). Fertilization

Direct feeding of fish and fertilization of water are considered an essential part of small pond and reservoir management. It is often undertaken in lakes up to 100 or more hectares in size. Animal manures, especially pig, are used to stimulate plankton growth. The Chinese rule-of-thumb is to raise 15 or more pigs per hectare of water (see section 5.4.2). Green grass and vegetables are fed to grass carp, which, in turn, produce animal (fish) manure and food for other fishes. The Chinese say: “Feed one grass carp well and you feed three other fishes”.

In most countries, fertilization of large lakes and reservoirs is not considered as a practical fish-management tool. The fish manager also has little influence on the overall development of the surrounding land. China, however, recognizes that its arable land must be fully utilized to feed its people. Thus, a high premium is placed on utilization of waters in the most efficient way possible. Fish management, the Mission found, is given full consideration in agricultural planning, especially at the commune level. The Chinese planner, it seems, would regard an attempt to improve a lake fishery without considering the surrounding land as incomplete and wasteful.

There is little discussion of the use of human sewage in water management. It is clear nonetheless that considerable effort is being put into improving methods to ferment and sterilize such wastes for both land and water fertilization (see section 5.4.2). Bulk or large-scale harvesting

In large lakes and rivers, harvesting is accomplished in more or less conventional ways (e.g., gill nets and/or pair trawling). But in the smaller lakes and new reservoirs methods of obtaining a large percentage of the stock in a short time are emphasized. Seine nets up to 5 km long are common (e.g., East Lake, Wuhan). Encircling nets and seines up to 1 or 1.5 km are regularly used. Most of the work is done manually. Such seines may even be used as beach seines, with additional hauling ropes at regular intervals along the net (Solecki, 1966).

An interesting technique used is that of driving fish toward one end of the lake or large bay with boats, with the boatmen beating the water as they move forward together. After proceeding for some distance (100 m or so) a net is set behind the boats to prevent the fish from returning (Fig. 3). After repeating the process the first net is removed to be used for the next blocking. When the fish have thus been concentrated, they are fished from the remaining area with conventional gears such as encircling nets. In some cases (e.g., Ho Lung Reservoir) the last blocking net set incorporates a trap (Figs. 4a and 4b).

Fig. 3

Fig. 3 Poster at East Lake showing successive positions of the blocking nets used to concentrate fish into one arm of the lake for harvest

The remaining fish are driven into this trap. Such an operation requires 20 to 50 persons, and for big lakes it may extend for 20 or more days.

Fig. 4a

Fig. 4a Lifting the trap portion of a large blocking net used in reservoir harvest (Ho lung Reservoir, Kwangtung Province)

Fig. 4b

Fig. 4b Emptying the trap, Ho lung Reservoir

The method seemed very efficient to the Mission. But the investment in fishing equipment is high. Permanent dikes are sometimes built to reduce the length of nets needed for concentrating the fish. The system is primarily effective for the grass, silver and bighead carps, which remain in the upper part of the water column. Obviously the system is only practical where it is possible to market large catches all at once. Subdivision

Lakes and reservoirs are frequently subdivided to increase the efficiency of production and harvest. On reservoirs such as Ho Lung, visited by the Mission, dikes have been built across several bays. These shorten the length of the roads needed to give access to various parts of the lake shore. In addition, they form protected ponds in which to raise fry to a size at which they may escape from predators when moved into the lake itself. These nursery areas are small and shallow, so that systematic removal of unwanted fish is possible and their subsequent re-entry from the lake unlikely.

Subdivision is used also to separate sections where water plants like lotus are grown from the fishery areas, to partition recreational facilities from the main lake, and to facilitate harvest (see section

In Taihu Lake, Mission members were shown a dike constructed across a large bay. The enclosed portion of about 150 ha was converted into fish ponds for intensive fish culture. Built in three months by 2 200 workers with only small tools, this dike will increase the fish production of that bay from about 7 tons/year to perhaps 700. It seems likely that subdivisions of lakes and reservoirs will be used increasingly in China to convert parts of such bodies to intensive fish culture. Bottom grading and clearing

Prior to 1958, the reservoirs built in China were rarely or only party cleared of trees before flooding. In other parts of the world, clearing is discouraged as dead trees and other such left-over structures enhance the productivity of reservoirs, making more fish available. However, the Chinese practice of stocking and feeding in small reservoirs may reduce the importance of this effect. The advantage of leaving trees, therefore, appears correspondingly small. On the other hand, the trees hamper fishing operations, preventing the use of moving gear, an important harvest method in China. Therefore after 1960, all areas to be flooded in small reservoirs were not only cleared, but also all stumps and other potential snags were removed and the bottom graded to an even contour to make fish harvesting as easy as possible.

It is much less practical to attempt to clear the bottoms of medium and large reservoirs. The Chinese, therefore, attempt only to clear natural coves, and other areas about 10 ha in size (2 li in circumference) where this would facilitate fishing operations. As supplementary feeding is generally not done in these larger water bodies, the extra biological productivity of uncleared bottom is likely to be more important.

4.3 Environmental problems

China's handling of environmental problems is like that of the ancient Chinese artisans carefully carving a block of jade into a work of great detail still preserving its basic form. Mountains are levelled and swamplands are converted to manageable lakes with regulated water level, ponds and croplands, with a massive application of manpower. But at the same time, large programmes of reforestation and erosion control are under way, in an attempt to reverse the long over-use of Chinese hillsides and mountainsides and restore the ancient landscape.

China attempts to use resources to the fullest but the ecological implications of such development are considered. Waste, of any kind, is reduced as much as possible and the range of fishculture practices seen and discussed by this Mission provides good examples of how wastes are recycled back into productivity.

Substantial development of industry has created noticeable air and water pollution problems. The Mission was informed that government departments for environment problems have been recently created at both national and provincial level. Standards for air and water quality have been written into law. New factories are required to meet these standards, but most of the older ones are not, unless special local problems exist.

A severe drop in fish production of the Nun-chiang River, Tsitsihon, in 1969, resulted from discharge of waste water. The waters of a large reservoir near Peking became polluted with industrial effluents resulting in bad taste of the fish. These incidents helped show the Chinese the importance of such legislation. Both of the above problems have now been corrected.

However, a different kind of concern arises from the large-scale efforts to domesticate production. The conversion of swamplands, especially in large lakes, to fish ponds and fields is seen elsewhere as a potential threat to water quality. It reduces the natural filtration of water. Wild birds as well as fish require such areas for breeding and sometimes food.

The Chinese seem aware of such problems though they were not discussed with the Mission. In Taihu Lake, shallow marshy and swampy areas needed for natural reproduction of several kinds of fishes have been set aside as reserves and cannot be destroyed or even fished.

It seems likely, however, that the Chinese will prefer to find alternative ways of fulfilling the ecological roles played by wetlands and swamps (e.g., the anchored clumps of grass put out in Taihu Lake). Large-scale conversion of swamps to fish ponds or other uses of high utility will probably continue.

4.4 Summary and recommendations

The management systems for lakes and reservoirs that have evolved in China merit close study and even emulation by some of FAO's Member Governments. It is characteristic of Chinese development that such methods evolve in place. In general the approaches fit her own social and economic system. It is impressive to note that specific local conditions and constraints are well provided for and projects, like pieces in a jig-saw puzzle, fit into place with each element matched to the local resources and setting.

It is thus necessary to view their programme of stocking, fertilizing, and fishing all available waters in the context of China's emphasis on agriculture as the key to development and of the whole programme of agricultural production that reflects that policy. It is a system in which, when needed, industry can be expected to - and does - provide capital for agricultural investments.

Even more significantly, cost/benefit ratios appear to be evaluated in terms of overall development rather than on an individual project basis. Thus, the cost of clearing a reservoir near a city may not be evaluated against the return from sale of extra fish but rather by such factors as equalizing fish consumption, stimulating pig production, and so on.

The concept of controlling fish stocks through replenishment with artificially-raised fingerlings warrants reconsideration in the light of Chinese experience. It is worth noting that such stocking of lakes and reservoirs is also widely practised in India, and other areas of Asia. Special attention should be given, in cases where such stocking is proposed, to the feasibility of constructing predator-free subareas for fingerlings and adjacent facilities for fry production.

It is particularly important for other countries to note the advantages of all-round integrated management of water resources. This is a very recent development in Chinese practice but a very impressive one. In those countries where expansion of freshwater fish production is a significant element in development plans, special efforts should be made to ensure that fish and farm go hand in hand, in planning and in practice.

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