Inland Fisheries

1.2.1.2. Reservoirs of the world

Worldwide there are about 60,000 large reservoirs (>15 m dam height), totalling 4,00,000 km² in water surface and about 6,500 km³ in volume. Asia possesses the greatest amount, followed by North America. Asia possesses nearly 65 % of the global total of reservoirs by number and 31% by volume. Most of the reservoirs are in China. The area of the Chinese reservoirs accounts to about 20,000 km². Larger better known reservoirs account for about 25% of the water stored in reservoirs. More than 14,000 small water bodies are found in the countries of South Africa.

List of the world's largest reservoirs by surface area

S.No.	Name of the reservoir	Country	Area (km2)
1	Lake Volta	Ghana	8,482
2	Small wood Reservoir	Canada	6,527
3	Kuybyshev Reservoir	Russia	6,450
4	Lake Kariba	Zimbabwe, Zambia	5,580
5	Bukhtarma Reservoir	Kazakhstan	5,490
6	Bratsk Reservoir	Russia	5,426
7	Lake Nasser	Egypt, Sudan	5,248
8	Rybinsk Reservoir	Russia	4,580
9	Caniapiscau Reservoir	Canada	4,318
10	Lake Guri	Venezuela	4,250

List of the world's largest reservoirs by volume

S.No.	Name of the reservoir	Country	Volume (km3)	Volume (cu mi)
1	Lake Kariba	Zimbabwe, Zambia	180	43
2	Bratsk Reservoir	Russia	169	41
3	Lake Nasser	Egypt, Sudan	157	38
4	Lake Volta	Ghana	148	36
5	Manicouagan Reservoir	Canada	142	34
6	Lake Guri	Venezuela	135	32
7	Williston Lake	Canada	74	18
8	Krasnoyarsk Reservoir	Russia	73	18
9	Zeya Reservoir	Russia	68	16

In many reservoirs, fisheries have been pushed to the level reaching overexploitation due to excessive fishing. A study on the status of fish stocks and fisheries of thirteen medium-sized African reservoirs over 300 km³ concluded that adequate data exist in only a few cases to produce annual yield figures or estimates. Deterioration in data collection has also been noticed in the countries of the Commonwealth of Independent States (ex-USSR), where previously long-term data series greatly assisted in the management of fish stocks and fisheries in reservoirs. Deep reservoirs tend to stratify, especially in the tropics, creating an environment with little or no oxygen along the bottom where fish cannot survive; effectively limiting fish habitats to the near shore region and the open water. Where pelagic species are present these will quickly proliferate and form large populations that can be exploited by fisheries. However, in river systems without permanent lakes, there may be no or only few pelagic species and a large part of the fish fauna may not be able to adapt to life in standing water in a reservoir. To compensate for any loss in fish production it is common practice to stock reservoirs with fish species that are better suited for this type of aquatic environment.