Reservoirs of Sri Lanka and their fisheries

Table of contents

Sena S. de Silva
Department of Zoology
University of Ruhuna
Matara, Sri Lanka

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ISBN 92-5-102735-8

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This document is the result of on-going interest of the Working Party of Experts on Inland Fisheries of the Indo-Pacific Fisheries Commission in the development and management of reservoir fisheries in the Indo-Pacific countries. It reviews the development of the inland fishery of Sri Lanka, where the introduction of the exotic cichlid, Oreochromis mossambicus, has led to an unprecedented growth in reservoir fish yields.

The following is a list of documents published by FAO which deal with reservoir fisheries management in the Indo-Pacific region, planning for inland fisheries under constraints from other users, and management strategies including stocking.

Baluyut, E.A., 1982 Assessment of problems in planning river basin development involving a hydroelectric scheme. FAO Fish.Circ., (753):24 p. Issued also in Spanish

Baluyut, E.A., 1983 Stocking and introduction of fish in lakes and reservoirs in the ASEAN (Association of South East Asian Nations) countries. FAO Fish.Tech.Pap., (236):82 p.

Baluyut, E.A., 1986 Planning for inland fisheries under constraints from other uses of land and water resources: general considerations and the Philippines. FAO Fish.Circ., (798):44 p.

Bhukaswan, T., 1980 Management of Asian reservoir fisheries. FAO Fish.Tech.Pap., (207):78 p.

Petr., T. (ed.), 1985 Inland fisheries in multi-purpose river basin planning and development in tropical Asian countries: three case studies. FAO Fish.Tech.Pap., (265):166 p.

Sreenivasan, A., 1986 Inland fisheries under constraints from other uses of land and water resources: Indian subcontinent and Sri Lanka. FAO Fish. Circ., (797):68 p.


FAO Fisheries Department
FAO Regional Fisheries Officers
Selector SI
For bibliographic purposes this document
should be cited as follows:

De Silva, S.S.,1988 Reservoirs of Sri Lanka
and their fisheries. FAO Fish. Tech. Pap., (298):128 p.
Sri Lanka, a continental tropical island of 65,000 km2, is reputed for its ancient irrigation reservoirs, constructed over the last 2000 years. The island, which is devoid of natural lakes has 3 ha of artificially created lentic waters for every km2. These reservoirs are mostly confined to the dry zone which receives less than 187 cm of rainfall per annum.
The reservoirs vary in age, size, hydrology, catchment characteristics and usage. In the perennial reservoirs the development of fisheries is very recent and is associated with the introduction of the cichlid Oreochromis mossambicus (Peters) in 1952. The inland fishery yields approximately 27,000 to 30,000 tons year-1 and the average production of the perennial reservoirs is estimated to be 283 to 307 kg ha-1 year-1, with a range of 40 to 497 kg ha-1year-1, based on natural recruitment of these fish stocks.
The strategies for optimization of the yield from perennial reservoirs are different from those for seasonal reservoirs, which are small reservoirs that tend to dry out for three to four months a year. The latter group of reservoirs accounts for about 30% of the known total reservoir surface area on the island, and fisheries depends on regular stocking of fish, largely carps.
This study reviews the development of the fishery and its management and the biology of the constituent species. The possibility of using the Sri Lankan reservoir fishery as a model for tropical reservoirs is discussed.

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 2.5Water resources
  2.5.2 Floodplain Lakes
  2.5.3 Groundwater
 2.7Human settlement patterns
 3.1Historical aspects
 3.2Recent developments
  3.2.1Gal Oya Scheme
  3.2.2Walawe Ganga Scheme
  3.2.3Mahaweli Ganga Scheme
  3.2.4Kirindi Oya Scheme
  3.2.5General Aspects
 3.3Overall status
 3.4Perennial and seasonal reservoirs
 4.1General aspects
 4.2Inland fish fauna and introductions
 5.1Reservoir fish fauna
 5.2Biology of reservoir fishes
  5.2.1Biology of O.mossambicus
  5.2.2Other exotic fish
  5.2.3Indigenous Species
 5.3Reservoir capture fishery
  5.3.1The development of the fishery
  5.3.2The fishery, gear & crafts
  5.3.3Individual reservoir fisheries
  5.3.4Collection of statistics
  5.3.5Management of the fishery
  5.3.7Socio economic aspects
  5.3.8Future Developments
 5.4 Reservoir culture fisheries
  5.4.1 Seasonal tank aquaculture programmes
  5.4.2Culture fishery in major perennial reservoirs
 6.1Success of Oreochromis mossambicus
 6.2Future of Oreochromis mossambicus
 6.3Use of irrigation canals for fish production
 6.4Predictive models
 6.5Development programmes
 6.6Freshwater fish as a protein source
 6.7Research needs