A Preliminary survey of 21 Ceylon lakes. 1. Fisheries of two lakes, Parakrama Samudra and Minneriya Wewa

Fourteen species of indigenous fish and three species of introduced fish commonly used for food are present in Parakrama Samudra and Minneriya Wewa. Commercial fishing is done throughout the year in these two lakes by gill nets, shore-seines ("Ma-del" nets) and cast nets. From records of fish landings maintained from 1957 it is seen that the production of fish at Parakrama Samudra has increased from 41 pounds per acre per annum in 1957 to 117 pounds per acre per annum in 1962 and at Minneriya Wewa from 11 pounds per acre per annum in 1957 to 118 pounds per acre per annum in 1962. Tilapia mossambica formed the chief constituent of the catch at both these lakes and it was due to this fish that the commercial fisheries at both these places were successful. It is recommended that fishing effort be further increased in both these lakes and records be kept to note any tendency towards over-exploitation.

A Preliminary survey of 21 Ceylon lakes. 2. Limnology and fish production potential

Some morphometric, physical and chemical conditions of 21 lakes in Ceylon are described. The values for the organic matter in the plankton and for the dry weight of bottom fauna in the lakes have been calculated. These values have been utilised to evaluate the potential fish production figures for the lakes. Fishing trials were made in each lake. Suggestions regarding mesh sizes and time of fishing are put forward.