A Preliminary Studies on Fish Production in Relation of Primary Production of the Western Coastal Waters in Sri Lanka

Abstract

The present study deals with an account of the results of an investigation on plankton primary production using Oxygen technique in the coastal waters of the western coast in Sri Lanka. Magnitude of primary production and its monthly variations were studied. Factors governing the primary production such as; transparency of water, temperature, phytoplankton density, and dissolved nutrient concentration, their variation in time have discussed and an attempt has been made to relate these parameters with primary production. Mean photosynthetic rate measured over the continental shelf of west coast was 0.944 g Cm2 dol.This would amount to an annual gross production of344.0 g C m+Depth integrated total primary production from the continental shelf of west coast for an area of 1050 km2 was 361830 tones. The present fish yield from the same area is around 2000 tones (200 tones in terms of Carbon), which is only 0.06 percent the Carbon produced by primary production. Compare to intensely exploited waters where, 0.2- 0.3 percent of the primary production is harvest as fish, potential harvest from the western shelf waters would be 31/2 to 5 1/2 times the present yield.