Fishery and biology of Sardinella gibbosa was studied on material collected during
the period March 1979 to December 1980 from gill net fishery in Negombo. There
was a 100% increase in fishing effort from 1970 to 1980 and this has resulted in a
drop in catch per unit effort. Total production of S. gibbosa has also dropped from
503 MT in 1979 to 302 MT in 1980. Length weight relationship for Indeterminates,
males and females were found to be significantly different from one another. The sex
ratio was 1:1 and there was no seasonal trend in sex composition. The parameters of
the Von Bertalanffy’s growth equation for S. gibbosa were L = 17.0 cm, K = 2.2 (year)
and t0 = 0.082 (year). The total mortality (Z) was 10.2 and a high exploitation rate of
0.66 was observed. • There seem to be two recruitments per year. One spawning
period extending from April, May to September was indicated.