Age determination and growth studies of Gerres oyena (Forsk) in the Arabian Gulf waters

Age determination and annual increases in both length and weight was made for Gerres oyena (Forsk) by the examination and measurements of scales. A linear relationship between the body length and the anterior radius of scale has been established with an intercept of 1.942 cm on the length axis. The annuli first appeared on the scales in April and the mean monthly growth increased progressively from April till October when maximum growth was recorded. It was also noticed that, there was a good relation between the annuli formation and water temperature. The annuli were formed on the scales at a water temperature range of 21 to 26 degrees C. The length-weight relationships was estimated and given by the equation: W=0.00812 L3.13. The condition factor, K for the different size groups ranged between 0.72 and 0.88 and increased with length. Characteristics of scales, beside the time of annulus formation and its validity as a year mark have been discussed