Length-frequency data on Saurida elongata and S. undosquamis (Synodontidae) from bottom trawl survey conducted in 1984 in the Southern Gulf of Thailand were analyzed using the Compleat ELEFAN software. The seasonal pattern of recruitment suggests two uneven pulses per year, one stronger than the other. Yield-per-recruit analyses suggested that the investigated stocks are presently overexploited. Possible sources of bias for the analyses presented here are discussed.