Abstract: Biological characteristics of P. elegans were studied in the coastal water of the Sinop from November 2002 to July 2004. The density low in winter, followed by a general increase as seasonal fluctuation of population density indicated summer and autumn. A cohort of small prawn was identified in May. The largest female measured 69 mm while the corresponding value for males was 60 mm. The proportion of ovigerous adults rose during springs to peak about July the fell to zero by October and ovigerous prawn were taken in six months of the year. A multiple regression of DGR (equation) on temperature and starting length was produced and the growth of juvenile prawn calculated. Females of P. elegans outnumbered males in all months in the study period.