GROWTH AND REPRODUCTIVE BIOLOGY OF PALAEMON XIPHIAS RISSO, 1816 (DECAPODA: CARIDEA: PALAEMONIDAE)

Aspects of growth and reproductive cycle of the prawn Palaemon xiphias were studied in Alfacs Bay (Ebro delta, Spain) from December 1989 to December 1990. Growth is continuous throughout the year. Adult females are larger than males. Sexual differences related to length-weight were noted. Longevity was estimated to be 14-17 months. The growth equation estimated for males is: L, = 50[1 - exp{–1.57(t + 0.31) - ((0.45)(1.57)/ 2π)sin(2π(t – 0.9))}] and for females L, = 70[1 - exp{–1.92(t + 0.15)((0.6)(1.92)/2π)sin(2π(t - 0.9))}], where L, is length (mm) at age t (in units of years). Ovigerous females were recorded between April and October. They were most numerous in May and June. Some of the early specimens appearing in the benthic population in summer had already spawned at the end of the reproductive period. The number of spawnings by a single female was a minimum of two. The number of eggs (range: 318-2,750) carried by females was related to their size: y = 0.000727x3.5868; r = 0.91752; N = 30, where y = egg number and x = total female length (mm).