CRAYFISH (PROCAMBARUS-CLARKII) CONDITION THROUGHOUT THE YEAR IN THE LOWER MONDEGO RIVER VALLEY, PORTUGAL

A study was performed to document the seasonality of crayfish (Procamb arus clarkii) condition in the lower Mondego River valley, relating it to sex and to reproductive state. Two sampling programs were carried out, and Fulton's condition factor was determined for individual crayf ish. The first sampling program was performed from June 1992 to Januar y 1993 and the second from May 1993 to September 1994. Twenty-five bai ted traps were set overnight, spaced 5 m apart. In 1992-93 a total of 337 crayfish were captured, average post orbital carapace length (POCL ) 3.19 cm, average weight 17.18 g and average condition factor 0.49. I n 1993-94, 2149 crayfish were captured, average POCL 2.94 cm, average weight 15.39 g and average condition factor 0.54. Reproductively activ e (Form I) males were abundant from May to October. The average condit ion factor was dependent on sex and reproductive state, but the season al pattern of variation was similar for females, for all males, for re productive males (Form I) and for non-reproductive males (Form II). Fo rm II males had the lowest average condition factor. Form I males had the highest average condition factor. From December to May there was a gradual decrease in condition, ending as a steep decrease. This may b e explained by a mass moulting to reproductive forms. A postreproducti ve decrease in condition was observed in September and October. Our da ta corroborate the idea that there is a relation between male conditio n and reproductive activity.