Length - weight relationship and condition factor of Phycis phycis (Linnaeus, 1766) and Phycis blennoides (Brunnich, 1768) [Actinopterygii, Gadiform, Phycidae] in the gulf of Tunis

Abstract

In our study length-weight relationship are presented for 213 Phycis phycis and 270 Phycis blennoides caught between September 2007 and August 2008 and collected from trawler fishing in the Gulf of Tunis. The lengthweight relationships and the condition factor were computed separately for sexes and for different seasons. The parameters of the length-weight relationship for the population as a whole are all well correlated (r super(2)0.92, p < 0.001). The type of growth is isometric for P. phycis while it is majorant allometry for P. blennoides. The comparison of the regression of the weight according to the total length of males and females, of the two species, shows that the growth is therefore identical. The study of seasonal variations indicates that the slope did not differ significantly (p > 0.05) between seasons for P. phycis. However, it differs significantly (p < 0.05) for P. blennoides; during the summer season, autumn and winter, where the growth is isometric; however in the spring it presents a majorant allometry. The condition factor was calculated according to sex and months and confirmed respectively these results