Age and growth of Cobitis paludica in the Lozoya River (Central Spain)

Age and growth patterns of C. paludica was examined in the River Lozoya (Ce ntral Spain) where permanent water in main river channel is restricted to s mall isolated ponds. The maximum observed lengths were 83 mm in females and 57 mm in males. The population of C. paludica was represented by six age g roups, i. e. from 0+ to 5+. Large differences in life-span between sexes we re observed, e.g. the oldest female was in age 5+ and male in age 3+. Age v alidation was made by analysis of length frequency diagrams using Bhattacha rya's method, followed by the modal class progression analysis. The most li kely solution consisted of 6 age groups with separation index values greate r than 2. The explained distribution was significantly different from the o bserved distribution (chi (2) = 52.861, df = 9, P<0.001 for females and <ch i>(2) = 73.391, df = 6, P < 0.001 for males). The von Bertalanffy equations that defines growth pattern were: L-<iota> = 91.78[1-e(-0.239(l+1.246))] ( r(2) = 0.804) for females and L-iota = 59.3[1-e(-0.68---+0.616))] (r(2)=0.7 22) for males. The weight - length relationship calculated for each sample occasion showed no differences in slope between sexes.