Growth and mortality of brown trout, Salmo trutta fario in Lar dam, Iran

    The length-weight relationship, age, growth parameters, sex ratio, mortality and exploitation rate of Salmo trutta fario were determined in Lar dam. The sex ratio (male: female) was ۱:۱.۸۴ which differed significantly from the expected ۱:۱. The length-weight regression was (females) and (males) indicating a negative allometric growth for both sexes. Growth parameters were estimated as L∞ = ۴۵.۰ cm, K = ۰.۲۷ yr-۱, t۰ = -۰.۲۳ yr. The instantaneous coefficients of natural, total and fishing mortality were estimated as ۰.۴۰ yr-۱, ۰.۷۵ yr-۱ and ۰.۳۵ yr-۱. The results showed that S. trutta fario is moderately a rapidly-growing species in Lar dam. The exploitation rate was ۰.۴۷. Therefore, the population appeared to be in good condition in ۲۰۰۴.