en Stock assessment Stock assessment پژوهشي Orginal research papers <p>  </p><p>  The length-weight relationship, age, growth parameters, sex ratio, mortality and exploitation rate of <i>Salmo trutta fario </i>were determined in Lar dam. The sex ratio (male: female) was 1:1.84 which differed significantly from the expected 1:1. The length-weight regression was (females) and (males) indicating a negative allometric growth for both sexes. Growth parameters were estimated as <i>L</i>_∞ = 45.0 cm, <i>K</i> = 0.27 yr^-1, <i>t</i>₀= -0.23 yr. The instantaneous coefficients of natural, total and fishing mortality were estimated as 0.40 yr^-1, 0.75 yr^-1 and 0.35 yr^-1. The results showed that <i>S. trutta fario</i> is moderately a rapidly-growing species in Lar dam. The exploitation rate was 0.47. Therefore, the population appeared to be in good condition in 2004. </p> Salmo trutta fario, growth parameters, exploitation rate, Lar Dam 47 37 http://jifro.ir/browse.php?a_code=A-10-1-135&slc_lang=en&sid=1 H. Fazli hn_fazli@yahoo.com 10031947532846002743 10031947532846002743 Yes H. Azari 10031947532846002744 10031947532846002744 No M. Moghim 10031947532846002745 10031947532846002745 No D. Kor 10031947532846002746 10031947532846002746 No E. Nabavi Jelodar 10031947532846002747 10031947532846002747 No H. Taleshian 10031947532846002748 10031947532846002748 No