Some Biological Characteristics of the Brown Trout Salmo trutta fario (Linnaeus, 1758) in Tonekabon River

Document Type : Research Paper

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Abstract

This research has been conducted in Tonekabon River in 1996. 190 fish samples were take from diferent age groups of 0+ , 1+ , 2+ , 3+ ,4+ . Results indicated that the most highest and lowest abondant were %63, %5.7 in Dohezar and intersection of Dohezar and Cehezar respectively. Maximum body length and weight were 175mm and 84.5g in Dohezar respectively. Mimimum body length and weight were 27mm and 0.39 g in Cehezar, respectively. Highest abundant belonged to 2 years age group with 112.3mm average length. Sex ratio was 1:1.4 (female to male). Condition factor of male and female were almost equal (1.268 and 1.257 respectively). Highest feeding intensity was in spring and the lowest was in autumn. Main preys were Simulium, Plecoptera and Ephemeroptera. Growth was positive alometric. Absolute fecundity ranged between 168-379 with an average of 268 eggs .

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