Investigation of Some Biological Characteristics of the Silver Crucian Carp, Carassius gibelio (Bloch 1782) Population in Lake Eğirdir


Abstract: Biological characteristics such as sex, age and length compositions, growth, condition factor, reproduction, mortality and exploitation rates of the silver crucian carp, Carassius gibelio (Bloch 1782), population in Lake Eğirdir were investigated between March 2001 and February 2002. According to the 616 specimens ranged in age groups from I to VI, the percentages of male and female individuals in the population were 53.4% and 46.6%, respectively. The fork lengths of the samples ranged from 9 to 33 cm. Allometric growth was also determined among the lengths and weights of both sexes. Incremental growth rates in length and weight for both males and females showed a significant decrease after the age of 2. It was estimated that females had higher L{\infinity}o (L{\infinity}o = 34.2 cm) and lower K (K = 0.316) values than males (L{\infinity}o = 29.5 cm and K = 0.470). Mean condition factors of males, females and the combined sexes were calculated as 2.401, 2.594 and 2.498, respectively. It was determined that the condition factor of both males and females increased with fish size. First maturity length (L_m) was estimated at 9.7 cm for males and 10.3 cm for females. The most intensive period for reproduction was from April to July, although reproduction lasted until August. Total (Z), natural (M) and fishing mortality (F) and exploitation (E) rates were estimated at Z = 1.01 year^{-1}, M = 0.63 year^{-1}, F = 0.38 year^{-1} and E = 0.38, respectively.

Keywords: Lake Eğirdir, silver crucian carp, Carassius gibelio, population structure, growth, condition factor, reproduction, mortality and exploitation

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