Population dynamics of Barbus grypus (Heckel, 1843) and Barbus barbulus (Heckel, 1847) in Karoon River, south-west Iran

Barbus sp. fish samples were collected during November 2007 to October 2008 from five landing stations in Karoon River: Gotvand, Shoshtar, Molasani, Ahwaz, and Darkhoin. During one year of study, more than 2000 specimens of B. grypus and B. barbulus were measured, mean±SD length values for this species were 37.94±8.18 and 43.62±10.27, respectively and maximum and minimum total length were 20-76cm and 20-94cm, respectively. Mean±SD of weight values for this species were 873.2±1092.45 grams and 778.59±725.97 grams, respectively and maximum and minimum weight were 52-11170 grams and 52-4675 grams, respectively. Growth and mortality parameters were calculated for B. grypus and B. barbulus as L∞: 86.64, 132.9 and K: 0.27, 0.17 and t0: -0.46, -0.66, M: 0.50, 0.33, F: 1.22, 1.04, Z: 1.72, 2.72, 'Ф: 3.31, 3.48, E: 0.71, 0.76, respectively. According to the exploitation coefficient, B. grypus and B. barbulus stocks are overfished hence we suggest a decrease in exploitation coefficient. Based on results and their comparison with the American Fisheries Society (AFS) indices, these species are classified in moderate to high vulnerable group fishes.