On the life history of spirlin Alburnoides bipunctatus (Bloch, 1782) in the qanat of Uzineh, northern Iran


Abstract: Within the wide distribution of spirlin in Iran, populations of this species inhabit a great variety of habitats, including qanats. We hypothesized that qanats may contribute to habitat-specific variation in the life history of the fish. To test this, a total of 240 specimens of Alburnoides bipunctatus, caught in the qanat of Uzineh (northern Iran) from October 2007 to August 2008, were examined for life history attributes. The population had a 5-year life cycle. The weight-length relationship (WLR) was estimated as W = 0.0068TL^{3.2559} for males, W = 0.0079TL^{3.2067} for females, and W = 0.0072TL^{3.2387} for the population, having a positive allometric growth in all considered groups. The von Bertalanffy growth function (VBGF), fit to back-calculated size at age data, were: L_t = 14.07(1 - e^{-0.27(t + 0.92)}), L_t = 15.37(1 - e^{-0.23(t + 1.08)}), and L_t = 14.83(1 - e^{-0.24(t + 1.04)}) for males, females, and the population, respectively. The sex ratio was not significantly different from parity. The reproductive season, evaluated from the gonadosomatic index (GSI), extended from April to August, with 3 peaks in April, June, and August for females and 2 peaks in April and June for males. The absolute fecundity ranged between 234 and 7728 eggs with a mean of 1407 eggs. The relative fecundity ranged from 60 to 550 eggs g^{-1}, with a mean value of 255 eggs g^{-1}. The oocytes ranged in diameter from 0.50 to 1.70 mm with a mean value of 1.06 mm. Comparison of these results with those previously reported in the literature implies that the life history of the species is variable. This variability may be interpreted as phenotypic plasticity and respond to habitat characteristics to improve fitness locally.

Keywords: Alburnoides bipunctatus, age, growth, reproduction, qanat, Iran

Full Text: PDF