جستجوی مقالات مرتبط با کلیدواژه "زیست شناسی تولیدمثل" در نشریات گروه "زیست شناسی"

The Sefidrud stone loach/Berg loach, Oxynoemacheilus bergianus, is native to the Eurasia and little is known about this species. Some biological characteristics of the species were examined in 358 specimens collected monthly from the Kordan River in Alborz Province, by dip and seine nets during September 2013 to August 2014. The total length range was 32.36-74.36mm (50.95±10.3SD), and the total weight range was 0.31-4.06g (1/12±0.68SD). The maximum age of the specimens, based on otoliths, was 5+ years for females and 4+ years for males. Based on macroscopic gonad observation, the age of maturity was 2+ for females and 1+ for males. Sex ratio was 1M:0.9F and maturation cycle consisted of five stages. The gonadosomatic index indicated that reproduction of the fish in the river system occurred between March and June, with the highest average value of 9.47 for males in April and 13.42 for females in May. Oocyte diameter ranged from 0.15 to 1.33mm, with a mean value of 0.44mm. Absolute fecundity ranged between 360 and 2560 eggs, with a mean of 1130±670 eggs. Absolute fecundity and total length (r2 = 0.58) and total weight (r2 = 0.66) were moderately correlated. The mean relative fecundity was 580±190 eggs per gram of body weight. Therefore, O. bergianus is a species with a premature sexual maturity, high fecundity than that of other loaches and reproduction happen gradually in March to June.

Some aspects of reproductive biology of Capoeta razii, an endemic cyprinid species from the Sefid River in the southern Caspian Sea basin, were studied by monthly sampling throughout a year. Age, growth, sex ratio, spawning season, fecundity, gonado-somatic, modified gonado-somatic and Dobriyal indices were estimated. The sex ratio (F: M) was obtained as 1.00:2.63, and the percentage of males was greater than females. The mature males and females were longer than 88 and 148 mm in total length, and 1+ and 2+ in age, respectively. The spawning of C. razii took place from late May to late August when the water temperature was between 19.7 and 22.8◦C. At the beginning of the reproduction period, the average gonado-somatic index values were 10.0% ranging from 4.03% to 15.90% in ripe females. The estimated gonadal indices showed that the ripe males were ready to spawn earlier than females. The average egg diameter was 0.99±0.65, ranging from 0.2 to 2.3 mm. The averages absolute and relative fecundity were 4386±2174 and 66.3±37.8, respectively. The absolute fecundity was significantly related to body weight and gonad weight.