Digital method for the frogs fertility assessment in the common frog (Rana temporaria)

The convenient modern way of frog fertility assessment is offered. A spawn clutch taken from a breeding pond was placed into the device of the original design made of glass. After photography and the conversion of an image into black-and-white, the file with the image of the spawn clutch was imported into the vector graphic editor CorelDRAW X6. After such procedures as i) increasing the brightness and visibility, ii) tracing by a contour, and iii) flattening the rate of itemization, the number of ova was received as a number of limited vector objects in the "Curves" division. The number of ova in 49 spawn clutches of Rana temporaria was counted in three different ways. These were direct counting, the offered assessment method by the vector graphic editor, and bulk sampling method. Statistical analysis of the results of the three quantitative methods is given. The proposed method allows determining the fertility of tailless amphibians on a large number of spawn clutches with minimal time and sufficient accuracy. At that the integrity of clutches is not broken and mucous membranes are not damaged.