Reproductive biology of the invasive sharpbelly, Hemiculter leucisculus (Basilewsky, 1855), from the southern Caspian Sea basin

Abstract

The sharpbelly, Hemiculter leucisculus , an invasive species, has expanded its range throughout much of Asia and into the Middle East. However, little is known of its reproductive information regarding spawning pattern and season that could possibly explain its success as an invasive species. This research is the first presentation of its reproductive characteristics, which was conducted based on 235 individuals collected monthly throughout a year from Sefid River, in the southern Caspian Sea basin. Age, sex ratio, fecundity, oocytes diameter and gonado-somatic index were calculated. Regression analyses were used to find relations among fecundity and fish size, gonad weight (Wg) and age. The mature males and females were longer than 93.0 and 99.7mm in total length, respectively (+1 in age). The average egg diameter ranged from 0.4mm (April) to 1.1mm (August). Spawning took place in August, when the water temperature was 23 to 26°C. Average gonado-somatic index values for females at the beginning of the reproduction period (March) and in ripe mature spawning females (August) were 2.90% and 16.97%, respectively. The averages of absolute and relative fecundities were 19978.6 and 607.1 eggs, respectively. The absolute fecundity was significantly related to body weight, ovary weight and age. A potentially high reproductive capacity, comparatively small eggs, short time of eggs’ development, fast sexual maturation, short life span, tolerance to a wide range of environmental conditions, all promote the invasion of this invasive sharpbelly in freshwater ecosystems of the temperate climate zone.