Induced Spawning, Fertilization Rate and Hatching Rate of Brill, Scophthalmus rhombus

Abstract

An experiment was performed to obtain ovulation in female brill, Scophthalmus rhombus, to fertilise the oocytes, to describe the hatching rate and to assess their potential for aquaculture development. Broodfish were captured between 6 to10 meters depths by the gill nets then transported to a commercial hatchery in Çanakkale, in the northwest cost of Turkey, where the experimental trials took place. The females (31 specimen) weighed between 498 and 1620 g and the males (25 specimen) between 218 and 644 g.The Broodfish were divided into two groups and treated with: a) a saline injection (control group), b) single injections of luteinizing hormone-releasing hormone analog (LHRH-a; single injection: 25 µg kg-1, induced group). Females successfully ovulated with a hormone dose of 25 μg kg-1. The eggs and the sperm were obtained by hand-stripping and then fertilized artificially. Mean egg fertilization varied between 1.0 % and 21.2 % in control groups and 12.5 % and 37.5 % in induced groups, where hatching ranged from 0 % to 6.82 % in control group and 8.7 % to 46.2 % in the induced group. Hatching occurred approximately 110-115 h after fertilization at 14 ± 1°C. There were significant differences in the fertilization and hatching rates between the hormone induced and the control group (p<0.05, Pearson’s and Yates’ χ2 test, respectively)

Keywords

• The brill, Scophthalmus rhombus, induced spawning, fertilisation, hatching