Induced spawning in bream, Abramis brama (L.), using carp and bream pituitary extract and hCG

Induced spawning in bream, Abramis brama (L), was studied using acetone‐dried common carp pituitary (CP) and bream pituitary (BP) with or without the addition of human chorionic gonadotrophin (hCG). The total dose administered to fish was of 5.0 mg kg−1 BP or 4.0 mg kg−1 CP with or without 2000‐2200 IU hCG kg−1 for females and 2.5 mg kg−1 BP or 2.0 mg kg−1 CP with or without 1000–1100 IU HCG kg−1 for males. In all male treated groups 100% of spermiation was observed: in females the most effective method was a triple injection with hCG and carp pituitary, resulting in 79% of females ovulated (over 68% of eyed eggs). Biological quality of eggs, expressed as a percentage of eyed eggs, was negatively correlated with time elapsing between resolving (final) injection and ovulation. Spawning success, expressed as a value of Se (spawning effectiveness coefficient), was higher in fish treated with triple injection.